Rear End


Pictured above are the gears in the rear end of a car.

What you do:

Choose a gear ratio that gives you the traction, acceleration and top speed you want.

Factors to consider:

1. Race cars have rear end gear ratios of around 4.11 to 1 or higher. This is necessary due to the tall tires used at the drag race track. The average car on the street has a rear end gear ratio of about 3.73 to 1.

2. Traction is affected by gear ratio. Higher gear ratios, such as 5.13 to 1, help to get the car moving. However, the gearing may be too high to put all the power of a race engine on the ground.

3. The higher the gear ratio, the quicker your car will accelerate.

4. The lower the gear ratio, the higher the miles per hour your car will be able to reach. Keep in mind, your engine has to have enough power to push the car up to that speed.

The HiPerMath equation is:

miles per hour =                           rpm x tire diameter                          
                             transmission gear ratio x rear end gear ratio x 336

Try out the gearing on the track to see what your car will do.

mph = miles per hour
rpm = revolutions per minute