Ray's 1987 944 LS1 Build & Swap

Having built these cars ranging from 1984 to 1989, I have never used the blue wire. Typically I was buying 1-wire alternators, but found that wasn't needed. The standalone harnesses have the single trigger wire needed to excite the alternator.

This effort is widely known as a simple DIY task that many before me have documented.  I used most of that advice, improvised a bit, and added some relevant quality photos.
(Did I ever mention photography is a hobby of mine??)

The following is how I got it done.

First, I had to round up my replacement seals and the necessary tools.

The seals where purchased from 944Online as part of a TA Seal Replacement Kit.  Of course, you can buy them separately as well.
MT Output Shaft Seal, Elring brand - PN: 016 409 399B   ~$4.00 EA.

The seal puller is made by Pittsburgh Tool (China) which I picked up at my local Advance Auto for about $15.

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<Seals Being Replaced>

Each stub axle flange is secured with one M8 x 1.25 x 87mm, bevel head “screw” (as Porsche lists it) and is removed using a 6mm Allen Head socket.  Metric Allen head bolts/screws are generally Grade 12.9.
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<TA Seal, O-rings, and Cooling Tube Looms>                    <Standard “hawk beak” Seal Puller>                            

Driver’s Side Seal Replacement

Once again, cleanup of all bolt threads and head engagement shapes is essential.  I used my homemade M8 x1.25 thread cleaner bolt to clear the treaded holes in the flange for the axle shaft CV Joint bolts.  A power drill/driver makes multiple passes almost effortless.  I was a bit surprised at how much debris I removed.  All clean now!!  
For the Allen head socket of the axle flange screw, my small flat blade screwdriver did the job.

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<Cleaning Stub Axle Flange Threads>                 <Unexpected Thread Debris>

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< M8 Stub Axle Flange Bolt (Screw)>                              <Axle Flange Bolt Removal>            

To remove the flange bolt, the flange must be immobilized.  I used two spare M8 bolts that were long enough (about 25-30 mm) to thread fully into the flange and still have enough extension to engage a large screw driver or pry bar.  Because the flange bolt is not particularly tight (31 lb-ft spec), I was able to immobilize the screw driver by hand.  If need be, it could easily be braced against an obstruction.

After removal of the flange bolt, I used some blue masking tape to mark the original position of the flange relative to the case.  I did this as a precaution but in hind sight it was probably unnecessary.

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<Stub Axle Flange Removal>                             <Measuring Original Seal Depth – ~6.25mm>

The next task was to measure the insertion depth of the existing seal.  This will be needed when installing the new seal because there is no seal stop on the DS of the TA case housing.  Mine measured 6.25 mm.  I understand Porsche makes a relatively inexpensive seal installation tool to ensure proper depth and alignment.  

Next, I proceeded to remove the old seal.  Use caution to prevent dirt or debris from entering the TA case. The longer side of my seal puller, which has more of a curved “beak,” worked well, facilitating proper positioning of the beak under the seal while at the same time placing the fulcrum of the tool on the beveled edge of seal housing (white arrow).  The beak must be positioned under the seal between the inner seal lip surface and the outer “shell.” This engages the metal core of the seal and avoids scarring the smooth surface of the housing.  Once positioned properly, a mild bump (or two) on the tool handle and the seal will pop right out.  Note: If you have trouble pulling the seal, something is wrong.  Reevaluate your seal tool positioning and try again.

Caution: Lift the old DS seal at the 3 o’clock position (tail end) to avoid accidental contact of the hawk beak with the speed sensor gear which is located at the 9 o’clock position (front end). (See Photo at the end of this post.)

Following removal, I cleaned up the housing in preparation for the new seal and noticed a scar in the housing. Pretty sure I didn’t do it so I suspect it happened during a previous seal change (yellow arrow). Other than that, the seal case surface was in good shape.

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<Seal Removal>                                                   <Nick in Seal Race>

Part of the recommended new seal preparation was to pack it with grease to help retain the spring wire under the seal lip. I used AMSOIL synthetic bearing lube which is OK because my TA is non-LSD (5P).  If you have an LSD TA, the forum experts say the grease must be free of MoS2 (molybdenum disulfide).  
Apparently, Moly additives don’t play nice with Porsche OEM LSD clutch packs.

To address my housing nick, I applied some Permatex Permashield in the nick, and a thin coat on the perimeter ribs of the seal.  Permashield is a non-hardening sealant which acts like a lubricant as well.

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<New Axle Seal>                                                  <Seal Prep with Bearing Grease and Sealant>

To install the seal properly, it must remain radial with the axle shaft and case housing.  Once set in position (by hand), it can be driven in with any flat surfaced cylindrical object that is approximately 50-55 mm in diameter.  A 2-inch OD exhaust pipe adapter and a rubber mallet worked well for me.   Not much force is needed and slow and steady is best.  Check the insertion depth in all 4 quadrants as you go.  Make adjustments as needed to keep the seal radial.

Check the axle shaft for a wear grove from the old seal.  If there is none, install the new seal at the original depth.  If there is a slight wear grove, adjust the seal depth position about 0.5mm +/- so the seal lip contacts a pristine section of the axle shaft.  Shafts with more than slight damage will require replacement.

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<New Seal Installation>                                             <Checking the New Seal Depth – 6.25mm>

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<Synthetic Grease on the Axle Shaft>                      <Flange Bolt Installation - 31 lb-ft>

Before reinstalling the axle shaft flange, I applied a thin coat of synthetic grease on all contact surfaces. I used the blue tape reference points to install the flange exactly as it came out.  Finally, I used Permatex blue threadlocker on the flange bolt and tightened it to 31 lb-ft as per Porsche specs.

Passenger’s Side Seal Replacement

The PS axle seal is replaced in the same fashion with one exception.  Unlike the DS, the case housing has a seal “seat” (green arrow) to prevent over insertion.  At full insertion, the seal measured 7.8 mm from the housing surface.

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<PS Case Seal Seat>                                                 <DS Speed Sensor Gear @ 9:00>

Next Step….  Removing the Rear Case Section

Raymond-P wrote:
So….while under the dash, I progressively drilled out the clevis pin hole until it fit over the pedal post.  This was challenging but after 4 incremental attempts, I’m happy to report the required hole diameter is 9/32”!

connected my throttle cable this last weekend and shoulder drilled to 9/32 on the bench vise.
did not slip over the pedal. I think it needs an extra 32nd so i'd recommend 5/16".

also on my end instead of the speed nut i used a 1/16 pilot bit on the nubbin of the porsche pedal and then went to a 3/32 bit so i could push the cotter pin through. Note, if you go this route, gravity will work against you in trying to insert from the bottom (easiest and up towards the firewall) as it will just fall back out. you need to make a tiny bump in the center of the cotter pin but keep the tips flat so you can still push it through the hole. The bump will give some resistance so gravity doesn't win, after that you just grit your teeth and take some pain with bending the ends of the cotter pin back around the shaft of the pedal since it will be even more of a challenge to get pliers in there at least it was for me cause i am too lazy to remove my steering wheel or the seat. back and arms are pretty sore today.
lol

With new axle shaft seals in place, I was finally ready to do the 5th gear swap.  From the procedures I’ve read, this is not particularly difficult but there are a few challenges.  My resources included:
Greg Sloan’s 944 V8 Conversion Manual - 944 Transaxle 5th Gear Swap
(This can be found in the Forum Wiki)
Rennlist – Gearbox Reinforcing Plate Installation
(The Forum Wiki also lists the article - Audi Transaxle Rear Case Reinforcement, however the link appears to be broken.)

The 1st challenge was acquiring the low ratio 5th Gear Set.  Lots of documentation can be found on how the early NA transaxle’s 5th gear sets and synchros are interchangeable with the later model Turbo transaxles.  Below are some source options that I gleaned from Clark’s Garage:
Transaxle - 016K
Transaxle Codes -  QM, 8Q, QL, 4M
Vehicle - 944 (83-85) NA
5th Gear Ratio - 0.7297
Gear Tooth Count - 37/27

By comparison…  below are the numbers for most of the remaining transaxles used in S and Turbo cars:
5th Gear Ratio - 0.829
Gear Tooth Count - 35/29

It took about 3 months but eventually, Dimi at Flying Horse Motorsport LLC found me a 944/951 “Super Long” 5th Gear Set that I believe was removed from an Audi transaxle.  
5th Gear Ratio - 0.684
Gear Tooth Count - 38/26
List Price - $350 (+ shipping & tax)

Dimi also fixed me up with gaskets and a new end cap seal (~$70).  PNs can be seen in the following photo:
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<0.684 5th Gear Set / Case Gaskets / Case End Seal>

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<TPC Case Reinforcement Plate>  

While I was waiting for Dimi to track down the gears, I prepared an active spreadsheet to compute vehicle speed with a 27/8 ring and pinion gear set (3.375 FDR) and various combinations of 5th gear ratios, wheels, and tires.  

The factory 0.829 5th gear set in my ’86 5P TA, with factory turbo 16” rims and P225x50 tires will get me down the road at 66 MPH @ 2500 RPM.
By comparison, the 0.684 5th gear set results in 64 MPH @ 2000 RPM.  

Normalizing these results, the RPM savings is about 425 RPM at 65 MPH. That works for me!!!  

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<Vehicle Speed Spreadsheet>

If you would like to run this spreadsheet with your vehicle combination, just PM me and I can send it to you or send me your tire, rim, and gear specs in the yellow and orange highlighted sections of D1 and E1 and I’ll run it for you.

So, in this Part 1, my objective was to remove the rear case and get it milled ¼” to accommodate the TPC steel reinforcement plate.  Below is the procedure I used.

Case End Cap Seal Removal - This is a rubber covered metal unit with no design mechanism for removal.  
1. Punch a clean hole in the seal about ½ way from the edge to the center. (I used a nail)
2. Turn in a 3/16” x ~1-1/4” long self-tapping hex head metal screw. (I used a ratchet)
3. Turn in the screw until just enough shaft remains exposed to grab it with ViseGrips and still fit a  
   large flat blade screw driver or pry bar under the ViseGrips.
4. Position your screw driver or pry bar against a raised section of the case and pry off the case end
   seal.  This will reveal the main shaft rear bearing retaining bolt.  I understand this may be standard
   hex head bolt in NA transaxles but in the Turbo units, the bolt is a unique hollow M17x1.0x17mm
   triple square bolt.

Main Shaft Retaining Bolt Removal – For a Turbo TA you will need a 12mm triple square
    socket.
1.  Insert the socket in the bolt and give it a sharp strike with a decent size steel hammer.  I used my
    16oz framing hammer.  This “shock” fractures the structure of any rust or other compound holding
    the two parts together and facilitates removal.
2.  Guidelines say you will likely need a GOOD impact gun to remove this bolt.  That is likely
    true. My Harbor Freight “Earthquake XT” impact gun with an advertised 700 lb-ft of torque didn’t
    cut it.  (Go figure!) Plan B required a ½” ratchet with a 24” floor jack handle extension, a large
    screwdriver and pry bar to lock the axle shafts, (both must be locked with a non-LSD TA) and my
    framing hammer.  
    Note, Plan B only works if you use happen to have your TA mounted to an engine
    stand.
3.  While applying nearly all my body weight to the end of the floor jack handle, I struck the handle
     sharply about 14 inches from the socket.  After the third strike…movement.  Woohoo!!
4.  Remove the bolt.  Mine did not turn easily and I had to use the jack handle and ratchet nearly 50%
    of the way.  Whatever thread locker the factory used really worked well!
5.  Remove the 7 – M8x1.25x44mm case bolts using a 6mm Allen head socket.
6.  Evenly pry the rear case section away from the adjacent iron center case section (just slightly).
     This will push the main shaft bearing outer race off the shaft.
7.  Carefully remove the thrust washer and the bearing outer race.  Inspect for damage/wear and set
     aside to be cleaned if OK.
8.  Remove the rear case.

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<Removing the Case End Seal>                          <Screw Placement in Case End Seal>

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<Triple Square Main Shaft Bearing Bolt>                 <HF Earthquake Impact Gun>                        

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<Immobilized Axle Shafts & Ratchet Set-up>    <M17 Triple Square Main Shaft Bearing Bolt>      

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<Shaft Bearing Outer Race & Washer>             <Exposed Stock 0.829 Turbo 5th Gear Set>
           
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<Inside of Rear Case Section>                         <Rear Case Milled ¼” and Cleaned>

With the rear case in hand, the first thing I noticed was a significant amount of particulate “debris” in the lower half.  Upon inspection, I could see there was also blasting media present!  There was evidence of a gasket breech in the top left area which would explain both conditions.

