Turbo-Hydramatic 425
 | This article needs additional citations for verification. (December 2009) |
| Turbo-Hydramatic 425/325/325-4L | |
|---|---|
 A THM 425 transmission, produced between 1965 and 1978, at the Ypsilanti Automotive Heritage Museum | |
| Overview | |
| Manufacturer | General Motors |
| Production | 1966–1985 |
| Body and chassis | |
| Class | 3-speed longitudinal automatic transmission |
| Related | Turbo-Hydramatic 125 Turbo-Hydramatic Turbo-Hydramatic 180 |
| Chronology | |
| Successor | 4T60 |
Turbo-Hydramatic 425 (TH425 or THM 425,[1] 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.
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
See also
[edit]References
[edit]- ^ "Hydramatic 375, 400, 475 & 425 Systematic Trouble Shooting" (PDF). 1973. Archived from the original (PDF) on 2017-09-09.
External links
[edit]- Troubleshooting manual (1969)