Techno Duck's LS1 conversion

As Harold said, it attaches using the original bracket from the 944. Look back at the second post on page 11 and i posted some info on mounting it.

Just got back from Hershey where the car was well received. One or two looked and shook their head with the 'what the hell...' attitude but i had a dozen or so people i talked with in length about it. Mostly everyone just laughed when i opened the hood and showed them   .

I currently have around 1100 miles on the swap. The car performed fantastic today though it was not without some issues that popped up upon arrival. A quick pit stop at a Target parking lot and i was back on my way. Ill explain later... for now i need to relax with a beer.. my right ankle is killing me from the 400 miles of throttle i was giving it   .. seriously its sore!

Had some shifting issues pop back upon arrival at Hershey (About 200 miles). The car drove fantastic the last few days and on the entire ride out. I was driving with a group and we were hauling ass, car averaged 19mpg on the way out (untuned!).

When we got to Hershey i was basically unable to get the car into reverse. The clutch felt a bit 'off', just hardly noticeable that it was not as firm as it usually is. First gear was difficult to engage as well, the car basically needed to be rolling just a little in order to get it in. Basically it was shifting via all synchro i think. About 40 miles into my trip home i decided to stop and bleed the clutch. It was 95% highway the entire trip back, but i knew i would likely get caught in traffic in Manhattan (Which i did!). Bought two pints of brake fluid from one of the most sketchy Autozones i ever visited, got out of dodge and stopped at a Target parking lot. The remote bleeder line is a god send, bled the clutch right there in the parking lot with an empty  water bottle and a 11mm and 14mm wrench. The clutch felt immediately better, shifting into first was now possible but reverse still extremely difficult.

I got the usual black fluid, on the right is what i pulled out in the parking lot. On the left is what came out after i bled it again when i got home. I know this is a common issue among Corvettes.

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I noticed the dust boot on the pushrod of the master cylinder was a little wet with brake fluid today. Rebled the clutch again and it is not at all better. Reverse is still nearly impossible to engage with the car running, first gear requires a bit of force (too much for normal). Car off, it shifts beautifully.

I have a few things to check tomorrow, going to check the clutch is fully disengaging. Then will see if swapping the shift linkage rod back to the original makes any difference.

This shifting issue is strange as its very similar to how the car felt previously with the old transmission that was uber low on fluid. Its getting frustrating because this is the only issue the car really has and it really ruins the ability to drive it. I was really expecting a good bleed to fix the difficult first and reverse engagement, but it hasnt. I was thinking its possible the master is not disengaging the clutch fully, as evidence by the fluid around the dust cover. But really not sure what to think right now.

Air gets in my lines, probably by the fluid boiling there are no leaks, and the shifting deteriorates. I open the remote line tip, immerse it in the clutch fluid reservoir, pump the pedal a few times, close the nipple on the remote line and the shifting is greatly improved. The last time I did this method the line was kept low to not create a high point and the shifting has been better than ever. Good luck. Your car looks great, BTW.

I'm having almost the same issue.. mine just gets hard to shift into first and reverse but not impossible. Was starting to wonder if my trans is bad similar to how yours was. Whenever I bleed the clutch the fluid is all black, you'd think there has to be a fix for this by now? The other day I bled it with some lower quality fluid, was fine for a couple days and then went to sh*t very quickly. I wonder if the higher boiling point fluid makes a difference?

Personally, i dont see how heat could be causing the shifting issues. The clutch line between the master and throwout bearing is not routed anywhere near the exhaust and also has a thermal sleeve on it, same with the remote bleed line. This same thing was happening previously with my other trans and it was not at all hot out, i am talking between 30-40 degrees ambient and i was just cruising around my area, no track or hard driving. Today it was maybe 40-50 ambient, no traffic at all on the way and probably 170 miles of the 200 i did was all highway.

The black fluid as i understand it is clutch dust as analyzed by some of the Corvette owners. So maybe that is causing some underlying clutch disengagement issues.

I am just really at a lost as to what is causing this 1st and reverse engagement problem. Its getting really frustrating. Going to spend some time on it today, hopefully i find something definitive.

Do you have a short shifter installed? I'm using XSchop's short shifter along with the thrust washer mod on the shift lever up front. Also have the small shift linkage arm with new ball joints but have not installed it yet. I'm wondering if the short shifter could be part of the problem.

Also, one of the corvette guys was saying he had problems with the Valvoline synthetic fluid. But I haven't noticed it to be any worse than the other brands I've tried.

