How to Come Up With a Differential Ratio

A differential is a set of metal gears. If you have a vehicle, such as a lawn mower or a rear-wheel drive automobile, your vehicle has a differential. The large gear inside the differential housing is the ring gear. The smaller cone shaped gear inside the differential housing is the pinion gear. Differential ratios are denoted as a decimal number. For example, a 4.11 differential, commonly used in vehicles that require high torque has 37 teeth on the ring gear and 9 teeth on the pinion gear. There is a simple way to come up with the gear ratio for the differential in your vehicle.

Instructions

1. • 1

     Count the teeth on the larger ring gear and write down the number.

   • 2

     Count the number of teeth on the smaller cone shaped pinion gear and write down the number.

   • 3

     Divide the total number of ring gear teeth by the total number of pinion gear teeth to obtain the ratio.