I brought the rear case to a local machine shop to have ¼” of material milled off the mating surface. After a week and a few days, the work was done.  Sean Domhoff at Domhoff Automotive Services in Fombell, PA did a great job as far as I could tell.  He also did a thorough job cleaning out all the old debris that was present in the case.  Total cost was $120 plus PA tax for 1 hour of set-up and machine time.

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<TPC Reinforcing Plate Test Fit>                           <Case Surface Flatness Test>

I test fit my TPC steel reinforcing plate on the end case and all mounting holes lined up perfectly.  In addition, I looked for gaps between the steel plate and the aluminum case to check for flatness.
All good!!  

Next Step….  5th Gear Swap and Reassembly

Okay folks....

In my last post, I mentioned how my blown rear case gasket allowed some road dirt into the case.  Even more concerning was the presence of my 70 grit glass bead blasting media.

Before I do the 5th gear swap, I feel a need to thoroughly flush the entire case.

I'm sure there are products on the market for this purpose but I was hoping some of you experienced forum members would share a tried and true recommendation.

TIA for your thoughts!! 

A resource I expected to be helpful was the Greg Sloan Manual description of the 5th gear swap.  To be frank however, it came up short for me.  Part of the problem was me not knowing the transmission terminology used and that was exacerbated by the inadequate photo support of the narrative.  Most concerning was the lack of detail provided in the actual process of the gear swap.  On the other hand, I understand that the write-up is probably more than adequate for the experienced Porsche transmission mechanic.

So… for the rest of us DIYers that will likely only do this once in our lifetime, I’ll do my best to provide a clear and comprehensive account of my experience.  Before I do however, I want to thank Bob at HotRodz of Dallas for schooling me on the finer points of Porsche transmission “play.”  He was just a text away whenever I got stuck or needed advice.  MANY THANKS BOB!!!!!!!

The first thing I needed (and wanted) to do was learn the names of the parts I was about to disassemble.  I used an online 1988 Porsche Parts Manual ’85-’88 exploded view and parts list to get up to speed.  

Some discrepancies I found included:
• Part 23 – “Four-Point Bearing” inner and outer bearing races are not shown.
• Part 25 – “Screw” for the main shaft end of a turbo TA is an M17x1.00x17mm Grade 12.9 Triple Square hollow bolt as noted in my previous post.
• Part 46 – “Clamping Screw” for the 5th gear is actually an M10x1.50x22mm Grade 8.8 hex bolt with an attached heavy washer.

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<Gear Box, 5th Gear, Exploded View>

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<Gear Box, 5th Gear - Parts Numbers and Descriptions>


Moving forward, when the Parts List was lacking, I assigned names as needed.  These included what I called the “Shifting Gear Hub” and the “Shift Fork Ring Gear.”  If you happen to know the proper name for these parts, please let me know so I can edit the text.

Step 1 – Remove the Inner Bearing Race, Clutch Hub, and Synchronizer Ring
As recommended, I stood the transaxle on end for the entire process.  A Harbor Freight hardwood dolly worked well and provided the ability to roll the TA out of the way when I wasn’t working on it.  Be careful not to tip it over!!

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<Stock 5th Gear Set – TA Upright>

The Inner Bearing race is pressed tight against the Clutch Hub.  Most likely, a “clamshell” type bearing remover is the tool of choice.  Unfortunately, I didn’t have one, so I followed Bob’s advice and used a “thin flat” chisel to separate the race from the Clutch Hub flange.  My weapon of choice was a wood chisel because it was soft steel, and the tapered / flat end design was perfect for this application.  With the tapered side up, I used light hammer taps in a radial pattern to increase the space between the race and the Clutch Hub flange.  I then used a 16” pry bar to gently pry the race completely off the main shaft.  Once again, I used a radial pattern when applying force to avoid binding.  Be sure to use the Clutch Hub flange as the fulcrum and not the Clutch Hub teeth.  Slow and steady works best here.  
I did not need or use any heat to perform this step.

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<Getting Started with a Wood Chisel>                     <Progressing with a Pry Bar>

With the Inner Bearing Race off, the Clutch Hub lifts off easily by hand, and the same for the Synchronizer Ring. This fully exposes the Circlip (Snap Ring) which is removed in Step 2. (See Green Arrow)

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<Inner Bearing Race Lift Off>                                            <Clutch Hub Lift Off>

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<Synchronizer Ring Lift Off>                                      <Fully Exposed Shifting Gear Assembly>

Step 2  - Remove the Shifting Gear Assembly
Case Preparation - In the previous photos you probably noticed bits of paper towel stuffed into the case section thru ports.  This is to prevent any small parts or debris from accidently falling into the adjacent gearbox case.  That would lead to a boatload of extra work that I don’t even what to think about!!!  It is highly recommended that you block these ports. Shop rags would do the job as well.

The Greg Sloan Manual procedure warns you about small parts flying about if you try to remove the Shifting Gear Assembly in pieces.  In the photo above, all the “small” pieces involved are labeled:
    Green Arrow – Circlip or Snap Ring
    Yellow Arrow – Wire Spring Retainer
    Red Arrow – Synchronizer Detents
The “large” pieces of the assembly are the Shifting Gear Hub (being replaced), and the Shift Fork Ring Gear.

The proper procedure is simultaneous removal of the entire Shifting Gear Assembly and the Shift Fork.  
First, I removed the Snap Ring with a pair of snap ring pliers.  You’ll need a decent pair that will hold the Snap Ring securely as you must navigate it over the exposed length of the main shaft.  
Next the Shift Fork must be disengaged from the Shift Rod by removing the Tensioning Sleeve which is essentially a split pin made from rolled spring steel.  Use the proper diameter drift chisel to drive the pin out. (DON’T LET THAT PIN FALL IN THE CASE!)

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<Removing the Snap Ring>                                  <Removing the Tensioning Sleeve>

With the Snap Ring and Tensioning Sleeve removed, the Shifting Gear Assembly and Shift Fork can now be lifted off the main shaft without incident.  While the Shifting Gear Assembly offers no resistance, the Shift Fork is a tight fit on the Shift Rod and needs a little persuasion.  With the Shift Rod fully extended, I used my 8 oz ball peen hammer to gently coax off the Shift Fork while simultaneously lifting off the Shifting Gear Assembly.   Once the Shift Fork is off the Shift Rod, the Shift Fork can be removed from the Shift Fork Ring Gear and the Shift Gear Assembly can safely be set aside for later disassembly. Nothing will come flying apart as long as the Wire Spring Retainers remain in place.

After the Shift Gear Assembly is removed, the caged halves of the Needle Bearing Set can be removed from the main shaft. There is a small Thrust Washer below the Needle Bearing Set that can also be removed if cleaning is needed.  I set everything aside for clean-up and additional disassembly.

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<Shifting Gear Assembly Removed>                  <Removal of Main Shaft Needle Bearing Set>

Step 3 - Removal of the Final Drive 5th Gear.  
I removed the 5th Gear Clamping Screw (M10x1.50x22mm Grade 8.8 hex bolt) with my impact gun.  Using the impact gun precluded locking the axles. The hex bolt has a heavy washer permanently installed just below the head.  It was clear that blue threadlocker was used in the prior installation.

A 2-arm 3” gear puller is the proper tool to remove the 0.82 Turbo 5th Gear.  The case is designed to accommodate a puller, but the puller arm jaws must be no more than 10mm in width.  Also, the jaws must be no more than 4mm in thickness (height) to fit under the gear.  My 4” gear puller was too big for the job when used as designed.  On the plus side, the puller arm claws were <10mm wide and about 3mm thick, so they fit under the gear.  The bad news is, I couldn’t use the puller arm connection links like normal.  The solution for me was to bolt the puller arms directly to the puller cross bar.  Not exactly the design configuration but the adaptation worked.

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<5th Gear “Clamping Screw” Removed>               <4” Gear Puller Adaptation>                        

It is important to be sure the puller arm claws are fully engaged under the gear.  For this operation, I used a 17mm ½” drive socket and a breaker bar to turn the puller shaft.  My approach was to tighten the tool and then give the shaft a couple hammer strikes, …rinse and repeat.  This worked to break loose the gear then I used my impact gun to finish the job.  Note: The case indents prevented the puller from rotating for the intial ½” +/- of pull, however once the puller arms clear the indents the axles must be locked.  My pry bar and a large flat blade screw driver were up to the task.

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<Puller Arm Claw Full Engagement>                       <Axle Lock Setup and ½” Breaker Bar>      

Removing the gear revealed Part 44 – Adjusting Shim.  There were no markings on the shim, but it measured 1.70mm thick which matches PN 16 311 391B.  This is undoubtedly the required gear alignment shim as determined by the factory, and answered my question regarding the placement depth of the replacement NA 5th gear…that would be “all the way.”  I also noticed the NA gear set has 2 small grooves in the teeth while the Turbo gear set has 3 small grooves.   It must be some secret German code (LOL)… I’m wondering what it really means, anyone know?

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<5th Gear Lift Off and Adjusting Shim>                    <NA Gear (Lt) and Turbo Gear (Rt)>

Below are all the components encountered so far.  Clockwise from the bottom left, they are:
    Needle Bearing Set
    Shifting Gear Assembly
    Inner Bearing Race
    Synchronizer Ring
    Clutch Hub
    Outer Bearing Race
    Heavy Cupped Washer
    Main Shaft Hollow Retainer Bolt
    5th Gear Final Drive
    Adjusting Shim 1.70mm
    Gear Retaining Bolt
    Snap Ring and Tensioning Sleeve – in the center.

All parts are ready for clean-up!

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<All the Pieces So Far – Uncleaned>

Step 4 - Disassembly of the Shifting Gear Assembly
Two Wire Spring Retainers hold the Detents in place which in turn hold the Shifting Gear Assembly together.  Refer to Step 1 where the top retainer is identified with a yellow arrow.  Not knowing exactly how everything goes together, I was really just winging it.
First, I set the assembly on a clean flat surface and removed the top Wire Spring Retainer by prying it out with a small flat blade screw driver, starting at the straight end.  That was simple enough, and once removed, the Shift Fork Ring Gear will come off, but I DID NOT remove it just yet.  I knew from the GS Manual there was a bottom Wire Spring Retainer as well but the exploded view doesn’t show you where it lives.  Without the Shift Fork Ring Gear in place, this spring would likely “launch” along with the 3 Detents, so the retainer should be removed first. I think this is the mistake some folks make the 1st time around.  

Next, I slid the Shift Fork Ring Gear up just enough to reveal the lower Wire Spring Retainer and removed it with a small screwdriver starting at the straight end.  It slips out under the Detents somewhat easily.  Remember the Shift Fork Ring Gear will come off if you push it too far.

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<Lower Wire Spring Retainer Revealed>            <Lower Wire Spring Retainer Removal>

With both Wire Spring Retainers removed, the Shift Fork Ring Gear can now be safely slid off the Shifting Gear Hub and the three Detents removed.  See Step 1 where the Detents are labeled with red arrows.  I was surprised to see how much crud had accumulated under each of the Detents.

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<Lift-off of the Shift Fork Ring Gear>              <Detent Removal – There are 3 Total>

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<Crud Build Up under the Detents>                      <Shifting Gear Assembly Components>

Step 5 - Gasket Surface Prep and General Cleaning
All parts involved are metal, so my generic brake cleaner safely did a great job of removing oxidized gear lube.  I used a brass wire wheel in my cordless drill as needed.

Porsche PTFE/Graphite Coating
When I began to clean the Synchronizer Ring, I was concerned at the amount of “carbon like build-up” that appeared to be on it.  I was expecting bright brass but soon learned that the black is a factory coating of PTFE Graphite and should remain.

“PTFE Graphite 10% combines the excellent chemical resistance, low coefficient of friction, and extreme temperature range of virgin PTFE with a graphite filler providing additional strength and stability. The filler produces a lower coefficient of friction making it a great wear choice for dynamic components.”  
Ref: Cope Plastics - [You must be registered and logged in to see this link.]

As I continued my cleaning effort, I found that the fork ends of the Shift Fork were also coated with PTFE Graphite.  Again, this coating should remain.

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<Synchronizer Ring w/PTFE Graphite>                 <Shift Fork w/PTFE Graphite>

For cleanup of the center case mating surface, the first order of business was to block or cover the case through ports to prevent gasket debris from finding its way into the center case section.  I used wads of paper towel again.  

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<Center Case Mating Surface – Before>               <Old Gasket Removal>

Next, I used my trusty wood chisel (by hand) to remove the factory paper gasket which was well attached.  
A little clean up with the wire wheel and all looked new again.  The new TPC steel reinforcement plate has been ready and waiting for well over a year and the surface of the milled end case section looked brand new.

