What is a M21 Muncie transmission?
What is a M21 Muncie transmission?
Even after 45 years, the Muncie four-speed is still a very popular transmission with Chevrolet muscle car enthusiasts, and it is easily adaptable to a wide range of GM and other non-GM vehicles. The 2.20:1 ratio first gear is usually referred to as the Muncie M21 transmission; based on GM’s production codes.
Is the M21 a good transmission?
The M21 was for higher performance cars, which makes it a great box to use in a rod. A close-ratio gearbox keeps shift points closer together, which keeps rpms up. With a close-ratio box a driver can run through the gears and keep the engine in its power band so it performs in street racing or drag racing.
What kind of transmission does a Muncie M21 have?
The M21 & M22 is a Muncie engineering design, this transmission is aluminum case, extension housing and side cover. The side cover has seven bolts and two shift cams. The synchro rings have 35 teeth and the unit has a 4 step cluster gear.
What is the casting number on a Muncie 4 speed transmission?
The casting number 3925660 denotes this as a 1968 – 1970 Muncie with a 1-inch cluster shaft. In order to correctly identify a Muncie four-speed transmission, several visual clues are needed, and those cues involve the casting numbers on the case, side cover, and tailshaft.
What was the transmission ratio for the GM Muncie?
The Muncie’s appearance, design, and operation did not change much during the transmission’s use in GM production cars. However, there were several design upgrades and modifications made during the total production run. The Muncie four speed was produced in two ratios: the wide ratio (M20) and the close-ratio (M21).
What kind of transmission did a Saginaw MuscleCar use?
Depending on how you ordered your musclecar in the ‘60s and early ‘70s, you might have even benefitted from the famous Muncie transmission. It’s no secret that the Saginaw and Borg Warner transmissions were not built to handle the kind of power that a Muncie transmission could withstand.
When did the Muncie M20 wide ratio transmission appear?
There is strong evidence the Saginaw M20 wide ratio transmission did not appear before February/March of 1966, so all M20 4-speeds are assumed to be Muncie before this date.
When did the Muncie 4 speed transmission come out?
1964 to 1968 Muncie 4-speed transmissions can be identified from later models by the way the transmission arms attach. Early Muncie side covers had a stud and the shift arm attached with a nut on the stud while the 1969 and later model side covers had a hole and the shift arms attached with a bolt.
What kind of transmission does a 1968 Chevelle use?
The same is true if you are going to install a 1964-1967 Muncie transmission into a 1968-1972 Chevelle. The Hurst Competition Plus Shifter fits both with and without console.
What kind of shifter do I need for a 1969 Muncie?
Those installing a 1969 or later Muncie into 1964-1968 Chevelle and using a Hurst Competition Plus shifter must get the proper shifter tower assembly for the 1964-1968 Chevelle and the installation kit for the 1969-1972 Muncie due to the shift arms bolting onto the transmission differently.
