stingraynick75

I tried a search on this but couldnt find anything...what is the differance between a M21 and a M22 transmission?

Larry B.

Try here http://www.5speeds.com go to the Muncie 4 speed section..




[Modified by bluevetteman, 5:48 AM 8/13/2003]

stingraynick75

Thanx bluevetteman...here is a quote from that site....."Please note that there are 7 different Muncie input shafts. All 26 spline inputs came with 32 spline output shafts and all 10 spline inputs came with 27 spline output shafts. A common mistake is thinking that all "fine spline" 26 spline input shafts are M22 heavy duty types. This is not true. An M22 gearbox has a 20 degree helix angle on the gearset as opposed to a 45 degree angle. Also M22 gear sets were of a higher nickel alloy. The straighter angle was designed to produce less end loading of the gear train and less heat but created more noise, thus the nickname "rockcrusher". The higher nickel alloy allowed for more impact of the gears. Another misconception is if you have a drain plug you have an M22. Again this was only true when the first M22 boxes were created. But all 3925661 castings had drain plugs."


:cheers:

Jughead

There's a pic at my site below of the M-22 I'll use. It has a 10 spline input. It's been sitting in my garage since Jan and can't remember if it has a drain plug.

70PurpleLS7

To hear one when your going thru 1st and 2nd gear is amusing, it almost sounds like a granny gear in a truck.

Chuck Harmon

The angle on the gears is a very important key to strength AND power. The greater the gear angle, the more energy is consumed trying to push the gears sideways. Non synchro racing transmissions have straight cut gears. Richmond used to make one with the 5 speed.

To illustrate the point, when I did my chassis dyno I used 6th gear and made about 465-470 rwhp. I then tried 4th gear and made 483rwhp. The reason is that the ROD 6 speed uses the more shallow M22 angle for the first 5 gears and then uses an approximately 45 degree angle for 6th for quiet cruising operation. This is also why the od gear is more prone to failure with high torque ingines.

Chuck

Crash Dummy

Thanks for posting the discussion guys. I've been looking for identification #'s that I *should* find on my '71. From what I saw I the casting # should be 3925661 and if it is in fact a M-22 it should have #'s P1(month A-K)(date)C.

With "C" designating M-22. Correct? Could I assume you might find an earlier year Muncie tranny in your vette? As in a P0K15C.... a '70 built on December 15 and M-22 in a early production '71 vette?


[Modified by bgrice, 12:01 PM 8/13/2003]