Clutch driving a 833 manual

[Ingemar Viklund]

Testdrove a 69 Roadrunner with a 440/833 manual, supposed to have a centerforce clutch installed. Clutchpedal wasn't superhard to press down, but man..holding it down any kind of time was like a workout and the returnspring felt superhard. Slip just a little bit with your foot and BOING..Pedal throws right back up. I'm new into 4speed mopars, always thought a manual car would be cool but now i'm confused. Is this normal? Can it be adjusted?

 

[Paul_B]

I haven’t drove an old mopar with a center force clutch. I can say that my 68 Coronet’s clutch is easier to push/hold than some other cars I’ve had. I had a late model Ford Mustang that had a clutch that was stiffer than my Coronet.

As another thought, some clutches require the big over center spring on the clutch pedal under the dash be removed to work properly.

 

[Dave6T4]

I had a CentreForce diaphragm clutch in a 1967 Coronet station wagon that I built with a 440, 4-speed. I am pretty sure that I removed the over-centre spring (35 years ago). The clutch gripped real well, and was not difficult to operate. My wife and both of my kids drove this car.

 

[hunt2elk]

While I love the CenterForce dual diaphragm 23 spline clutches, I can't stand the same model in a 18 spline. Same issues as you stated, it was so bad that my wife couldn't even drive the car...

 

[dvw]

Did it still have the dash mounted over center spring installed? It doesn't need it with the CenterForce unit. We've had one in my wifes Challenger since 2003. She drives it with no issues. Multiple drag strip passes and street. Nicest clutch I've ever had.
Doug

 

[gkent]

Wondering why an 23-spline would be any different than an 18-spline. They'd both use the same pressure plate, just a different disk. Unless one is for an 11" flywheel versus 10-1/2".

The pressure against the pedal is completely dependant on the application. A regular old "street" set-up would have a lighter pressure PP than a race clutch would. Subsequently the street clutch pedal would take far less effort to depress and hold.

 

[toolmanmike]

Testdrove a 69 Roadrunner with a 440/833 manual, supposed to have a centerforce clutch installed. Clutchpedal wasn't superhard to press down, but man..holding it down any kind of time was like a workout and the returnspring felt superhard. Slip just a little bit with your foot and BOING..Pedal throws right back up. I'm new into 4speed mopars, always thought a manual car would be cool but now i'm confused. Is this normal? Can it be adjusted?

I see you were just driving the car and you don't own it. Under the dash on the pedal linkage, there is an over center spring. From what you described, it is still installed and needs to be removed for that clutch.

 

[hunt2elk]

Wondering why an 23-spline would be any different than an 18-spline. They'd both use the same pressure plate, just a different disk. Unless one is for an 11" flywheel versus 10-1/2".

The pressure against the pedal is completely dependant on the application. A regular old "street" set-up would have a lighter pressure PP than a race clutch would. Subsequently the street clutch pedal would take far less effort to depress and hold.

There is a difference in the spring pressure between the two, I don't know why. I even pulled my 18 spline out and sent it back to Centerforce, they said it was within spec, but adjusted it down to the minimum for me. It still sucked. I sold the car, but if I kept it, that clutch would have went straight in the scrap pile.

 

[Bird 426]

The overcenter spring is there to help you push the clutch in, it's not a return spring. It's for the high pedal pressure of the 3 finger Borg and Beck style pressure plate.

 

[Bird 426]

I have an 11 in 18 spline Centerforce clutch in the Road Runner and it shifts just fine.

 

[moparedtn]

There is a difference in the spring pressure between the two, I don't know why. I even pulled my 18 spline out and sent it back to Centerforce, they said it was within spec, but adjusted it down to the minimum for me. It still sucked. I sold the car, but if I kept it, that clutch would have went straight in the scrap pile.

I did not care for the 18 spline 11" (diaphragm) clutch from Centerforce either - but mostly because of the nature
of that type of clutch as much as anything I think.

I didn't care for the comparatively short engagement/disengagement part of the pedal travel (felt like an on-off
switch to me) and I also didn't like not having the over-center spring installled with it either, since a part of that
springs' duties is to return the pedal fully upright against the stop.
Other brands of diaphragm clutches may be different, but I haven't tried any....
I returned to the B&B type clutch on Fred and its' just more comfortable for me.

