The Proper RC Car Motor Gear Ratio Setup and Its Effects


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As an RC car racer, we should be aware of that in order to increase the overall running performance of our RC car, upgrading to a powerful motor is only one of many options available. In fact, being able to set up the right gear mesh is even more important.

First, we need to learn how to calculate a gear ratio. While it is a very effective way to increase the performance of our RC cars, it is not hard to learn. However, before we step into the learning process of how this calculation can affect our RC car’s performance, we look at the formula of gear ratio calculation first.

How gear ratio is calculated

Gear ratio calculation is simply calculating the resulting speed of two linked gears. The gear attached motor is the driver and the other is driven by the first gear. Then, to calculate the gear ratio is to divide the number of teeth on the driven gear by the number of teeth on the driver gear.

Why we need to know the gear ratio calculation

As the gear ratio gets smaller, the speed goes up. For example, take Tamiya tt02 as an example.   Its stock pinion gear is 22T and stock spur gear is 70T, then as soon as you replace the 22T pinion with one of 25T, the speed should go up as now the gear ratio has been decreased from 3.18 to 2.8.

As the pinion gear gets bigger, the speed will go up, but the torque decreases; the load on the motor will be heavier with the possibility of hot temperature after the motor’s running for a while.

On the other hand, as the pinion gear get smaller, the speed will go down, but the torque increases; the load on motor will be lighter (use less energy) with lower temperature.

How gear settings affect the performance of an RC car in a race track

On a large race circuit, the track usually has long straight roads, with more big corners to turn. We will use bigger pinion gear in order to increase speed.

On a smaller race circuit, the track usually has shorter straight roads, with.many small corners to turn. We will use smaller pinion gear in order to increase torque that is necessary for this type of road condition.

Important things to remember during car settings

When the motor is too hot, we should consider replacing the stock pinion with a smaller one.

After turning a corner, on a straight road, if an RC car cannot increase its speed to its potential, we should replace with a bigger pinion gear.

When an RC car exits a corner, and it cannot increase its speed at that point, we should use smaller pinion gear to increase torque.

Replacing the spur gear also have the above-mentioned effects, but the results are just the opposite.

The manual that comes with a new motor will state the limitation of pinion/spur gears that can be used with.

If you are considering replacing a stock motor with a brushless one, you might want to read this post on how to replace with a brushless motor


When beginners first run on a race circuit, they usually cannot run their RC car at its full speed. However, as they get more practice, they will think that they should replace the stock motor with a faster one. However, besides replacing a speedy motor, they should also learn how to set up the gears right as they have a great impact on an RC car performance. If they can follow each point discussing gear mesh in this post, in the near future, they should be able to step up on the winning position in a race.

Thank you for reading this post.

Written by Carlos Santos, your webmaster


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