Replacement Clutch Recommendations for '69 L71?

[Douglas P.]

Hello All,

I'm looking for recommendations regarding which replacement clutch kit (11"/10-tooth spline) to go with for my '69 L71 w/M21 & 3.55 gears. The original clutch pressure plate shows its years of service and since I have the engine apart for rebuild I'd like to replace both the clutch disc and pressure plate. (Yes, the flywheel will be resurfaced.) I'm considering OEM type replacements offered by the Corvette parts suppliers/NAPA/etc.. as well as options from Hays, RAM, and any others?

Doug

[Keith B.]

Re: Replacement Clutch Recommendations for '69 L71?

I like my Centerforce

[Joe L.]

Re: Replacement Clutch Recommendations for '69 L71?

Hello All,

I'm looking for recommendations regarding which replacement clutch kit (11"/10-tooth spline) to go with for my '69 L71 w/M21 & 3.55 gears. The original clutch pressure plate shows its years of service and since I have the engine apart for rebuild I'd like to replace both the clutch disc and pressure plate. (Yes, the flywheel will be resurfaced.) I'm considering OEM type replacements offered by the Corvette parts suppliers/NAPA/etc.. as well as options from Hays, RAM, and any others?

Doug

Doug-----


If you want a clutch as close to the original as possible, I would use a LUK clutch kit for your application. Also, I do not recommend using a surfaced flywheel in a Corvette. I would use a new one. One is still available from GM for your application under GM #3991469.

[Ken A.]

Re: Replacement Clutch Recommendations for '69 L71?

If you want the BEST, then buy a Sachs K552-03HD. No gimmicks, but will handle all the torque you can give with a reasonable pedal.

[Michael M.]

Re: Replacement Clutch Recommendations for '69 L71?

I use a Centerforce Dual Friction behind my 427 with great success.

[Scott S.]

Re: Replacement Clutch Recommendations for '69 L71?

Also, I do not recommend using a surfaced flywheel in a Corvette. I would use a new one. One is still available from GM for your application under GM #3991469.

Joe,

Can you go into more detail about why you recommend a new flywheel? I was thinking of having my clutch rebuilt by Fort Wayne with a NOS friction disc and using my original (SB) flywheel, but if there are reasons not to, I would like to understand why.

[Jim D.]

Re: Replacement Clutch Recommendations for '69 L71?

Joe,

Can you go into more detail about why you recommend a new flywheel?

I would be interested to know as well. I resurface the flywheel whenever I replace the clutch regardless of what kind of car I'm working on. Never had a problem with any of the Corvettes I've done over the years.

[Joe L.]

Re: Replacement Clutch Recommendations for '69 L71?

Joe,

Can you go into more detail about why you recommend a new flywheel? I was thinking of having my clutch rebuilt by Fort Wayne with a NOS friction disc and using my original (SB) flywheel, but if there are reasons not to, I would like to understand why.

Scott and Jim------


Here are the reasons:

1) Whenever a flywheel is surfaced it is also weakened, regardless of how little material might be removed. However, it is often necessary to take a pretty significant cut to eliminate all of the minute surface cracking. Most machine shops don't want to take multiple cuts so the cut they do take will be on the "heavy" side in the interest of "removing more material than may be necessary but making sure it's right in just one cut";

2) With a 63-81 Corvette, clutch geometry has to be PERFECT. If not, you will often end up with a situation in which when the specified pedal free play is achieved, you will have incomplete disengagement at full pedal deflection. Or, with full disengagement at full pedal deflection you have insufficient or no pedal free-play. Most of the time, even with perfect, as-new, original components you won't be able to achieve proper pedal free play with complete disengagement at full deflection. Surfacing the flywheel slightly changes clutch system geometry and often exacerbates the aforementioned clutch adjustment problem.

[Jim D.]

Re: Replacement Clutch Recommendations for '69 L71?

Thanks for your views on the subject but I've never run into the problems you mentioned. All dis-engage correctly with the correct amount of pedal free play. With all the variation/play/wear in the linkage etc., I don't see how removing .030 off the flywheel would have any effect. It never has for me.

[Joe L.]

Re: Replacement Clutch Recommendations for '69 L71?

Thanks for your views on the subject but I've never run into the problems you mentioned. All dis-engage correctly with the correct amount of pedal free play. With all the variation/play/wear in the linkage etc., I don't see how removing .030 off the flywheel would have any effect. It never has for me.

Jim-----

The clutch system in any 1963-81 Corvette is a multi-levered system. In such a system, a small change in one area of the system can make a big change in another area. Such is the case here.

For my original owner 1969, from the day it was new with all new components it was impossible to achieve anything like the factory-specified pedal free play and still have complete dis-enagement at full pedal deflection. At a later time, I replaced all of the components with new GM components of the known-correct part number including the rods, levers, cross shaft, springs, fork, pressure plate and disc (but not including the flywheel which I did not have surfaced). The same clutch adjustment problem continued.

I have had the same experience with several other Corvettes that I've been involved with, especially after flywheel surfacing. Also, I've spoken with many folks that have had the same problem. In fact, as I vaguely recall, this issue has been discussed on this board in the past. I've even spoken with folks that, after clutch replacement and flywheel surfacing, ran out of adjustment on the pedal rod (the only place in the system that an adjustment can be made).

In any event, if you've never had the problem, consider yourself fortunate.