List of GM transmissions

General Motors (GM) is an American car designing and manufacturing company. It manufactures its own automobile transmissions and only occasionally purchases transmissions from outside suppliers as needed. GM transmissions are used in passenger cars and SUVs, or in light commercial vehicles such as vans and light trucks.

While there is much variation within each type, in a very general sense there are two types of motor vehicle transmissions:

  • Manual – The driver performs each gear change by operating a gear shift lever combined with a manually operated clutch.
  • Automatic – Once the driver place a gear range selector in its automatic position, usually "Drive" or "D," the transmission selects gear ratios based on many factors, including engine speed, vehicle speed, engine load, accelerator position, gear range selector position, road incline/decline, and more.

For the purposes of this article, there are two primary types of engine orientation:

  • Longitudinal – These transmissions are designed to work with engines that are mounted in the vehicle longitudinally, meaning that the engine's crankshaft is oriented in the same direction as the length of the car, front to back. The transmission is often designed separately from the final drive components, including the rear axle differential. In rare cases (such as the 1961-63 Pontiac Tempest, as well as rear-engined cars such as the original Volkswagen Beetle and the Chevrolet Corvair) the transmission and rear axle are combined into a single unit called a transaxle.
  • Transverse – These transmissions are designed to work with engines that are mounted transversely in a front-wheel drive vehicle, meaning that the engine's crankshaft is oriented in the same direction as the width of the car, left to right. These vehicle applications combine the transmission and front axle into transaxles. Many such vehicles orient the engine/transmission combination so that the transmission is on the left side of the vehicle and the engine is on the right, although exceptions may exist. Often the transmission and the final drive portions are combined into a single housing because of restricted space.

Several types of automatic and manual transmissions are described below, all of which may be found in both longitudinal and in transverse orientations, depending on engineering need, cost, and manufacturer choice.

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