please ignore this thread.
 

im building a '77 omega and ive found a borg warner rock crusher 4 spd to put in it but i need some beef to turn it. i found a pontiac 400 and i was wondering if a pontiac 400 and a chevy 400 were the same and is it a big block or a small block cause a 400 is right on that line. sorry i didnt mean to make 2 post! i got lost.

No they are not the same two different beast. Never heard of a borg-warner rock crusher But muncie makes a rock crusher trans.



Cole

rock crusher
 

ive been told that its a borg-warner but ive not picked it up although i have been told that they have not been made since the eighties. ive also had some old hot rodders tell me that muncie never made the crusher it was borg but all the same visa-versa

In "old hot rodder" circles, Borg Warner is known for the T-10 4-speed and variants. Muncie is known for the M20 wide ratio 4-speed, M21 close ratio and M22 close ratio "rock crusher".

Google it.

Then the "old" hot rodders you have been talking to are senile. 'cobalt327' told you the facts.

Better find a trans ID guide to take with and make sure it's not a Saginaw. I don't know how many people have told me that they had a Borg Wwarner T-10 or Muncie "Rock Crusher" for sale and it turned out to be a Saginaw.

Pontiac used three different Muncies. The M20 wide ratio, the M21 close ratio, both of which had helical gears, and the M22 close ratio with straight cut gears, asa "The Rock Crusher".

d73
 

the transmissoins will not bolt up probraby more horeses in the pontiac

The transmissions won't bolt up to what?? The Pontiac bellhousing or the Chevy bellhousing?

What are you trying to say David? That statement didn't make sense.

Interesting- considering the thousands of Pontiac's that came equipped w/the Muncie through the years. Like the one I own (M20) from a '69 Le Mans...

lmao amusing thread here

also to confuse things some more the M20 rpo code is the 4 speed top loader trans code for the old 60s and 70s trucks

Let's start at the beginning. First, the Pontiac and Chevy motors are completely different designs with different bore, stroke, castings, and bolt patterns. The motor mounts are different. The bellhousing bolt patterns are different. The accessory brackets and locations are different. The exhaust manifolds are different. The starter motors are different and are on opposite sides. The only thing they have in common is the distributor cap!

The Chevy 400 is in the small block family. Pontiac motors have all one family (excepting 301s and 267s with their shorter deck height) so there is no big/small block distinction.

As for the trans, the BELLHOUSINGS are different, but with the correct bellhousing, you can bolt any GM-compatible trans to either motor.

pontiac.
 

ok im going with the pontiac 400 and as for the trans some one is picking it up on there way through okc but it was 75 bucks and if it explodes after puting it in ill just get a different tranny plus i have a buick trans in the shop that looks just like the pontiac trans siting next to it. the buick tranny being a good one and the pontiac having huge holes and cracks all over.
thanks for all the input, i will up date on the 4 spd

The transmission should bolt up to the bell housing with no issues. A Chevy bell housing will not bolt up to a Pontiac engine and visa versa. The standards were pretty much interchangeable back then. The only issue will be to get the right spline and pilot bearing for the clutch and crank up front and the correct yolk and drive shaft length for the back.

The rock crushers were called that because they were noisy due to the straight cut gears. The straight cuts were supposed to be stronger.
The m-22 is easy to work on. I rebuilt a few back in the day.

The BW transmissions were not bad either but everyone wanted a Muncie

The m20, m21, etc are rpos I think had more to do with being close and wide ratios. My old boss had a 79 camaro with a factory 4 speed it was a super t10 and had the m21 rpo on the option sticker. Muncies supposedly didn't come in vehicles past 74 or 75 but some Canadian cars received them later on. I guess they were using up old stock.