Turbo-Hydramatic 425

Turbo-Hydramatic 425 (and later 325) was an automatic transmission developed and produced by General Motors . The THM425 was a derivative of the THM400; most parts directly interchange and some others will interchange with minor modifications. The internal parts spin the opposite direction in the THM425; the helical angle of the planetary gears is "reversed" and the one-way clutches freewheel in the opposite direction, for example. The THM425 was developed for the 1966 Oldsmobile Toronado and the 1967 Cadillac Eldorado. A lighter-duty transmission known as the THM325 replaced the THM425 in both car lines after the 1978 model year. 1979 and later longitudinal engine front-wheel drive vehicles used the THM325. The THM325 became the THM325-4L with an overdrive added in 1982, but all vehicles using this transmission switched to more-conventional transverse engine mounting in 1986.

Applications:

• THM425
  • 1971-1979 Cortez Motor Home
  • 1966–1978 Oldsmobile Toronado
  • 1967–1978 Cadillac Eldorado
  • 1973-1978 GMC motorhome
• THM325
  • 1979–1981 Buick Riviera
  • 1979–1981 Cadillac Eldorado
  • 1979–1981 Oldsmobile Toronado
  • 1980–1981 Cadillac Seville
• THM325-4L
  • 1982–1985 Buick Riviera
  • 1982–1985 Cadillac Eldorado
  • 1982–1985 Cadillac Seville
  • 1982–1985 Oldsmobile Toronado

See also

• List of GM transmissions