Poll: Muncie M20 vs BW Super T10

[ScottH]

Just wondering what opinions are out there on the comparison between these two four speeds. Any experiences, info, etc. would be appreciated.

Thanks.

[drink2mny]

Well here's my .02
I have a close ratio '64 M20 in my '64 442 (check my signature).
Its sits behind a 340horse 330 olds.I have never had any problemswith it. I don't race it, but I do every once in a while chirp tires all 4 gears when I feel cocky next to someone with muscle or even a ricer. Plus you know you have to see how much rubber your car will lay. I've dumped at 32-3400rpm with out a problem. I've had the car since '95 and I am just now going through the motor and trans, just to have them fresh again.

Not too sure on the other tranny
like I said my .02
hope this helps

[Mike C]

By definition, the M20 is a WIDE ratio box. With a 2.52 first gear, it is compareable to the 2.48 first of some of the ST10. Some have a 2.64 first and an even rarer 2.88. GM switched to the Super T10 in 1974 from the Muncie. The newer T10 that is now made by Richmond is fully synchronized INCLUDING reverse while the older Super T10 and Muncies are synced in forward gears but not reverse. I personally prefer the T10, but I have both in my cars. THe close ratio M21 is virtually useless with anything smaller than 4.10 gears. It has the distinction of being the closest ratio production 4 speed ever made...

[drink2mny]

Hey Mike C, your right. the M20 is a wide ratio
For some dam reason I keep thinking that mine is a close ratio because of the numbers

when in fact
mine is the '64 model
'63-65
2.56 1st
1.91 2nd
1.48 3rd
direct 4th
2.64 reverse

'66-later
2.52 1st
1.88 2nd
1.46 3rd
direct 4rth
2.59 reverse

with m21 and m22's close ratio's
being made as early as '65
2.20 1st
1.64 2nd
1.28 3rd
direct 4th
2.27 reverse
you can see why you need steep gears for a m21 or m22

[breeh]

I had an M22 in my Camaro with 3:73's for awhile and burned up several clutches. The close ratios were designed for road racing from what I have read. They are not good for drag racing.

[ScottH]

Thanks for the info. A couple of followup questions:

First, which of the two is more desireable in terms of performance, endurance, and pricing. The reason I ask is I have both and need to sell one, so I'm trying to determine which one to let go.

Second, Mike can you explain why you stated "THe close ratio M21 is virtually useless with anything smaller than 4.10 gears"? I have heard this before but don't quite understand the reason behind it. Either way, I guess the M21 I have for my 55 running 4:88's on the street should work out well?

Thanks to everyone for the great info!

[Class of 69]

My factory original 70 SS 454 Chevelle came with the M22 and 3:73 posi. I never had any clutch problems, and I drag raced this car quite often. At about 550 horse, it did stretch the case and take all the teeth off the counter gear. If you are planning on a high horse engine, my advice would be the ST10. For a car under 425 horse any of the Muncie's will work fine.