Diaphragm vs borg and beck

Hi all,

I have a '67 XR7 with a 289 and 4spd top loader. I was planning to replace the borg and beck style clutch with a diaphragm one but the clutch cover that I received is smaller than the borg and beck one that come out of the car so it doesn’t bolt up to the flywheel. The clutch discs are the same, it’s just the cover (pressure plate) that is different. My question is, do I have to stick with the borg and beck style or did I just receive the wrong clutch cover and somewhere out there is the correct diaphragm style cover? The company (Alto) says they do not have the correct diaphragm cover for the car.

Paul V.

After checking the trans ID tag, it turns out the trans that I have in the car came out of '72 Fairlane with a 351. This combo used an 11" clutch so that explains the difference. Whoever installed it must have used the flywheel and clutch out of the Fairlane. Problem solved (hopefully).

You likely also have the bell housing for the 11 inch clutch, and 164 tooth flywheel. As opposed to the stock 157 tooth flywheel and small bell housing (for the 10 inch clutch).

Centerforce makes what you need in a diaphragm PP.

Yes, after reading more about the differences it would appear that I have the larger bell housing and 164 tooth flywheel. I’ll be crawling back under the car tonight to count the teeth. There is a flywheel on ebay that looks like it’s drilled for both size clutches but I’m waiting for confirmation from the seller on this. http://www.ebay.com/itm/201239180197?item=201239180197&viewitem=&sspagename=ADME:X:AAQ:MOTORS:1123&vxp=mtr

I HATE diaphram clutches,I would get a replacement Long Style Clutch and Pressure Plate!! Roy.


Why would you ever want to use a Diaphram clutch ? They stick to the floor at high RPMs !

That’s true only if you retain the return spring under the dash. If you remove it, all functionality is retained, even at high RPMs.

Thanks for the extra comments. I didn’t even think about the return spring being an issue. Almost done bolting everything back up so I’ll test it out and post an update on how it feels. I actually liked the feel of the lever clutch it had but figured since it is basically a stock 289, I’d give a diaphragm clutch a try. I’m basically restoring the car to daily driving condition and wanted the clutch to feel nice and easy.

Agreed. The Long clutch design simply is better. If you have a generic motors car you must use a diaphragm clutch because the linkage was designed for that style. Ford linkage is designed to use the superior Long clutch. Using a diaphragm clutch in a Ford product in general is just a bad idea with no benefits.

The stock Long clutch is buttery smooth and works effortlessly. Installing a Generic Motors clutch will give you difficult engagement because the pedal leverage is not going to be appropriate.

Bovine Feces.

Again, Bovine Feces.

I am speaking from personal experience - the Long clutch works awesome, and the diaphragm clutch caused untold headaches for me. In a GM car the opposite is true, my '66 Tempest had linkage set up for the diaphragm clutch and it worked fine in that car, while a Long clutch did not, for the same reasons.

Without the spring you would lose the freeplay !

Freeplay is determined by the underhood spring, not the underdash spring. The latter reduces the forces needed to engage the Bork/Beck clutch.

Right, the one that goes from the firewall under the brake booster/MC to the top of the equalizer bar.

I am speaking from personal experience as well. Years ago I tried and tried to get an (11") Long style that had enough grip but could not get it without a super stiff pedal - and breaking every piece of clutch linkage along the way, pushrod through the throwout fork end, bending equalizer top arm regularly, frame pivot coming loose from it’s bracket, broken bellhousing fulcrum, excessive wear of the rod ends, broken pressure plate lever stirrup (on a brand new Zoom plate), you name it. This is because the way they make the clutch more able to handle the power is with heavier springs in the PP.

My Centerforce Dual Friction DF700000 (11") setup works awesome (with under-dash pedal spring removed as specified), much less pedal effort and it (and only it) in my experience is as you say “buttery smooth”, a heavy-springed Long style was anything but. The CF has patented weights on the spring fingers that increase pressure with RPM. The pedal effort is around or perhaps even less than a (stock) Long style and the linkage is loving it. AND, it goes right in place of the Long style, same throwout bearing too.

My 408C is pushing somewhere between 450-500 HP and the CF unit is working pretty well. I can under the right circumstances (with 3.25 gears) overpower it but the pedal feel and smoothness of operation is unparalleled in my experience. I suspect the overpower issue will subside once I install the 3.89 gears I have.

I would consider going back to a Long style if I could get one that will handle the power without resorting to super heavy PP springs and the resulting super stiff pedal. Until such a time as that happens I am firmly in the Centerforce dual friction diaphragm clutch camp. Isabel is currently at 8000 trouble free and pleasurable driving miles since May of 2011 when the car was “finished”.