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< Wire Wheel Cleaning>                                    <Center Case Mating Surface – After>

For proper torqueing of the case bolts, I cleaned all the threaded connection holes with my M8x1.25 tap and wire wheeled the threads of all the bolts.

As mentioned in Part 1, I sourced two new factory paper gaskets from Dimi at Flying Horse Motorsports, LLC [You must be registered and logged in to see this link.].  At the time of purchase, I asked about using gasket sealant. Having experience with TA rebuilds, and installation of the steel reinforcement plate, Dimi advised me that using sealant on the gasket surfaces was the proper approach. A good oil resistant RTV is recommended and my Permatex Fuel Resistant Permashield fits the bill.

General Reassembly
Assembly is generally the reverse order of breakdown but with the NA 0.684 5th gear stack and the TPC reinforcement plate. All other components are interchangeable, and everything should be “Spick and Span” for this step...not to mention your hands!

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<All Internal Parts - Clean>

Step 6 - Installation of the NA 5th Gear
After coating both sides of the 5th Gear Adjusting Shim with synthetic oil, I installed it over the output shaft and then carefully lined up the 5th Gear on the output shaft splines.  Then I set a 1-1/4” socket on the gear to distribute forces, stacked on my brass drift, and used my 8 oz. ball peen hammer to drive the gear fully into place.  The shim assures the gear is set properly.  No heat was needed or used in this procedure.

To lock it down, I put blue threadlocker on the retaining bolt and torqued it to 51 lb-ft.

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<Placing the 5th Gear Adjusting Shim>               <Installing the 5th Gear>

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< 5th Gear Installed>                                        <Torqueing the Retaining Bolt – 51 lb-ft>

Step 7 - Reassembly of the Shifting Gear Assembly.  
This is done in several sub-steps:
a) Place the Shifting Gear Hub on a clean flat surface.  (I did this at the dining room table!)
b) Orient the Shift Fork Ring Gear with the shorter machined surface facing down.
c) Align the Shift Fork Ring Gear matching the 3 ring gear tooth grooves with the 3 Detent slots in the Shifting Gear Hub, and then slide the Shift Fork Ring Gear on as far as it goes.

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<Shift Fork Ring Gear Tooth Grooves>             <Orientation of the Shift Fork Ring Gear>
     
d) Insert the 3 Detents into the Detent slots of the Shifting Gear Hub.  Be sure the flat side of each Detent faces outward.

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<Alignment of the Shift Fork Ring Gear>           <Placement of the Detents>

e) Install the top Wire Spring Retainer by inserting the bent end into one of the Detents to hold it, and then wrap it around to hold the other 2 Detents in place.
f) Carefully pull the Shift Fork Ring Gear up just until you hear a distinct “CLICK.”  No further.  The ring gear will be approximately flush with the top of the Shifting Gear Hub.

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<Top Retaining Wire Spring Installed>                 <Shift Fork Ring Gear Pulled Up>

g) Turn the assembly on its side exposing the lower portion of each Detent.
h) Install the bottom Wire Spring Retainer by hooking the bent end under one of the Detents not used by the bent end of the top retainer.  Wrap the bottom retainer around the Shifting Gear Hub using a flat blade screwdriver to press the wire under each of the remaining 2 Detents.

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<Lower Retaining Wire - Detent 1>                      < Lower Retaining Wire – Detent 2>

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< Lower Retaining Wire - Detent 3>                        <Synchronizer Alignment>

Step 8 - TPC Steel Reinforcement Plate
Once both Retaining Wire Springs are installed, the Shift Gear Assembly is ready to be installed on the main shaft.  However, the TPC Reinforcement Plate must be installed first.

To get started, I did a test fit of the TPC plate and it fit perfectly.  Then I wiped the case mating surface with brake cleaner to remove any oil and did the same for the TPC plate.  Next, I got one of my new case gaskets, coated both sides with Permatex Permashield and carefully placed it in position on the case. A thin uniform layer on each gasket surface is all that is needed.  Avoid excess sealant. This was followed immediately by placement of the TPC plate.

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<First Gasket in Place>                                         <TPC Reinforcement Plate in Place>

Step 9 - Installing the Shifting Gear Assembly
With the Shifting Gear Assembly upright and the Shifting Fork Ring Gear pushed down, I coated the Shift Fork with some synthetic oil and positioned the fork into the Shifting Fork Ring Gear.  The entire assembly is now ready to be placed on the main shaft.  First the bearing Thrust Washer must be installed and then the Bearing Set halves.  All should be coated with synthetic oil.
 
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<Thrust Washer Installed on Main Shaft>         <Bearing Set Installed>

The Shifting Gear Assembly and Shift Fork can now be set into place on the main shaft and shifting rod respectively.  As with removal, I had to gently tap the Shift Fork down the shifting rod with my ball peen hammer.   As it moves down, the gear set engages.

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<Shifting Gear Assembly and Shifting Fork>         <Initial Placement on Shifting Rod>

Once the Shift Fork hub and shifting rod holes align, the Tensioning Sleeve can be hammered into position.  With the Shifting Gear Assembly pushed down fully, the Snap Ring can be installed to hold it in place.

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< Alignment of the Shift Fork and Rod>             <Installing the Snap Ring>

The Synchronizer Ring can now be placed in the Shifting Gear Assembly, followed by the Shift Gear Hub. All parts should be well oiled.

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<Synchronizer Ring Installed>                                <Clutch Hub Installed>

With the Clutch Hub in place, the Inner Bearing Race can now be installed on the main shaft.  It’s a tight fit.  I used a socket and brass drift to gently hammer the race down against the flange of the Clutch Hub.

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<Installing the Inner Bearing Race>                      <Unexpected Gap>

I thought I was finished with the race and proceeded to prepare and set the second gasket.  On a whim, I moved the shift lever to see the effect on the Shifting Gear Assembly.  To my surprise, the main shaft gears dropped about 1/8 in. and I realized the inner Bearing Race was not completely seated.  A few more hammer blows and the problem was solved.

Step 10 – Rear Case Installation
With the second gasket already in place, I cleaned the mating surface of the rear case with brake cleaner, oiled up the ball bearing, and installed it.  I put blue threadlocker on each of the Allen Head case bolts, except the one that secures the oil cooling line retainer clamp (I’ll have to remove it later to install the Oil Cooler tube). All bolts were torqued in and alternating pattern to 18 lb-ft.

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<Rear Case in Place>                                            <Rear Case Installed>

Step 11 – Main Shaft Retainer Bolt & Rear Cover
The last mechanical step was to install the Main Shaft Retainer Bolt and Cupped Washer.  The Cupped Washer should be installed with the curve up to maintain a preload on the bearing when the Retainer Bolt is tightened. Blue Loctite should be applied to the bolt threads. This bolt is torqued to 110 lb-ft, which presented a challenge with the TA resting on a floor dolly.

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<Main Shaft Retainer Bolt & Cupped Washer>                            <Torqueing the Bolt>

As shown in the photo above, I used a ratchet strap to secure the TA to my tire stack and a 4x4 garage beam support post (green) that you can barely see.  The axle stops are also required for this step.  Next, I used my air wrench to drive on the Retainer Bolt.  My Earthquake XT Compact did the job this time because I replaced all my air line fittings with “High Flow” units and removed a restrictive inline water filter.  When I checked the torque with my Husky torque wrench, I had every bit of the prescribed 110 lb-ft and probably a bit more.

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<New Rear TA Cover>                                                  <Rear Cover Installation>

The final step in this adventure is placement of the Rear Cover.  The Rear Cover is a rather thick piece of sheet metal coated with a rubber compound.  The perimeter of the cover has multiple ribs in the coating to enhance a good seal.  I filled these ribs with Permatex Permashield and used a large homemade socket (from my Jeep days) and a mallet to drive the cover into place.  Be sure to keep the cover square with the case to prevent distorting the cover.  I drove the cover down until it was just a shade lower than the case lip.

While I had easy access, I replaced the O-rings for the oiler cooler line.  This is easy enough with a small hook pick but use caution not to let one fall inside the case.  Turns out my oil ports had a considerable amount dirt present…no wonder they leaked profusely!

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<O-Ring Part Number>                                        <O-Ring Removal>

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<New O-Ring Installed>            <Completed 5th Gear Swap & Reinforcement Plate Installation>

MISSION ACCOMPLISHED!!!!!

Compared to my last “novel,” this post is more like Cliff Notes!!

After getting the crossmember cleaned up and installing new Turbo axles, it was time to reinstall it in the car.  (The wife also wanted her side of the garage back!)  

This is a multi-person job (at least 2) because the crossmember must be perfectly aligned with the chassis mounting points.  The process involves constant adjustments side to side, up and down, and forward and back until all 6 mounting locations are aligned and fully in place.  I originally thought I could get a few bolts started by hand and then wrench the unit into position. Man was I wrong!

At each mounting location, connection bolts can not even be started until the crossmember is fully in position because none of the mounting locations independently align.

Once again, I used a Porsche Parts Manual V-Page to learn the proper parts nomenclature for a correct narrative.  Below is the exploded view of the crossmember.  I’ve marked it up to identify the parts in play, and the required bolt torque values as taken from LindsayRacing.
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<Crossmember Exploded View>

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<Rear Crossmember Prepared for Installation>

This is how I got it done:
The first step was to round up all the fasteners needed and get them cleaned up.  I had them bagged and labeled but somehow, I managed to lose the two M8 x 1.25 x 25mm hex head shoulder bolts and locking nuts that connect the Cross-Tube Strut to the chassis Supporting Mount.

I had no luck finding replacement steel locking nuts, and I don’t trust the nylon lock nuts I had on hand, so I opted for lock washers.  I picked up Grade 10.9 flange bolts, washers, lock washers, and hex nuts at my local Rural King which is my best hardware resource in a 25-mile radius.  The only caveat was their 25mm flange bolt did not have enough shoulder length.  The solution was to buy the 35mm flange bolt which did. I cut the length down to 25mm with my cutting wheel to achieve the necessary clearance between the rear shock.

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<Rural King “Black” Hardware Grade 10.9>                            <35mm Bolts Cut to 25mm>

Alert: Be sure that the bearing flange mounting locations are fully accessible and not blocked by lifting pads or jack stand arrangements.

Step 1: Move the Rear Suspension Under the car
I used a transmission jack centered under the cross-tube and secured it with the ratchet strap.  For balance and stability, I used my floor jack and a length of 2x4 to support the axle hubs and axle shafts.

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<Rear Suspension Installation Support>

Step 2: Align the Mounting Locations
This is the part where you need a helper (or 2).  Align the mounting points forward and back, and then side to side.  Then carefully rotate the rear cross-member about the horizontal axis of the car (IE axle line) until each mounting point on the cross-member is equidistant from its respective mounting location on the chassis.  Once the cross-member is properly aligned, slowly begin raising each supporting jack simultaneously.

Step 3: Remove the Ratchet Strap
While raising the cross-member, keep an eye on the space between the cross-tube and the chassis floor. You will need enough clearance here to remove the transmission jack ratchet assembly depending on your equipment.  I needed about 3 inches.

Step 3:  Raise the Crossmember into Place
Continue raising the crossmember guiding the bearing flanges into their mounts and simultaneously guiding the cross-tube struts into the slots in the frame mounting support.  Continue raising until all mounting points are fully in position.  This may take some persuasion of the cross-tube struts with a rubber mallet and/or micro adjustments of the bearing flange using a supplementary jack.  A large drift or the circular end of a pry bar will help align the bearing flange in its mount.

You will know all is properly aligned when you can start all the fasteners by hand.

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<Bearing Flange Positioning>                                 <Cross-Tube Strut Positioning>

I didn’t take a positioning photo of the frame supporting mount but as you can see in the photo below, the frame in this area is sloped and the bolts mount normal to the face of the frame.  This is a clear example of how the components must be fully in position before fasteners can be installed.

With all the fasteners started by hand, wrench tightening can take place followed by the proper torque application.  None of the connections are candidates for thread locker compound.

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<Cross-Tube Strut – Torque 17 lb-ft>                      <Frame Supporting Mount – Torque 34 lb-ft>

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<Completed Installation Passenger Side, Frame Mount Bolt Torque 34 lb-ft>

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<Completed Installation>

Note in the photo above that the shocks are not connected.  This is because I could not bring the mounting locations into alignment with the shocks, even with a jack under the trailing arms and the shocks fully extended.

I have it on good authority that more chassis weight is needed to sufficiently rotate the central torsion bar located inside the cross-tube.  I guess the shocks will have to wait until I install the transaxle!

Installing the Transaxle is next!!!

As I was preparing the transaxle for installation, I realized that I failed to reinstall the “protection plate.”  

Without understanding what this plate was, my 1st reaction was… what exactly does it do???  …and do I really need it?

