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Does a Smaller Spur Gear Make an RC Car Faster?

If you want to know if a smaller spur gear will help your car’s performance keep reading. Also, learn tips on selecting gear ratio and what controls overall speed for your car.

Does a Smaller Spur Gear Make an RC Car Faster?

Yes, a smaller spur gear will make an RC car faster in terms of top speed. A smaller spur gear will decrease the gear ratio, which in turn will increase the top speed of the RC car.

However, it is important to note that while a smaller spur gear will increase the top speed, it will also reduce the torque and acceleration of the RC car. This means that the RC car may take longer to reach its top speed and may struggle on surfaces that require more grip or on steep inclines.

Understanding the Gearing System

The gearing system consists of two main gears: the pinion gear and the spur gear. The pinion gear is the smaller gear attached to the motor, and the spur gear is the larger gear connected to the car’s driveshaft.

The ratio between the sizes of these two gears is called the gear ratio. The gear ratio is a key factor that affects the speed and torque of the RC car.

Speed vs. Torque

Speed and torque are inversely related. A higher gear ratio (smaller pinion gear or larger spur gear) will give the RC car more torque and acceleration but will decrease its top speed.

Conversely, a lower gear ratio (larger pinion gear or smaller spur gear) will reduce the torque and acceleration but will increase the top speed.

Finding the Right Balance

It is essential to find the right balance between speed and torque based on the type of terrain on which you will be driving your RC car. For example, if you are racing on a flat, smooth surface, a smaller spur gear and higher top speed may be advantageous.

However, if you are driving on a rough, uneven surface or a track with lots of sharp turns, having more torque and acceleration may be more beneficial.

Additionally, driving at high speeds for extended periods can cause the motor and other components to overheat. Therefore, it is important to consider the capabilities of your RC car and the conditions in which you will be driving it before making any changes to the gearing system.

How Do I Choose the Gear Ratio for My RC Car?

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Choosing the right gear ratio for your RC car involves a balance between speed and torque, and depends on factors such as the terrain you will be driving on, the power of your motor and battery, and the weight of your car.

Experimenting with different gear ratios can help you find the perfect balance for your particular RC car and driving style.


The terrain you will be driving on is an important factor in choosing your gear ratio. For flat and smooth surfaces, a lower gear ratio (higher speed, lower torque) is usually suitable. For rough or hilly terrain, a higher gear ratio (lower speed, higher torque) is recommended.

Motor and Battery

The type of motor and battery you are using can also affect your choice of gear ratio. A more powerful motor can handle a lower gear ratio, as it can provide enough torque even at higher speeds. Similarly, a higher voltage battery can provide more power to the motor, allowing you to use a lower gear ratio.

Weight of the Car

The weight of your RC car will also affect its performance. A heavier car will need more torque to accelerate and climb hills, so a higher gear ratio may be necessary.

What Controls the Speed of an RC Car?

The speed of an RC car is influenced by various factors including the motor type, battery power, gear ratio, tire size and type, aerodynamics, and weight.

By understanding how these factors affect the speed of an RC car, enthusiasts can modify and optimize their vehicles for better performance and speed. Here are the main factors in more detail:

Motor Type:

The motor is the heart of any RC car and is primarily responsible for its speed. There are two main types of motors used in RC cars: brushed and brushless.

  • Brushed Motors: These are the most common type of motors used in entry-level and mid-range RC cars. They are cheaper and easier to maintain but tend to be less efficient and slower than brushless motors.
  • Brushless Motors: These are more advanced and offer higher speed and efficiency than brushed motors. They are also more durable and require less maintenance. Most high-performance RC cars use brushless motors.

Battery Power:

The battery supplies power to the motor and hence has a direct impact on the speed of the RC car. The voltage of the battery affects the RPM (Revolutions Per Minute) of the motor, which in turn affects the speed of the car. Higher voltage batteries will result in higher speeds.

However, ensuring that the motor and other electronic components can handle the increased voltage is important.

Gear Ratio:

The gear ratio is the relationship between the number of teeth on the pinion gear (attached to the motor) and the number of teeth on the spur gear (attached to the wheels).

A higher gear ratio (more teeth on the spur gear relative to the pinion gear) will result in more torque and acceleration but lower top speed. A lower gear ratio (fewer teeth on the spur gear relative to the pinion gear) will result in higher top speed but less acceleration.

Tire Size and Type:

The size and type of tires used on an RC car also affect its speed. Larger diameter tires will increase the top speed of the car but may decrease acceleration. The type of tire (slick, treaded, off-road, etc.) will also affect the grip and handling of the car, which can indirectly affect its speed.


The aerodynamics of an RC car can have a significant impact on its speed. A well-designed body shell that reduces air resistance will allow the car to achieve higher speeds. Winglets, spoilers, and other aerodynamic aids can also help to increase downforce and improve the handling of the car at high speeds.


The weight of an RC car is another important factor that affects its speed. A lighter car will have better acceleration and top speed compared to a heavier one. However, it is important to ensure that the car is not too light as it may affect its stability and handling at high speeds.