Centerforce Duel Friction Clutch

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Ivoryk3ys78

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Trying to find some info out for my dad. He has a 69 Roadrunner that he has been running an 11" Centerforce duel friction clutch in for quite a while. He had taken the spring out becasue he was told it would want to stick to the floor with it there. He did have that trouble at the track when power shifting several years back.

He is wanting to know if he should put the spring back in or should he have a different pressure plate or different clutch altogether. The clutch is very hard to pedal. He likes how strong it is and he just looked at it and everything looks good but would like it not to be so hard to press.
 
I had a Centerforce DF II in my 5.0 Mustang and hated it. If he is racing then I'd look to something better. I like McLeod, but other brands work well too.
 
He races very little. We got to the track maybe once or twice a year. I know when he got it he just wanted to get a strong clutch. He has a 383 thats capable of 113mph.

I don't know if its just something that's inherently what that clutch is like or if he should have something setup different with spring or pressure plate or something.


I had a Centerforce DF II in my 5.0 Mustang and hated it. If he is racing then I'd look to something better. I like McLeod, but other brands work well too.
 
Definitely do not use the overcenter spring. The high-rpm "sticking to the floor" is exactly why they need to be removed.

Make sure that his car has the proper pedal ratio (according to Centerforce, that clutch only needs 3/8" of finger movement to completely disengage with .030 plate departure). Typical B&B clutches call for more like .050-.060.

I have the 10.5" DF behind my 451 and engagement is somewhat abrupt. At first the pedal was quite heavy, but it's loosened up a little with use. Not sure what wore-in.
 
There are 2 different pin spreads 6" and 5 1/4 " what do you have Geometry means a lot.

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I found the CFII disc too harsh for street as well. I swapped to a factory 340 disc. They won't take 400 hp for too many launches but with a lil kindness can last a couple of summers. I also took a lil preload out of the PP, cuz she has the flyweight rpm compensation
Mine now is super easy on the leg. It has the V8 pedal-ratio, originally off a 340 car.
 
I have a 10.5 inch Centerforce Dual Friction in my 65 Barracuda. The stock assist spring was too heavy for a diaphragm clutch; I replaced it with a lighter spring and it's just right now. Don't ask me what that spring came out of; I just found it in my stash of miscellaneous parts.

I'm probably not real up to date about what's available, but a stock replacement 340 clutch would invariably slip when speed-shifting, while the Zoom street/strip clutches I ran next didn't slip (until they wore out) but they were left knee killers and didn't last all that long, either.

I don't speed shift anymore because the Centerforce does have a really harsh engagement if you do, but it has lasted longer than any other clutch I've had in the car since I put a 340 in it back in the spring of 1973.
 
Its all about the Geometry. What is the total travel at the throw out bearing? and what does the pressure plate call for? These are things you have to determine. If your car was here I could help you. Its not so you will have to diagnose of what you have. I don't know your car or what it was or was changed to after 40 plus years.
 
Its all about the Geometry. What is the total travel at the throw out bearing? and what does the pressure plate call for? These are things you have to determine. If your car was here I could help you. Its not so you will have to diagnose of what you have. I don't know your car or what it was or was changed to after 40 plus years.

Ok, if this is of any help.
I got this clutch with a flywheel I bought. If it holds up to my ´68 SS Barracuda nostalgia racer I don´t know.
It´s an 11" (172 t) and it will go with other early B-Body parts. Have the 5 1/4" pedals now.

20200913 clutch forum post.jpg
 
Is the center of the disc or plate pictured glass beaded as it looks to be? If so its not worth using. If you would ever have seen one of those disc's come up through your floor , Dash and Windshield you would understand why I ask.

I wouldn't know the answer to your question every plate manufacture has a different release throw per application. You have to do your own homework there.
 
Is the center of the disc or plate pictured glass beaded as it looks to be? If so its not worth using. If you would ever have seen one of those disc's come up through your floor , Dash and Windshield you would understand why I ask.

I wouldn't know the answer to your question every plate manufacture has a different release throw per application. You have to do your own homework there.

Yes, well shouldn´t use this tread, but here is a close-up pic anyway.
Thanks

20200913 clutch forum post.jpg 2.jpg
 
I have dual mcleod, I had to remove OH spring also. Was sticking, I was pulling it back up with my foot every shift. I removed it this morning. It comes back like a bad penny now
 
The OEM clutch assist spring helps offset the high pressure needed to open a Borg and Beck clutch assembly. If you disconnect the linkage bar to the Z bar, and push the clutch pedal in, after it goes down a ways (1/3, 1/2 ? can't quite remember), it will all of a sudden slam to the floor. Then you have to manually pull it back up. That's the assist spring in action. A diaphragm clutch doesn't require nearly so much pressure to disengage, to the OEM assist spring is much stronger than it needs to be. So the pedal either won't come back up on its own, or it won't come up smoothly.

If you remove the OEM assist spring, then you have no assist. The diaphragm clutch may be easier to disengage than an unassisted Borg and Beck, but it may be a bit higher than you're fully comfortable with. Such was my case. The lighter spring gave it just enough assist to make for a light pedal that would readily come back on its own.

One thing to remember is that a diaphragm clutch does not require nearly so much plate departure as a Borg and Beck. My memory is that B&B is .080-.090, whereas the diaphragm is .030-.035. Too much plate departure on a diaphragm clutch can make it hang open or even cause the release fingers to hit the clutch plate. Instead of adjusting a diaphragm clutch for OEM clutch pedal free travel, I remove the clutch cover, push the pedal to the floor (either with someone to help or using a two by four), then measuring plate departure with a feeler gauge. That leaves the clutch pedal kinda low when your foot is off of it, so I screwed a block of wood to the floor beneath the carpet to limit pedal travel, which puts the pedal more or less in its factory position when not being used. You may or may not want to do this. Some like a lower pedal.

To possibly help you visualize the lighter assist spring I've installed on mine, here's a pic. As I said above, I don't know its original application, but it was the right length and provided just the right amount of assist.

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Mine I have at 3/16” between bearing and clutch at high pedal. I noticed, with spring that it never really expanded the coils at full pedal, yes it would move. But the curve on the dash side would only rotate instead of expanding the coils. Not sure if this is applicable to every application, but It sure changed my day
 
I have a Centerforce II clutch and flywheel in my '69 Dart. I only drove it a few times last year before I tore it apart, but had no issues with the clutch being harsh or sticking to the floor. The stock over center spring was in too. Do not have it running with new engine yet. Did remove the over center spring, clutch pedal pushes in harder than what I remember.
 
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