After determining the official name of this plate as the protection plate, I started checking around regarding its purpose, and my research ended with correspondence from Kevin Gross, owner of Catellus Engineering, Inc.  http://www.catellusengineering.com/
Kevin is a reputable Porsche transaxle rebuild specialist in MA.  He advised me that factory Porsche training materials, indicate the plate protects the fuel tank from puncture during a rear-end collision.  The application is apparently used on late models with a plastic (polyethylene) fuel tank, apparently ’86 to ‘92.

CONCLUSION: Looks like the safe thing to do was install the plate.

In the photo below on the left, I set the plate in place behind the TPC steel reinforcement plate (yellow arrow) lining up the holes with the Allen bolts already in place.  It appeared to be a simple bolt on.

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<Protection Plate Set in Place>                                 <Bolt Through Driver’s Side Mounting Tab>

I removed the two rear case bolts used to mount the plate and then connected the driver’s side mounting tab of the protection plate.   In doing so, I noted that the protection plate must ride up over the TPC plate to be bolted tight.   No problem…yet.

When I got to the passenger side, it was evident the rear case contour of the protection plate was not compatible with the contour of the TPC plate and therefore the passenger side mounting tab would not line up.

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<Passenger Side Mounting Tab Misaligned>                   <Protection PL overlap in TPC PL – PS>

The fundamental issue is the larger perimeter TPC plate now occupies the space where the smaller perimeter of rear case has been milled off.  The protection plate is not contoured for the larger perimeter of the TPC plate.

Caution: You might think grinding the TPC plate to reduce its perimeter would solve the problem, but this would surely compromise the strengthening characteristics that it provides, and I would not recommend this.  

Although it is not apparent exactly why, the increasing positive performance record of the TPC plate is empirical evidence that the current design improves the viability of the 944 TA in higher HP applications.

The Solution:  My Rubber Mallet!!

This was a long shot, but it appeared that re-contouring the protection plate might do the trick. There were several perimeter gaps that supported this theory.  I started on the driver’s side with the mounting tab loosely tightened down, and used my rubber mallet to recontour the protection plate to match the TPC plate.  After about 10 minutes of massaging the metal, SUCCESS!!

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<Completed Installation – Rear View>                     <Covered TPC Plate – Front View>

It's a bit hard to see but the protection plate now fits like a glove and fully covers the TPC reinforcing plate.

Now on to the Transaxle install…

Awesome stuff raymond. i also had no clue what the hell that piece could possibly do. Thanks for digging that neat info up!

also interesting that yours didn't fit perfectly mine went on and lined up with the holes no problem but perhaps mine had been beaten up before when it was taken out of an abandoned new jersey car that Ian from 944online salvaged for me (5R TA with LSD vs. my old 944S unit AGP with bummed 2nd gear synchro).

Great advice to others on rubber mallet'ing it into shape!

The transaxle assembly (TA) connection to the Central Tube (Torque Tube) bell housing involved several small but important sub-activities that are best done before you get under the car.  They include:

1. Preparing the connection bolts
2. Preparing the drain and fill Screw Plugs
3. Installing the guide Dowel Sleeves
4. Test fitting the oil cooler Support bracket
5. Lubricating the Drive Shaft splines
6. Preparing the drives haft Clamping Sleeve
7. Connecting the Transmission Carrier (optional)
8. Installing the Shifting Rod Tube
9. Parking-Brake Cable placement

(Bolded part descriptions in this post are from the Porsche Parts Manual)

To get started, I mounted the transmission to my buddy’s transmission jack.  I’m sure you got a glimpse of it in my Protection Plate post. This time I made sure the jack was in the correct position under the transmission center of gravity and I used wood shims to make sure the mounting face was vertically plumb.  You want to get this right to minimize manual positioning while under the car.

Note that I positioned the jack screw drive towards the back to allow easy access with my impact wrench for lifting.  I also set the tilt feature of the jack in the front at the full down position so I could easily tilt the back of the transmission down as necessary.  I did this set-up before I installed the Protection Plate.

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<Transmission Mounted to Transmission Jack>

1. Preparing the connection bolts
This step is not very exciting but it’s always important to make sure you have all your fasteners cleaned up and in hand.  
There are four (4) connecting bolts:

3 – M12, 8mm Allen Head bolts.  Two of them are used at the top positions of the transmission case as shown in the diagram below where the guide Dowel Sleeves are located.  These fasteners thread into the Central Tube bell housing and use flat washers under the Allen head.  The third M12 Allen Head bolt w/washer is used on the PS at the bottom location of the transmission case and connects the oil cooler Support bracket.  A hex nut and lock washer are used to secure it.

1 – M10, 17mm Hex Bolt and Nut with washer.  This bolt is located on DS lower case and simply clamps the transmission case to the Central Tube bell housing.
All threads, external and internal, were cleaned with a wire wheel or tap as necessary.

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<944 Transmission Case Exploded View – Bolts>

2. Preparing the drain and fill Screw Plugs
Cleaning the drain and fill Screw Plugs while they were easily accessible just seemed to make sense. A 17mm Allen Key socket is needed to remove the plugs.  I pulled them both and removed any old sealant remnants.   I applied Permatex PermaShield on the drain Screw Plug and torqued it in place to 18 lb-ft.  Then I labeled the torque on the fill Screw Plug (so I wouldn’t have to look it up again) and snugged it into place.  I will apply PermaShield and tighten it after filling the transmission with new gear oil.

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<Drain and Fill Plugs>                                       <Installing the Guide Dowel Sleeve>

3. Placement of the guide Dowel Sleeves
There are two (2) guide Dowel Sleeves used in this mating and they are important for proper alignment of the transmission case and the Central Tube bell housing.  If the interface is not perfectly aligned, you will be hard pressed to connect the drive shaft Clamping Sleeve.

4. Test fit of the oil cooler Support bracket
Based on the Porsche exploded parts view, I was missing some of the supplemental hardware to connect the oil cooler Support bracket.  I had the correct M8 bolt and lock nut but nothing else.  I made the missing sleeve from 5/16 ID copper tubing and dug up a flat washer and lock washer to complete the assembly.  The bracket itself had some distortion of the transmission case mounting flanges where the M12 Allen Head bolt passes through.  I had to massage that a bit so that it fit properly, and the hex nut could be put on.
After the test fitting, I removed the Support bracket and set everything aside for later.

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<Oil Cooler Support Mounting Hardware>                     <Oil Cooler Support Bracket Test Fit>

5. Lubricating the Drive Shaft Splines
This step is for corrosion protection and ease of installation.  Porsche calls just about every “shaft” that carries power a Drive Shaft.  In this case we’re talking about the transmission Drive Shaft or main shaft.  After I bead blasted this shaft long ago, I coated the splines with anti-seize and that kept it in good shape.  Now after wiping off the dust and spiders that had accumulated from sitting around, a applied some synthetic bearing grease to ease installation.

At the end of the day, the properly torqued Clamping Sleeve will secure the transmission Drive Shaft to the Central Tube drive shaft so there should be NO MOVEMENT.

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<Synthetic Grease on the Transmission Drive Shaft>  <Drive Shaft Clamping Sleeve>

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< Clamping Screws – New vs Old>                             <Rural King Cap Screw Replacements>          

6. Preparing the Driveshaft Clamping Sleeve
This effort was mostly clean-up of the interior splines.  At disassembly, it was clear that someone in the past had difficulty with alignment of the Clamping Sleeve and tightening of the Clamping Screws (bolts).  The bolts are M10 x 1.50 x 40mm Allen Head bolts, Grade 12.9 and my originals were well beat up!  I elected to replace them with 50 mm units I purchased at Rural King for only $2.89 each.  Porsche replacements (PN 931 421 240 00) go for ~$10 each.  The Clamping Sleeve is independently balanced so if the new bolts are identical there should be no issues.  They do have a smaller shoulder depth, but I don’t believe that’s an issue when properly torqued.

7. Connecting the Transmission Carrier
I removed my stock AGP transmission with the Transmission Carrier still bolted on. This wasn’t too tricky so I figured installing the 5P transmission would just be a reversal of that process.  This was my justification for mounting my rehabbed Transmission Carrier to the 5P transmission beforehand.

There are only two 13mm hex bolts, M8x1.25x100mm, with washers and 13mm lock nuts that get the job done.  The bolts pass through the transmission case on the DS where the heads fit into hexagonal recesses.  The washers and locking steel nuts on the PS are torqued to 17 lb-ft.  My steel lock nuts did not provide me with much confidence, so I used blue threadlocker for a bit of insurance.

Note that the fuel filter mounting bracket should be on the front PS of the carrier.

Later I decided to remove the Transmission Carrier for easier transmission maneuvering.

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<Transmission Carrier Bolts - DS>                                    <Steel Lock Nuts - PS>

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<Installed Transmission Carrier>                                          <Shift Rod Protective Tube>

8. Installing the Shift Rod Protective Tube
This is an easy step as the tube is symmetrical and is a snug “slip fit” into the transmission case shift rod access hole.   Push it all the way in until it hits the exterior stop lug.  
In the photo above, I installed the Clamping Sleeve at this point, pushing it all the way back on the transmission Drive Shaft splines.  You get a STAR is you noticed that the top PS mounting bolt hole does not have a guide Dowel Sleeve in place!  That 2nd sleeve remained in my Central Tube bell housing during disassembly…so I do have two.

All the mounting bolts and the oil cooler Support will be removed for the actual install.

9. Parking Brake Cable Placement
While the transmission was out of the way, I thought it best to make sure the Parking Brake Cable assembly was correctly mounted between the rear suspension Cross Tube and the Seat Well Transverse Strut.

I soon learned that I had installed the strut INCORRECTLY during the Central Tube rehab phase, and there was absolutely no room to mount the Parking Brake Cable in the Cross Tube mounting brackets where it belongs.  In fact, the mounting brackets were now deformed from impacting the strut when I installed the rear crossmember.

Note:  The Seat Well Strut was preventing the Cross Tube from rotating under load which is why I could not install the rear shock absorbers!!   Mystery solved!!

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<INCORRECT Seat Well Strut Installation>                          <Strut Removed, DS Cable in Place>

After removing the strut, I restored the Parking Brake cable mounting bracket and installed the cable.  This is done by sliding back the protective rubber boot and pulling the cable, so it fits in the narrow slot of the bracket hole. Releasing the cable allows the fitting to slip into the hole and then a locking clip is inserted to keep it there.  

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<PS Parking Brake Cable Installation>                          <Short-term Rubber Boot Repair>

Unfortunately, the 36-year-old rubber boots on my cable would rather tear than slide over the brass fitting retainer ring… and when they did slide over, they wouldn’t stay there.  I used small zip ties to hold them in-place and wrapped the torn ends with self-sticking electrical tape. Time will tell if this holds up.

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<Correct Strut Orientation>                                   <Correctly Installed Rear Seat Well Strut>

Now I can get down to business….

Next up…. Installation!!

With the prep work completed, I could now get serious about installing the transmission.  My good college friend Bob came over to give me a hand and he was extremely helpful!

To get started, I raised my MAXJAX lift as high as possible and rolled the transmission under the car.   About a half second later it was obvious that the process would be so much easier without the Transmission Carrier that I just installed.  So, off it came… just two bolts.

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< Transmission Under the Car >                    

Installing the Shift Rod
Before getting too much further with alignment, the Shift Rod must be installed. From the back, I guided mine thru the Central Tube bell housing portal and along the top left side the Central Tube up to the shifter location.  It will go most of the way forward with the bend facing upward and the back end set screw hole at 9:00 as you face forward.  When you hit resistance, rotate the Shift Rod clockwise until the set screw hole is facing upward (12:00), and you will be able to push it further forward.  Do this until the back of the Shift Rod is protruding from the bell housing enough about an inch or so.

In the photo below you can see the Shift Rod in position thru the bell housing portal, and you can also see that 2nd guide Dowel Sleeve.

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< General View from the Rear >

I raised the transmission jack slowly (Photo A) until the spare tire well became a clearance issue (Photo B).  At that point I used the tilt feature of the jack and tilted the back of the transmission down.  This allowed me to raise the jack sufficiently to initiate engagement of the Shift Rod Protective Tube in the bell housing and transmission case simultaneously, with the Shift Rod inside (Photo C).

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< Photo A >                                                                            < Photo B >

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< Photo C >

Next, I raised the transmission jack and simultaneously tilted it forward, so it was back in the original horizontal position.  At that point I was able to start the connection bolts by hand, beginning with the M10 bolt on the DS lower transmission case (Photo D).

