hderr

It’s a 62, original a 340 hp, now a 327 pass car block, 4 speed Hurst, Borg-Warner T-10.
I took the trans/clutch out Dec of 15 for slipping clutch and bad 2nd gear
which it has had since purchase in summer of 14.

I haven’t been able to get the clutch to release regardless of the adjustment on the clutch bellcrank rod.

I’ve replaced the original three finger clutch with another three finger, but the
new kit came with the shorter throwout bearing and different shape fork.
I checked with supplier and was assured that it would work with my correct
bellhousing..
Thinking my slightly bent clutch bellcrank rod might be the adjustment
problem, purchased a new one. The new one has a adjusting clevis stud
with a different smaller stud diameter 5/16” than the old one, 7/16”.
Hmm… so I put the old clevis 7/16” on the new rod, tried to adjust, and
clutch still not releasing.

I’ve never been happy with the geometry of the bellcrank rod and how it
pushes on the clutch fork. The rod angles up to the front of the car
about 13 degrees. Not parallel to ground as I’d expect.

I’m wondering if I have the wrong clutch bellcrank lever?
Thoughts?
Hank
In Cheyenne

ILBMF

A shorter throwout brg would definitely raise a red flag to me.

JohnZ

I think you're dealing with a bunch of mis-matched "Bubba" parts in the clutch linkage, and in a Corvette it only takes ONE to result in inability to adjust the linkage. You MUST have:

1. Corvette bellhousing, machined for externally-installed 13/16"-16 clutch fork ball stud (P/N 3729000) with a female Allen hex drive. If your bellhousing has a ball stud that installs from the inside out, you have a) the wrong bellhousing, and b) the wrong ball stud - that combination was only used on passenger cars and trucks.

2. Have no idea why you got a 3-finger Borg & Beck coil spring clutch - that's dinosaur technology, which was abandoned by GM in 1962, replaced at the end of 1962 with the "bent-finger" diaphragm-type pressure plate and "short" (1-1/4" long) throwout bearing. Passenger cars and trucks used the "flat-finger" diaphragm clutch and the "long" (1-7/8") throwout bearing.

3. The clutch linkage (clutch fork, rods & levers & swivels, etc.) is ALL Corvette-unique (not used on any other Chevy); it only takes ONE wrong part and you end up with inability to get the clutch adjusted properly.

Check every part and make sure you have the right ones, or you'll never get it adjusted.

hderr

So,…
Do you have the correct bell housing? Bell housing is 3779553- “I need a
part for my classic Corvette” 1995 by research specialties says that this
is correct, page 97. The clutch ball stud is externally inserted with a
male allen wrench, I can not see the part number.
Why original-ish clutch? When I bought this car I knew my ownership
would be passed on to someone else in the not to distance future who
might appreciate my attempt to bring it back to original. I've tried where
possible in the hoses, bolts, gaskets, ... to replace with OEM. Discussion
on this forum was very mixed about clutch replacement, flat or fingered.
Three finger worked before so thought I would stay with that. I
favored to do fingered knowing it was going back.

It was working before, perhaps I should have lived with the slipping
clutch and bad gear, at least I could get to the beer store. Who needs
more than 1st gear!

hderr

That was my thinking too. I checked with supplier and assured it was kinda
six of one...
I think the shape of the fork makes up for the shorter bearing, based on the shapes and searching done here. Appreciate your response.
Thanks, Hank

ILBMF

Assuming you replaced the clutch with the exact same geometry pressure plate as the one you removed, then I would blame the throwout bearing since it is shorter. Just because you used a 3 finger style doesn't mean the geometry is the same.

I don't know any other details than that, but if I were you I would pay attention to what JohnZ has to say because he's about the best source of early Corvette knowledge you will probably ever have access to.

wmf62

John

as i'm sure you are aware, while not ideal, the truck bellhousing will work

Bill

DansYellow66

I believe that is incorrect. The more forward reaching fork will primarily affect the linkage adjustment. It might do a little good but basically just results in poor geometry. If you had a lot of extra room for increased pedal and linkage travel (they usually don't), used an adjustable ball and bellhousing fork opening could accommodate a long fork throw then the fork and TO bearing might be made to work. The only things that will properly make up for a shorter TO bearing are:

- a much longer fork ball to move the fork and TO bearing closer to the clutch fingers.

- a clutch with more extended fingers that extend further back to meet the short bearing.

In addition a differently configured bellhousing (than stock) might completely reconfigure the inside geometry but their length is usually dictated by input shaft length to fit the crank so it can't vary much.

GEM '62

John's the man when it comes to quality information. I'm not having so much trouble that I can't drive. When I find a place to get under the car, I will try to adjust the free play. Heading for Fortworth and then Austin today.

Plasticman

Bill,

The truck bell housings come with a larger center hole, and will not work. The transmission input shaft bearing housing centers in that hole for proper engine to trans alignment.

Now if he is using "TRUCK" transmission (like our MY6 trans), then he would have to use a bell housing with the larger hole.

Additionally, the trans does not center (keep it's alignment) with the 4 mounting bolts (they are much too sloppy for the precision alignment needed).

There are rings available to use a truck bell housing with the smaller passenger car (including Corvette) transmissions.

John (plasticman)

hderr

Just to clarify,
I have the correct bellhousing.
The clutch ball stud is externally installed with an allen wrench. Not sure on
the length, but appears to have been in the housing for a long time, not
that that means anything. I will try to get an approximate length.

The pressure plate is a three finger purchased as part of the kit including
the “short” throwout bearing and fork.

So, would the 3-finger plate be the problem? Should have gone with the diaphragm style?

GTOguy

As an auto tech in industry who has replaced many, many clutches, I have to say that shorter throw-out bearings never seem to work out, at least for me. I recommend replacing parts with like parts, not different ones that are supposed to fit. As much of a hassle as a trans is to r&r, it's your call. I'd get replacement parts that match the old ones. BTDT toooo many times.

wmf62

3-fingered Borg & Beck pressure plates were used for a long time, but they are OLD technology, replaced by the diaphragm type. AND, are great for building up the left leg....

if you are not adverse to changing pressure plates, I highly recommend you change to a 'bent fingered' diaphragm type; your leg will appreciate it...

and, it may fix your problem if all the other parts are correct.

Bill

wmf62

yes

and, it's by far the cheapest way to get an open bottomed bellhousing (I 'dislike' the full aluminum ones....)

Bill