# First Gear

First gear is in the transmission. It is described by a ratio. If you have a first gear ratio of 2 to 1, that means the first gear in the transmission turns 2 times for every 1 turn of the engine. Pictured above are manual transmission gears.

## What you do:

Choose a gear ratio that gives you the traction and acceleration you want off the line.

Factors to consider:

1. The average car on the street has a first gear ratio of about 3 to 1, but a race car has much more power and needs a first gear ratio of about 2 to 1 to get enough traction off the line.

2. Traction is affected by gear ratio. Higher gear ratios, such as the 3 to 1 gears of a regular car, 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 in that gear. 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.

Definitions:
mph = miles per hour
rpm = revolutions per minute