Borg-Warner 35 transmission

The Borg-Warner 35 transmission (BW-35) is an automatic transmission produced by the BorgWarner company. This article also applies to variations—the M-36 and M-37. When this article refers to "M-3x" it refers to all models. When model number specific it will use the exact model number.

The "3" in the number refers to the specific series of transmission. The M-3x, 4x, 5x and 6x transmissions are all aluminum cased transmissions that are related to the M-35 (the first of the aluminum Borg-Warner automatics). In this case the rising series number is relative to transmission strength—a larger number will withstand more power than a smaller number. This isn't, however, a general rule with Borg-Warner automatics. The earlier M-8 and M-1x cast iron case transmissions are much stronger than the aluminum models, although the M-6x may handle as much power as the M-1x series. The second number refers to a specific variation. This usually indicates a higher torque load capability, but may refer to other variations that may not increase torque rating.

The M-3x has three forward and one reverse gears. The selector lever varies depending on years and car models the transmission is used in. All models follow a quadrant which has six stations. Early models have two drive positions marked with a "2" and a "1" (P-R-N-D2-D1-L; Park, Reverse, Neutral, D2, D1 and Lock). These models start off in Second gear when in the D2 position. This is useful for economy in relatively flat terrain and for starting on slippery surfaces (wet mud, snow, ice, etc.). When placed in the D1 position the transmission shifts through all three forward gears. In "Lock" the transmission can be locked to prevent upward gear changes and will provide maximum engine braking in 1st gear and moderate engine braking in 2nd gear. By selecting L from stationary, or before an upward gear change into 2nd gear, the transmission will become locked in 1st gear. By selecting L from D2 or D1 while in 2nd gear, the transmission will become locked in 2nd gear or from D2 or D1 when cruising below 55 m.p.h (88 k.p.h.) will effect an immediate downward change and lock in 2nd gear. In both these instances, the transmission will automatically change down into 1st gear when the car speed drops below 5 m.p.h. (8 k.p.h.). Should 1st gear be required earlier, reduce the car speed to below 30 m.p.h. (48 k.p.h.) and effect a "kick-down" gear change. Many people assume they have a two speed transmission because they expect the first Drive position (D2) to shift through all three gears as all automatic transmissions have done since 1968. Some vehicles had the same system without the D1 and D2, instead just having D, and only 5 stations on the quadrant.

Starting in 1965 the M-3x was made with the now common P-R-N-D-2-1 shift arrangement (Park, Reverse, Neutral, Drive, Second gear, First gear). AMC called this "Shift-Command" to differentiate it from the D2/D1 models, since either could be ordered in an AMC/Rambler automobile from 1965 to 1967.

The M-36 was introduced in 1965. It is essentially the same as the M-35 except that it has provisions for an external transmission oil cooler. The M-35 was air cooled by the torque converter with a fan on it. The M-35 case has provisions to be drilled for an external cooler, but no U.S. models used an external cooler and do not have the internal provisions to mount one. There may be European models that were equipped with external coolers. An external oil cooler made it suitable for heavier vehicles and/or towing heavier loads. AMC used the M-36 behind the 232 six in their Ambassador starting in 1965.

The M-37 is first mentioned in the 1967 AMC Technical Service Manual (TSM). It was used behind the 232 in larger vehicles. It has a higher torque rating than the M-35 and M-36. By 1967 the M-36 was relegated to the 199 six, the 232 received the stronger M-37 in all AMC vehicles.

European models may differ.

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