GM's Automatic Safety Transmission (AST) was a semi-automatic transmission released in 1937. The first mass-produced fully-automatic transmission developed for passenger automobile use was the GM Hydramatic introduced in 1940.[1] The Hydramatic was a big success, and had been installed in the majority of GM models by 1950. Throughout the 1950s, all GM Marques continued developing automatic transmission designs, both jointly and independently. Early models included:
Introduced in 1964, Turbo-Hydramatic use quickly spread across all GM divisions, and they became referred to simply as Hydramatics (like GM's original automatic of totally different design), except for the Super Turbine 400 model. By the 1970s, Turbo-Hydramatic variants had replaced all of GM's early automatic transmission designs. In Argentina, the Turbo Hydra-Matic was marketed as the "Chevromatic" in the 1970s. Starting in the early 1980s, the Turbo-Hydramatic was gradually supplanted by four-speed automatics, some of which continue to use the "Hydramatic" trade name.
Initially, models were designated with the letters TH/THM/ST followed by the series/version number. In 1987, GM switched to a simpler naming scheme for their transmissions (Example: 4L80E)
The next-generation transmissions, introduced in the early 1990s, were the electronic Hydra-Matics, still based on the Turbo-Hydramatic design. Most early electronic transmissions use the "-E" designator to differentiate them from their non-electronic cousins, but this has been dropped on transmissions with no mechanical version like the new GM 6L transmission.
First-generation longitudinal (Rear Wheel drive)
1991–2001 4L30-E — 4-speed light-duty (used in BMW, Cadillac, Isuzu, and Opel cars)
1992– 4L60-E/4L65-E — 4-speed medium-duty (used in GM trucks and rear-wheel-drive cars)
1991– 4L80-E/4L85-E — 4-speed heavy-duty (used in GM trucks)
First-generation transverse (Front Wheel drive)
1995–2010 4T40-E/4T45-E — 4-speed light-duty (used in smaller front wheel drive GM vehicles)
1991–2010 4T60-E/4T65-E/4T65E-HD — 4-speed medium-duty (used in larger front wheel drive GM vehicles)
1993–2010 4T80-E — 4-speed heavy-duty (used in large FWD GM vehicles, only with Cadillac NorthStar V8 and Related Oldsmobile V8)
Muncie M20 — 4-speed longitudinal wide ratio manual transmission made by GM at their Muncie, Indiana factory
Muncie M21 — 4-speed longitudinal narrow ratio manual transmission made by GM at their Muncie, Indiana factory
Muncie M22 — 4-speed longitudinal heavy duty narrow ratio manual transmission made by GM at their Muncie, Indiana factory
Saginaw M26/27 transmission — 3 and 4-speed longitudinal light duty (less than 300 hp) wide ratio manual transmission made by GM at their Saginaw, Michigan factory
Muncie M62/M64 — 3-speed longitudinal transmission made by GM
Muncie SM318 transmission — 3-speed transmission used from 1954 through 1969 in both passenger car and truck applications. Also found in wide and narrow ratio configurations.
Muncie SM319 transmission — 3-speed transmission physically identical to the Muncie SM318, with an added Borg Warner overdrive unit.
Muncie SM420 transmission — 4-speed manual used up to 1967, very similar to sm 465 except small changes to gear ratios and location of reverse.
New Process Gear NP435 - 4-speed longitudinal transmission used in a select handful of 67-72 GM pickups
New Process Gear A833 RPO MY6 or MM7 — 4-speed longitudinal A833 overdrive transmission made by New Process Gear for early to mid 1980s General Motors Light Trucks
Muncie SM465 — 4-speed longitudinal manual used in 68- 91 Chevy 1/2 3/4 and 1 ton trucks
Borg-Warner R-11 overdrive - 3-speed manual transmission with electric overdrive Ford used them up until 1975 in trucks.
Borg-Warner T-50 transmission — 5-speed longitudinal manual - used by GM in its RWD H-Body cars and a few other limited light duty applications from 1976 to 1978;
^Hendrickson, James; Holmes, Alan G.; Freiman, David (2009). General Motors Front Wheel Drive Two-Mode Hybrid Transmission. SAE World Congress & Exhibition. doi:10.4271/2009-01-0508.
^Miller, Michael A.; Holmes, Alan G.; Conlon, Brendan M.; Savagian, Peter J. (2011). "The GM 'Voltec' 4ET50 Multi-Mode Electric Transaxle". SAE International Journal of Engines. 4 (1): 1102–1114. doi:10.4271/2011-01-0887.
^Conlon, Brendan M.; Blohm, Trevor; Harpster, Michael; Holmes, Alan G.; Palardy, Margaret; Tarnowsky, Steven; Zhou, Leon (2015). "The Next Generation 'Voltec' Extended Range EV Propulsion System". SAE International Journal of Alternative Powertrains. 4 (2): 248–259. doi:10.4271/2015-01-1152.
