3-Finger vs. 11-Finger Clutch?

[Bob B.]

Hi all,

My 1960 originally had the 3-finger clutch that required the gorilla clutch assist spring. When I put in a replacement 11-finger clutch, I'd push in the clutch and the gorilla spring would keep the pedal on the floor, so I had to disconnect it.

Based on this, it would seem to me that this means that the 11-finger clutch has much less pressure on the clutch plate and would make it more prone to slipping. Is this correct?

Can anyone recommend a good heavy duty clutch that will work with the gorilla spring without the pedal staying on the floor?

Thanks,

Bob

[Joel A.]

Re: 3-Finger vs. 11-Finger Clutch?

The diaphragm type("11 finger") clutch pressure plates use a different leverage than the 3 finger type, which means they do not require as much pedal pressure to operate(think of it as a longer pry bar). They will still hold just as much pressure on the clutch plate. In fact, at higher rpms, they will actually put more pressure on the disc, due to centrifugal force on the diaphragm. The pressure plate you installed should work just fine. That's the way most replacement clutch kits are these days, unless you get one from a specialty supplier that rebuilds the Borg/Beck(3 finger) style pressure plates.

[Mike M.]

Re: 3-Finger vs. 11-Finger Clutch?

i had a buddy, in the early 60's, who experienced a mangled right ankle after an 11 finger diaphram clutch pressure plate stuck open during a full throttle shift in his sbc. the explosion also mangled the firewall/cowl on his 57 chevy. ever since, i've used 3 finger borg and beck pressure plates i've had rebuilt by fort wayne clutch(they ad in hemmings). and believe me, all my shifts(during competion) are full throttle ones. never had a 3 finger stick to the floorboards.i don't find the fort wayne plates requiring any excessive left leg forces. .mike

[Stuart F.]

Re: 3-Finger vs. 11-Finger Clutch?

I actually went the other way in my drag racing days. I had a B & B with white springs and it was so heavy that my dash would actually torque (57 Chevy). I had to use two clutch push rods welded or brazed togther to keep from bending them and one of the brakets under the dash broke where it was spot welded (had to drill out spot welds and replace with bolts). That was all the rage back in the day, but I got tired of it and it was hard to power shift. BTW, the B & B's do have weights that swing out from centrifugal force to apply more pressure at high RPM's. At any rate, I went into my local Chevy dealer's parts room and found me an 11" truck pressure plate and a couple of driven discs that had what appeared to be more metal impregnated in them. I applied a swirl pattern to both the flywheel and pressure plate using a "0" sandpaper disc, my theory being to get more adhesion through friction rather than pressure. That clutch worked like a dream and lasted the entire season of power shifts at Great Lakes Dragway. I could practically "toe" it as opposed to using 2 feet! Also, low 13's with street tires was not too bad for a 270 hp.

Stu Fox

[Joe C.]

Re: 3-Finger vs. 11-Finger Clutch?

The diaphragm is known as a Belleville spring and works somewhat like the bottom of an old fashioned oil can when pressure is applied via the release bearing.

I have had the problem that Mike M refers to (known as over-centering) when I was using a standard duty Borg (Borg Warner) clutch assembly. It was recommended to place a block under the clutch pedal, OR adjust clutch freeplay such that disengagement takes place when the pedal is right on the floorboard. The clutch that I have been using over the last few years, a Ram dual friction disc with heavy duty pressure plate, has not over-centered without the use of a block under the clutch pedal, even when the freeplay is adjusted per factory specs (1 1/2").

[Dick W.]

Re: 3-Finger vs. 11-Finger Clutch?

50 years ago there was a marked difference in pedal pressure, but modern B & B clutches are easy on the old legs

[Jim L.]

Re: 3-Finger vs. 11-Finger Clutch?

I had a B & B with white springs and it was so heavy that my dash would actually torque (57 Chevy). I had to use two clutch push rods welded or brazed togther to keep from bending them and one of the brakets under the dash broke where it was spot welded (had to drill out spot welds and replace with bolts).

What is the significance of the white springs?

My '57 Chebby has a Borg & Beck pressure plate (stock GM replacement, no idea how the springs are painted) and the pedal force seems perfectly normal to me.

Jim

[Stuart F.]

Re: 3-Finger vs. 11-Finger Clutch?

Dick and Jim;

The springs available for the B & B clutches were of varying strengths. The whites were the strongest, and it was easy for a shop so equipped to take the pressure plates apart to change them, or use a combination to taylor the pressure plate for its intended use. Often the change was made when the unit was in for balancing along with the engine. The other reason was to repair them as they were prone to breaking the pivit pins/holders. I still have some in my junk drawers - cracked right through. Three were used and provided the adjustments for the fingers. They usually adjusted the fingers, then the adjusting nuts were staked in place. When one would break, the finger would not actuate and gears would grind, etc.

Stu Fox

[Stephen L.]

Re: 3-Finger vs. 11-Finger Clutch?

Had a B&B style 3 finger clutch failure that was very hard to find. The clutch quit disengaging on my wife in a very busy intersection.
(Really pissed her off...)
Hauled it home, removed the clutch etc. and found nothing apparent; throwout bearing, arms, rods etc all in good shape. Finally discovered the 3 fingers were fractured inside the clutch housing so they would flex when pressure was applied rather than release the clutch. Have been wary of B&B style since. This was one of those Hi-performance clutches.....

[Domenic T.]

Re: 3-Finger vs. 11-Finger Clutch?

I had the same problem (pedal sticking on floor) while power shifting the diaphram style pressure plate. I also made the mistake of using the strong springs and bending/breaking the linkage. The springs were the rage then and were meant to hook up a wide set of slicks. With street tires you only need the lesser pressure springs, and you can shift much faster without all that pressure.
I chose the borg & beck 3 finger because of the (sticking to floor). I also tested 2 Diaphram clutches given to me from HAYS in Hunting Beach CA back in the early 80's. They had weights fastened to the fingers of the diaphram. Didn't work good at all, I removed them.

DOM

[Stuart F.]

Re: 3-Finger vs. 11-Finger Clutch?

When I say I ran street tires I should qualify that by noting they were 2 sizes over Goodyear double Eagles with the treads worn near slick. It was the most I could run in B/S in 1961. The first half of the season we could only run 3-speeds so power shifting was not an option. When we were allowed 4-speeds, then I realized the white spring B & B was not the way to go.

I have a bunch of the broken pivot bolts (I guess that's what you would call them) to show for it.

Stu Fox