OkeeGuy

back in the early 70's i had a 68 roadster (vert) and it seems like i remember the nickname "rock crusher" being used to reffer to the 4 speed trany...the Muncie i believe...
can anybody straighten me out on this one? am i recalling correctly or am i dreaming?

Pete79L82

The rockcdrusher or M22 is the same trans as a M21 close ratio muncie with the exception of having much straighter cut gears.

This is an M20 - M21



This is an M22



Notice the difference in the angles of the gears, This was done to help with sideloading the cluster gear against the case. Straighter cut gears also take less HP to turn but are noisier, hence the name "rockcrusher".

Stingy74

I think a rocker crusher was an m22. Had straight cut gears or something, I can't remember. I think they found their way into l-88 and zl1 cars.

bence13_33

Yes, there was a Muncie Rocker Crusher...if I remember correctly it was the M22. The gears in the tranny were cut slightly different which made them stronger than the normal Muncies. Hopefully redvetracer will chime in, he seems to know a lot about the Rock Crushers.

OkeeGuy

man...is there ANYTHING that you guys dont know??!!??
thanx guys :)

robzr

The M22 "Rock Crusher" I believe has gears cut at a 22 degree angle vs. 45 for the M20/M21 (degrees from memory). M20 (wide ratio) had wide gear spread for use with taller rear gears, while the M21/M22 (close ratio) had the same narrower gear spread for use with a shorter rear end. I have read that the 45 degree style gears actually have more gear tooth contact at a given time which makes them stronger (contrary to popular belief). The M22 generates less friction which means less heat and lower temperatures, which is desirable for ROAD racing. This has been subject to some controversy.

If you have any questions, without a doubt the man to talk to is a guy named Wally who runs http://www.muncie4speed.com he is a regular on chevelles.com and knows his muncies. I think he is working on a 5 speed muncie right now.

Rob

Alwyn678

They were put in quiet a lot of muscle cars including my 67 Firebird

Indy Year 25

I had a '71 Z28. I always thought it had a Muncie "T10" rock crusher. Was I misinformed?

The tranny whined. I loved it.

Gordonm

The T 10 transmissio nwas a Borg Warner unit. Muncies were either M20 M21 or M22 (rock crusher)

Vetterodder

The vast majority of M22's produced were sold over the counter rather than being installed in cars at the factory. I've lost count of the number of times someone has claimed his tranny was a "Rock Crusher". In most cases, they learned that they had a Muncie and their fantasies went from there :). Years ago I went to look at a modded late `70's Camaro that had been advertised as having a "Rock Crusher" trans. It sure sounded like one but it turned out to be a worn out Saginaw box :).

67HEAVEN

Whattaya talking about. My 1966 SS427 Corvair came with a special mid-mounted M-22 rock crusher along with twin Paxton superchargers and cross-drilled rotors at all four wheels. The guy that sold it to me swears that this was a COPO car built specially for Ralph Nader. It was heater and radio delete so I believe him. :jester

Wrencher

Anyone that's ever driven a car with an M-22 "rockcrusher" (me) will tell you that they are NOISY! It's kinda like side pipes: you don't need a radio because you can't hear it anyway. If it goes by with a whine like a blower, but different, it's a rockcrusher. You don't need one unless your racing... Heck, the new 5 and 6 speeds are way better.

Hans

BDAZVET

Check out May`s Car Craft. Make your own Rock Crusher. That guy`s five speed may be just around the corner. :cool: