Turbo-Hydramatic 425
Encyclopedia
Turbo-Hydramatic 425 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:
Automatic transmission
An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...
developed and produced by General Motors . The THM425 was a derivative of the THM400
Turbo-Hydramatic
Turbo-Hydramatic is the registered tradename of a family of automatic transmissions developed and produced by General Motors. These transmissions mate a three-element torque converter to a Simpson planetary geartrain, providing three forward speeds plus reverse.The Turbo-Hydramatic series was...
; 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
Oldsmobile Toronado
The original Toronado began as a design painting by Oldsmobile stylist David North in 1962. His design, dubbed the "Flame Red Car," was for a compact sports/personal car never intended for production...
and the 1967 Cadillac Eldorado
Cadillac Eldorado
The 1953 Eldorado was a special-bodied, low-production convertible . It was the production version of the 1952 El Dorado "Golden Anniversary" concept car, and borrowed bumper bullets from the 1951 GM Le Sabre show car...
. 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
Longitudinal engine
In automotive engineering, a longitudinal engine is an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, front to back....
front-wheel drive
Front-wheel drive
Front-wheel drive is a form of engine/transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel drive vehicles feature a transverse engine, rather than the conventional longitudinal engine arrangement generally found in rear-wheel drive and...
vehicles used the THM325. The THM325 became the THM325-4L with an overdrive
Overdrive (mechanics)
Overdrive is a term used to describe a mechanism that allows an automobile to cruise at sustained speed with reduced engine RPM, leading to better fuel economy, lower noise and lower wear...
added in 1982, but all vehicles using this transmission switched to more-conventional transverse engine
Transverse engine
A transverse engine is an engine mounted in a vehicle so that the engine's crankshaft axis is perpendicular to the long axis of the vehicle. Many modern front wheel drive vehicles use this engine mounting configuration...
mounting in 1986.
Applications:
- THM425
- 1971-1979 Cortez Motor HomeCortez Motor HomeCortez Motor Home, also commonly called a Clark Cortez, is a Class-A motor coach made in the United States between 1963 and 1979. Only 3211 of the units were built in this period. The Clark Forklift Company began making these small motorhomes in 1963 in Battle Creek, Michigan...
- 1966–1978 Oldsmobile ToronadoOldsmobile ToronadoThe original Toronado began as a design painting by Oldsmobile stylist David North in 1962. His design, dubbed the "Flame Red Car," was for a compact sports/personal car never intended for production...
- 1967–1978 Cadillac EldoradoCadillac EldoradoThe 1953 Eldorado was a special-bodied, low-production convertible . It was the production version of the 1952 El Dorado "Golden Anniversary" concept car, and borrowed bumper bullets from the 1951 GM Le Sabre show car...
- 1973-1978 GMC motorhomeGMC motorhomeThe GMC motorhome was produced by the GMC Truck & Coach Division of General Motors for the 1973 through 1978 model years in Pontiac, Michigan, USA. It was the only complete motorhome built by a major auto/truck manufacturer producing what GMC hoped would be their halo vehicle...
- 1971-1979 Cortez Motor Home
- THM325
- 1979–1981 Buick RivieraBuick RivieraThe Riviera by Buick is an automobile produced by Buick in the United States from the 1963 to 1999 model years, with 1,127,261 produced.A full-size coupé or personal luxury car, the early models of the Riviera in particular have been highly praised by automotive journalists and writers.A common...
- 1979–1981 Cadillac EldoradoCadillac EldoradoThe 1953 Eldorado was a special-bodied, low-production convertible . It was the production version of the 1952 El Dorado "Golden Anniversary" concept car, and borrowed bumper bullets from the 1951 GM Le Sabre show car...
- 1979–1981 Oldsmobile ToronadoOldsmobile ToronadoThe original Toronado began as a design painting by Oldsmobile stylist David North in 1962. His design, dubbed the "Flame Red Car," was for a compact sports/personal car never intended for production...
- 1980–1981 Cadillac SevilleCadillac SevilleThe Cadillac Seville is a luxury-type car that was manufactured by the Cadillac division of American automaker General Motors from 1975 to 2004, as a smaller-sized top-of-the-line Cadillac...
- 1979–1981 Buick Riviera
- THM325-4L
- 1982–1985 Buick RivieraBuick RivieraThe Riviera by Buick is an automobile produced by Buick in the United States from the 1963 to 1999 model years, with 1,127,261 produced.A full-size coupé or personal luxury car, the early models of the Riviera in particular have been highly praised by automotive journalists and writers.A common...
- 1982–1985 Cadillac EldoradoCadillac EldoradoThe 1953 Eldorado was a special-bodied, low-production convertible . It was the production version of the 1952 El Dorado "Golden Anniversary" concept car, and borrowed bumper bullets from the 1951 GM Le Sabre show car...
- 1982–1985 Cadillac SevilleCadillac SevilleThe Cadillac Seville is a luxury-type car that was manufactured by the Cadillac division of American automaker General Motors from 1975 to 2004, as a smaller-sized top-of-the-line Cadillac...
- 1982–1985 Oldsmobile ToronadoOldsmobile ToronadoThe original Toronado began as a design painting by Oldsmobile stylist David North in 1962. His design, dubbed the "Flame Red Car," was for a compact sports/personal car never intended for production...
- 1982–1985 Buick Riviera