With the transmission case bolted to the Central Tube bell housing, I re-installed the Transmission Carrier on the transmission (Photo E).  The Transmission Carrier is connected to the frame with one M10x1.50x50mm, 17mm hex bolt and washer on each side.  These bolts are torqued to 34 lb-ft.  Note the position of the fuel filter mount.

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< Photo D >                                                                      < Photo E >

The 5P transmission is now sitting in its new home with all connection bolts snug.

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< Completed Transmission Installation >

Now for tying up the loose ends…

Oil Cooler Support Bracket - Before putting the final torque on the case bolt connecting the bracket, I installed the supplemental support connection hardware, torqued to 17 lb-ft.

Drive Shaft Clamping Sleeve – A quick visual check thru the bell housing access port shows the Central Tube Drive Shaft was still flush with the end of the tube.  This position is correct for my engine and car combination and must be maintained exactly to ensure proper insertion of the Drive Shaft nub in the flywheel pilot bushing.  Note: Your Drive Shaft projection may be slightly different.

The Clamping Screw (Allen Head Bolts) locations on the Clamping Sleeve are symmetrical but 180 degrees out of phase.  There are two access ports on the bottom of the Central Tube bell housing for tightening these screws. The small round port at the front allows direct perpendicular tool access to the front Clamping Screw.  Just behind the round port is a larger trapezoidal hand hole port for access to the Clamping Sleeve.  This port allows you to move the Clamping Sleeve into its final position and permits torque wrench access for proper tightening of the rear Clamping Screw.  

The engagement process involves manually sliding the Clamping Sleeve forward from its “pre-install” position on the transmission Drive Shaft splines until the Clamping Screw holes align longitudinally with the semi-circular spline gap of the transmission Drive Shaft and the rectangular spline gap of the Central Tube Drive Shaft.

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< Oil Cooler Support Bracket Installed >                 < Center Tube Drive Shaft Extension Check >

For the Clamping Sleeve to slide into place, the Drive Shaft splines must be exactly aligned.   This is done before tightening the transmission case connection bolts so that micro adjustments can be made as needed.

The approach can be somewhat of a trial and error process, maneuvering the transmission relative to the bellhousing until the alignment is spot on.  With the correct alignment, the Clamping Sleeve should slide easily into the proper position without tools.  Remember you do not want to alter the Central Tube Drive Shaft projection.

Positioning the Clamping Sleeve correctly on the Drive Shafts and properly torqueing the Clamping Screws is critical. To get the position correct, I first noted the location of the rectangular spline gap in the Central Tube Drive Shaft as being exactly centered in the round tool port.  Then I rotated the Clamping Sleeve and transmission Drive Shaft so that the sleeve split would be visible thru the tool port.

With the sleeve split aligned as noted above, my first attempt at engaging the Clamping Sleeve was to try snugging all the transmission case connection bolts, and then check the spline alignment.  I was THRILLED when I was able to engage the Clamping Sleeve on the first try!!!!

I then slid the Clamping Sleeve forward on the transmission Drive Shaft engaging the Central Tube Drive Shaft until I could see that the front clamp was positioned exactly over the rectangular spline gap of the Central Tube Drive Shaft, and (importantly) that the spline gap was still exactly centered in the tool port.  This confirmed that the Central Tube Drive Shaft DID NOT shift forward in the process.  I’m sure the bearing grease helped in this regard.

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<Positioning Front Clamping Screw>                                   <Rotating the Engine>

With the front clamp correctly located, I could now proceed to installing the Clamping Screws.   For the front screw, I turned the engine to rotate the Clamping Sleeve so the front Clamping Screw can be installed thru the tool port.  Rotating the engine was easy enough using my torque wrench and a socket on the harmonic balancer bolt.

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<Test Fit of Rear Clamping Screw>                                   <Installing the Rear Clamping Screw>

I first installed the front Clamping Screw by hand.  Then I took the second Clamping Screw and installed it backwards (again by hand) in the rear clamp location.  This was a test fit only to make sure the rear Clamping Screw fit perfectly in the semi-circular splice gap of the transmission Drive Shaft. There is very little clearance here, so it must be right.

Next, with both screws turned in by hand, I used an 8mm Allen Head socket and torqued the front Clamping Screw to 60 lb-ft as recommended by Bob at Hotrodz of Dallas.  Bob also advised me to NOT use any threadlocker (for the sake of the “next guy”).  The spring action of the split sleeve significantly increases the “off-torque” value so no worries here about them coming loose.

With the front Clamping Screw torqued in place, I removed the rear Clamping Screw installed for alignment, turned the engine to rotate the Clamping Sleeve about 180 degrees, and then re-installed the rear Clamping Screw in the proper orientation.  I was able to start the rear screw by hand but needed a small ratchet to get past some minor resistance.  Torqueing the front screw apparently shifted the sleeve just a shade.

To properly torque the rear screw, DO NOT USE extensions and a universal.   Instead you will want to make rotational adjustments so you can insert and squarely align your torque wrench through the trapezoidal hand hole port.  This will allow full direct engagement of the 8mm Allen head socket and direct torque application.

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<Torqueing the Rear Clamping Screw>                      <Inserting the Rubber Access Port Covers>

To complete the effort, I pushed the rubber port covers into place.  A large screw driver helped get that stubborn last corner in place.

Case Connection Bolt Torqueing – The last bit of “heavy lifting” was to torque the case bolts.  Recall that they were all snug in the process of aligning the Drive Shafts.

I started with the PS lower case M12 Allen Head bolt and 19mm hex nut that also holds the oil cooler Support in place.  I used a 10mm Allen Head socket and torqued it to 62 lb-ft.  
Next was the DS lower case M10 hex bolt and nut. I used a 17mm socket and wrench and torqued it to 31 lb-ft.
Next was the PS upper case M12 Allen Head bolt at 62 lb-ft, and the DS upper case M12 Allen Head bolt at 62 lb-ft.  Because these bolts do not use lock washers, I put blue threadlocker on each.


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<Lower Case DS Bolt Torqueing>                                <Upper Case PS Allen Bolt Torqueing>

Shift Rod Connection to the Shift Linkage – Coming down the home stretch, connecting the alloy Shift Rod to the transmission shift linkage is a one bolt operation.

From the interior of the car, I pushed the Shift Rod back until it was nearly in contact with the shift linkage.  Then I aligned the threaded hole in the Shift Rod flange with the detent in the shift linkage connection shaft (both at 9:00).   After a shot of penetrating oil, a little persuasion from the front with a rubber mallet moved the Shift Rod nearly into position.

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<Shift Rod Interior Shifter End>                                        <Shifter Rod Threaded Hole Aligned>

Light taps on the back of the shift linkage while holding the Shift Rod, moved the rod into final alignment.   Placement of the M8 tapered end lock bolt was simple enough.  I applied blue threadlocker and 15 lb-ft of torque.  Remember the Shift Rod is a light alloy so the threaded hole in the flange end will strip in a blink if you get too aggressive.

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<Final Positioning>                                                           <Custom Locking Wire>

Locking Wire - Other procedures I’ve read talk about a “locking wire” on the lock bolt to keep it in place and prevent it from getting lost.  I did not have one on my car, so it was time to improvise.  I used a plated steel cup holder wire that perfectly fit the hole in the lock bolt head. The Shift Rod is about 20mm in diameter, so I fashioned a wire pin with a perpendicular 20mm loop hook.  I positioned the pin to resist counterclockwise rotation of the bolt, bent the straight end over to prevent twisting and then zip-tied it in place.   I’ll have to check on it down the road to make sure it’s working!!

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<Completed Locking Bolt Connection w/Wire Lock>

The final loose ends for now were reconnecting the back-up light switch on the PS and the speedometer sending unit on the DS.  There is only one way to connect the speedometer sending unit and I have it on good authority that the back-up light switch wires are interchangeable.

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< Back-up Light Switch >                                            < Speedometer Sending Unit >

Now if I could just find that locking clip for the speedometer sensor pigtail!!

Coming soon….fuel pump, and connecting the axles.

Well, I changed my mind and decided to connect the axle shafts 1st and get it over with.  After all, it is supposed to be a straightforward bolted connection.

Fastener Prep
I started with a “surgical” clean-up of the 12 remaining M8x1.25x50mm flange bolts (Triple Square Cap Screws) and the 6 remaining washer plates.  Note, these are the smaller washer plates.  
I followed the same procedure as detailed in my post dated Friday Jan 06, 2023.  Below is the link:
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Importantly, I mechanically cleaned all the debris from the triple square socket heads and chased the treads of each screw with a die.  Each was then cleaned with brake cleaner and given a spray on / wipe off application of light oil.

As part of the fastener prep, I had to round up the VSS package that came with my TPC conversion kit.  

Note for those unfamiliar: VSS is an acronym for Vehicle Speed Sensor.  In this application, the VSS uses a stationary, permanent magnetic sensor (reluctor) mounted to the transmission housing.  The sensor is triggered by the teeth on a "reluctor ring" which is a toothed ring or gear that rotates with the axle shaft.  The reluctor sensor provides vehicle speed information to the ECM like how the crankshaft and camshaft sensors provide position and engine speed information. Collectively, this information is the basis for tuning the ignition timing for maximum performance and overall drivability.

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< Cap Screws, Plate Washers, TPC Reluctor Ring >                        < TPC VSS >

Collecting the VSS is relevant because the reluctor ring component of the sensor must be attached to the DS axle on the outside of the CV Joint Flange.  I had some concern that the added 3 mm thickness of the reluctor ring would compromise the minimum required thread embedment of the cap screws in the drive shaft flange.  So….the engineer in me just had to do some checking.

Cap Screw Engagement Check
Previously, I calculated the required thread engagement length in a 4130 axle stub needs to be at least 11.6 mm to fully develop the 12.9 Grade connection screws.  

Trivia Note:  I learned something about mechanical fastener semantics that most of you probably already know.  A “bolt” always has a “nut” to provide clamping force.  I’m completely familiar with this.  On the other hand, a steel fastener that threads into a tapped hole in a solid mounting surface is a “screw.” Thread physics are the same.

Calculating the thread engagement length with the reluctor wheel AND plate washers:

    Available Drive Shaft Flange Depth     12 mm
    Measured Cap Screw shaft length       48 mm
    CV Joint Flange thickness                  33.2 mm
    Plate Washer Thickness                     2.5 mm
    Reluctor Wheel Thickness                  3.0 mm

    Thread Engagement: 48 – 33.2 – 2.5 – 3.0 = 9.3 mm < 11.6 mm Reqd.  NO GOOD!

The apparent solutions included 1) buying longer cap screws or… 2) deleting the plate washers.  My preference was to delete the plate washers.  In my mind I had two good reasons, the reluctor ring/plate washer sandwich could compromise critical clamping forces, and the reluctor ring at 3 mm could certainly satisfy the load distribution duties of the plate washers.  Bob at Hotrodz of Dallas confirmed my logic… THANKS BOB!   I also got a green light from Spense…much appreciated!

Calculating the thread engagement length with the reluctor ring only:

     Thread Engagement: 48 – 33.2 – 3.0 = 11.8 mm > 11.6 mm Reqd.  OK… GOOD TO GO!

The TPC reluctor ring has an excellent powder coated finished and only required a wipe down to remove any errant grease or oil.

CV Joint Interface Prep
Once again it is imperative to completely remove ALL paint, dirt, and/or grease that may be present on the CV Joint Flange and the axle shaft flange.  This needs to be a metal on metal interface.  I used brake cleaner and paper towels to get the job done.

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< Cleaning the Drive Shaft Flange >                            < Guide Pin thru the CV Joint Flange >

Installing the DS Axle Shaft
With all mating surfaces completely cleaned, I used my guide rods once again to align the CV Joint Flange with the drive shaft flange.   Below is the procedure that worked for me:

1. Align the CV Joint so that it’s relatively normal (perpendicular) to the axle shaft.
2. Straighten the axle and slide the entire axle shaft assembly into the wheel hub as far as it will go.  
    This will give you about ½ inch of clearance for installation. Mine would not move by hand so I  
    placed a brass drift on the center section of the CV Joint and used my rubber mallet to coax the
    assembly over. It doesn’t take much.
3. Rotate the drive shaft flange until there is a mounting hole at the top.
4. Rotate the axle shaft until one of the CV Joint mounting holes is at the top.
5. Grab the CV Joint, pull it to the rear several inches, and then raise it above the drive shaft flange up
    to the 12:00 position.
6. Carefully align and lower the CV Joint Flange into position adjacent the drive shaft flange.  There
   should be no contact yet (and NO grease contamination).
7. Holding the CV Joint is this position, I hand threaded one of my installation guide pins into the axle
   flange top mounting hole.
8. I then hand threaded a second guide pin in a mounting hole around the 8:00 position.
  (These guide pin locations allow installation of half the reluctor ring in the 1:00 to 7:00 position)
9. Carefully squeeze together the CV Joint and drive shaft flanges by hand, shifting the entire axle
    shaft assembly toward the drive shaft flange.
10. Set in place one reluctor ring half and hand start 3 of the connection cap screws in the available
     holes.  (You will need to deform the CV boot out of the way to do this.)
11. Continue to squeeze the joint and hand tighten the screws sequentially until the axle assembly is
     fully pulled into place and the joint is closed.
12. Snug the 3 cap screws with triple square socket.
13. Remove the guide pins, place the other half of the reluctor ring, and install the remaining 3 cap
     screws.
14. With all 6 cap screws snug, torque them in 3 phases to 15/25/35 lb-ft using the standard
     hexagonal tightening pattern.

