A vehicle's rear end gear ratio can have a major effect on how the automobile runs. Changing the rear end gears in your vehicle can be one of the most cost-effective ways to modify its performance. There are many things to consider when choosing a rear end gear ratio, however. Changes in the rear end gears can affect your vehicle's top speed, acceleration and fuel economy. Consider how you want your vehicle to run when changing the gear ratio, and it will be easy to choose the right rear end gears.
Determine the rear end gear ratio you want your automobile to have. For high speeds, such as those found in high performance sports cars, you want to have a higher rear end gear ratio. Drag racing cars commonly have a rear end gear ratio of 4.10 to 1. For more power to be used in towing or pulling with a vehicle, such as a truck, the rear end gear ratio is generally lower. A common rear end gear ratio in trucks is 2.73 to 1. The gear ratio calculator at Corral.net can be useful for taking into consideration the engine speed, vehicle speed and tire size at a given time when choosing a proper gear ratio.
Locate what parts are available for your vehicle that will give you the gear ratio that you are looking for or something close to it. The rear end gear ratio is determined by the relationship between the number of teeth in the ring gear versus the number of teeth in the pinion gear. To find out the ratio that any combination of two gears will give you, divide the teeth on the ring gear by the teeth on the pinion gear.
Choose a rack gear and a pinion gear where the relationship will provide you with the gear ratio you selected for your vehicle in Step 1. For instance, if you are building a drag racing car and looking for a 4.10 to 1 gear ratio, you could choose a ring gear that has 41 teeth and pair it with a pinion gear that has 10 teeth.
