The Muncie SM420 is a heavy duty, four-speed manual
transmission
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** Propulsion transmission, technology allowing controlled application of power
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that was produced from 1947 to 1967 by
General Motors
The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...
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
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 Muncie, Indiana; it was designed to replace the somewhat similar Munc ...
in 1968.
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 135lb, which is 40 pounds less than the SM465 that replaced it. While the construction is dated by modern standards, these are sought after by off-road enthusiasts due to the ruggedness and gear ratios.
Gear ratio
* 1st - 7.06:1
* 2nd - 3.58:1
* 3rd - 1.71:1
* 4th - 1.00:1
Specifications
* Weight: 135 pounds
* Length: 10.4 inches
* Height: 17 inches
* Input shaft: 1 1/8 inch, 10-spline
See also
*
Muncie SM465 transmission
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 Muncie, Indiana; it was designed to replace the somewhat similar Munc ...
*
New Venture Gear 4500 transmission
The New Venture Gear 4500, commonly called NV4500, is a 5-speed manual transmission manufactured by New Venture Gear and used in General Motors and Chrysler products from 1991 to 2007.
The NV4500 is a very popular 5-speed manual conversion and upg ...
*
List of GM transmissions
General Motors is an innovator of automatic transmissions, introducing the Hydra-Matic in 1940. This list includes some GM transmissions.
Automatic transmissions
Early models
The GM Hydra-Matic was a success and installed in the majority of GM ...
External links
The Novak Guide to the GM Muncie SM420
References
Automobile transmissions
General Motors transmissions
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