To find the axle gear ratio of any GM vehicle, locate the RPO sticker (typically located in the glove box) and write down any codes starting with F, G, or H.

Identify your GMC or Chevrolet rear end gear ratio by the RPO Codes, usually located on the placard labeled “Service Parts Identification” inside the drivers door panel or glove box.

A lower (taller) gear ratio provides a higher top speed, and a higher (shorter) gear ratio provides faster acceleration. . Besides the gears in the transmission, there is also a gear in the rear differential.

The gear ratio expresses the ratio of the output torque to the input torque. Thus, we can multiply the torque supplied at the motor shaft (the input) by the gear ratio to find the torque at the wheel axle (the output). Transmitting power through a series of gears can also affect rotational speed.

The conventional procedure for selecting gear ratios is to pick ratios that run the engine rpm to redline at the end of the medium and longest straights, and pick the lower gear ratios to minimize the rev drop at each shift. This method minimizes the number of shifts per lap.

Double Reduction gear Double reduction gears are generally used in applications involving very high speeds. In this arrangement the pinion is connected to the input shaft using a flexible coupling. The pinion is connected to an intermediate gear known as the first reduction gear.

The “reduction” or gear ratio is calculated by dividing the number of teeth on the large gear by the number of teeth on the small gear. For example, if an electric motor drives a 13-tooth pinion gear that meshes with a 65-tooth gear, a reduction of 5:1 is achieved (65 / 13 = 5).