TorqueFlite A904 Transmissions – Jim O’Clair @Hemmings

TorqueFlite A904 Transmissions – Jim O’Clair @Hemmings


Chrysler’s venerable lightweight is a durable, versatile option

Although the cast-iron TorqueFlite three-speed transmission had been available as early as the 1956 300C and Imperial models, a smaller, more economical version, the light-duty TorqueFlite six, or A904, was first released in 1960 for six-cylinder engines. The A904 transmission could very well be considered the grandfather of most of the Chrysler automatic transmissions to follow.

First introduced for use with the push-button dash controls, the early 904s still used a cast-iron bellhousing and a ball-and-trunnion-style output yoke, but the physical dimensions and weight were smaller than that of the older TorqueFlites. They did not use a flex plate to attach the torque converter; instead, the crankshaft on the six-cylinder engines had a large eight-bolt flange to attach to the torque converter.

Flex plates and linkage shifting were added for the 1963 model year, and the output shaft was converted to a standard slip yoke in 1965, the same year the larger-cousin 727 was released. A904 transmissions were original equipment on all 170, 198 and 225 six-cylinder engines, as well as the 273, 318 and 360 (two-barrel) V-8 engines until 1978.

Derivatives of the 904 include the AMC Torque Command 6, the A909 (a 904 with lockup converter), the A500 (904 with a fourth gear added to the rear of the case), the Baby 904 (Mitsubishi-based compacts, the Arrow and Colt), the A998 (904 with an extra friction plate, usually found in 318-equipped vehicles), the A999 (904 with two extra friction plates, for 360 V-8 engines) and the 30RH (904 with computer-controlled lock-up converter often used in Jeep applications).

Gear ratios remained the same from its inception until 1980: 2.45:1 first gear, 1.45:1 second gear, 1:1 third gear and 2.22:1 reverse. First gear was dropped to 2.74:1 and second was lowered slightly to 1.54:1 when this wide ratio gear set was used in all 1981 and newer 904 transmissions. All 904 transmissions up to 1977 had a hydraulic 10.5-inch converter, although the 1977 models used a low-slip converter of similar size. 1978 and newer 904s all used a 10.5-inch lock-up converter.

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