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< Step 10 - Starting the Cap Screws >                < Step 11 – Flanges “Squeezed” Tight >

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< Snugging the Cap Screws >                                              < Locking the Axle Shaft >

For cap screw torqueing, you will need to lock the axle shaft.  I didn’t have a helper for this, so I used a 1-1/4” socket and power bar on the main wheel hub nut.  Torqueing is simplified by rotating the axle shaft assemble until the cap screw being torqued is at or near the 1:00 position.  This minimizes interference by the CV boot and still gives easy access.

Installing the VSS
Next, I used 2 – M8 x 1.25 x 20mm 10mm Hex Flange bolts (screws?) to mount the TPC Speed Sensor.  Be sure that the sensor is mounted normal to the reluctor ring. To keep the bolts secure, I used washers and lock washers. Each was torqued to 17 lb-ft. after proper sensor gap adjustment.

Sensor Air Gap Adjustment
After round two or the cap screw torqueing sequence, I set the sensor air gap.
From what I could gather in my research, the electronics of a fixed magnet reluctor work best when the sensor and reluctor “pulse” ring air gap is as small as possible but large enough for reliability considering dimension variables and potential future corrosion or debris.  The advertised recommended air gap is all over the place, ranging from “pretty close,” to 0.010 - 0.020 inches, to 4 mm, to the thickness of a zip tie, to the thickness of US quarter (0.070 in.), and to 0.040 inches.   Bob and Spense both provided the approach that WORKED on their cars, and that would be 0.040” and 0.070” respectively.   Clearly there is some serious wiggle room here.

My approach was to set the air gap to 0.035 inches with a feeler gauge, “spin” the wheel, and see what happens!   A 360- degree rotation test revealed my reluctor ring was a bit flat at the split interfaces.  At these positions the gap increased by about 0.010 inch.  Subsequently, I reduced the gap on the remainder of the ring to 0.030 inches so the maximum gap at the flat spots was 0.040 inches. CALLING IT GOOD!  Below are some pics:

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< Torqueing Cap Screw at 1:00 >                            < Setting the Sensor Air Gap to 0.035 in. >

A look at the back of the drive shaft flange revealed full embedment of the cap screws.  Perfect!!

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< Full Drive Shaft Flange Engagement >                              < VSS Pigtail >

I also received my new VSS pigtail in the mail.  I ordered an Airtex 1P1006 made in USA, from Amazon, but I got a WVE unit made in China.  Not a bad company, and the exact same application but…   Not worth the hassle of sending it back.  I guess I’ll give it a try.

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< Completed DS Axle Shaft and VSS Installation >

Now… rinse and repeat for the PS axle.

Up Next... Installing the Oil Cooler

On the passenger side (PS) there's not quite as much room to work but the process went smoothly without any complications.  Below are some pics, just for the record:

Once again, proper clean-up of mating surfaces is paramount.  Be sure to clean any grease from the connection screw holes too.

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< Clean CV Joint Flange >                                                < Clean Drive Shaft Hub Flange >

After pre-aligning the connection holes, I was able to pull the axle shaft back into the wheel hub by hand.  Then I raised the CV joint into position and place the first installation Guide Rod.  There seemed to be a bit more clearance on this side…about 3/4 inch.

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< Pre-alignment of Mounting Holes >                      < Placing the First Installation Guide Rod >

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< Placing the Second Installation Guide Rod >          <  First Washer Plate and Screws Installed>      

With two guide rods in place, I easily slid the axle CV Flange up against the drive shaft hub flange.   Next I installed the first washer plate and two connection screws, hand tightened only at first.

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< Torqueing the Connection Screws >                       < Installation Complete>

Once all the connection screws were in and snug, the axle could safely be rotated so that torqueing the screws could be done efficiently.  Again, I used a standard hexagonal pattern and a 3-phase approach 15/25/35 lb-ft.  I put a dot of pink nail polish on each screw head as each torqueing operation was complete.  This was a good way to make sure all connection screws have been torqued properly.

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<  Updated and Reconditioned Transaxle in Place >

Finally, the car has a rear end again.  Time for another Happy Dance!  

Up Next... Installing the Oil Cooler  

I did a thorough cleanup of the cooler tubing and fins using a water-based degreaser concentrate and a stiff bristle brush.  For a few debris packed areas, I had to break out my generic Brakleen.  

The cleaning took about an hour, however, I spent twice that effort to straighten out all the bent cooling fins.   This process was tedious but easy enough because the tube and fins are aluminum.  A small flat blade screwdriver worked well for me.

I completely dried the cooler using compressed air and then spayed on a coat of flat black heat paint.

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<  Repainted Oil Cooler >                                               < Looks Like I have a LEAK >

When the oil cooler was dry, I proceeded to do a proximity test fit.  I quickly realized that the installed oil cooler will encroach on the space required to install the upgraded SS rear fuel lines and the LS1 “return-less” fuel filter/ pressure regulator.  Looks like the oil cooler install is going to have to wait…

Fast forward 2 weeks after returning from SoCal... I see a dark ring around the oil cooler mid-length of the straight run (see photo above).  Nothing shows a wet oil leak like flat black paint!!!

So now I need some FORUM ADVICE to fix it.

Pinpointing the leak should be easy enough but sealing it permanently is another matter.  I’m open to suggestions on the best way to proceed…especially because it’s aluminum.

Option 1 – Replace with new… only $1400
Option 2 – Hot solder dip (like radiator repair)
Option 3 – Pin-point “cold” solder (works good for pin-point electronics)
Option 4 – Liquid Steel external patch
Option 5 - ???????

Your advice is much appreciated!

Mine looks worse than yours but didn't bother to clean, hopefully I don't have a leak either.

Might be worth applying say couple pounds of air after plugging an end to see if it's good before I waste a bunch of expensive amsoil through a hole.

My vote is for option 2. Once you find your leak I'd cut the fins to get good access and then pull out a super hot torch (not propane) and with an aluminum rod that is fluxed braise a bead over the hole. You won't lose a tonne of cooling by removing some fins and well worth the sacrifice to get it sealed up and not pay 1400 for a new one. I actually think I'd cap the ports before I bothered to pay that much lol especially with our Canadian peso. Lol

Thanks Gutterboy for your comments on the oil cooler leak repair.  I’m going to find that leak soon and see exactly what I’m up against.

In the meantime, I’ve been preparing to install my new fuel pump, GM filter/regulator, and SS fuel lines. This meant cleaning up the fuel pump mounting plate, the hanger strap, and importantly…replacing the internal fuel tank strainer.  

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< Renewed Fuel Pump Mounting Pieces >                        New Fuel Tank Strainer >

This strainer is located inside the fuel tank and advertised to filter out all particles over 5 microns. That’s small indeed, but essential to assure longevity of the electronic fuel pump.  I speculated on NOT changing the factory strainer, but the consensus of the Forum gurus is CHANGE IT! Reportedly, the filter screen tends to break down after 30 or 40 years…go figure!   I have also seen a few YouTube videos of guys changing their strainer only to find it completely covered with petroleum slime.

I purchased a new Porsche unit on Amazon from Porsche Conshohocken, PA.
PN: 928 201 081 04
$67 plus tax

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< Existing Fuel Tank Strainer Outlet >                   < 17mm Hex Head on Strainer Housing >

Tank Strainer Removal

Removing the old fuel tank strainer should have been a simple effort but mine seemed to be “fused” into place and I had some concerns that too much torque might crack my plastic fuel tank.  The strainer is a Purolator so it appears to be a replacement and perhaps it was installed with some type of thread sealant as leak insurance.

1st Attempt - I used a 17mm deep socket on a 12” ratchet to the left of the strainer and gave it a good pull down.  The entire tank deflected downward but the strainer did NOT break loose.  I didn’t get too crazy with it because it just shouldn’t be that tight.  To play it safe, I applied Liquid Wrench and let it soak for 24 hours.

2nd Attempt - I put the ratchet handle to the right of the strainer and pushed up.  There was minimal tank deflection, but the strainer still did NOT budge!  Again…I could have applied more torque, but I didn’t want to break anything.

I got some advice from Bob at Hotrodz of Dallas regarding stress relief on the tank by engaging the tank strainer housing as leverage against the ratchet.  I tried doing this with a large set of channel locks, but it was just not the right tool.  I could not get a decent grip on the housing without imparting a significant compression force which probably made the problem worse.

I even tried using an adjustable plumbers crescent wrench, but it really didn’t fit.  For good measure, I gave the strainer another shot of Liquid Wrench and then some Amsoil MP which performs very well as penetrating oil.

3rd Attempt - Another 24 hours later, I tried applying more torque using my power bar set up….still no movement.   I even tried using the channel lock pliers on the housing of the strainer (bigger diameter =  more torque)…still no movement.

4th Attempt - At this point, I put the 17mm deep socket on my impact gun.  I figured this strainer is coming out…even if I do end up breaking something.  At first, I gave it a go on setting 1 (lowest) but after about 20 seconds, I only managed to shake out lots of dust from around the tank. Then I tried setting 2 and…OUT IT CAME!!

In hind sight, the impact gun was the way to go.  There seemed to be little trauma to the tank with no twisting or deflection.  I’ve read horror stories of the metal tank housing spinning out and or the tank itself cracking at the housing connection, so I’m thankful none of that happened.  I do think the penetrating oil helped and would recommend that as a prep…several days in advance.

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< Tank Sludge >                                                  < Mystery Compound >

Once the tank strainer was out, I was happy to see the tank was clean inside except for a 1/8” thick layer of tar-like sludge on the very bottom.  That’s what you get when you let fuel sit for 30+ years! I got this out (mostly) with a microfiber cloth and solvent.  The old strainer was actually in pretty good shape too with no tears, breakdown, or clogs.

My only other concern was the presence of some hard mystery compound at the bottom of the tank fitting.  It was a solid application and impervious to the fuel solvent I used.  I started to scrape it off but then realized it may be a leak repair and left it be.  Recall that the filter screen had been replaced at least once so someone was in there working.  

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< Old Purolator Tank Strainer &                                 < New Tank Strainer Installed >
New Porsche Tank Strainer >

Tank Strainer Installation

Installing the new tank strainer was a snap.  To prevent the aluminum threads from seizing (again), I sparingly applied some anti-seize and lightly coated the gasket with Permatex Permashield.  

Now the question…how tight should it be???

My Internet research did not turn up much:
 

• A Pelican Parts forum member posted Porsche Workshop Manual specs for his ’75 911S at 0.8-0.9 “meterkilopond” which converts to 5.8 – 6.5 lb-ft.
  

• Some Rennlisters indicate the factory just hand tightened the strainer (whatever that is), and some said 1/8 turn after gasket contact.
  

• Most forum entries indicated tightening just “snug” enough for the gasket to seal.
  

I settled on tightening the unit until the gasket was fully engaged with some compression and stopped at 10 lb-ft.  I’ll check for leaks in Part 2 and update as needed.

Next up….Part 2 - Installing a new fuel pump and lines

Raymond-P wrote:It’s fairly well known that the LS oil pressure and water temperature sensor/sending units are not compatible with the factory Porsche gauges.  Unfortunately for me, this didn’t “click” until after I purchased new LS sending units and installed them as part of my engine build.  Worse yet, I installed the engine before knowing this as well and now the swap just got a bit more difficult!!

I started by purchasing the correct pieces from Kent at TPC:
Water Temp Sending Unit - $36
LS Engine to Porsche 944 dash gauge
VDO A2C59517248-5 (Includes cooper washer)

Oil Pressure Sending Unit – Adapter Kit - $120
    • LS Engine to Porsche 944 dash gauge
       VDO 360-009, 0-80 psi, +/- 6 psi,
    • Auto Meter Brass Metric Adapter #2268, M16 x 1.5 to 1/8” NPT / 27 TPI
       (with copper compression washer)
    • Brass 45-degree elbow – 1/8” NPT (required for clearance)

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<VDO Temperature Sending Unit>                              <VDO Oil Pressure Sending Unit, TPC Kit>

My 1st obstacle was removing the factory LS oil pressure sending unit.  Not a big deal if you have the proper tool…which I did not.  Amazon Prime to the rescue!  (~$15)

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<Factory Oil Pressure Sending Unit>                                < Sending Unit Removal Socket>

After vacuuming out any remaining loose sealant threads, I applied Permatex liquid Teflon thread sealant to the Auto Meter metric adapter in conjunction with the cooper crush washer, and tightened it in place using a 7/8” socket to 20 ft-lbs.  The max recommended torque was 25 ft-lbs.

