Clutch release bearing and fork - Help request

[medic911]

I have been trying to get my transmission and engine re-mated (1988-stock) after dropping them to fix some oil leaks. Having a heck of a time with the forks and clutch release bearing.

After trying to mate these puppies by myself, had the brilliant idea to use a little craft hot glue to hold the bearing in place while inching the fork behind it (with phone help from Phillipj of this forum). Seemed to work but I didn't really like the look of the interface between the fork and bearing. It just didn't look solid. I thought that once the tranny and engine were bolted, all would be well.

Apparently not.

After putting the engine/trans back in the car, the first thing I tried was the clutch. Obviously not working. Using a fiber-optic scope I have, peeked in and sure as *****, the fork and bearing have parted ways. I can still see the bearing, at least the top tongue, but somehow the fork has popped off and is now on the wrong side.

Now faced with pulling the engine/tranny yet again (third time for this).

Any ideas on what the heck is happening and how to fix it?????

BTW-The clutch was working perfectly before I dropped the engine.

thx. Jeff

[Ken911]

Well when you bolt the tranny to the engine just look in that vent hole in the top and you can see if it's lining up as you slide them together. This is assuming you didnt make the mistake of dropping the engine by it's self and leaving the tranny in the car. if thats what you did just pull the tranny out line them up and bolt them together on the garae floor so you can see what you are doing.

[medic911]

Did it on the garage floor so had a good view. Not sure you could do it in the car if the pieces were separate. (Tried that..fail!!!)

[Ken911]

LOl yeah usually when people have trouble it's because they are trying to connect them in the car. you have all the linkage removed from the tranny correct? especially the spring? Any way to double check it's connected correctly i reach under and try to rotate the fork after it's connected. if it rotates then you missed the ears on the throw out bearing. I have also reached into the hole with a long screwdriver to rotate the throw out bearing to make it align better as i was sliding it together.

[medic911]

Ken911. Yeah, I had the spring off and both the engine and tranny on the floor. Could see the mating of the fork on the bearing fingers. Was really surprised to see it become disengaged during install. Because I hot glued the bearing in place, it is less likely that I engaged only the top finger and not the bottom but I suppose it's possible even though I think if I did that, the nearing would swing out on the top as the bottom of the fork pushed in the bottom finger of the bearing

The definition of insanity is doing the same thing over again and expecting a different result so not sure how to make sure it's rock solid this, the third, time.

[krasuskyp]

nothing helpwise to add unfort

but

I'll add

^this^ is toootally why I retorted "no thanks" to all my idjut friends' suggestions "dood yer gonna do the clutch while the engine/trans are out right?"

I know me

I know my luck

"this" would be me

well, that and the fact my spring center'd clutch only has like 25k on it and is fine

good luck, sorry to hear - I'm sure w/ the insight of some of our brethren here you'll be squared away in short order

[jwasbury]

I've re-united trans with engine a couple of times. It can be a bit tricky. As Ken mentions, the key is peeking in that access hole to be sure everything is lining up. You have two variables you must work as the trans and engine are being pushed together: 1) the angle of the release fork (which you can control from the bottom of the trans by keeping a hand on the splined shaft), 2) the position of the "tangs" on the throwout bearing (which you have a partial view of from the inspection port at the top of the bell housing).

I think this is a two person job. One person controls the release fork angle and using a screw driver insures the throwout bearing "tangs" are positioned for the two parts to correctly interface. This is the finesse job. The other person is the muscle - pushes the trans around. That throwout bearing really wants to rotate, and if the position of the tangs is off by even a little bit, the release fork arms will push them out of position. Since you can only see the top part of the throwout bearing tangs from the inspection port, its not always obvious if the position is correct.

Good luck

[Ronnie's.930]

Medic, you mention in your first post that the first thing you did after installing the engine/transmission unit was to try the clutch, and I just want to double check that you did this before starting the engine for the first time. I ask, because if you start the engine for the first time, with the clutch cable unhooked (clutch arms free to move about with no resistance from cable, omega spring, and so forth), release bearing fork can move enough for the release bearing to come off of the fork. Unfortunately, I know this from experience, and got to do a gut punch, "do over" for that very reason.

Once the release bearing and fork are situated correctly, and the fork arm is not allowed to move around after that, there really is no way for the fork to come off of the release bearing.

[jwasbury]

Originally Posted by Ronnie's.930

Once the release bearing and fork are situated correctly, and the fork arm is not allowed to move around after that, there really is no way for the fork to come off of the release bearing.

^Ronbo is spot on. If everything is correct, once the trans and engine are bolted together, the release fork and throwout bearing are captive and can't come apart, and the bearing "tangs" cannot rotate. This is something you can verify before you reinstall the engine and trans in the chassis.

[krasuskyp]

Originally Posted by jwasbury

...other person is the muscle - pushes the trans around.

and

Originally Posted by jwasbury

^Ronbo is spot on.

ahHA!

I just KNEW Ronalittle's been aimin to grow a puny muscle or 3 to best push all those trans'es around.

Makes perfect sense now, thanks for confirming he's "spot-on". We all know which spot (manstarfish)...

[Ronnie's.930]

^^^ Paul, would you like to see my errrr, ummmmm, "muscle" - pics (need a very large computer monitor to get the full effect) or in person?!?!?!?

[Ken911]

I guess it comes with practice this my 4th or 5th? clutch plus a couple times out for rebuild. I always do it myself just make sure it's lined up correctly. Rotate the fork about 45 degrees then wiggle and push it together a little at a time keep checking the alignment through the hole. If it starts to move just stop and stick a screwdriver in there and adjust it. Usually i have the engine propped up on blocks on the heat exchangers, so I hold the engine from tipping with one hand while I lift and slide the tranny on with the other. After starting it over the studs with both hands.

[medic911]

Pulled the engine again and retried the fork/bearing connection. Tan out of time to hook up clutch springs etc. will report when I get back to it maybe sat or Sunday

[kas930]

Since I happen to be getting ready to re-install my motor/transaxle and I had taken a picture of the area in question I thought that I'd share. I tried to circle to clutch fork.



I'm also very proud of my dolly set up. With this configuration and two jacks I was able to roll the motor/trans in place and mount by myself in about 15 minutes.

[Ronnie's.930]

Originally Posted by kas930

I'm also very proud of my dolly set up.

You should be - that rig looks very nicely done!

[JFairman]

All the clutches I've done on BMW's are the more common type where the throw out bearing pushes on the clutch spring and they are very easy to assemble.. They hold big horsepower work smoothly and they work fine.
Why did Porsche do it this more difficult to assemble way with the throwout bearing pulling on the clutch spring to disengage it?
Do they just like to over engineer things to make them more difficult?

[medic911]

Nice pic of the bearing. Love the garage. If my looked like that I wouldn't need a kitchen!!

Dropped, re-engaged the bearing ad remounted engine yesterday. Will try clutch tomorrow. Looked at their, I am amazed how tenuous the interface between he fork and bearing fingers appears to be. Doesn't seem to be that great a design. My 1988 is my first Porsche so I don't know if they changed this design later on. I hope so.

Thanks for all the I info. Will repost when I re attempt Monday afternoon.

[mreid]

I don't know if this helps or not, but it seems your year requires a fork modification:



Our host sells the kit:

[Ronnie's.930]

^^^ 1988 (the OP's year model) still uses the cable operated release bearing lever (not the hydraulic one pictured above) - that began for the Turbos in 1989.

[mreid]

Ah, thanks for the clarification!