Chevrolet Repair: 95 4.3 Chevy 4x4 clutch, chevy 4x4, clutch plate

Question
QUESTION: The clutch on my friends 95 4.3 V6 5-speed Chevy truck will not disengage.

Clutch disc, T.O. bearing and pressure plate have been changed already, as well as the fork and master and slave cylinders.

It does not seem like the slave cylinder is engaging the fork properly.  The pivot ball does not seem excessively worn, but it is worn a little.

When we torque the pressure plate to the flywheel (new also) it seems that the fingers pull in too far, but I'm not sure.

I am stumped, could it be a problem with the engine thrust bearing, I do not feel play in the crankshaft?  Is there a measurement to check without dropping the pan?

Any advice will be greatly appreciated, as my part swapping does not seem to be doing the trick.

Thanks,

Dan

ANSWER: Hey,

 Ok, I just want to narrow this down a bit first and ask some questions please.

1.  How does the pedal feel?  Is there freeplay at the top or does it have none?  Does the Pedal go all the way to the floor with no resistance?
2.  Was this the original problem or did this start when you replaced the clutch plate and pressure plate?
3.   Are you sure there is enough travel in the slave?  Have you actually watched it move the clutch fork?  
4.  Did you use used parts or an aftermarket rebuilt clutch plate?
5.  Was there any indication of oil leakage from the rear main seal? was the old clutch oily?

w

---------- FOLLOW-UP ----------

QUESTION: 1. My friend said that the clutch pedal went straight to the floor one morning with no resistance, but that he had been having a bit of trouble with shifting (disengagement) for a few days.
2. After problem 1, we suspected the hydraulic system, so we removed the slave, and there seemed to be no contact between the throwout bearing and the pressure plate fingers, when you moved the fork manually.
3. The slave has been replaced a few times while taking the trans in and out several times, it is a poor design the relies on a plastic strap to keep the piston from pushing out to far.
After we reassembled everything, the strap on the new slave cylinder broke because there was no resistance from the clutch fork, it was swinging freely.
4.  It is my friends truck and he has bought the clutch parts at either advance or autozone.  But I'm not 100% convinced he has the right parts.  Are there any measurements we can take?
5.  I don't see signs of oil leakage.

Thanks again.
Dan

ANSWER: If the pedal was pushed down when the slave was not engaged to the fork it is now broken.  Hydraulic pressure will take the end of it apart.
It sounds like something is wrong with one of your new parts.  Is there any way the clutch fork is bent? Is the fork engaged properly into the release bearing? It's a little tough to diagnose this without looking at it but you need to get your pedal problem straightened out first.  If the pedal goes too far (throw is too far on the release bearing) it will be tough to shift and the pressure plate will be damaged.

 Have him try to push the clutch in 80 percent of the way and see if it shifts in and out a bit better.  This would give you an indication of whether or not the slave is going too far.  

Wayne


---------- FOLLOW-UP ----------

QUESTION: At this point if we assemble it and push in the clutch pedal the slave would break again.  As the slave engages the fork, and the fork operates the throwout bearing, but the throw out bearing does not contact the pressure plate.

I am looking for specs or measurements for the whole assembly.  I think that either my friend has the wrong flywheel or pressure plate or the thrust bearing of the crankshaft may be worn causing the flywheel to be too far from the transmission.  Is there a measurement that can be taken from the block, to see if the flywheel has the correct dimensions?

Answer
Hey,

 Not really a measurement.  That really isnt a specification that you follow.  YOu should compare with the old parts and re look up the part numbers.  Wrong parts are a pain in the ass but it does happen.
  It sounds like something is not assembled properly or its the wrong parts.  If thrust bearings were out of the motor that bad you would have engine oil all over the place from a bad rear main.  There is no way its the thrust bearings.

Wayne