The Synchro-mesh 465 or SM465 is a heavy-duty, four-speed manual transmission built by General Motors for use in light and medium duty trucks from 1968 to 1991 at the factory in Muncie, Indiana; it was designed to replace the somewhat similar Muncie SM420 transmission, which had been in production since just after World War II.
| Muncie SM465 | |
|---|---|
 | |
| Overview | |
| Manufacturer | General Motors |
| Production | 1968–1995 |
| Body and chassis | |
| Class | 4-speed manual |
| Chronology | |
| Predecessor | SM420 |
The SM465 can be found in Chevrolet and GMC full-size trucks, Blazers, Suburbans, among other models. Some applications beyond one-ton pickup trucks came with larger input shafts. Favored by off-road drivers, the SM465 has a very low first gear suitable for rock-crawling. The SM465 has developed a reputation as a highly durable transmission. For the 1992 model-year, the SM465 was replaced in 3/4- and 1-ton pickup truck applications by the New Venture Gear 4500 transmission.
Design
editGM literature also often referred to this as a CH465, referencing Chevrolet.
Gear ratios are:
- First - 6.55:1
- Second - 3.58:1
- Third - 1.70:1
- Fourth - 1.00:1
- Reverse - 6.09:1[1]
The SM465 features dual provisions for power take-offs. The 1988-91 versions have an aluminum top with improved shift feel. The 1985 and newer versions utilize a hydraulic clutch release, replacing a mechanical linkage in older versions. A common wear factor in the form of abuse leads to having to manually hold the gear selector in third. [citation needed]
There have been three different output shafts for pickup trucks. Early four-wheel drive was a short 10 spline. Later, a 35-spline version was for 2 wheel drive, whereas 4WD units had a 32-spline output shaft.[1] The SM465 was the only manual transmission available for 1988-1991 R/V-series trucks and SUVs.[citation needed]
See also
editReferences
edit- ^ a b Verne Simons (October 22, 2014). "Mating the SM420 to an AMC Four-Cylinder - Granny Gearing". Motor Trend. Retrieved January 23, 2022.
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