Squeaking Hydraulic Clutch?

[79vette]

I have a 1986 K5 I swapped an SM465 and a hydraulic clutch into about 5 years ago. I wore the first clutch out with a bunch of off road shenanigans, and replaced it about a year ago. I also did a new fork and ball stud with the new clutch, since the 35+ year old originals were pretty worn.

It was dead silent for a year, and was the best feeling truck clutch I've ever experienced. For about a week, there has been an increasingly loud squeak coming from the bellhousing area when I press the clutch in and the pedal feel has become really coarse and rough, like a bearing filled with sand. I pulled the fork boot out and lubricated the pivot stud and fork as best I can with the transmission in place and it got some quieter and feels some better, but the squeak is still there. Its pretty loud if you press the clutch slowly, and is much quieter if you press it very fast.

Has anyone had a similar symptom with a hydraulic clutch in a square body? I can't imagine what else could be squeaking except for the actual pressure plate fingers, and any lube on the pressure plate (even if it was possible to access) seems like a bad idea...

My '88 square body has the original ball stud and fork and at least a 10 year old clutch and its dead silent, so I am not sure what is wrong with the new parts in my 86 that would make them suddenly start squeaking after a year of service. I'd really hate to have to change the stupid ball stud every year just to keep it from squeaking. Its at least a day of rolling around on my back on the concrete to get the transfer case, trans, and overdrive splitter out of the truck to get to the clutch and then put all that crap back in...

[Richard]

Sounds like the throw-out bearing is shot. Was it replaced with the new clutch? Unfortunately, transmission has to come out to replace the bearing.

[79vette]

Originally Posted by Richard

Sounds like the throw-out bearing is shot. Was it replaced with the new clutch? Unfortunately, transmission has to come out to replace the bearing.

Yes, I replaced the throw out bearing with the new clutch. It has less than 10k miles on it.

It does not squeak at all when the pedal is not being moved, only when you are actively pressing it in. With the clutch all the way in, all the way out, or with the clutch pedal held stationary in a partially-engaged state there is no noise. It really sounds like it is coming from the pivot stud, but I could be wrong...

I would have expected a throwout bearing to make noise when under load (ie when holding the clutch released), but this one does not do that. Its just squeaky when the pedal is moving. Also the noise does not change with the engine on or off. Is it possible for a throwout bearing to somehow make noise when the engine is off and the vehicle is stationary?

[Richard]

Originally Posted by 79vette

Yes, I replaced the throw out bearing with the new clutch. It has less than 10k miles on it.

It does not squeak at all when the pedal is not being moved, only when you are actively pressing it in. With the clutch all the way in, all the way out, or with the clutch pedal held stationary in a partially-engaged state there is no noise. It really sounds like it is coming from the pivot stud, but I could be wrong...

I would have expected a throwout bearing to make noise when under load (ie when holding the clutch released), but this one does not do that. Its just squeaky when the pedal is moving. Also the noise does not change with the engine on or off. Is it possible for a throwout bearing to somehow make noise when the engine is off and the vehicle is stationary?

If noise is there when motor is off check the linkage. You mentioned a bearing feeling like it was not smooth which is why I suggested the throw-out bearing.

[cerial]

If it squeaks with the truck off it may just be the rubber pad or the pedal bushings.

Pull the rubber pad off the pedal and see if it eliminates the squeak. If it does rock auto has new ones for cheap.

60% of the time it works every time.