Turbo-Hydramatic 425

{{More references|date=December 2009}}

{{Infobox automobile

|image=Ypsilanti Automotive Heritage Museum May 2015 057 (1965-78 THM 425 transmission).jpg

|caption=A THM 425 transmission, produced between 1965 and 1978, at the Ypsilanti Automotive Heritage Museum

|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

}}

Turbo-Hydramatic 425 (TH425 or THM 425,{{cite web|url=http://www.bdub.net/manuals/THM_425_Trouble_Shooting.pdf |title=Hydramatic 375, 400, 475 & 425 Systematic Trouble Shooting |date=1973|archive-url=https://web.archive.org/web/20170909050020/http://www.bdub.net/manuals/THM_425_Trouble_Shooting.pdf |archive-date=2017-09-09 }} 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 (using components sourced from the THM200) 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. Bellhousing pattern used the 1967-90 Buick-Oldsmobile-Pontiac-Cadillac V8 pattern throughout its entire lifecycle.

File:Ypsilanti Automotive Heritage Museum May 2015 058 (1978-85 THM 325 transmission).jpg

Applications:

• THM425
• 1971–1979 Cortez Motor Home
• 1966–1978 Oldsmobile Toronado
• 1967–1978 Cadillac Eldorado
• 1973–1978 GMC Motorhome
• 1973–1978 GMC TransMode multi-purpose vehicle
• 1972–1978 Revcon motorhome
• 1989–1993 Vector W8
• THM325
• 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