944Hybrids: 924/944/968 and 928 V8 Conversions
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HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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how much power can a N/A tranny take?

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Post  kfsaleh944 Sun Mar 15, 2020 5:25 pm

im planning on doing a 1JZ-GTE engine swap on my 944, since the 1jz is 280 hp stock, can the n/a tranny handle that amount of power without breaking the r&p?

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Post  Rich L. Sun Mar 15, 2020 9:06 pm

I think your answer is 20% engine power and 80% driving style. I ran the original n/a transmission in my 944 with a 400 hp, 400 lb/ft LS1 on the track for 3 years, probably 15k miles. I ran it hard for long session on multiple day events. It did fine, no broken parts and no darkened fluid. The only reason I change the trans was to add an LSD. And that trans is working well too.

The trick here is mechanical sympathy. I never did a clutch-drop launch. I never pounded a shift. I never raced anyone stoplight to stoplight. All my usage was gentle launches, good warm-ups and then hard, full-throttle 3rd-5th gear running.
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Post  kfsaleh944 Mon Mar 16, 2020 7:58 am

Rich L. wrote:I think your answer is 20% engine power and 80% driving style. I ran the original n/a transmission in my 944 with a 400 hp, 400 lb/ft LS1 on the track for 3 years, probably 15k miles. I ran it hard for long session on multiple day events. It did fine, no broken parts and no darkened fluid. The only reason I change the trans was to add an LSD. And that trans is working well too.

The trick here is mechanical sympathy. I never did a clutch-drop launch. I never pounded a shift. I never raced anyone stoplight to stoplight. All my usage was gentle launches, good warm-ups and then hard, full-throttle 3rd-5th gear running.

makes sense, ill do my best to drive it with mechanical sympathy. thanks for the advice.

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Post  Hotrodz of Dallas Mon Mar 16, 2020 12:06 pm

But, not everyone is that lucky. I had a built 944 turbo that made 400 whp and 340 ftlbs torque. Installed an NA trans and it lasted about a week of running it on the highway racing other cars. Never dropped the clutch and never speed shifted. Probably raced someone 4-5 times total. It sheared all of the teeth off of the pinion gear and some off of the ring gear. While I know some people make them last awhile, most won't handle more than about 200 ftlbs of torque.
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Post  kfsaleh944 Mon Mar 16, 2020 2:36 pm

it depends on the previous owner and how well he treated the car. But its a risk im willing to take since the car is terribly slow, and i cant stand driving a slow car.

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Post  turbobob924 Wed Mar 25, 2020 9:52 am

I had my buick V6 swap for a while which made 600ft lbs at the wheels
I blew up a couple transmissions due to

Sticky tires
Weak transmission mounts which caused bad shell hop

My current 86 turbo trans is still doing ok

Hope to get my LS swap done this year but it's all in storage now while I'm moving back to Ohio
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Post  Raymond-P Sun Apr 25, 2021 11:37 pm

So guys....

I'm about to put an '86 5P with oil cooler in my build project.  My engine output is unknown but I'm hopeful for 450 hp in its NA state.

At one point I considered swapping the final drive gear but I've decided to put that off so I can get the car together sooner.

I have the case reinforcement plate but after reading Rich L's experience in this thread, I'm wondering if it's really a "must do" modification.  Plus, it seems the adjoining case section is cast iron so where is the gain??

For this year, I'm willing to drive "gently" as long as I can bear it. Rolling Eyes

Thanks in advance for any thoughts.
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Post  LalaLady944 Mon Apr 26, 2021 8:47 pm

Why the need for case reinforcement plate? I see it in the TPC website and I’m curious as to the necessity of it?
I’m just getting started on my 87s LS swap and I’d hate to miss a little something that’s an easy upgrade now than regret it in a big way later. Especially now with the gearbox lying out on the floor for seals and a oil cooler.

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Post  sharkey Mon Apr 26, 2021 10:03 pm

the reinforcement plate is really something that addresses a problem with the na trans, and porsche addressed it in the turbo/s2 boxes. na transmissions are known for the rear case breaking around the rear pinion shaft bearing. there are a couple reasons for this, one is the case isnt strong enough to deal with shock loads that push the pinion shaft back in the case. the other is worn/incorrect bearing preload causing the pinion shaft to have freeplay (its on taper roller bearings and should always have preload), and that freeplay essentially allows the pinion shaft to act like a hammer on the pinion bearings when you get on and off the throttle. porsche/audi addressed the issues with the rear case breaking by going to larger pinion bearings and strengthening the rear case on the turbo/s2 transaxles.

the case stiffening plate is a great idea to help solve the problem on the na transaxles, and its not a bad idea to put one into the turbo transaxle.

i have a thread in the transmission section detailing my AOR rebuild and stiffening plate install, and there are plenty of pics.

