70 Challenger Clutch Noise

[Lodicub]

I have a 70 Challenger RT with a 383 and a 4 speed. All factory, all numbers matching. With engine running a high pitched rotating noise develops when letting the clutch pedal out. The noise goes away with clutch all of the way out or all of the way in. It is certainly there when parking the car in either forward or reverse. We are on the  third throwout bearing so we do not feel that is the problem. My class A certified mechanic and an FAA license aircraft I.A. mechanic are both baffled. Any suggestions will be appreciated.

[JonH]

First guess is throw out bearing. Second would be pilot bushing.

[Lodicub]

Thank you

[70 Challenger Lover]

I would also guess the throwout bearing. Some folks like to adjust the pedal so that it has no slack but in doing so, the throwout bearing is constantly making contact which would cause it to fail regularly. Of course riding your foot on the pedal is another way to cause the same problem.

I am puzzled why you are on the third throwout bearing. Does the problem go away with each new bearing only to reappear later? And are the old bearings coming out wiped out? If so, it's definitely a throwout bearing but you would need to identify why they are not lasting long.

[Chryco Psycho]

It could be a broken disc too where part of the facing has broken away , chatters between totally locked & totally released . Don't ask how I know !!
more info would help , did the other brgs change the problem , does the squeal slow down as the pedal is released ?
What type of clutch , 3 finger or diaphragm ?

Welcome to the site from Panama 

[JonH]

One more thought although the symptoms as you describe, do not point to it. It could be the thrust bearing going out on the crank. Not likely given your description, and not even sure you would hear it. Just throwing it out there. Still believe throw out or pilot bushing.