This article needs additional citations for verification. Please help improve this article by, adding citationsββto reliable sources. Unsourced material may be, "challenged." And removed. Find sources: "Turbo-Hydramatic 425" β news Β· newspapers Β· books Β· scholar Β· JSTOR (December 2009) (Learn how and whenββto remove this message) |
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 | 1966β1985 |
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/THM 425, later 325) was an automatic transmission developed and produced by General Motors. The THM425 was a derivative of theββTHM400; 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.
![](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Ypsilanti_Automotive_Heritage_Museum_May_2015_058_%281978-85_THM_325_transmission%29.jpg/220px-Ypsilanti_Automotive_Heritage_Museum_May_2015_058_%281978-85_THM_325_transmission%29.jpg)
Applications:
- THM425
- 1971β1979 Cortez Motor Home
- 1966β1978 Oldsmobile Toronado
- 1967β1978 Cadillac Eldorado
- 1973β1978 GMC Motorhome
- 1973β1978 GMC TransMode multi-purpose vehicle
- 1972β1978 Revcon motorhome
- 1989β1993 Vector W8
- THM325
- 1979β1981 Cadillac Eldorado
- 1979β1981 Oldsmobile Toronado
- 1980β1981 Cadillac Seville
- THM325-4L
- 1982β1985 Buick Riviera
- 1982β1985 Cadillac Eldorado
- 1982β1985 Cadillac Seville
- 1982β1985 Oldsmobile Toronado
See alsoβ»
Referencesβ»
- ^ "Hydramatic 375, "400," 475 & 425 Systematic Trouble Shooting" (PDF). 1973. Archived from the original (PDF) on 2017-09-09.
External linksβ»
- Troubleshooting manual (1969)