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Post  Hotrodz of Dallas Tue Apr 27, 2021 8:18 am

The strengthening plate has guide holes for the shift rods which adds some support as well. This seems to make the shifting a little more precise.
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Post  LalaLady944 Wed Apr 28, 2021 8:26 am

Great explanation. Thank you.
So if my 87s has the original gearbox the plate may not be a necessity but offers a good insurance policy for hard driving. 🙄 yeah I’m probably gonna need it.
Thanks again.

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Post  Raymond-P Wed Apr 28, 2021 9:16 pm

Reposted with photos.


Last edited by Raymond-P on Wed Apr 28, 2021 9:39 pm; edited 1 time in total (Reason for editing : No Pic Links)
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Post  Raymond-P Wed Apr 28, 2021 9:37 pm

LalaLady, (Repost with Pics...)


It appears you're going down the same road as I am.  I just pulled the AGP transaxle from my '87 944S and I have always considered it an NA (normally aspired) engine vs. turbo charged models.  

I'm sure the forum experts will correct me if this is a wrong assumption on my part.

Anyway, I purchased a 1986 5P turbo transaxle with oil cooler, but no LSD, as a starting point.  All the LSD models seem to be unavailable or at best crazy expensive.  With some direction/input from one of the forum gurus, I concluded I could live without the LSD.  (At least for a while!)

Here is a link to transaxle information from Clark's Garage:
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There is a lot of good information on the Clark site....definitely worth a look!

According to this data, your '87944S transaxle is either an AGP like mine or an AGR with LSD.  As far as I know, neither of these have an oil cooler option like the turbo transaxles do.   Perhaps the oil cooler mod you mentioned is a custom add-on with electric pump although I'm not sure that's been done on anything but a turbo transaxle that has the correct oil ports.

Below are comparative pics of my AGP and 5P transaxles... pardon the dirt, I haven't cleaned them up yet.
Turbo Transaxle
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944S Transaxle
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Regarding the case reinforcement plate, Sharkey’s post cleared up a lot.  I did notice that the center case section in both he AGP and the 5P trans is cast iron.(NA vs. Turbo) Other than added support of the shift rods as noted by Hotrodz of Dallas, I’m still struggling with how a steel plate adjacent a cast iron case adds strength to the adjoining aluminum case.

I have the reinforcement plate, and I guess I should read Sharkey’s AOR build thread to see his rational. Other than the hassle of sending out the back case unit to be milled, the modification seems pretty simple.
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Post  LalaLady944 Thu Apr 29, 2021 8:35 am

Thank you for the details.
I am working backwards on my build - rear to front - I want to use an aftermarket pump and small Aero cooler/fan/thermostat unit to keep the gearbox cool on track days. Thought I’d plumb it out of the drain and return to the fill.

I have been meaning to clean off the crud so I can see which gearbox I have but life happens, I’ve had to switch gears to home repairs.

Cast iron being a fairly soft material and any shift rod guides would probably get worn and wonky so I can see how the plate could improve the shift feel.
But on the other hand so can new shift linkage and shirt shifter kit from Only944 and I won’t have to break the case to install it.

My son says I should pick my battles and not spend too much time and money inside the gearbox and save it for a winter rebuild after I get It driving. 🤷🏻‍�


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Post  Hotrodz of Dallas Thu Apr 29, 2021 11:16 am

LalaLady944 wrote:Great explanation. Thank you.
So if my 87s has the original gearbox the plate may not be a necessity but offers a good insurance policy for hard driving.  🙄 yeah I’m probably gonna need it.  
Thanks again.  

My recommendation is don't spend any money on your S trans. It is geared too low for the LS engines. Save that money for a turbo trans. It will be wise money spent on a correct and stronger trans.

Depending on your tire diameter, the S trans will have you at about 3000 rpm at 70 mph.
The turbo trans will be about 2500 rpm at 70.

Plus you won't have to do as much shifting at lower speeds. That's a big plus on the track.
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Post  LalaLady944 Thu Apr 29, 2021 8:24 pm

So that must be why I see folks swapping out original 5th gear for a larger diameter one. I was wondering what was up with that. Thank you HotRod

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Post  Hotrodz of Dallas Fri Apr 30, 2021 8:45 am

LalaLady944 wrote:So that must be why I see folks swapping out original 5th gear for a larger diameter one. I was wondering what was up with that.  Thank you HotRod

Some of the turbo transmissions have a short ratio 5th gear as well. They also benefit from the gear swap. But overall, every gear in the turbo is better than the NA transmissions.
For the deep wallet guys (not me Neutral ), a re-geared 968 trans is even better. Has one more overdrive gear and handles a lot more power.
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