I'm getting my 72 chevelle engine put back in and wanted to replace the clutch set. It may be a stupid question, but what is the difference between the Borg & Beck design vs. the diaphragm design and which one would be better for my car. It has a 3:31 rear gear, 450 hp 402BB, and a 4 speed muncie. A Hays SFI steel flywheel has also been purchased that will accept 10.5" or 11" clutch disk. I'm looking to do mostly street driving. Thanks in advance, any help is appreciated.

I'm getting my 72 chevelle engine put back in and wanted to replace the clutch set. It may be a stupid question, but what is the difference between the Borg & Beck design vs. the diaphragm design and which one would be better for my car. It has a 3:31 rear gear, 450 hp 402BB, and a 4 speed muncie. A Hays SFI steel flywheel has also been purchased that will accept 10.5" or 11" clutch disk. I'm looking to do mostly street driving. Thanks in advance, any help is appreciated.

I would say 90% of the clutches are the diaphram type. Advances in clutch technology have made them the unit of choice.

The three finger Borg & Beck units were used back in the day before the advances in clutch design. They have higher pedal pressure for the most part. There are a few notable exceptions, McLeod made a three finger style pressure head based on the Ford style clutch that was real nice and was lower on pedal pressure.

They may still make this, not sure.

The "Long" style pressure plate has a different bolt pattern.

The 3-finger Borg & Beck used rollers between the fingers and the housing to increase
holding pressure as RPMs went up (when rpm dropped the rollers would dislodge allowing you to disengage the clutch)

Unless your car has an 'Overcenter" spring in the clutch pedal housing----stay with a diaphram. The overcenter spring is similar to 1/2 size hood spring. This thing not only pulls the pedal back up to it's stop-----But it also helps with pusing in the clutch.
All of my Chrysler products had a Borg & Beck-----if that spring is broken---can make the pedal depression very tough on your right knee.

My 79 Chev had a Borg & Beck-----with the diaphram, it it much easier to operate, and I have had no issues with it in 15yrs. I tow a 18ft flatbed with it. My right knee is much happier now

The "Long" style pressure plate has a different bolt pattern.

The 3-finger Borg & Beck used rollers between the fingers and the housing to increase
holding pressure as RPMs went up (when rpm dropped the rollers would dislodge allowing you to disengage the clutch)

Unless your car has an 'Overcenter" spring in the clutch pedal housing----stay with a diaphram. The overcenter spring is similar to 1/2 size hood spring. This thing not only pulls the pedal back up to it's stop-----But it also helps with pusing in the clutch.
All of my Chrysler products had a Borg & Beck-----if that spring is broken---can make the pedal depression very tough on your right knee.

My 79 Chev had a Borg & Beck-----with the diaphram, it it much easier to operate, and I have had no issues with it in 15yrs. I tow a 18ft flatbed with it. My right knee is much happier now

Early corvettes used that "overcenter" spring. It is external and nearly impossible to attach. It has been my pleasure to remove them when switching to diaphram clutches:yes::yes::yes::yes:

if that spring is broken---can make the pedal depression very tough on your right knee.....

.....I tow a 18ft flatbed with it. My right knee is much happier now

Well shoot, there is your problem dude. You should be using your left leg for clutch operation. :D It is much easier this way.

BTW...I have always used a Borg-Beck in my Chevelle. What is the "overcenter" spring you guys are referring to. I don't have one. Any pics or diagrams showing it?

The "overcenter" spring, at least on Mopars, is located on the clutch linkage up under the dash. It's supposed to help depress the clutch AND help the pedal return to the top of it's travel.

The spring is what gives stick shift Mopars their characteristic (IMHO) junky feeling when driving them. It makes them worth crap to powershift, also. It makes the clutch pedal tend to "linger" too long near the floor during high rpm powershifts. At least at the rpms you'd be willing to twist one of those slug Mopars.;)

Back in about '73 or '74, we replaced the pressure plate in a friend's '69 440 Road Runner with an 11" diaphragm clutch and removed the overcenter spring using a comealong.

Doing this made the car drive and feel almost like a GM car. So much smoother and easier to powershift. If you closed your eyes so you couldn't see the crappy interior finish, and didn't listen to the tinny Mopar rattles, you thought you were driving a GM car. Of course, the steering still sucked, the ride and road noise was horrible, and the brakes were typically grabby, but at least it KIND of felt like a GM car.;)

It worked so well and so many guys in the area found out what we did, that removing the spring and installing a diaphragm clutch became a cottage industry for several years around my home county.:)

We never did find a cure for the rattles or the exposed Phillips screws in the dash falling out.:D


Randy

Well shoot, there is your problem dude. You should be using your left leg for clutch operation. :D It is much easier this way.


Geez----I have my moments.
I'm Blond AND Polish----so it's easy to get simple things mixed up:D.

Randy--
Have Mopar issues, do you???
My 68 Roadrunner and 69 GTX----very clunky
67 Chrysler 300----had 2 of em----very tight cars
My current 82 Dodge pick-up------yep----what you said!!!