i am currently running a 1987 iroc with stock 305 tpi 5 spd. i believe with the 700r4, i have now had the clutch replaced twice. the first time i brought it in it was doing this rumbling with the clutch depressed, i assumed the release bearing was to blame.. after taking it apart i saw that my apparently new clutch (says the guy who sold it to me) had all the fins of the pressure plate bent out of shape. replaced the clutch and release bearing.... unfortunately for me i got a bad clutch with a warped pressure plate.. again replaced the clutch and the release bearing. drove car for about one month just for light cruises.. now guess what... yup release bearing is acting up again, with clutch depressed it sounds like something is still spinning and doesnt sound like the bearing is spinning freely.... WHAT is going on!! if you have any ideas please let me know

 

oops probably should have put this in transmission and drivetrain my bad

 

For the record, the transmission is a T5. Considering your car is an 87, and assuming it is the stock trans, it is non-world class.

Anyhow, have you checked the clutch master and slave cylinder for leaks?

 

I had (well actually it comes back at times) something similar. With clutch pushed in it would make a hell of a noise and become harder to shift into gear. Took out the tranny and the roller pilot bushing was demolished. Took it out and put in a solid bushing and occasionally I still get the noise. I'm thinking that my input shaft has a slight wobble to it allowing it to hit the bushing but that is a whole other subject.

 

Only two bearings are being used with the clutch depressed- the throwout bearing (which you have already replaced) and the pilot bearing that's pressed into the end of the crank and supports the end of the transmission input shaft.

Guess what I'm going to suggest you replace next?

 

Since it seems like you're eating throw out bearings, I would check to make sure that the bearing isn't riding on the pressure plate fingers when the clutch is engaged (pedal up).

 

thnx for the input guys, going to have it out on friday or maybe monday to take a look at whats going on. i will let you know what i see