M22 1st gear Q (variations)

[Wayne M.]

[Joe L.]

Re: M22 1st gear Q (variations)

Wayne-----

I'll have to research the specifics of this later. However, I believe that the GM #3879998 is interchangeable with the GM #3924796. In fact, I believe that the 3924796 gear, first used for 1968 with M-22, replaced the GM #3879998 gear for SERVICE of all 65-72 M-22s.

The GM #3849408 sleeve was used for ALL 64-67 with Muncie and 68-70 with M-20 & 21 Muncie. The GM #3932228 was used for 68-70+ with M-22. However, I THINK that both of these sleeves were replaced by the GM #3978781 sleeve which SERVICES ALL 1964-74 Muncie 4 speed applications of all variants.

During the late 60s-early 70s there was available from GM a roller bearing, Muncie M-22 1st gear which, as far as I know, did use a special sleeve. However, I don't think that this gear (or sleeve) was ever used on a PRODUCTION M-22 transmission. I think that it was an over-the-counter piece sold to racers for REAL HD applications in which some trouble had been experienced with the conventional M-22 1st gear and sleeve.

I can tell you this for sure: the GM #3924796 1st gear is NOT a roller bearing-type first gear and it DOES work perfectly with the 3978781 sleeve. I used both parts when, a few years ago, I assembled my M-22 from all NOS parts which I acquired 20 years ago.

I'll check further on this matter, though, and report what I find out.

[Bill Clupper]

Re: M22 1st gear Q (variations)

The difference in the later sleeve is in the machining which allows greater lube to enter (and leave) the gear/sleeve area. There are interchangable for all practical purposes with the possible excepton of endurance roadracing.

[Joe L.]

Re: M22 1st gear Q (variations)

Bill and Wayne-----

Yes, the 3978781 sleeve has a rather unusual external machined configuration. The 3932228 MAY have this also. The 3849408 doesn't, though.

A little more information on this although it's pretty much as I stated earlier with respect to the parts.

The GM #3879998 M-22 1st gear was used for 1965-67 model years. The GM #3924796 was used for 68-72. The GM #3879998 was discontinued in March, 1970 and replaced for SERVICE by the GM #3924796. There was no requirement that the sleeve be replaced when the 3924796 gear was used in place of the 3879998 so, apparently, the 3924796 is compatible with the earlier sleeve, although I don't know if either are compatible with the non-M-22 GM #3849408 sleeve. I expect that they would be, though.

The non-M-22 GM #3849408 sleeve was discontinued and replaced by the GM #3978781 sleeve in July, 1970 and the M-22 sleeve, GM #3932228, was discontinued and also replaced by the GM #3978781 sleeve in August, 1977. The difference in replacement dates is likely due to the longer time which it took to exhaust GMSPO inventory of the M-22-only GM #3932228 sleeve. As Bill mentioned, the GM #3978781 was an improved design sleeve applicable to ALL Muncie transmissions.

The roller bearing M-22 first gear was an over-the-counter piece only as I had recollected. This piece was GM #3965752. It was used in conjunction with sleeve GM #326578, washer GM #326579, and bearing GM #9433516. ALL of these components were discontinued from SERVICE during the 1982-83 period.

[Rob M.]

Re: M22 1st gear Q (variations)

Sounds like this question is answered but for informational background, Corvette Magazine has a good 2 part series on Muncie 4 speeds. Look in the archive section on their web site.

Rob

http://www.corvettemagazine.com/

[Wayne M.]

M22 -- Thanks, guys

Comforting to know the history and that these GM components are interchangeable.