What is the gear ratio on a M20 Muncie?
What is the gear ratio on a M20 Muncie?
2.56:1 ratio
The 2.56:1 ratio is referred to as the M20. Muncie also had a second close-ratio transmission coded M22 and known as the “rock crusher,” which was used behind performance big-block engines and in some Corvettes.
How do I know if I have Muncie M20 or M21?
If you examine the 1966-’70 wide-ratio M20 input shaft, there are two grooves cut amid the 10 splines. From left to right are the three basic Muncie input shaft/countershaft combinations. On the left is the M20 countershaft and 10-spline input shaft. In the middle is the M21 countershaft and input shaft.
How do you tell a Muncie M20 from M22?
The M20 and M21 have the same cut to the gears, the M22 is a straighter cut resulting in a greater strength. Since the M20 and M21 look the same one way to tell them apart (aside from the grooves on the input shaft) is the tooth count on the cluster gear. There are 7 different input shaft possibilities on a Muncie.
How do I identify a Muncie M20 transmission?
Another way to confirm that the transmission is original to your car is most Muncie four-speed transmissions will have a Vehicle Identification Number (VIN) number stamped on the main case. The engine and transmission were stamped at the same time by the final assembly plant.
What is a Muncie rock crusher?
An M-22 “Rock Crusher” is a Muncie four-speed transmission for cars made by General Motors in the 1960s. You can identify several unique signs that identify an M-22 “Rock Crusher,” even if it does not have a GM hallmark imprinted on its surface.
Why is it called a rock crusher transmission?
The M20 and M21 cluster gears are cut at a 45-degree angle. The reduced gear angle of the M22 created a problem with noise (hence the name “rock-crusher”). Performance seekers decided to live with the noise when the benefits of increased durability from the gear-tooth angle outweighed the gravelly clatter.
What is Rock Crusher transmission?
Why is M22 called rock crusher?
M22 gears are also made of a higher-grade nickel alloy. The M20 and M21 cluster gears are cut at a 45-degree angle. The reduced gear angle of the M22 created a problem with noise (hence the name “rock-crusher”).
How much is a M21 Muncie worth?
Muncie 4 Speed M20 or M21. $2899.99 OR WITH Muncie CORE exchange $2499.99. If you have no useable core the price is $2899.99!!
Where were Muncie transmissions made?
The Saginaw Michigan SM465 is a heavy-duty, four-speed manual transmission built by General Motors for use in light and medium duty trucks from 1968 to 1991 at the factory in Saginaw, Michigan.
Did Ford ever use a Muncie transmission?
It was used right up to 1971 in the Ford Pickup F100 with an overdrive. The T10 shares the same case design, gear centers, and 3-4 synchronizer as the T85.
What cars came with a Muncie 4 Speed?
10-spline units came in these vehicles: 1964-70 Chevy Corvettes and Pontiac Tempest 1967-70 Buick Special, Firebird and Camaro 1969-70 Grand Prix 1963-69 Impala 1965-70 Nova and Olds Cutlass/F-85 and Chevelle (except 1970 w/454-cu.in.
What kind of input shaft does a Muncie M20 have?
Cangialosi tells us all M20 and M21 transmissions were produced with both 10- and 26-spline input shafts. The 26-spline input shaft came into production later in the 1970s for the M20 and M21. What you will find in your search for the right Muncie four-speed is conflicting information from different sources.
What is the ratio of the Muncie M21 transmission?
The 2.20:1 ratio is commonly designated as the Muncie M21 transmission. The 2.56:1 ratio is commonly referred to as the M20.
What are the different types of Muncie 4-speeds?
Some of the best Muncie builders participate on that page. Just three types of Muncie 4-speeds are available based on the RPO (regular production option) code used when a car was ordered: the M20 (standard wide-ratio), M21 (close-ratio), and M22 (heavy-duty close-ratio). (The M does not stand for “Muncie.”)
How does the Saginaw four-speed compare to the T-10 and Muncie?
The Saginaw four-speed box is quite similar to both the T-10 and Muncie four-speed transmissions. However, neither compares to the Muncie in terms of strength. That the Muncie has much in common with the T-10 is no accident. It was a matter of economics when Chevrolet needed a four-speed manual transmission for the Corvette in the mid-1950s.
