Turbo-Hydramatic 425

Infobox Automobile
name=Turbo-Hydramatic 425/325/325-4L
production=1966–1985
manufacturer=General Motors
class=3-speed longitudinal automatic transmission
successor=4T60
related=Turbo-Hydramatic 125
Turbo-Hydramatic
Turbo-Hydramatic 180
similar=Ford C-4/C-5

Turbo-Hydramatic 425 (and later 325) was an automatic transmission developed and produced by General Motors . The TH 425 was a derivative of the Turbo-Hydramatic 400; although some parts directly interchange; and some others will interchange with minor modifications (the internal parts spin the opposite direction in the 425; so the helical angle of the planetary gears is "reversed" and the one-way clutches freewheel in the opposite direction, for examples.) The TH 425 was developed for the 1966 Oldsmobile Toronado and also used on the 1967 Cadillac Eldorado and all GMC front-wheel-drive motor homes. A lighter-duty transmission known as the TH 325 replaced the TH 425 in both car lines after the 1978 model year. 1979 and later longitudinal engine front-wheel drive vehicles used the TH 325. The TH325 became the TH325-4L with an overdrive added in 1982, but all vehicles using this transmission switched to more-conventional transverse engine mounting in 1986.

Applications:
* TH425
** 1966–1978 Oldsmobile Toronado
** 1967–1978 Cadillac Eldorado
** 1973-1978 GMC motorhome
* TH325
** 1979–1981 Buick Riviera
** 1979–1981 Cadillac Eldorado
** 1979–1981 Oldsmobile Toronado
** 1980–1981 Cadillac Seville
* TH325-4L
** 1982–1985 Buick Riviera
** 1982–1985 Cadillac Eldorado
** 1982–1985 Cadillac Seville
** 1982–1985 Oldsmobile Toronado

ee also

* List of GM transmissions