m22 trans 71 vette

[Mike S.]

how do you tell 71 vette has m22 trans or not

[Warren F.]

Re: m22 trans 71 vette

Mike:

If your transmission is original to your 1971 model and has the partial matching vin stamping to your particular car, then the transmission stamping should have the letter C after its date code stamping.

[Joe L.]

Re: m22 trans 71 vette

Mike and Warren-----

Yes, the "C" suffix code stamping is the only way to externally tell the difference between a 1971 M-22 and any other 1971 Muncie variant.

Very few M-22s were ever originally installed on 1971 Corvettes, though. They were an available option with LS-6 and were also supplied as part of ZR-1 and ZR-2 packages. That didn't total very many cars.

[Mike S.]

Re: m22 trans 71 vette

joe the trans has the big 400 type yoke.thanks mike

[Michael H.]

Re: m22 trans 71 vette

Joe,

As you, and everyone else know, I know very little about 68 and newer but wouldn't the M-22 have had a drain plug that the M-21 would not have had? I know as soon as I click "post message", I'm going to be sorry I did but I thought all M-22's had this feature.

In the dark on 68 and newer Michael

[Warren F.]

Re: m22 trans 71 vette

Michael;

In the beginning of M22 production, the early years did indeed have 2 drain plugs in the main case, when M20 & M21 units cases were not drilled for this feature.

However in later years all M20, M21 & M22 transmissions featured the second drain plug.

[Michael H.]

Re: m22 trans 71 vette

Thanks Warren. I learned something. I knew I should have stayed out of this. Hopefully, I'll remember to leave the C3 things to the C3 people.

[Mike S.]

Re: m22 trans 71 vette

warren is the only way to tell if trans is m20,m21,m22 is to pull trans and count rings on input shaft. thanks mike s.

[Warren F.]

Knowledge base

Michael:

For several years now, I've been seriously thinking of getting a C2 car, reading your posts have made me more aware of the uniqueness of these models, than I ever dreamed of knowing.

In fact, the more I learn of '63 thru '67 Corvettes, the more I think it would be foolish for me to think I could find a original, correct Big Block model on my own without some of the members assistance!

[Warren F.]

Re: m22 trans 71 vette

Mike:

That would be one way, however, not necessarily fool proof, if the input shaft has been changed. A better way is to pull the side cover and check the helix angle of the gears, the more straight cut gears are noticeable from the standard M20, M21 gears.

[Michael H.]

Re: Knowledge base

You're not alone Warren. I've been involved in these cars for over 40 years and I'm still learning. We're all fortunate that we have this incredible amount of knowledge from the DB at our finger tips.

As I have once again proven, I know very little about C3 but I suspect that they also have their secrets, just like C2. I'm amazed at some of the things I read and learn about C3. Problem is, I'm too old now to remember what I learn.

Michael

[Joe L.]

Re: m22 trans 71 vette

Mike-----

All 1971-74 Muncies use the same output yoke as a THM-400. The output yoke size has nothing to do with whether the trans is an M-22, M-21, or M-20. Some folks think so, but that's not the case.

[Joe L.]

Re: m22 trans 71 vette

Michael-----

The drain plug was a feature of M-22 transmission cases from 1965 through 1969. Beginning in 1970 with the first use of the GM #3925661 main case, all of the cases were drilled and tapped for the drain. I wouldn't be surprised if some 1970 models may have been "shorted" the drain plug, but by 1971 I think that all Muncies had it, regardless of variant.

[Michael H.]

Re: m22 trans 71 vette

Thanks Joe. I remembered that all the service cases in 70 or 71 had the drain plug but I assumed it was a service only thing and not assy line. I'm proving I know near zero about C3.

[Tom P.]

Re: m22 trans 71 vette

Muncies don't have 2 drain plugs. One plug is a drain plug and the other is a FILL plug.
Also, on 65-69 Muncies, a drain plug is NOT indicative of an M-22. If the tranny has ever been rebuilt, the boss for the drain plug could have been drilled, tapped and a drain plug installed. In over 35yrs of rebuilding Muncies, I've only had one person who did not want the drain plug installed. When I do this, I REMOVE the donut magnet in the bottom of the case and install a magnetic drain plug.