Table of Common Gear Ratios Table of Drive Ratios
Q & A Table of drive ratios for 4.5" NASCAR
Gear Ratio Terminology
Gear ratio: The number of teeth on the spur gear dived by the number of teeth on the pinion gear
Lower gear ratios: When the numerical value of the gear ratio gets larger, the gear ratio is said to decrease. For example, a gearing of 8-38 (4.75) is lower than 9-36 (4.0). Lowering the gear ratio will typically increase brakes and acceleration while decreasing top speed. As the gear ratio lowers, the number of times the armature must revolve per tire revolution increases.
Higher gear ratios: When the numerical value of the gear ratio gets smaller, the gear ratio is said to increase. This is also referred to as using a taller gear. For example, a gearing of 11-38 (3.45) is higher (taller) than 10-36 (3.6). Higher gear ratios will typically increase top speed while decreasing brakes and acceleration. As the gear ratio gets higher, the number of times the armature must revolve per tire revolution decreases.
Drive ratio: The drive ratio is the number of times the armature must revolve for the rear tire to revolve once. The drive ratio can be calculated by dividing the gear ratio by the rear tire diameter. Increasing the drive ratio has the same effect as increasing the gear ratio.