200R4 Technical Information

by Dwight Chestnut
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The 200R4 is the model number of a transmission introduced by General Motors (GM) in 1982. This transmission is compatible with the GM Chevrolet, Buick, Pontiac and Cadillac brands. Owners can obtain key information about the transmission's workings in their cars by reviewing their history, critical systems, gear ratio, dimensions and horsepower.


GM introduced the GM 2004R as an overdrive version of the three-speed GM THM300 model. It offered a vast improvement in strength and durability over the THM200. Because the 200R4 was similar in size to the GM TM400 model, the 200R4 eventually replaced the THM 400 model.

Critical Systems

The internal hydraulic pump is the most critical part of the 200R4 transmission. The pump housing is precision-machined. Because of this precision, its performance level is impervious to heat, pressure and the age of the transmission.

Gear Ratios

The first gear ratio is 2.74-to-1, the second gear radio is 1.57-to-1, the third gear ratio is 1.0-to-1, the fourth gear ratio 0.67-to-1 and reverse is 2.07-to-1.


From the dimensions and the fit, an owner can determine the size, make and model of vehicle with which the transmission is compatible. The overall length of the transmission is 27- 11/16 and height is 19 1/8 inches.


The 200 R4 can reach up to 500 horsepower and requires a 12-volt feed to control the torque converter.

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