M21 or M22..What are the adavantages of each?

[Peter G.]

1968-1974 4 speed transmissions..what is the advantages of the M21 versus the M22. I understand that the M21 was used with diff ratios that were in the higher range. 3:55 and higher, but what else? Is the M22 more user/driver friendly?

[Joe L.]

Re: M21 or M22..What are the adavantages of each?

1968-1974 4 speed transmissions..what is the advantages of the M21 versus the M22. I understand that the M21 was used with diff ratios that were in the higher range. 3:55 and higher, but what else? Is the M22 more user/driver friendly?

Peter-----


The 4 gear ratios for the M-21 and M-22 were the same. The M-22 gearset is stronger than the M-21, both in terms of the helix angle of the gears and the material that the gears are manufactured from. The downside of the M-22 is that it makes quite a bit more noise and this is not desirable for street operation. Basically, the M-21 is a close ratio 4 speed designed for street operation and the M-22 is a close ratio 4 speed designed for off-road/racing applications. It's as simple as that. Can an M-21 be used for racing? Yes. Can an M-22 be used for the street? Yes.

[Wayne M.]

Re: M21 or M22..What are the adavantages of each?

Here's the different helix angle of the gear teeth that Joe mentions.

From my experience, the noise is mostly a problem (or an advantage in my neighborhood) in 1st gear.

[Peter G.]

Re: M21 or M22..What are the adavantages of each?

Thanks guys for the info. Another question comes to mind after reading in another thread..Can you put a M21 high performance insides into a numbers matching stock M22 case without any detection?

[Russ S.]

Re: M21 or M22..What are the adavantages of each?

Thanks guys for the info. Another question comes to mind after reading in another thread..Can you put a M21 high performance insides into a numbers matching stock M22 case without any detection?

Peter, Didn't you mean to reverse that question to read:Can you put a M22 high performance insides into a numbers matching stock M21 case without any detection?

[William C.]

Re: M21 or M22..What are the adavantages of each?

The actual cases are identical. NO difference except the stamping on the side. M-22 guts will be easy to ID by anyone who knows how to listen in the lower gears.