Parts/Drivetrain/Pinion gears/RC4WD 4/1 Ultra Compact Gear Reduction Unit (540 Motor)
RC4WD 4/1 Ultra Compact Gear Reduction Unit (540 Motor)
RC4WD

RC4WD 4/1 Ultra Compact Gear Reduction Unit (540 Motor)

Part # RC4ZU00121.0(1)
Where to buy
$22.99
AMain Hobbies
Seen Oct 12, 2026
$22.99Buy
Prices are as last seen at the store; stock is not tracked.

About this part

Reduction Overview:

The RC4WD 4/1 Ultra Compact Gear Reduction Unit for 540 Motors is designed to fit any RC truck, car, robot, airplane, or boat that uses a standard 540 motor. It will work as long as there is enough room for the extra length (.7 inch / 18mm).


Features:

  • 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

Specifications:

  • 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

Includes:

  • (1) RC4WD Ultra Compact GRU
  • (1) 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.

Reviews1.0 · 1 review

Craig Busbeeon RC4WD 4/1 Ultra Compact Gear Reduction Unit (540 Motor)

Very disappointed! Theres no holes to mount to transmission, It says in description there are 6 gears, There's 3 one for the motor,one for the internal output, and one for the idler, and it's 2mm thin! Won't last very long even if it had holes to mount! Could drill holes,but for the wasted 41$ Id rather not waist time with this piece of garbage. I just went and bought 2 of the 4 internal geared planetary reduction boxes 23$ each. These things are great! The 4 internal gears are at least 8 to 10mm thick!

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