Mine feels no heavier than stock? It works very well with the stock master and throw… Is your experience with the dual disk RAM or ?

EDIT: I reread…you mentioned that you feel the stock pedal is heavy and you are trying to go lighter. I would agree that RAM would be similar to stock.

 

Hmmm, tdreggi's last reply made me realize that I was ***-uming C4toC2's car has a ZF6 with pull-type clutch whereas the thread was started with a discussion of the earlier 4+3 push-style clutches. There's a biiiiiiiiig difference there in terms of what parts are available what differences there are among them. For the ZF6 clutches, all the pressure plates are now made in China and have the same pedal effort and lack of quality. I don't know for sure about the earlier 4+3 clutches, but I'm thinking they are the "standard" GM push-style clutch for which there is still a very wide range of choices, provenance, and quality.

I am very sorry for any confusion I caused. C4toC2, let us know what year and transmission your C4 has so we are sure we are on the same page.

 

Pedricd,

Thats correct, I feel Centreforce has a much lighter pedal than Stock. All mine are single plate. Im assuming pedal and grip would be improved with the dual clutches, but they've always been outside my budget.
I agree the RAM is about the same as Stock.

But, its not really accurate answering generically, as the pedal effort is gonna change dependant on which clutch tier is selected. The typical Street/AutoCross/HPerformance models built to 450HP are likely similar to stock. If selecting models for higher HP cars, they'll be built with higher clamping force, to match their application, and likely have a harder pedal. Depending how much is done with pressure versus pad compound. Ive driven Vettes with RAM and MCleod before, but obviously not every model.

Matt,
My Vettes are all 85,86,87. But my race Vettes had been converted to ZF6.
Im not sure on availabilty/options of ZF era pull clutches, you'd know better than I.
The Centerforce isnt low cost, but it is one option thats available, and has quality manufacturing.
The Centerforce DF matches up well with a ZF, both being rated to handle 600HP or so.
Im not convinced the Centerforce Dual Friction compounds are anything special over other manufacturers, although appropriately selected.
But their clutch design is unique.

 

My McLeod chattered when new and it went away after a couple hundred miles. (Shook the car violently as well) as far as pedal pressure/effort... the stock 84 unit was a much heavier action than the McLeod. That however seems to be opposite of most here. My other car has a mechanical linkage clutch... thats a heavy one. The vette doesn't bother me. I have the super street pro version of the one Greg has.

 

Again, the discussion above is informative and much appreciated.

I have a 65, 327 coupe with mechanical clutch linkage. With the practice I have had lately, I can pull the clutch in about an hour. It still is a pain in the *** and putting it back together always takes longer.

I owned Camaro(s) in the 70 - 80' and never had problems like this. If you were careful and put things together correctly, things just worked. From recent experiences with the 65 corvette, we seem to be challenged to attain quality parts in may areas.

Regarding the pivot ball, it is adjustable, is adjusted longer than stock and was required because my steel flywheel is "thinner" than the original. I set is up so with correct free play, the clutch free play adjustment is in the middle of the threads on the clutch pedal rod. I would agree with tdereggi's statement above that at initial engagement the clutch is trying to grab, the disc springs are compressed and then it lets go. I have been tempted find a hill and hang/hold the car on the hill with the clutch and burn it a bit, (who knows, it could fix it). If the issue is indeed non uniform pressure from the pressure plate as I believe, the burn spots will show up on one side of the pressure plate/flywheel -and I will need to resurface the flywheel again.

I am considering the center force option at this time but I will call them. I need to understand a bit more about what is "special". Years ago, stories of flying weights scared me off, and I went with Mcleod.

 

C4toC2, My first go around, I didnt chose Centerforce either, for three reasons. First the cost was high, like $700 for the kit. And second, because I was considering customizing to use a hydraulic throw-out bearing, and there was no good way to cure preventing the bearing from hitting the centerforce counter weights. And 3rd, because there were some reports that occassionally a few weights would stick and cause the clutch to go off balance. At the time, I needed a SFI bellhousing, and the pre-made ones didnt have the correct slave cylinder mount, thus the hydraulic T/O idea. In the end, I had a custom SFI bellhousing made, and they fabricated the mounting for the slave cylinder in appropriate place, so I could retain the standard Fork method and stock throw-out bearing, and I didnt need the hydraulic solution anymore. That was better anyway, cause hydraulic bearings can leak, and its a lot of work to access the clutch on a C4 to perform maintenance. I had a look-in plate cut in to bell housing, so if a centerforce centrifical weight got stuck, I could look-in bell house and see that, or even reach in to unstick. So I gave the centerforce a try. Several forum members just removed the weights from the clutch and didnt use them, to avoid that risk. But Centerforce advises against that. The centrifical weights are half the benefit of the clutch, deigned to increase clamping force at higher rpms, with increasing pedal effort, and really do help, so I chose to keep the weights installed. I never once had a problem with the weights. And the clutch really grabs well at full RPM full acceleration around the race track.

The key to the light pedal is the ball bearings, though. Not only does it create a low friction pivot point, but more importantly the ball bearings allow the pivot point to change, so greater leverage can be used to add mechanical advantage. You can increase clamping pressure, and then use leverage to reduce that pressure at the foot.

https://www.centerforce.com/articles/technology cu 3/5: street clutch technology video talks about it briefly.

At the end of the day, if leverage isnt being used, increasing clamping force will increase pedal effort. And if pedal effort is reduce, you can be assured the clamping force is being reduce.
So if someone doesnt have a demanding need, they can buy a weaker clutch to reduce their pedal. Or if on budget, a cheap stock clutch is just fine. Simpler designs have fewer components that could fail, so if someone has a high load demanding need, like a high HP drag car, I certainly see the benefit of buying a simpler design clutch. Or maybe someone has strong legs, and doesnt care about pedal pressure. Could also be solved by redesigning and changing sizes of master and slave cylinders to gain the mechanical advantage though hydraulics. Or could use a longer pedal to increase leverage. Better grip can be solved with pad compound, but that has side effects on smoothness and loudness. For street cars, smoothness and quietness is important. Or can just pay a few more dollars, and just get the Centerforce DF, which was designed to reduce pedal effort without compromise, and be done with it.

 

For me the clutch selection has ended with Centerforce. I tried 3 pressure plates in different configurations.
This is what I found.

Mcleod Street Pro
1. very smooth
2. Great engagement and release
3. around 62 pounds max actuation pressure measure at the pedal.
4. Pressure plate weight is about 16.5 Lbs
5. Nicely made

Luk
1. Does not engage uniformly and chattered/shook the car, engagement marks only on one part of the pressure plate
2. engage/disengagement is fine
3. around 50 pounds max actuation pressure at the pedal
4. Pressure plate weight is about 13 Lbs
5. not as nicely made but it also only cost $100 for the whole clutch kit

Centerforce 1
1. very very smooth
2. Great engagement and release
3. around 42 pounds max actuation pressure measure at the pedal.
4. Pressure plate weight is about 17 Lbs
5. Nicely made - close to
I found that I could not use the factory "Flange bolts" with the Centerforce because of clearances around the mounting holes. I went with std grade 8's and lock washers.

Each of the three clutch required a different height for pivot ball adjustment.
My Fly wheel is a 30lb steel - runout is .005"
My disk is an organic made by Hayes
The clutch linkage is factory 65 corvette lever system, set on the "non race position". Everything is greased
Throughout bearing is a all steel unit with a "semi floating" actuation surface.


I would not mind the Mcleod if I had not ruined my knee playing soccer years ago. The 20 Lbs difference in pedal effort is the decider.