C1 Transmission Yoke

[Rick C.]

[Gary C.]

Re: C1 Transmission Yoke

Rick,

The Powerglide driveshaft yoke is shorter than the 4 speed yoke.

Why that P&A's only show 1 part number ?

Gary
....

[David B.]

Re: C1 Transmission Yoke

The universal joint PN 3712379 Grp. 5.55 in the '57 P & A is a 16 spline yoke. Do not know how Joe measured but it is 6.17 end to center of hole. The spline length is 4.93.

[Joe L.]

Re: C1 Transmission Yoke

I need to make sure I get the correct transmission yoke now that I’m replacing the 4-speed in my ’62 with the correct Powerglide. The Powerglide takes a 16 splined yoke whereas the one that was with the 4-speed was 26 splined. Joe Tripodi in his Chassis Restoration Guide writes that the yoke for the 55-62 3-speed and 4-speed transmissions was a different length (4-15/16”) than the one for a Powerglide which he says has a 3-3/4” shaft. However, when I look through my October 1961 parts book I only see one yoke listed for all 55-62 and in the AIM, I don’t see any differentiation. In fact, in the AIM the driveshaft is called a “propeller shaft & universal joint assembly.” So, does that mean the driveshaft arrived at the plant with universals and front yoke installed? There is only one driveshaft for ’62 so if it all arrived together, there must have been only one yoke. Any thoughts?

Thanks,
Rick

Rick-------


I know of no transmission yoke originally used for any 1955-62 Corvette other than the GM #3712379. This includes both original manual and original Powerglide automatic transmissions. This yoke is of 16 splines and 4-15/16" spline length. The 3712379 was discontinued without supersession in July, 1983 but is available in reproduction.

All 1963-82 Corvette driveshafts were delivered to PRODUCTION with u-joints and transmission yoke installed and balanced as an assembly. I'm virtually certain that the same was true for C1 Corvettes.

[Rick C.]

Re: C1 Transmission Yoke

Thanks to all. The fact that there is only one size reproduction is what prompted my question. Thank you!

Rick

[Gary C.]

Re: C1 Transmission Yoke

Joe,

Am puzzled, but that's nothing new. Once upon a time, I bought a wrecked '57 for some of the body panels. That car had a powerglide transmission. The yoke had a shorter shaft around 3 1/2 inches long.

Like you said the P&A's only show 1 Corvette yoke #3712379.

Gary
....

[Joe L.]

Re: C1 Transmission Yoke

Joe,

Am puzzled, but that's nothing new. Once upon a time, I bought a wrecked '57 for some of the body panels. That car had a powerglide transmission. The yoke had a shorter shaft around 3 1/2 inches long.

Like you said the P&A's only show 1 Corvette yoke #3712379.

Gary
....

Gary------


Are you sure the car had an original Powerglide?

[Gary C.]

Re: C1 Transmission Yoke

Joe,

Not sure if it was original to the car or not, but it was a '57 dated PG with Corvette tailshaft on it. The guy that bought the PG transmission was happy with the numbers and dates. Didn't remember that I still had that driveshaft until I cleaned out my shop when I downsized in 2019.

Weird huh.

Gary
....

[David B.]

Re: C1 Transmission Yoke

There were in fact 2 different yokes used at least in '57.
# 3712379 listed in Grp. 5.555 (designed 12-21-53) . It had a 16 spline length of 4.93 which I guess is the same as 4 15/16.
# 3744777 not listed in the P&A book. Designed 11-28-56 for the '57 4 speed optioned Corvettes (very low option). It's 16 spline length was 3.53 (Tripodi was close) the net difference in length is just the opposite of that mentioned. Do not know if GM continued to use 3744777 in later years or simply adjusted driveshaft. However, revisions are shown made 5-18-60.

[Joe L.]

Re: C1 Transmission Yoke

There were in fact 2 different yokes used at least in '57.
# 3712379 listed in Grp. 5.555 (designed 12-21-53) . It had a 16 spline length of 4.93 which I guess is the same as 4 15/16.
# 3744777 not listed in the P&A book. Designed 11-28-56 for the '57 4 speed optioned Corvettes (very low option). It's 16 spline length was 3.53 (Tripodi was close) the net difference in length is just the opposite of that mentioned. Do not know if GM continued to use 3744777 in later years or simply adjusted driveshaft. However, revisions are shown made 5-18-60.

Dave------


I find GM #3744777 as applicable to 1958-61+ passenger cars. I can find no Corvette applications. It was discontinued in August, 1961 and replaced by GM #3707059, a pre-existing part.

[David B.]

Re: C1 Transmission Yoke

No surprise there Joe, was aware 3744777 could be used on pass cars. The important thing to note was the yoke casting was able to be machined to suit a number of applications. The cast/machine print 3744778 (11-28-56) shows 8 revisions (some minor) in '57, 3 in '58 and 9 in '60. Prints 3744777-78 were in early '57 4 speed file what ever that might mean. Possibly early production part ---??
As always I remain open to target practice!