Hey guys...im lookin at a 70 1/2 (hey, at least its camaro and tranny related..) it needs ground up restoration and im willing to do it, and its got a muncie 4 speed too...i was wondering what kinda abuse/torque the muncie can take so i can build my engine according to what the little baby can take.
thanks,
dave

 

Which muncie M20 M21 or M22 "rockcrusher" the 22 is the strongest of the three with streighter cut gears and the 21 and 20 are more helical and shift easier. Car Craft a few months ago did a build using aftermarket cases and put like 500 ft lbs torque to it.

 

unless your drag racing on slicks there isn't much you can do to hurt the muncie. i have one in my old car, have had them in other old cars, have rebuilt several, and even drag raced a few of them. other than the syncros going out never broke one.

 

Super T10 is a little stronger than Muncie (except for M22).
Both good solid trannies that'll take a lot of abuse (compared to late model trans). Some parts have been hard to get for the old Muncies, but aftermarket companies are finally starting to make new parts for them now.
They offered them behind big blocks, so you should be as safe with the Muncie as any other trans.Any tranny can be broken if it's abused (banging gears and launching hard with slicks).
-Rich-

 

yea i think its either an m20 or 21....its a RS if that helps...i really hope its a m22 though...i think it should hold up to my worked up 383 if it can handle a big block

 

Having built many of these in the past, they are fairly good units with the case being the weak point. The M-20 is the wide ratio unit with two circular grooves on the input shaft. The M-21 is the close ratio with one circular groove on the shaft. The M-22 is a close ratio with no grooves on the shaft. The M-22 was a very noisy unit & from I had seen in the past they were not any stronger than the other two when setup correctly. The ratios are as follows, Wide ratio; 2.52 - 1.88 - 1.46 - 1.00. Close ratio; 2.20 - 1.64 - 1.27 - 1.00. The ST10 is a much stronger unit when setup correctly, and offers a much better selection of gear ratios than the muncie. If you can locate an early case with the 7/8" cluster gear shaft, you can machine the case to the 1" shaft with slightly more interference and have them move the hole .006 closer to the main shaft. After that freeze the case in dry ice for 48 hours. We found this to work very well in the past for longer life. When installing the syncro rings make sure you copy the early muncie of having the slots that release oil for quicker shifts. The after market might have these with the slots, I do not know.

 

It's sure nice to hear someone with a lot of credibilty say something good about the Super T-10.I've been telling guys for years that they are as strong or stronger than an M20-21 but that "Muncie" name carries too much weight with the uninformed.I have a Super T-10 in a second gen Z28 with an estimated 375 horse 350 and it's plenty tough enough for that.There is a Camaro nut in our area that races one with a T-10.He says the trick is to put the Super T-10 gears into the "early" T-10 cast iron case.What's your take on this?How would my stock '79 Z28 Super T-10 stand up behind a 500 horse big block in a street car?

 

The ST-10 we were running was a 2.43 gear set in a 3,000 lb. vehicle running 406-428 ci. FE series Ford motor, running 10.50's at 126 mph in 1975-76, never broke the transmission, and this was with an aluminum case instead of the cast iron. The Ford case was made from a better grade aluminum than the GM. I have used the GM 2.64 gear set with much success in the 1970's & 80's. With the right clutch setup it should do fine.