Turbo-Hydramatic

Turbo-Hydramatic or Turbo Hydra-Matic is the registered tradename for a family of automatic transmissions developed and produced by General Motors. These transmissions mate a three-element turbine torque converter to a Simpson planetary geartrain, providing three forward speeds plus reverse.

The Turbo-Hydramatic or Turbo Hydra-Matic (THM) series was developed to replace both the original Hydra-Matic models and the Buick Dynaflow. In its original incarnation as the Turbo-Hydramatic 400, it was first used in the 1964 model year in Cadillacs. The Buick version, which followed shortly thereafter, was known as the Super-Turbine 400. By 1973, THM units had replaced all of GM's other automatic transmissions including Chevrolet's Powerglide, Buick's Super Turbine 300, and Oldsmobile's Jetaway. 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.

Although the Turbo Hydra-Matic name alludes to the original Hydra-Matic developed by General Motors' Cadillac division in the late 1930s, the two transmissions were not mechanically related.

Turbo-Hydramatic 180

Turbo-Hydramatic 180 was an automatic transmission developed and produced by General Motors. It was a light-duty derivative of the Turbo-Hydramatic and was manufactured and used in Europe and Asia in a variety of longitudinal engine vehicles. The TH180 was later renamed 3L30 and was replaced by the 4L30-E in the 1990s. It was also manufactured by Holden as the Tri-Matic transmission and used in Holden vehicles from 1970 to 1988.

Applications:

Turbo-Hydramatic 125

The Turbo-Hydramatic 125 was the first in a line of automatic transmissions from General Motors designed for transverse engine application. Introduced in 1980, the line evolved into today's 4T40/45/65/80 line.

Turbo-Hydramatic 125

The 3-speed Turbo-Hydramatic 125 was introduced in 1980 and produced through 2002. It carried over some parts from the light-duty Turbo-Hydramatic 200 and 350, but was generally a new design.

The 125 was renamed 3T40 later, following GM's new naming convention. The 4T40-E replaced it starting in 1995.

Applications:

Turbo-Hydramatic 125 C

This was a later model of the 125 that debuted for 1982 and included a torque converter clutch or TCC. The TCC acts similar to a clutch in a manual transmission vehicle, in that at speeds above 50 MPH a combination of engine vacuum- and temperature-sensing valves, and a dedicated brake switch - and in later models an ECU - activated a solenoid which engaged a clutch physically locking the impeller and turbine inside the torque converter together causing engine power to be transferred directly to the transaxle. The C in Turbo-Hydramatic 125 C denoted the use of a TCC. The solenoid that controls this is notorious for failure due to overheated plastic componentry, and problems indicated by an engine stall when stopping from speeds greater than 55 MPH. This occurs because the clutch does not disengage, and as the affected vehicle's speed nears zero miles per hour, the engine is forced to decelerate to zero rpm.