GM Automatic Transmission

TH400 - Turbo Hydramatic 400 - Turbo 400

The TH-400 was first introduced during the 1964 in Cadillacs and Buicks. The following year, the TH-400 could be found in Oldsmobiles and then Chevrolet’s. Originally the TH400 was known as the Super Turbine 400. TH-400 automatic transmissions are a fantastic 3 speed automatic transmission and back up some serious GM torque from the small block 350 to the big block 396 and 454.

The oil crunch in the 70s and 80s caused the phase out of the TH-400 3 speed automatic transmission in favor of the more fuel efficient 4 speed automatic 200-4R and 700R4 automatic transmissions.

Performance Automatic Racing Transmissions

The TH-400 is an extremely popular transmission in its day as other non-GM companies used the TH-400 including Jeep, Jaguar, Rolls Royce and AM General. Today the TH-400 is a popular automatic transmission for street cruisers, hot rodders and drag racers.

GM changed the naming strategy of its automatic transmissions around 1990 to a number such as 4L60 where the 4 means 4 speeds, the L means longitudinally placed in the vehicle and a strength number of 60 in this case. The TH-400 was renamed as the 3L80. Same idea: The 3 is for 3 speeds, L is for longitudinally placed, and 80 is the strength rating.