Muncie SM420 transmission

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The Muncie SM420 is a heavy duty, four-speed manual transmission that was produced from 1947 to 1967 by General Motors for civilian use in a variety of pickup trucks, buses, dump trucks and heavy equipment. They were used in some military vehicles into the 1980s. It was replaced in civilian vehicles by the Muncie SM465 transmission in 1968.

Contents

Design

The transmission has a 7.05:1 ratio first gear, which is one of the lowest "granny" gears ever produced in a production transmission. It weighs 135, which is 40 pounds less than the SM465 that replaced it. While the construction is dated by modern standards, these are sought after by offroad enthusiasts due to the ruggedness and gear ratios. [1]

Gear ratio

Specifications

See also

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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. It was designed to replace the somewhat similar Muncie SM420 transmission, which had been in production since just after World War II.

References

  1. 1 2 Verne Simons (October 22, 2014). "Mating the SM420 to an AMC Four-Cylinder - Granny Gearing". Motor Trend. Retrieved January 23, 2022.