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< Socket / LS Sending Unit / TPC Swap Kit>             < Torqueing the Metric Adapter to 20 ft-lbs>

Next up was the 45 deg brass elbow.   More liquid Teflon and then several turns until the fitting was tight and most importantly pointing outward.  I used a small crescent wrench to get it done.   I repeated the process with the sending unit itself but only hand tightening as much as possible.  With the Teflon sealant still soft, I could make final adjustments to the overall unit position to provide clearance for the vacuum line to the manifold port. (blue tape)


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< Brass 45-degree Elbow in Place>                           <VDO Oil Pressure Sending Unit in Place>

Regarding temperature sending unit, I have two sending units I’m planning to use.
1) The factory LS sending unit which feeds the ECM, and
2) the TPC sending unit which feeds the dashboard Porsche gauge.  

As far as I know at this point, this is viable… of course I’m always open to Forum suggestions!

My wiring harness has a sending unit lead for the LS unit on the front of the driver’s side head, so I put my new LS temperature sending unit there.  The corresponding water jacket port on the passenger side head was plugged.  I replaced it with the VDO temperature sending unit.

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<LS Temperature Sending Unit – DS Front>            <VDO Temperature Sending Unit – PS Rear>

Next up, some wiring harness connections behind the intake and hopefully the fuel rail cross-over line.

Can you explain How the Coolant Dash to the new VDO sensor is wired? There are two Blue/Green and Blue/Yellow on the 14pin Dash connection. Do both of those wires go to the VDO coolant Sensor? On the Same post? There's only one on that Sensor.....

viperbmw69 wrote:
Can you explain How the Coolant Dash to the new VDO sensor is wired? There are two Blue/Green and Blue/Yellow on the 14pin Dash connection. Do both of those wires go to the VDO coolant Sensor? On the Same post? There's only one on that Sensor.....

Viperbmw69....Always a good question and fortunately for both you and me, the answer was provided most recently by Bob at Hotrodz of Dallas in response to Gutterboy's inquiry during his wiring efforts.

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In a nut shell, the Blue/yellow wire should be connected to the TPC sensor.  I understand the sensor is "self grounding" to the head so if we don't get good gauge performance, it could be due to an abundance of sealant on the threads.

The Blue/green wire normally would connect to the factory Porsche sensor and lights the temp warning light.  The Porsche sensor does not fit the LS motor sensor port, so unless it is adapted somehow/somewhere...no more "idiot light" for us.  Same issue with the alternator.

There is a more complete explanation in the Forum Wiki on Electrical Issues.

Hope this helps... I'm sure Kent or Bob can shed more light on the subject if the dash warning lights are desirable.

This has been a long time coming but my inventory of parts “yet to be installed” is finally getting SMALL!  
This time, I gathered all I had related to installing the new fuel pump.  These parts were mostly described in two previous posts:

Fuel Line Modifications – Part 1, Planning
Post  Raymond-P Mon Jan 31, 2022 12:46 am
Forum Page 8 of 10

Fuel Filter Question?
Post  Raymond-P Sat Feb 05, 2022 11:27 pm
Forum Page 1 of 1

Fuel Line Modifications – Part 2, Engine Side
Post  Raymond-P Fri Jun 24, 2022 1:59 am
Forum Page 9 of 10

For convenience, I’ve reposted my proposed fuel line configuration below:

HEADS UP…. Parts D, E, and F did NOT work as planned.  Read on!

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Parts List:

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One change right out of the gate was I reused the factory fuel hose from the tank strainer outlet to the fuel pump inlet.  This is a special 1/2-inch ID formed hose with a 120-degree curve that is expanded to 9/16-inch ID to fit the strainer outlet nipple. (~$30-$40 new) Because of the tight bend, it apparently has a rigid core of some sort, to maintain full flow.  Ordinary hose will collapse when bent to this angle is such a short length.  The hose brand was Continental and along with the factory clamps, was in good shape.  As with the tank strainer, I’m pretty sure the original hose was replaced at some point.  I’ll keep an eye on it for now and replace it down the road.

Fuel Pump Installation

Step 1 – Fuel Pump Check Valve
As noted in the Parts List, I purchased a new Premium Bosch fuel pump.  Thanks to Gutterboy, I learned that the part number listed is the Bosch PN for a universal unit, which gets you almost nowhere when you look it up.  The more productive PNs are N69548 and 94460810206.  It came with two fuel return check valves, one of which is the banjo bolt style I needed, and a pair of new copper flat washers. These are solid and not your typical “crush” washers, but the malleability of annealed copper works well for a metal to metal seal provided all surfaces are smooth.  I secured the fuel pump in my bench vise at the end housing blocks, and used a 17mm deep socket to tighten the check valve to 22 lb-ft.  

I got this torque spec from a respected 928 Rennlister who referenced his Porsche Mechanics Manual. Apparently a 928 uses a similar pump.  To be on the safe side, I tested the torque on the check valve in my old frozen pump… starting at 15 lb-ft and progressing in 1 lb-ft increments. I stopped the test at 22 lb-ft.  No movement of the check valve was noted…so it may actually have been tighter than that.  

Note: Copper and aluminum washers are “one-time” use items as they strain harden under load. They do NOT seal effectively when reused, often resulting in a fuel leak.  Always use new washers of the correct diameter or your connection is guaranteed to leak.

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< New Bosch Fuel Pump & Check Valves >                 < Used vs New Copper Washers >

Step 2 – Banjo Bolt to -6 AN Adapter
My plan to replace the factory 3/8-inch fuel line between the pump and filter-regulator, started at the pump outlet with a Russel Banjo Bolt to -6 AN adapter.  The adapter is machined aluminum and came with two aluminum flat washers which are softer than copper and perform the same sealing function.
 
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< Russel Banjo Bolt to -6AN Adapter >                 < Fuel Pump Terminal Hardware & Wiring Harness >

Step 3 - Fuel Pump Location Mock-up
Before securing the Russel Adapter with the factory cap nut, I mocked up the pump fitment in the fuel tank cover (pump mount) to make sure the outlet of the Russel Adapter was positioned favorably for connection to the filter-regulator.  

Considerations:

1. Wiring Harness: The fuel pump wiring harness is simply two wires in a plastic sleeve with a two-pin connector plug at one end and ring connectors at the other end.  The positive wire (power) is green w/black stripe and the ground wire is brown.  The positive terminal is a smaller diameter on this pump so there is no way you can connect the wire leads incorrectly.
   Note: Your pump and wire leads may be opposite.
   
   My factory fuel pump wiring harness was somewhat rigid in configuration, so I used it as a guide and rotated the fuel pump until the wire leads were “comfortable” on the pump terminals.  This placed the positive terminal at 11:00 o’clock relative to the longitudinal axis of the pump.  
   
   The new pump came with new ring connectors, terminal nuts, wave washers, and rubber terminal boots.  I cleaned up my factory wire lead ring connectors for reuse, but I did use all the other new parts, modifying the new boots slightly to fit over the factory ring connectors.  I tightened the terminal nuts until the wave washers were flat and the nuts were “snug.”
   

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< Fuel Pump Positioning Mock-up >                         < Cap Nut Tightening @ 9 lb-ft >

1. -AN Adapter Alignment: The first step here was to build the short connection line between the fuel pump and the filter-regulator.  I used my factory line to estimate the overall length of the new SS line.  The adapter end was a reusable Summit straight hose end to -6AN female fitting (Part D).  The Filter-Regulator end was a reusable Russel 90-degree hose end to -6AN female fitting (Replacement for Part D).  In between, I used a 2-1/4 inch segment of 3/8 inch SS fuel line.
   
   With the pump rotated as needed for wiring, I positioned the Russel Adapter for a straight shot out of the fuel pump cover through the factory access opening (see photo below). The desired position of the adapter was right over the negative terminal of the pump.
   
   You may also note in the photo that I mock-installed the tank line on the pump, and the inspection panel.  This was necessary to set the depth placement of the pump, so the inspection panel fit correctly.  I set it up for about a 1/4-inch gap.  The pump is held in place by a large SS screw clamp which allows the pump to slide fore and aft as needed before the clamp is tightened.
   
   Later in this process, I learned the hard way that the tightening screw of the SS clamp must be on the inside of the fuel pump cover to avoid interference with the support strap.
   
   I then removed the fuel pump and line assembly from the cover and fully tightened the – 6AN connection fitting to the Russel Adapter using the 1/4 TURN METHOD (See Below).  Next, I locked the adapter in place by tightening the cap nut to 9 lb-ft of torque using a 19mm socket.  This spec also came from the Rennlist 928 Forum.  I also removed the tank line. It will be installed after the pump and cover were in place.
   
   Checking this assembly for leaks will be impossible with a “puddle on the floor” being the only indicator.  I’ll be keeping my fingers crossed!!
   

Caution….It doesn’t take much torque to set the aluminum connection washers for a good seal.  Too much torque can deform the banjo, and a skewed wrench alignment can deform the check valve.  Both conditions will cause a leak so hopefully 9 lb-ft does the job.  We’ll see!

AN Plumbing Fitting Torque and Tightening Methods
(Compliments of Pegasus Auto Racing Supplies)  
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Background
The magic of the AN plumbing system is the 37° sealing flare.
The first system of flared fittings adopted by the Army Air Corps in the 1930s had a 30 degree flare. Soon the US Air Force and engineers at Wright Patterson Air Force Base refined the system, deciding that the 37 degree angle provided the best combination of sealing and resistance to damage (i.e., reusability). As you tighten the nut, the flare tries to guide the two flares into alignment, like a funnel. But perhaps even more important for us is that the torque required to seal AN fittings is quite low -- and forgiving!

Tightening Method 1: Torque
If your installation lets you use a torque wrench on the fittings, use the values in the table below. Torque values are shown in Pound-Inches (divide by 12 for pound-feet).

AN Fitting Size      Aluminum Fittings       Steel Fittings
3AN                     70-105                       95-105
4AN                     100-140                     135-150
6AN                     150-195                     270-300
8AN                     270-350                     450-500
10AN                   360-430                     650-700
12AN                   460-550                     900-1000
16AN                   700-840                     1200-1400

Note: These torque values are a general guide that covers most fittings. It is not intended to override any manufacturer's specific recommendations.
If you're not sure which size you're dealing with, check our AN Plumbing Fitting and Hose Size Guide.

Tightening Method 2: Counting Flats
In many cases, a torque wrench just isn't a practical solution. Fortunately, the forgiving nature of AN fittings allows a novel approach often referred to as the "Flats Method." Many engineers actually prefer this method over the torque method because it eliminates variables in friction due to material finishes.
Step 1: Assemble the fittings. Screw down the female nut until finger-tight. At this point the seat is making contact. You can double-check by trying to wiggle the tube portion of the female fitting. You should not be able to see any movement. If you see visible movement, try tightening the nut again while wiggling the tube. If the nut won't turn any further by hand, look for the reason why the nut stopped short.
Step 2: Mark the fittings. Using a permanent marker, draw a line on one flat of the hex on the male fitting and a matching line on the female nut (the two lines should line up). This is your reference mark.
Step 3: Tighten the fittings. Using a wrench, tighten the female nut 1/4 turn, or 1.5 hex flats. Check your reference marks to be certain that the nut has been tightened 1/4 turn.
Step 4: Mark the fittings again. Using your permanent marker, make a new reference mark from the female nut to the hex on the male fitting. The original mark, now offset, acts as a visual reference that this connection has been tightened. The new mark is a visual reference that the fitting is still tight. If this second mark becomes misaligned, it means the fitting is coming loose.
Remove the reference marks before re-using the fittings to avoid any confusion. (Brake cleaner is very effective at removing "Sharpie" ink!) This is why we use a marker instead of scribing the marks.

Too Tight and Still Leaking
If you or a well-meaning helper just couldn't control your strength and cranked down too hard on a fitting, you may encounter a persistent leak. Ironically, tightening the fitting further will probably not stop the leak. In this case, overtightening has damaged the fitting.

