64-65 and 66-67 Clutch Release Lever

[Michael H.]

Something I've always wondered about. What is the difference between the 64-65 and 66-67 clutch release lever. (usually referred to as the fork that operated the release bearing)

There were different part numbers for each. (too lazy to look them up)

I know that most of the other components of the system changed from 65 to 66 also, including the throw out bearing, cross shaft and other related linkage.

At some point after the 66 and later part was released for production, it also became the service replacement for 64-65.

If you use a 66-67 lever in a 64-65, it will function but the clutch adjustment is almost always near the end of the threaded portion of the rod that attaches to the clutch pedal. Is this the result of the incorrect lever or is there more to the story? Possibly the bearing length and/or pivot ball that changed for 66?

Would anyone happen to have one of each to measure/compare? Is there a slight difference in the shape?

[Jim R.]

Re: 64-65 and 66-67 Clutch Release Lever

Not sure but I always thought that the length of the pin bolted to bell housing wich the fork rides on was the difference, 64,5 had a different lenght pin than 66,7 along with as you stated a different clutch cross shaft, ran into this problem with a 65 that had a 66,7 pin installed in the bellhousing and the 64,5 clutch cross shaft and it was out to the very end of the adjustment rod and had to change to a 66,7 clutch cross shaft to get back to the center of the threads on the adjustment rod, as far as the fork I wasn't aware there was a different.

[Joe L.]

Re: 64-65 and 66-67 Clutch Release Lever

Something I've always wondered about. What is the difference between the 64-65 and 66-67 clutch release lever. (usually referred to as the fork that operated the release bearing)

There were different part numbers for each. (too lazy to look them up)

I know that most of the other components of the system changed from 65 to 66 also, including the throw out bearing, cross shaft and other related linkage.

At some point after the 66 and later part was released for production, it also became the service replacement for 64-65.

If you use a 66-67 lever in a 64-65, it will function but the clutch adjustment is almost always near the end of the threaded portion of the rod that attaches to the clutch pedal. Is this the result of the incorrect lever or is there more to the story? Possibly the bearing length and/or pivot ball that changed for 66?

Would anyone happen to have one of each to measure/compare? Is there a slight difference in the shape?

Michael-----


Some time ago I compared the 64-66 GM #3844493 and the 66-81 GM #3887177. My recollection is that the differences related to the thickness of the stock the forks were stamped from and the configuration of the cross section of the arms. As I recall, I could not discern any difference in angularity. I reported on this at the time with photos. I expect they're still in the archives.

[Joe L.]

Re: 64-65 and 66-67 Clutch Release Lever

Not sure but I always thought that the length of the pin bolted to bell housing wich the fork rides on was the difference, 64,5 had a different lenght pin than 66,7 along with as you stated a different clutch cross shaft, ran into this problem with a 65 that had a 66,7 pin installed in the bellhousing and the 64,5 clutch cross shaft and it was out to the very end of the adjustment rod and had to change to a 66,7 clutch cross shaft to get back to the center of the threads on the adjustment rod, as far as the fork I wasn't aware there was a different.

Jim------


1963-65 used clutch fork ball stud GM #3729000. This stud is 1-1/2" in overall length.

1966-E1975 used clutch for ball stud GM #3887159. This stud was 1-3/8" in overall length

L1975-81 used clutch fork ball stud GM #3729000. This stud is 1-1/2" in overall length.

The GM #3887159 stud was discontinued in May, 1996 and replaced by the 3729000.

I know of no source for the 3887159 stud or the equivalent thereof (unless one uses an aftermarket adjustable length stud).

[Michael H.]

Re: 64-65 and 66-67 Clutch Release Lever

Thanks Joe. I'll try to find it.