dme

I'm looking for ideas from those who have replaced and studied the wear patterns on their clutches.

I've been trailing this issue with my clutch for several years. New clutch followed by vibration/thumping in the clutch pedal after 1 or 2k miles. I take the clutch apart and the only obvious issue I find (the first time...and second) is excessive play in the throwout bearing... What is causing it?

What causes the feedback on the clutch pedal? (only after high torque/high rpm driving)
Possibility: the throwout bearing (TB) is moving off center (there is play in the throwout bearing between the fingers when at rest). The first time you use the clutch, the fingers squeeze the TB back to center and the vibration is gone.

Shouldn't the fork hold the TB in place and prevent it from moving off center?
The fork holds the TB in one dimension, but not two. There is sign of wear on the left fork arm inside from the normal wear surface (the bearing moves in and out (more to the left side) between the arms)

What causes the premature TB wear?
I think this is caused by the wear in the clutch fork (CF) arms. One side is worn more then the other side and therefore one side engages earlier then the the other. If you have more pressure on one side then this is going to 'kink' the bearing.

Is this caused by an overly worn CF arm, or should I carry this further back to a worn/bent CF shaft (the needle bearing have been replaced previously) or even all the way back to the clutch housing (not seated properly or 'bent')

I have obtained a another 'used' CF which shows less wear. Everything else from the pilot bearing back to the torque tube looks perfectly fine. My only clues are wear marks on the clutch fork. I hate to put this back together again only to have the issue reappear in a couple thousand miles.

Shoot me down or tell me why I might be on the right track. Any similar experience?

Van

The throwout bearing is held in "location" by the guide tube that bolts to the inside of the bell housing. How's yours?

Mike C.

Both of those fork ends look pretty worn although I'm not sure it would cause the problem. Does the guide tube show signs of wear on one side only? A bent CF shaft seems like a long shot but it should be easy enough to check (roll it on a known flat surface). I assume the TOB is new also?

xsboost90

ive seen about five of these cars that did the exact same thing.

dme

Your right on the guide sleeve. I missed the obvious there. I had looked inside to see if there was any scoring from the TT shaft and completely ignored the outside. Heck, I didn't even consider the guide sleeve for keeping the TB in place. Once I cleaned it up and took a look, there is definitely uneven wear on one side of the sleeve. So, symptom or a cause? Either way I'll drop by Zims tomorrow and add the guide to my list of parts.

Thanks for the feedback. Nobody around here to throw out ideas. The wife's eyes just glaze over when I talk about this stuff.

xsboost90

i put a new clutch, TO bearing, guide sleeve, pin, fork bearings, PP and resurfaced flywheel in a turbo and it still did this.

Mike C.

One other thought; I believe there should be 2 dowel pins that align the bellhousing to the block. If one or both of these are missing, the bolts may allow enough misalignment to cause a problem.

dme

Your not making me feel very optimistic. After this time (second attempt) I will have:
1. checked the flywheel
2. new pilot bearing
3. new friction disk
4. new pressure plate
5. new release bearing
6. new guide tube
7. rebuilt slave cylinder
8. checked torque tube

I'm even replacing the motor mounts and making sure the engine is in straight (yeah...desperation move). Motor mounts have always been a pain in the butt to put in this car. It is a lot easier to manipulate the engine when the TT isn't attached. If this doesn't do it then ...

boostskillz

I had this problem on a GMC with a Duramax/ Allison combo, three other dealers had put in transmissions without noticing the dowels were missing, replaced them, no more issues. I'd def. check that.