1965409mike
Member
can anyone tell me how to know from an m21 and m22 4 speed transmission ? there is one for sale and the number on it is 3925660 i need one to put behind my 409 in in my 65 biscayne
m20 m21 m22?
- Thread starter 1965409mike
- Start date
The 660 case was introduced for the 68 model year and does not indicate whether the trans is an M-20, M-21, or M-22, as they all used the same case.The surest way to tell an M-22 is to look at the gearset. it will be noticeably straighter cut gear than the others. that is what gives it the distinctive sound.
:
The M-22 used a 1" countershaft.
All Muncies starting with the 66 010 case used the 1 " countershaft. the 63-65 Muncies used the 7/8" shaft.
I am always amazed at the "muncie stuff"
Cecil has it right, as always.
bang
m20 - wide ratio early and late 2.56 /2.52 1st
m21 - close ratio
m22 - same as m21 but with the straighter cut gears (NOT Straight)
spline change 1968? 10 to 26 input and 27 to 31 spline output (PG / th350 to th400)
Cecil has it right, as always.
bangm20 - wide ratio early and late 2.56 /2.52 1st
m21 - close ratio
m22 - same as m21 but with the straighter cut gears (NOT Straight)
spline change 1968? 10 to 26 input and 27 to 31 spline output (PG / th350 to th400)
I couldn't find a picture but you can narrow down what transmission it is by counting the grooves in the input shaft. Here's a site that mentions it but they don't actually show the grooves.
http://www.nastyz28.com/chevy-manual-transmission-identification.php
I think there may be pictures of the grooves in the "By The Numbers" books.
Here's another site with tranny identification info.
http://images.google.ca/imgres?imgu...bv=2&hl=en&safe=off&ei=CFEQS-DnDM3vlAfIgaHFAw
http://www.nastyz28.com/chevy-manual-transmission-identification.php
I think there may be pictures of the grooves in the "By The Numbers" books.
Here's another site with tranny identification info.
http://images.google.ca/imgres?imgu...bv=2&hl=en&safe=off&ei=CFEQS-DnDM3vlAfIgaHFAw
Unless the input shaft has been changed, a new shaft will not have any groves either.
I couldn't find a picture but you can narrow down what transmission it is by counting the grooves in the input shaft. Here's a site that mentions it but they don't actually show the grooves.
http://www.nastyz28.com/chevy-manual-transmission-identification.php
I think there may be pictures of the grooves in the "By The Numbers" books.
Here's another site with tranny identification info.
http://images.google.ca/imgres?imgu...bv=2&hl=en&safe=off&ei=CFEQS-DnDM3vlAfIgaHFAw
Gm replacement imput shafts had the same marking as an original. I can't say if all the aftermarket components have the same markings or not.
Bill
Bill
The 660 muncies can be identified by rings on the input shaft. However, if you can see the gears, as mentioned above you will know for sure. Straighter gear set is m22.
m20 - two rings on input shaft
m21 - one ring on input shaft.
m22 - no rings on input shaft.
I believe the main(only) difference detween the m20 and m21 is the first gear gear ratio. The m22 and m21 have the same ratios. The m21 and m22 were made for road racing. If your driving on the street, you will likley be frustrated with a m21 or m22 in your car. Simply stated the m20 will take off from a dead stop better.
Please correct me if I wrong.
m20 - two rings on input shaft
m21 - one ring on input shaft.
m22 - no rings on input shaft.
I believe the main(only) difference detween the m20 and m21 is the first gear gear ratio. The m22 and m21 have the same ratios. The m21 and m22 were made for road racing. If your driving on the street, you will likley be frustrated with a m21 or m22 in your car. Simply stated the m20 will take off from a dead stop better.
Please correct me if I wrong.
M22 has a drain plug but I don't think that would be a good way to tell anymore. Did M21 ever get a drain plug ?
