C2 (1967) clutch

[Joseph E.]

With the arrival of the long July 4th weekend, I decided to begin the task of replacing the clutch in my '67 L79 roadster. The car now has just over 50,000 original miles. The clutch was giving indications that it was in need of replacement primarily by slipping when tested in the normal manner. Also, the clutch did not "grab" in 1st gear until almost fully released-adjustments to the pedal free play did not seem to affect this characteristic.

My questions are as follows: How important is it to have the new assembly (pressure plate and disc) balanced along with the flywheel and were factory assemblies balanced? If this is important, can the balancing process be accomplished without the presence of any other mechanical comnponents? I've spoken with one local engine builder who tells me he cannot balance the flywheel and clutch assembly without the crankshaft. Is this true? Lastly, I've been told that there are several variations of throw-out bearings for Chevrolet engines. If this is correct, which is appropriate for this model and engine. Any input from those in the know would be greatly appreciated. Thanks.

Joe

#45420

[Jack H.]

Re: C2 (1967) clutch

The engine was originally internally vs. externally balanced meaning 'add-on' items weren't balanced for that particular engine (just shipped close to neutral balance). But, most machinests take pride in what they do and try to turn out 'Swiss watch' assy's to get as close to zero-out as possible.

In this 'best of all worlds' scenario, yes, you'd like to balance the flywheel and clutch right along with the rest of the internal reciprocating + rotating mass components. But, it's most likely a case of 'overkill' for simply maintaining a good street machine....

Most simply balance the flywheel and clutch and put 'er back together when doing a clutch/tranny overhaul.

[Jim T.]

Re: C2 (1967) clutch

My original owner 68 327/350 Muncie close ratio/3:70 rear has about 98K on it now and still has the pressure plate and clutch I personally installed in 1973 when it had about 32K on it. The original clutch had one side really wore down compared to the other side. My wife slipped the clutch a lot to get the car going. I did not balance the new assembly or the flywheel. No problems with vibration all these years, did replace the throwout bearing again about 20 years ago. Just make sure the throwout bearing you put in is the same height as the one you remove. Check the archives for external application of grease of the prelubed throwout bearing and make sure it is installed correctly on the fork. Some bolts with the heads removed used as studs are helpful in installing the transmission.

[John H.]

Re: C2 (1967) clutch

Joe -

The flywheel should be neutral-balanced separately, and shouldn't be touched if the flywheel and clutch are subsequently balanced as an assembly; you don't want the flywheel to become a "custom" part. You want the 1-1/4"-long throwout bearing (passenger cars used a longer one - 1-3/4" or 1-7/8", I think).