Clutch didn't return, dropped engine/transmission to look inside

[OsoMoore]

Hey folks,
I had a failure where the clutch went to the floor and wouldn't return unless forced. The clutch release lever would not return to the engaged position.
I dropped the engine and removed the transmission. The fork seems in good shape, but some of the other components didn't look right. Here is what I found inside.








Something looks wrong with the loose ring inside the clutch plate and on the transmission input shaft. I'm also not sure if the ring the fork engages looks OK.

Any advice or ideas are appreciated - thanks!

[Blamecanada]

Looks like your throwout bearing has come apart. Novice myself. Here is a pic of mine when I split transmission and engine.

Good luck.

[Blamecanada]

[Walter_Middie]

Blamecanada - good picture. Here's a similar picture of mine:



It's possible that your throwout bearing just broke from old age and use, but double check the fork that it is not broken. Mine broke on the back side and was very difficult to see when it was mounted on the car.



You can see the top leg of the clutch fork has a crack in it. As you push on the clutch pedal, the asymmetric force on the throwout bearing will destroy it.

[OsoMoore]

Thanks for the input guys. I took a bunch of high quality pictures of your fork, and it looks good.
I'm going to look up how to replace the throwout bearing . I didn't find anything helpful in the clutch replacement article on our host.

[OsoMoore]

A few questions for the experts:
1) My clutch fork is hard to rotate on its shaft. I almost can't push it with one hand, without bracing my grip against something else. Should it be hard to move? Maybe its bearing is going out?
2) Regarding the old bearing (Release? Throw out? Not sure which it is called.) that was loose when I opened the car - is it broken entirely? Or some parts reusable?
3) Is there anything else I should serious consider replacing while I'm in here?

[Blamecanada]

Porsche calls it a clutch release bearing. Yours looks pooched. Think it comes with everything when you purchase it. The shaft the fork pivots on is clutch release shaft. It rotates on three bushings. You can remove the fork with a 4mm drift to drive out the split pin. Clean the shaft and grease it while probably help it move more smoothly.

[yelcab1]

You should be able to move that shaft with your fingers. If not, it needs service.
Your Throw out bearing is gone, it needs to be replaced and put back on the pressure plate.
Depending on the condition of your pressure plate an clutch, you might need to replace those too.

[RWebb]

wood nymph's hair is close but not a perfect match to car's paint

while yer in there... reach behind the fork with a bent probe and run it around to search for any cracks on that side

measure end of the forks for wear


I bet somebody did work w/o replacing the TO bearing - always a good precaution to toss those...

use a high temperature grease on everything in there - you won't a color that won't run...

[Gordo2]

Your throwout bearing appears to be shot...

Normally replaced when the clutch pack is replaced - but if your clutch & pressure plate are in good shape, you can just replace the throwout bearing and reinstall.

Good luck.

[Flat6pac]

At this point, drive out the roll pin on the fingers and drop the vertical shaft out of the bell
Remove the piñ on the long idler spring clutch arm. It’s tapered, only droves one way. Lose the pin.
What i do is use a small Allen to hold the fork in place on the vertical and hammer the roll pin in displacing the Allen.
Remove the long Arm and clean and lube everything.
The measurement across the fingers for the throw out bearing is 75mm.
Bruce

[s5uewf]

replace the clutch guide tube, as well, while you have it apart. It may just be the light but yours looks to be showing some wear. That will affect smooth clutch/pedal movement, as well

[porsche930dude]

the sticky pivot is what most likely toasted the throwout bearing. It kept too much pressure on it like resting your foot on the pedal all the time

[OsoMoore]

Originally Posted by yelcab1

You should be able to move that shaft with your fingers. If not, it needs service.
Your Throw out bearing is gone, it needs to be replaced and put back on the pressure plate.
Depending on the condition of your pressure plate an clutch, you might need to replace those too.

I dropped out the shaft and cleaned it up some. It looks clear of wear.

Originally Posted by s5uewf

replace the clutch guide tube, as well, while you have it apart. It may just be the light but yours looks to be showing some wear. That will affect smooth clutch/pedal movement, as well

Ok, that sounds good. I'm not sure how to get the guide tube out. It seemed very solidly in place. Any tricks?

Originally Posted by porsche930dude

the sticky pivot is what most likely toasted the throwout bearing. It kept too much pressure on it like resting your foot on the pedal all the time

That makes sense. There is some wear on the clutch fork edges (see pics). I'm not sure how bad it is.









EDIT: Nevermind, wrong tube. Is see what you mean, I'll re-inspect.

[rokemester]

Originally Posted by RWebb

wood nymph's hair is close but not a perfect match to car's paint

while yer in there... reach behind the fork with a bent probe and run it around to search for any cracks on that side

measure end of the forks for wear


I bet somebody did work w/o replacing the TO bearing - always a good precaution to toss those...

use a high temperature grease on everything in there - you won't a color that won't run...

+1 on very cute pic of “wood nymph”, adorable.

[pete3799]

You will need to drive out this pin in order to get the lever off of the rod. Clean and lube it so that it spins freely on the shaft. No need to replace the pin if you don't want to. I left mine out and just squirt some lube in the hole once in a while.

[Blamecanada]

To get the guide out you need a piece of heavy wire. Think welding rod stiff. You need to put a hook on either end and bend it semi circle(ish). Each hook goes into small holes at end of tube. Now use this loop to pry with a screwdriver or something similar against the end of the output shaft.

Take the two phillips screws out first. Takes a little effort but not bad.

[Blamecanada]

The wear doesn’t look too bad on your fork to me. Clean it out good inside the bushings where the shaft you took out rides before greasing. I just did a partial tranny rebuild and some minor work on my 915/3.0. So much too clean.

[hughc]

Originally Posted by Blamecanada

Porsche calls it a clutch release bearing. Yours looks pooched. Think it comes with everything when you purchase it. The shaft the fork pivots on is clutch release shaft. It rotates on three bushings. You can remove the fork with a 4mm drift to drive out the split pin. Clean the shaft and grease it while probably help it move more smoothly.

I just went thru a similar operation on my 83 sc.
The clutch and T/O bearing were still serviceable but I opted to replace them since I was already " there".
I manually re-surfaced the pressure plate and flywheel as there was no apparent damage other than dirt.
I automatically replaced the pilot bearing and the throw out bearing. The T/O bearing guide tube had noticeable wear on it
I removed the T/O bearing actuating shaft, cleaned and regreased it with multipurpose grease. Someone mentioned high temp grease and that can't be a bad idea.
I also replaced all three seals on the T/O bearing actuating shaft. Inexpensive and now is the time to do it.
Here is a caveat. While replacing the T/O bearing guide tube you should also replace the transmission input shaft seal but be careful
You must either empty the transmission of its oil or support the transmission such that the input shaft is pointing upward. Other wise you will end up with just another mess.
Another thing to consider, after you have serviced the T/O bearing actuating shaft and have it re-installed in location, be sure to properly locate the omega spring while the transmission is on the floor, (bench, kitchen table) as it will be so much easier than trying to do it after the transmission is in the vehicle.
Good luck.
Hugh

[Marc Bixen]

Change the fork, change the fork, change the fork. Enough said!