1960 clutch issue w/4 speed

[Paul J.]

Any help will be huge,
purchased a rebuilt 3 finger clutch, clutch plate and bearing. Replace blockers, bearings and is flied with 85/90w gear oil, RPM is at 600 (trans is shifting perfectly). My problem is, I'm unable to adjust the free play to 3/4-1" it is at zero free play now. the trans will not go into reverse at all without shutting it off , putting it into reverse and then restarting engine. It will go into 1st without grinding but I have to really force the pedal into the floor. Will an adjustable fork pivot help with this symptom? I really would like to make Detroit's Woodward Dream Cruise. Thanks Paul Jakel (66089) newest member

[Jimmy G.]

Re: 1960 clutch issue w/4 speed

There are two different throwout bearings Perhaps you have the incorrect one. I think my 60 has the longer one of the two

[Paul J.]

Re: 1960 clutch issue w/4 speed

Thanks Jim , I can check that seeing I retained my old bearing. However I'm an old mechanic and I probably did that when I installed it.

[Dan B.]

Re: 1960 clutch issue w/4 speed

Paul, are you saying you have tried to adjust the linkage per the ST-12 and that's where you are now?

I know it's hindsight, but why a rebuilt clutch vs. a brand new diaphragm type similar to what GM offered as a replacement ?

If you are at the end of the adjustment on the cross shaft, then my guess is either you have the wrong bearing or possibly the bearing is not in the proper place on the fork, or else (hope not) the rebuilt clutch has an issue. As an aside, I would also check the shifter rod alignment just to make sure it is on the money regarding your issue of not being able to go in reverse with the engine running. Hope you can make the cruise! Good luck, Dan

[Joe L.]

Re: 1960 clutch issue w/4 speed

There are two different throwout bearings Perhaps you have the incorrect one. I think my 60 has the longer one of the two

Jimmy------

All Corvettes except early 1955 use the shorter release bearing. These are currently 1-1/4". The 1-7/8" bearing was used for early 1955 as well as most other Chevrolet applications.

[Joe L.]

Re: 1960 clutch issue w/4 speed

Any help will be huge,
purchased a rebuilt 3 finger clutch, clutch plate and bearing. Replace blockers, bearings and is flied with 85/90w gear oil, RPM is at 600 (trans is shifting perfectly). My problem is, I'm unable to adjust the free play to 3/4-1" it is at zero free play now. the trans will not go into reverse at all without shutting it off , putting it into reverse and then restarting engine. It will go into 1st without grinding but I have to really force the pedal into the floor. Will an adjustable fork pivot help with this symptom? I really would like to make Detroit's Woodward Dream Cruise. Thanks Paul Jakel (66089) newest member

Paul------

Corvettes have very "finicky" clutch adjustment. If the flywheel and/or pressure plate have been machined, this can create an adjustment problem usually involving the inability to obtain sufficient free-play.

[Stephen L.]

Re: 1960 clutch issue w/4 speed

Paul,
I had a 3 finger clutch that had cracked fingers. When pushing in the clutch, the fingers would flex causing a longer throw for disengagement. After heating the clutch pedal arm inside the car for more "throw" without success, I removed the clutch and found the finger problem. Good luck.

[Larry M.]

Re: 1960 clutch issue w/4 speed

Paul,
I had a 3 finger clutch that had cracked fingers. When pushing in the clutch, the fingers would flex causing a longer throw for disengagement. After heating the clutch pedal arm inside the car for more "throw" without success, I removed the clutch and found the finger problem. Good luck.

In todays world you cannot take anything for granted:

1. New flywheels are not always flat.
2. Many clutches are made or remanufactured so they will no longer provide the correct clutch disc to PP gap at specified clutch finger depression.
3. New PP are not always flat and/or fingers are deformed or cracked.

The only way to do a clutch or flywheel replacement today is to do runout and flatness checks on the flywheel in addition to looking for correct surface finish, measure flywheel thickness and compare versus factory original, bolt PP to flywheel without disc and put into shop press with TO bearing, and then depress PP fingers to standard dimension and measure the gap all around the PP circumference.

And then use the correct Oillite pilot bushing with the correct ID and OD, installed with the proper driver.

And then, just maybe, the new setup will function correctly.

There no longer are any shortcuts to this job.

Larry

[Paul J.]

Re: 1960 clutch issue w/4 speed

Dan, I followed the ST-12 adjustment procedure. I read that diaphragm type plates where not a adequate service part for the 270 hp engine so, I wanted the original Borg & Beck style clutch, I had a problem when it came to getting one made in my country (US of A). Someone told me of a company and they came through for me. The bearings seem to be exactly alike. and I checked the fork placement on the bearing. that doesn't seem to be a problem. thanks for your input. Paul

[Paul J.]

Re: 1960 clutch issue w/4 speed

thank you, I can check that. I will reply if anything is found.

[Paul J.]

Re: 1960 clutch issue w/4 speed

Jim, I have the short throw out bearing, witch is what was in it. thanks

[Paul J.]

Re: 1960 clutch issue w/4 speed

Joe, I measured the two (old and new) bearings and they are both 1.250 in thanks for that info.

[Paul J.]

Re: 1960 clutch issue w/4 speed

God help me if machining caused this issue. Have you seen this first hand? I'm very worried that running it like this could tear up the thrust bearing in the engine, so I've taken it out of service.