RC4WD 4/1 Ultra Compact Gear Reduction Unit for 540Motor RC4Z-U0012

RC4WD 4/1 Ultra Compact Gear Reduction Unit for 540Motor RC4Z-U0012
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Price: $41.99

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Decrease speed and increase torque with the Ultra Compact 4:1 gear reduction unit for 540 Motor by RC4WD.

Where can you use this product?  This gear reduction unit is designed to fit any RC truck, car, robot, airplane, boat that uses standard 540 motor. It will work as long as there is enough room for the extra length (.7 inch / 18mm).

  • CNC machined high precision aluminum housing
  • Stainless hardened steel micro size internal gears
  • Custom made pinion gears
  • Universal, fit any 540 Motor
  • Engineered & Manufactured by RC4WD


  • Gear reduction ratio: 4:1
  • Overall diameter: 36mm
  • Length: 18mm (.7 inch)
  • Output Shaft OD: 0.12" / 3.2mm (with a flat surface for mounting standard RC pinion gears)
  • Total metal gears: 6
  • Total Parts: 11

What's Included:

  • One RC4WD Ultra Compact GRU
  • One Steel Pinion Gear

Note: Due to the added length, you will need some longer motor mounting screws. For example on a Tamiya clod axle, you will need two M3 46mm long screws.

About Gear Reduction Unit (Speed Reducer)

Speed Reducer lower motor speed through an increase in torque and a decrease in output speed. Speed Reducer, also known as gear heads or gearboxes, contain a set of gears, and input and output shafts. Speed Reducers are called a gear head when it is mounted directly onto a motor, not just a shaft. During equipment operation, the motor transmits power to the input shaft of the reducer. The speed reducer then converts this power into lower output speed, which the reducer transmits to the connected load through the output shaft.

Speed Reducers are utilized by a wide variety of industries. Common industries in which reducers are found include the materials handling; automotive; aerospace; recreational; construction; food and beverage processing; oil and gas; and textile industries. Reducers are used in a variety of applications, including automation equipment; conveyors; compressors; printing presses; pumps; compressors; generators; and robotics applications.

The formation of the gears in Speed Reducers are available in many manifestations. Each one is designed for specific load and torque capacities. An example is a cycloidal reducer, which is capable of providing high reduction ratios with high accuracy, with the use of rolling elements. Another formation is that of the planetary reducer, which handles large shock loads well. The name stems from a likeness to a solar system in which "planet" gears revolve around a "sun" gear.

Speed reducers are advantageous in many pieces of equipment. The benefits include speed optimization and performance improvement.


Important note: this product is designed for regular 540 brushed motor, its not designed to run on high power brushless motors! It will work, but it wont last a long time.


You might have to use a dremel and make the opening of the GRU a little bit bigger, if your motor doesn't fit. And the motor shaft might need to be cutted shorter as well.

This product was added to our catalog on February 11, 2021