M20 or M21
Thread Starter
Racer
Joined: Sep 2004
Posts: 495
Likes: 1
From: Spokane Washington
M20 or M21
This is a transmission question. In general will a Muncie M21 work with a 3.55 rear end ratio. Normally I believe the 3.55 used a M20 wide ratio and the M21 close ratio was used with lower ratios. This is for a 350 HP motor.
thanks
cal
thanks
cal
Burning Brakes
Joined: Jan 2003
Posts: 755
Likes: 32
From: Roswell Georgia
Typically, the 3.55 was optional with the wide ratio Muncie as the close ratio gearbox usually came with a 3.70 or higher rear end ratio. For a street driven Vette, I prefer the wide ratio Muncies or a Super T-10 for the flexibility for stop-n-go driving as well as the gas mileage.
If you're going to do any type of spirited driving or weekend racing/auto-xing with the 3.55, a close ratio M21 will work although you may have to hold the engine longer in each gear to reach the desired RPM before shifting. No big deal there though. Have fun!
If you're going to do any type of spirited driving or weekend racing/auto-xing with the 3.55, a close ratio M21 will work although you may have to hold the engine longer in each gear to reach the desired RPM before shifting. No big deal there though. Have fun!
Drifting
Joined: Apr 2002
Posts: 1,743
Likes: 37
From: Stockton Ca
I have a M-21 w/3:55 gears. First is too tall, get the wide ratio.
In a 5 sp, you can have it both ways. lol
I will be looking to trade my m-21 for an M-20.
315 rwtq does not need a close ratio box!
JMHO
R
In a 5 sp, you can have it both ways. lol
I will be looking to trade my m-21 for an M-20.
315 rwtq does not need a close ratio box!
JMHO
R
Racer
Joined: Jun 2009
Posts: 333
Likes: 22
From: Chicago Ill.
Trans
I have a 67 with a mild 350 . The car was a 327-350 , it came from the factory with a close ratio trans and a 4.11 gear. I removed the gear and installed a 3.55. It's not that bad to drive, but I only use this car to local use.
