With so many gear ratios to choose from, how do you pick the correct one for that never-raced-there-before track? Once you find the correct final drive ratio and match it to the engine’s powerband, the track you’re racing on becomes easier to master than you might think.
Understanding how to determine a ratio is one of the main keys in choosing your gear. This is done by determining the number of turns the engine needs to make to turn the tire one revolution. If the engine turns five time to make the tire turn once, you have a 5 to 1 (5.00) gear ratio.
Bruce Jones, crew chief for Crenshaw Motor Sports, says, “For a general starting point on a ¼-mile track, start with a 7 to 8 to 1 engine-to-tire rpm ratio. On a 1/3-mile track this measurement changes to 6 to 7 to 1. On a ½-mile track, use a 5 to 6 to 1 engine-to-tire rpm ratio. These can be adjusted up or down to fit your needs by changing the axle ratio. Ten points will increase or decrease the engine’s speed by approximately 100rpm.”
