Clutch Pivot Stud - Joe Lucia

[Pierre J.]

[Joe L.]

Re: Clutch Pivot Stud - Joe Lucia

Pierre----

The stud that you require is GM #3729000 and it's still available from GM. This stud was originally used on most 1955 through 1981 Corvettes and currently SERVICES ALL 1955-81 Corvettes (with manual transmissions, of course). It was also used on many passenger cars, including most, but not all, 1956 models. The GM #3729000 stud is 1-1/2" in overall length.

[Joe L.]

Addendum

Pierre-----

1956 passenger cars with 4 barrel carb used the GM #3729000 clutch fork ball stud. This is the same stud as Corvette. It has 13/16-16 thread size and a 21/32" ball.

1956 passenger cars with 2 barrel carb used 2 different ball studs. The first design was of GM #3769589. This stud used 7/16-20 thread and had a ball 11/16" in diameter. The second design, GM #3726574, also used the 7/16-20 thread size, but had a ball of 21/32". Unfortunately, I don't know the length of either of these studs.

The GM #3726574 was discontinued from SERVICE in January, 1963 and was replaced by the GM #3769589. GM #3769569 was discontinued in July, 1964 and replaced by GM #3850567. That stud was discontinued without supercession in August, 1984.

The passenger car stud is available from Danchuk (www.danchuk.com), an early model Chevrolet reproduction parts supplier. It is their part number 0351. However, I don't know if this stud will work for a Corvette application, or not. It will fit the passenger car bellhousing you have but I don't know if there will be another problem as far as usage in a 1956 Corvette. In any event, whatever length this stud is, that's likely the only length that you're going to be able to get.

[John H.]

Re: Addendum

The other issue here is exactly which bellhousing you have. Both Corvette and passenger car used the same casting in 1956 (3704922), but they were machined differently (and had different end item PART numbers as a result). The Corvette bellhousing was machined for the new 3729000 13/16"-16 ball stud as Joe described, which installs from the outside of the bellhousing; the passenger car bellhousing used the 3726574 ball stud, which had a 7/16"-20 thread and was installed from INSIDE the bellhousing. The clutch forks were also unique - Corvette used #3837147 with a special U-shaped retainer spring (3726571) riveted to the pushrod end, and passenger cars used #3726569.

[Joe L.]

Re: Addendum

John-----

The information that I have indicates that for 1956, the bellhousing used for passenger cars with manual transmission and 2 barrel carb was GM PART #3716595 and of casting #3704922. This is the bellhousing that uses the ball stud with 7/16-20 thread size.

1956 passenger cars with 4 barrel carb and 1956 Corvettes both used bellhousing GM PART #3731567. This bellhousing may have had casting #3704922 or 3733365. This is the one that used the 13/16-16 ball stud thread size.