Jon,

If you have brake fluid on the dust cap, there is a good chance you have worn a groove in the master cylinder by not having the pushrod properly aligned. I killed 3 mc's before getting it right. Not sure that this is the cause of your issues, but you should check it before it goes ka-put!

Supes, using the original linkage right now however i am using the linkage arm from Only944 (see above post) and also the shift lever with the thrust bearings on it. I dont think these are causing the problems because the car shifts perfect when the car is shut off without a hint of issue. Depending what i find when i pop that inspection cover off i may put the original shift linkage arm back on and see what happens.

Tim, that is something i was considering also. I was thinking perhaps because some fluid is coming past the pushrod seals its not giving full fluid displacement now. Going to try and rule this out today. Now regarding that angle, the master i am using is basically mounted directly onto the fireall using the sandwich plate that can be seen in older posts. Is that angle built into the 944 master or is it the firewall which gives the angle?

I'm getting very suspicious of 'cloned' parts lately.

Why not give the new and German made version a try:

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Pulled the inspection cover and actuated the clutch with the car idling. Its clear the clutch is not fully disengaging. The driveshaft never stops spinning with the clutch depressed. The only time it does stop is by shifting it into gear.. the synchros are probably not to happy with me right now

Ugh..

Ive got two spare master cylinders, a .7 and a 7/8" bore. Ill throw one of these in to get the car drivable again. Will take the 3/4" bore apart and inspect the bore.

What a pain in the ass.. i am getting sick of swapping these things out  

This 3/4" bore didnt last long, it has around 7-800 miles on it. Of which easily 2-300 miles was highway done yesterday.

I am tempted to get a stock master cylinder and see if that works.

That sucks. I'm kinda in the same boat. I started with a 13/16 master which didn't give me sufficient release of the clutch disc like you're getting. I swapped to a 1" which made the pedal very heavy but things worked well. But lately I've noticed the friction point rising earlier in the pedal travel. Instead of about halfway down, the clutch doesn't bite until the last bit of releasing the pedal. I'm worried I'll start getting clutch slip soon.

Should I pull things apart and re-measure the need for a shim? Should I swap to a smaller sized master? Should I just leave it? And lastly, why has this changed? Any thoughts?

Rich

Is it a result of the bell housing design? It seems to be mostly the corvette owners getting the black fluid. And most of us are using the corvette bell housing.

Check this thread regarding the black fluid. I believe it is just a not so great throwout bearing design. The way i see it, the bell housing is well vented for us with the design of the oil pan (plenty of gaps on the side!). So i would think its getting plenty of ventilation.

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I made some good findings today, the root cause was definitely the master cylinder. Will report back later.

Yikes...knew the clutch dust problem was bad, but not that bad....and what a great tutorial:

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(opens full screen)

And this is showing a C6 slave...the C5 slave doesn't even have the green protection bellows (yup, under the dust, it's green).

"over pressure" venting through the filler cap seems important as well.

Gotta be a better way than changing the fluid every few weeks 

btw...at 2:40 I think he has the movement backwards...no big deal.

I looked into the angle of the master cylinder and sure enough it was off. The firewall has the angle built into it, the pictures explain it best...

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Now here is how the master cylinder was mounted, the angle was off quite a bit. I didnt notice this little detail on the many times i have swapped master cylinders.

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After some more trimming...

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And further modification to the mounting bracket to fit the recess on the firewall...

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I took the old master cylinder apart and the bore does have some very light marks in the bore. It is a little surprising because the marks are extremely faint (But noticeable) and do not feel rough, but you can feel the difference in smoothness in the bore. The plunger / piston is metal, i wonder if something like teflon would have been a better (though more expensive) choice so the aluminum bore isnt chewed up by misalignment.

No pictures of the bore, difficult to get anything with a camera.

The first few shifts were perfect, but after 6-7 miles the clutch is not disengaging again. I did have some trouble bleeding it, so i suspect there is still air in the system. Going to pressure bleed it tomorrow.

I am a little untrusting of this still. Before buying another .75" bore master i may just continue running the 7/8" for a few hundred miles and see if it lasts.

I dont think the clutch dust will cause anything other than premature failure of the throwout bearing. Then you have to wonder how many C5's and C6's are around where the owner is not flushing the clutch on a routine basis. Personally i do not think it will cause any difference in the throwout bearing travel, also the dust contaminated fluid will never see the master cylinder.