I've driven plenty of other makes with sticks in them (honestly, my favorite was the one in my '89 5.0 Mustang,
which was a self-adjusting cable-type clutch mechanism on a diaphragm type clutch) from hydraulic to what have
you, but between the diaphragm type and the B&B type utilizing factory clutch linkage on our b-bodies, I'll stick
with the B&B.

 

[Bird 426]

We can agree to disagree about the spring duties. The clutch fork spring keeps the throwout bearing back from the pressure plate fingers and is responsible pedal play. On most cars, if the pedal linkage is disconnected and you pull the pedal all the way up with the overcenter spring attached, you can almost blow at it and it will hit the the floor. I do understand about the smoothness of a 3 finger over grabby Centerforce dual friction disc. Agreed.

 

[padam]

I had a Centerforce diaphragm for a couple years and I really liked it. It was a 23 spline.
The pedal pressure dropped off real nice as the clutch was depressed, and I think that is the biggest advantage to the diaphragm type.
They do grab quickly though and are a little hard to slip, that’s one of the reasons I got away from it since I race mine.
The centerforce plate is a little controversial, with some claiming that the weights are just a gimmick and don’t really do anything. I have no opinion on that.

I believe the purpose of the overcenter spring is twofold: provide assist to depress the clutch, and pull the pedal away from the linkage when the pedal is up. The reason for deleting it with a diaphragm is that not much pressure is required when the pedal is down, and the over center spring can hold the pedal to the floor. Not good!

A lot of the feel of clutch engagement is affected by the disk material and construction. Material can be organic which is smoother and more forgiving, or a variety of metallics which take heat and abuse better, but can chatter and grab. A street disk should have a sprung hub and marcel spring also.

Clutch selection is sort of like cam selection. If you over do it you probably won’t like the driving experience.

Ram clutches has a lot of great info on their site and catalog.

Of course it’s impossible to know what is really in that car without tearing it down. Even if it has the right parts, there are a lot of things that can make a clutch work lousy. Any deviation from the factory setup can throw in so many variables that it can be a long road to getting it the way you like it.

 

[dvw]

The CenterForce dual friction in ours isn't touchy at all. The over center spring is mainly for pedal assist and not needed with a diaphram style pressure plate. It has never shook, chattered or grabbed. Heck I can pull away from a stop and it sounds like an automatic.
Doug

 

[hunt2elk]

Maybe not true, but I heard that the overcenter spring has to removed on diaphragm clutches to prevent the pedal from staying on the floor when hammering the shifts.

 

[jdsgtx]

Testdrove a 69 Roadrunner with a 440/833 manual, supposed to have a centerforce clutch installed. Clutchpedal wasn't superhard to press down, but man..holding it down any kind of time was like a workout and the returnspring felt superhard. Slip just a little bit with your foot and BOING..Pedal throws right back up. I'm new into 4speed mopars, always thought a manual car would be cool but now i'm confused. Is this normal? Can it be adjusted?

If that’s a center force clutch it should not be like that although I believe they require you to remove the must’ve spring under the dashboard! I had one of these in front of my rock crusher, didn’t remove the spring and it still was easy! I got rid of mine and installed a dual disk because the horsepower of the engine overpowered the clutch

 

[Butch Harley]

66 years old centerforce clutch go to the gym.

 

[BSB67]

I’ve never had a problem with clutch pedal force, including my 3400 lb BB style. All the centerforce units that I’ve driven seem to require even less pedal force. But then again, I never hold the pedal down. Just for up shifts and occasionally for down shifts

 

[ynst]

Years ago I mistakenly put an 11" Centerforce behind my hemi. It slipped so bad under load at low rpm that I trashed it along with the one year old half worn disc. It had about 3,500 miles on it and was full of burn spots.

I became aware of the slippage whilst driving it up a long hill in Burlington, VT and watching the tach go up but the speedometer staying steady.

Too much torque and engine rpm too low for the counterweights to get thrown outwards (centrifugal force) to load the pressure plate.