Good morning,
Late 1969 C3 350 car. Trying to help my son with a new clutch install issue.
A while back, he ordered a Top Flight clutch kit: 11”, 10 Spline which Top flight says it is actually a AMS product according to Top Flight.
Release bearing according to them also, is a ACDelco unit.
After his install, his fork is almost touching the bell housing. Making it impossible to get the proper free play and adjustment with his stock pedal rod.
He tells me he used the original ball stud, and fork.

i’ve read a couple of posts that suggest getting a little longer pedal rod, to get the proper adjustment. So ??? Not sure where to go from here.
Asking here, if any one has the correct information from here, to correctly get the problem solved?


Thanks, Ed

 

Not to long ago I had a similar type of problem, do to health issues I wasn't able to do the clutch myself on my back so I had a friend who has a repair shop do it, and since he was doing a Favor and it's a toy he would do it when staff was available.
He put a clutch in and couldn't get it to adjust just like you he said he just didn't have enough movement to get release and even with a new clutch the adjustment bolt was 3 threads from off.
He put in a total of 3 clutches in and with some research and the forum it was found that the GM clutch system has about a 1/2" of travel to get a full release and the one in my car and 2 of first installs had about 3/4" needed to release.
In the end 5 clutches where brought to the shop 2 blindly installed and didn't adjust 3 more tested in a bearing press with a dial indicator to measure release points 2 of them failed at 3/4" and the one that's in the car that passed with a .470 release and that was a NAPA clutch

 

C2 / C3 clutches can be finicky. Clutch brand can make a huge difference:https://www.corvetteforum.com/forums...vel-range.html

 

From s carter's thread back in March. Lars knows these cars.

 

When I read the opening post, my very first thought was, "You bought a clutch from where?"
Top flight makes interior parts.
Been a few threads on the clutch topic in just the last couple years. A few where people ask for suggestions on type or brand of clutch. Lars did one a couple years ago where he actually tested the release of different clutches. Although he couldn't possibly test everything out there.
I personally run a RAM brand clutch. Perfect fit and install, lighter pedal than stock. And holding up well some 5 years down the line.

 

Thanks for all the comments. Did a PM to Lars and he sent his latest info on sizing clutch & parts.

Ed

 

Several years ago I needed my clutch replaced. I reached out to Ernie at Willcox and he suggested LUK as they were the only ones his shop used. Summit racing sells them and of course I ordered the wrong flywheel. The Corvette Only Shop, had me order the correct flywheel and Summit sent it directly to the shop. Boy, I know that I am not the only Forum Member who misses Ernie, he was always willing to help. I know that Lars has a wealth of information, and like Ernie, he is always willing to help. Thank You Lars.

 

I have had great experiences with the Centerforce Stage 2 clutch on a highly modified 427. The pedal feel is like the original clutch but the holding power is a big difference. This clutch works very nicely for a guy with a failed back and a hard time shifting at times.

What I like the most about the Centerforce Clutch is that as the speeds go up the centrifugal force is holding the clutch to the flywheel even tighter.

 

Good morning,
‘the real problem, is current web sites advertising that these products will fit your car. (Not all, but a few) Well OK yes they will fit. “But the real problem is, they don’t work as advertised”.
For someone, that is trying to enjoy working and fixing their own automobiles the cost is time, money, getting led in the wrong direction, etc.
For enthusiast, that only discover forums like this one, after they have trusted web sites selling products, get burned.
All the old timers, like Wilcox, etc. are surely missed.
Also thanks to Lars for your great info and repair work.

Have a great day, Ed

 

All of my clutch replacements have been with Centerforce and almost always that has been a satisfactory experience without some sort of maladjustment problem as talked about here.

They have a lightweight aluminum product line called LMC. Lightweight Metal Clutch (LMC) that is somewhat expensive but reduces the rotational inertia of the rotating mass of the flywheel and pressure plate assembly. In neutral you can notice blipping the throttle happens quicker. And under vehicle acceleration less power is needed to spin things up.

What I don't have are numbers. The power needed is elementary physics if you know the inertias. Maybe that data is out there, I have somewhat halfheartedly looked for it but never found it. It does make some sense however. Good advertising anyway.

The other thing that is good advertising are the counterweights that help grip the clutch tighter. Years ago I spoke with a tech at Centerforce who said that effect was maybe 10% more grip. Again I don't have and haven't found numbers to support that claim.

Lastly the counterweights themselves are seen by many to possibly increase vibration and a lot of people remove them. Intuitively it doesn't seem like they are self adjusting in that they align themselves to reduce vibration, it would seem once they get out of round they stay that way. The heavy part has a higher moment arm. Possible they settle back to a new position once you stop the motor. Seems like vibration could come and go with that effect. They're not that heavy and their radius is small so the "throw weight" inducing vibration, I wouldn't think would be that bad compared to all the other rotating metal. Opinions vary and they are but opinions, no numbers.

I vaguely remember trying to chase down whether these weights were ever patented which would require some analysis but also came up empty. A tech I spoke with at CF candidly thought they were mostly a gimmick with some useful effect but it wasn't dramatic.