Rich, i noticed the same thing when i was trying to figure things out before the transmission was swapped out. Obviously that was the main reason for my shifting issue but i suspect i had a few other things going on also. One thing that i found that basically fixed your symptoms was adjusting the freeplay on the pedal. Previously i had set my pedal with basically zero freeplay. So as the car heated up i am guessing the throwout bearing was pressing on the pressure plate with some small amount of force constantly. I would bleed the clutch, problem would go away. Drive around maybe 20-30 miles and the pedal engagement moves again. After giving the pedal 1-2mm of freeplay (as it says in the factory workshop manual) i never had those problems again.

This worked for me atleast.

Honestly with all the things that went into this engine swap i did not think most of my issues would be shifting related!

Thanks. I'll look at the free play. Glad you're making progress. Agreed on the shifting. That's what ended a session of mine stranded on track recently, short shifter came disconnected.

Rich

Those little grooves cause havoc. During one race it got so bad that hydraulic fluid was squirting onto my shoe every time I depressed the clutch.

This is getting very frustrating. Rebled the system again today with the help of a friend. Shifting it in the driveway it felt perfect. After 1-2 miles i was having difficulty getting into reverse again. After 20 miles it is right back to where i started, difficult to engage 1st gear at a stop, even 2nd from a stop takes more force than normal.

Really unsure what it could be, going to check all the fittings tomorrow and make sure everything is tight. Maybe even pressure test the system overnight.

This is something i was thinking about a few days ago, the master cylinder cap i have has no vent in it, i was thinking perhaps the system is pulling a vacuum in the reservoir as a result, so it cant draw fluid out. Seems kind of far fetched, but i have seen master cylinder caps with tiny holes in the caps before. I think ill try drilling a very tiny hole in the cap and rebleeding the system (for the 100th time).

Torque tube misaligned? Check to see if any of the adapter bolts came loose. I had a problem when the bolts came loose and the shaft was binding on the pilot bearing causing shifting issues. Does the shaft spin freely by hand with the clutch depressed? When this happened to me I could barley spin the shaft by hand with the pedal depressed.

The input shaft does spin freely by hand. I will check the bolts though, probably wouldn't be a bad idea anyhow with the extra vibration / rhythmic shake at idle.

Unfortunately i won't have too much time to mess around with this until the weekend. Getting pretty annoyed too.. Wasting way too much time off on this car again.

My plan of attack is to check torque tube and adapter plate bolts, rebleed the clutch again and vent the master cylinder cap with a tiny drill bit. Then see how that goes. Next up putting the original linkage rod back in.

If those things don't help.. I am seriously considering a Tilton pedal box. Hope Thom remembers how he installed the one in Milkman's car    

Got a screw in my right rear last night also.. This car is a real bummer sometimes.

Different car, but when I was having issues shifting out of gear in my Audi it was a bad pilot bearing...

Rebled system and vented the cap. Before leaving i can go through all of the gears no problem at idle (reverse also). After 25 miles i came back home. 1st gear is a little harder to engage, cannot get it into reverse anymore. So venting the cap made no change.

I am going to let it cool off overnight and try to go through the gears again tomorrow. I wonder if its heat related.

Something ive noticed also but forgot to mention. Where i usually park in the driveway has a very slight incline. If sitting in neutral the car will roll back very slowly. Ive noticed i can put the car into say first gear (car running), clutch in and off the brake. Car will roll back very slowly. Now if i start to release the clutch, maybe 10% into its travel off the floor the car will stop rolling. Push it back to the floor, car rolls, release slowly to 10% car stops rolling. I can do this consistently at will. Even on flat ground though, the clutch does not fully engage until 80% or so travel, this is to be expected with the 7/8" master cylinder i am using. The car does the same on flat ground, you can just  barely feel the engine 'bog' a little. Its really extremely faint, this engine has so much torque even at idle it hardly flinches.

Another thing i noticed. After bleeding the clutch, i can easily go through the gears at idle. I pulled the rubber inspection cover off the transmission bell housing and recorded what the driveshaft coupler is doing at idle. Push clutch in, start car... driveshaft does not spin at all, or atleast hardly any. Release clutch, spins at idle speed. Release clutch, driveshaft slows down as expected. Now when the car is difficult to shift, i can do the same test. Instead when i start with the clutch in the driveshaft spins immediately up to speed.

I am really not sure what to think at this point. Not sure if the hydraulics are to blame or there is an issue somewhere with either the clutch assembly, pilot bearing or input shaft.

I think a good check would be to start it up with the bell housing inspection cover removed and see what the clutch does with it running... though i am a little hesitant to get under it with it running and the inspection cover off... like my face will be right next to spinning drivetrain!

Having the car tuned on friday but i am quickly loosing interest in this car again, just wasting too much time on it. Probably going to park it and leave it be for a while after the tuning is done.

Did you ever try swapping the HTOB?