If you're lucky, the damage will be nothing more than minor scoring on the sealing faces. That type of damage can usually be fixed by adding a SECO 7 Seal (Part No. 3202-Size) and re-torquing properly using one of the methods above. More extensive damage to the male sealing face can be repaired using a Koul Tools Fitting Fixer (Part No. 3330-1xx).

Step 4 – GM Fuel Filter-Regulator Test Fit
I started this process using my original procedure and attached -6 AN adapters to the quick disconnect lines of the fuel filter-regulator (Parts E, F and G).  The Russel adapter at the fuel outlet just pushes into position and locks while the JCT 3/8-inch fuel inlet line adapter and JCT 5/16-inch fuel return line adapter, are secured in place with a lock clip.

To get a feel for how this was going to fit, I connected a reusable Summit straight hose end to -6AN female fitting (Part D) to each of the adapters.  Next, I removed the GM filter-regulator mounting strap (not needed) and positioned the assembly on the factory filter mount of the transaxle support using a SAE Size 36 Range 1-3/16" to 2-3/4" SS screw clamp.

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< GM Filter-Regulator & -6 AN Adapters >               < -6 AN Straight Hose Ends (FAIL) >

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< GM Filter-Regulator Test Fit  (FAIL) >

Based on the test fit, and considering the radius needed for the 3/8-inch SS hose, it was obvious the assemble was TOO LONG for the available space.  Connections to the tank line, feed line, and return line all have a compromising alignment.

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< Pump & Filter-Regulator                                   < -6 AN, 90 Degree, Swivel Hose End >
   with 90 Degree Hose Ends >

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< GM Filter-Regulator Test Fit w/90 degree Fittings (SUCCESS!) >

The solution was to replace the Summit straight hose ends with Russell 90-degree swivel hose ends (~$10 EA).  I went with the Russel brand because they were in stock and ready to ship.  These units were made in Taiwan.

Step 5 – Fuel Pump Install
Before getting started, note that I removed the 90-degree hose end from the filter-regulator input adapter (bottom) and used it to construct the pump to filter-regulator line seen in previous pictures.

Installing the fuel pump and cover was now just a matter of positioning the cover in place, connecting the tank to pump hose, securing the support strap to the frame, and connecting the pump to filter-regulator line.

I installed all new weather stripping around the pump cover which made installing the support strap a bit tough because the mounting bolt wasn’t quite long enough to start it without some means of jacking up the cover.  The simple solution was a replacement 30mm bolt which allowed me to hang the cover and pump while making position adjustments necessary to connect the tank to pump hose.

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< Longer Support Strap Bolt >                                   < Installed Tank to Pump Hose >

It was also necessary to loosen the filter-regulator mounting clamp so the AN fitting of the connection line could be attached.  I was happy that it fit perfectly!!  Again, I tightened the AN fitting using the 1/4 turn method.

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< Final Filter-Regulator Installation >

Only two (2) more lines require construction, 1) the filter-regulator fuel output line and 2) the filter-regulator to tank return line.  Each of these will be in the 12-inch length range.

Also, I need to figure out the best place to connect the filter-regulator ground strap????????

I’m open for suggestions!!

Stay tuned….

Moving forward, the next step was installing steel compression fittings to adapt the factor fuel line ends to AN connectors.

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< Factory Fuel Lines >

Remove the line clamp for better access to the fuel lines.  A 6 mm Allen wrench does the trick.  Be sure to fully insert the wrench to avoid stripping.  Once the clamp is removed, the lines can be moved away from the body for cutting operations.  I cut the flared ends off the factory fuel supply line (3/8 inch) and the factory return line (5/16 inch) using my Rigid mini tube cutter. Believe me, smaller is better here!!

Note:  Most mini-tube cutters are for SOFT metal like aluminum and copper.  The Rigid unit is pricy but has a good reputation for being able to cut steel tubing.  Go easy for blade longevity.
Reference Part 2 for Compression Fitting and AN fitting assembly Details.

Return Line - For the fuel return line, I wanted to leave factory flexible line intact.  To do this, I cut the steel line 2 inches beyond the connection flare, cleaned up the inside burrs, cleaned the exterior thoroughly, and installed a 5/16-inch steel compression fitting adapter to -6AN male (Part I).  Recall that on steel line, the cut ring makes the seal and the washer and O-ring are not used.

If you go this route, be sure you install the line nut before installing the compression fitting!!  You only get one shot with each cut ring line section.

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< Fuel Line Clamp Removed >                               < Cutting the Fuel Return Line >        
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< Steel Compression Fitting Components >              < Assembled Compression Fitting Adapter >

Also recall from Part 2, that proper compression fitting tightening on a steel line with PVF (Polyvinyl Fluoride) coating is 1 FULL TURN past finger tight contact.  Remember to mark the fitting with a Sharpie to accomplish this.

Feed Line - For the fuel feed line, I just needed to cut off the line flange, clean up the inside burrs, clean the exterior thoroughly, and install a 3/8-inch steel compression fitting adapter to -6AN male (Part H).  Again, the washer and O-ring are not used.

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< Cutting the Fuel Feed Line >                        < Completed Compression Fitting Installations >

Vapor Relief Line - Note in the photos above that the tank vapor relief line broke off at the clamp to the composite hard line that goes to the engine bay.  I repaired this connection with a short hard splice piece to the factory flexible hose, a new piece of fuel line from the splice piece to the factory hard line, and 3 new clamps.

SS Braided Line - The next step was estimating the required length of 3/8 inch SS braided line to connect the GM filter-regulator to the fuel line AN adapters.  I used a soft rubber hose to do this efficiently taking care that my selected routing did not interfere with any moving parts.

Adding Summit reusable -6 AN female fittings (Part D) was the next task.   I prepped the SS hose for cutting with two wraps of Gorilla Tape about 3/4-inch wide and a metal hose clamp. Once I put the clamp on, I trimmed away the exposed tape.  Cutting was done with a 3-inch cutting wheel.  This time around I only cut through the SS braid to avoid filling the hose with rubber “grindings.”

Also, I left the ~1/4-inch band of tape on the hose end to keep the SS braid from unravelling and facilitated installing the hose side fitting.

Note: When installing the hose side portion of the fitting, be sure to only turn it COUNTER CLOCKWISE.  It will “screw” right into place.  Check for full hose insertion before threading in the AN female end of the fitting.  Some thin oil throughout make the going a bit easier.

CAUTION:  Be sure to maintain complete cleanliness throughout every operation.  Lines and fittings should be flushed and/or swabbed to remove any dirt, metal shavings, or the rubber grindings.

Installing the Fuel Lines – At this point, all the connections are AN fittings. Be sure to hand start each connection and tighten finger tight.  I used the 1/4-TURN METHOD for final tightening.

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< Installed Fuel Lines >


Next Step… Checking for leaks     Wish me luck!!!

Raymond-P wrote:Once again, I’m turning to the learned forum community to help me decide the best course of action to resolve my header clearance problem.  If you have any “this worked for me” experience, I would very much appreciate hearing from you!

In my last post, the four relevant pics are shown below.  Cylinder #6 head pipe of the PS header is in full contact with the frame/heat shield that I installed.  The heat shield is only about 1/32” thick and I tried to squeeze a thin sheet of aluminum in the potential gap, but there is NO SPACE.  It’s tight!  

On the DS, the bell housing is about 3/16” clear of the tunnel insulation so there is room for a shift in this direction but not much and I know the cross-member can’t move.  The DS header collector flange has plenty of clearance between the A-arm mount, so no problem reducing that a bit.

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<PS Header Contact>                                                                       <DS Bell Housing Clearance>
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<DS Chassis Clearance>                                                                           <PS Chassis Clearance>

One last thing I checked was the angle of the torque tube since the support bracket and transverse strut provide only vertical support and have no physical engagement.  There is not much lateral space for movement in the TT tunnel and the TA ultimately dictates the lateral position of the TT.  

Theoretically the TA end of the TT could have been shifted to the PS which would contribute to the problem.  But as it turns out, the DS forward dog ear of the TT is all the way against the side of the tunnel and the PS dog ear has about 1” of clearance.  Centering the TT will be necessary to connect the TA and will require about 1/2” of movement toward the PS.  I tried moving it by hand with no success.  Clearly the header is preventing the required movement.   Something must be done to create the necessary clearance so the TT can be aligned.

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                                              <Torque Tube position in the TT Tunnel>

I took some rough measurements to determine how much header clearance is needed to afford moving the TT 1/2".  The approximate distance from the front dog ears to the offending header pipe, is 5.5 ft.   The distance from the header pipe to the motor mount (pivot point) is approximately 6".   Therefore, to move the back of the TT 1/2" at the front dog ears requires a swing angle of tan-1(0.5 in / 65 in) or 0.44 degrees.  Using the same trigonometric relationship, the required dent in the frame to provide clearance for this alignment movement would be tan 0.44 x 6" or 0.046".  That’s a little less than 1/16", but I'm just going to say 1/16".  

Now, from what I understand, the LS motor will “rock” about 1/8” to 3/16” or so toward the DS between load and no-load conditions (someone please correct me if I’m misinformed).  I'm estimating it will rock the opposite direction about the same amount under deceleration.

So the way I see it, I need 1/16" for installation alignment + 3/16" for engine movement, or 1/4" total clearance modification…minimum.  Below are my options:

A. Do Nothing 
    The engine position may normalize post start-up creating the required clearance.  It’s unlikely I’ll be
    able to connect the TA with this option.
The next two require dropping the engine and TT… (12-bolts, MAXJAX, floor jack, trans jack)
B. Frame Modification  ~1/4” depression in the frame.
C. Header Modification.~1/4“ depression in the header.
D. TBD Forum Guidance??

I’m leaning toward Option B right now because I don’t see a significant impact on frame strength, and I don’t want the inside and outside powder coat damage of Option C.  

It just seems logical to drop the engine now and fix this issue before I connect everything else.
If there is a better solution I don’t know about, I would love to hear it.

I’m looking forward to your input.  TIA!!

In the meantime, I’ll be in the garage replacing the boots on my steering rack!

Did you get your TT to fit in the middle? I am having the same issue but I have the standard headers and I do not see any clearance issues. my TT is almost exactly like yours in the picture over to the DS about 1in

viperbmw69,

Yes!  I did get it to move to the center position.  My problem was the PS header.  After creating clearance on frame rail, everything fit perfect.

If you have no header interference then it could be from front cross-member misalignment.  One side of the cross-member has slotted holes to assist in assembly and make alignment adjustments.  Perhaps try loosening the chassis bolts of the cross-member and then pulling the torque tube over to center the bell housing.  If it moves, great, center the torque tube and then retighten the cross-frame bolts.

The torque tube must absolutely be in alignment or you will not be able to connect your transaxle properly.

Loosen the crossmember bolts and the lower mount nuts. Move the torque tube to the center and re-tighten everything. Should be good at that point. An 1/8th inch movement at the engine crossmember makes a large movement at the back end of the torque tube.

learned this one the hard way for sure and was mystified and annoyed with my torque tube being off in exactly the same way.

one of the big things that got me to win this on my final go at putting the engine back in the bay after putting pressure plate on flywheel after my dry fit of the TT shaft was to play with the levelling of engine lift after also extending its reach since the LS went farther deep into the car than what my longest factory reach of my hoist would allow. After changing the pitch of the leveller it really made a huge difference in getting my bellhousing to bolt up much more easily and then with that angle satisfied the cross member bolts were much less stubborn and suddenly torque tube was perfectly spaced and aligned.

Lots of wiggle and shake and checking the angle of the engine and check / double check with a second set of eyes and then it went much easier.

had tonnes of struggle fighting that angle with not enough reach of my hoist to get the engine in enough before the main cylinder touches the bumper. And those issues just made it impossible for torque tube proper alignment. definitely still had to some undo the cross member bolts and bell housing for a bit more wiggle and jiggle and then all of a sudden there'd be a movement to which i suspect a dowel guiding pin had not been completely lined up and then all was well with the world and twisty/crooked issues.

loosen and jiggle, check angles and alignment. took several attempts but on the third time i put engine in it went much much better by paying attention to angle and alignment. i'll stop repeating myself now. lol

Raymond-P wrote:viperbmw69,

Yes!  I did get it to move to the center position.  My problem was the PS header.  After creating clearance on frame rail, everything fit perfect.

If you have no header interference then it could be from front cross-member misalignment.  One side of the cross-member has slotted holes to assist in assembly and make alignment adjustments.  Perhaps try loosening the chassis bolts of the cross-member and then pulling the torque tube over to center the bell housing.  If it moves, great, center the torque tube and then retighten the cross-frame bolts.

The torque tube must absolutely be in alignment or you will not be able to connect your transaxle properly.

Yep Got it!!!! Thanks everyone. I loosened the subframe and mount bolt and installed the TA. Now I just need to re torque