General Motors was an innovator of automatic transmissions, introducing the Hydra-Matic in 1940. This list includes all GM transmissions.


Early modelsEdit

The GM Hydra-Matic was a startling success, installed in the majority of GM models by 1950 and taking GM's competitors by surprise. Through the 1950s, all makers were working on their own automatic transmission, with four more developed inside GM alone. All of GM's early automatic transmissions were replaced by variants of the Turbo-Hydramatic by the 1970s.


The Turbo-Hydramatic was used by all GM divisions and formed the basis for the company's modern Hydramatic line. The basic rear-wheel drive Turbo-Hydramatic spawned two front-wheel drive variants, the transverse Turbo-Hydramatic 125 and the longitudinal Turbo-Hydramatic 425. A third variant was the light-duty rear wheel drive Turbo-Hydramatic 180 used in many European models.

07:36, 3 December 2006 (UTC)

Electronic Hydra-MaticsEdit

The next-generation transmissions, introduced in the early 1990s, were the electronic Hydra-Matics 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 6L80 transmission.

Today, GM uses a simple naming scheme for their transmissions, with the "Hydra-Matic" name used on most automatics across all divisions.

3/4/5/6 L/T ## -E
Number of forward gears L=Longitudinal
GVWR rating "E" for Electronic
"HD" for Heavy Duty
  • First-generation longitudinal
    • 1991–2001 4L30-E — 4-speed light-duty (used in BMW, 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
    • 1995– 4T40-E/4T45-E — 4-speed light-duty (used in smaller front wheel drive GM vehicles)
    • 1991– 4T65-E/4T65E-HD — 4-speed medium-duty (used in larger front wheel drive GM vehicles)
    • 1993– 4T80-E — 4-speed heavy-duty (used in large front wheel drive GM vehicles, especially Cadillac)
  • Second-generation longitudinal
  • Second-generation transverse
    • 2006– 6T70/6T75 — 6-speed medium-duty

Other automatic transmissionsEdit


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