Tamiya 70190 Mini Motor Multi-Ratio Gearbox Kit (12-Speed)

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The mini-motor gearbox kit from Tamiya makes it easy to get a small robot or plastic model moving. The kit includes one brushed DC motor and all the gears and parts to build any of the twelve possible gear ratio configurations: 4.6:1, 5.1:1, 9.7:1, 10.8:1, 20.4:1, 22.6:1, 42.8:1, 47.5:1, 89.9:1, 99.8:1, 188.7:1, or 209.7:1. The twelve gear ratio options give you the flexibility to choose the best speed and torque for your project. There are two possible output axle locations (only one output location is possible for any given ratio).

Parts included with the Tamiya 70190 mini motor multi-ratio gearbox (12-speed) kit with quarter for size reference.

The kit includes step-by-step illustrated instructions in both Japanese and English. A scanned copy of the instructions is available on the Pictures tab. The kit can be built with just a screwdriver, but the instructions recommend having side cutters, tweezers, and a modeling knife on hand. The gearbox kit’s motor has a 030 form factor that is smaller than the Tamiya gearboxes that use the Mabuchi FA-130 motor.

Box front for Tamiya mini motor multi-ratio gearbox (12-speed) kit.

Instructions for Tamiya mini motor multi-ratio gearbox (12-speed) kit page 4.

Box back for Tamiya mini motor multi-ratio gearbox (12-speed) kit shows the possible gear ratios in green.


  • 030-form-factor motor
    • Speed @ 3 V: 8400 RPM
    • Free-run current @ 3 V: 60 mA
    • Stall current @ 3 V: 600 mA
    • Stall torque @ 3 V: see picture to the right for torque table
  • 12 different gear ratios, which can be adjusted by changing the pinion gear and final gear position
    • 4.6:1
    • 5.1:1
    • 9.7:1
    • 10.8:1
    • 20.4:1
    • 22.6:1
    • 42.8:1
    • 47.5:1
    • 89.9:1
    • 99.8:1
    • 188.7:1
    • 209.7:1
  • 3 mm hexagonal output shaft compatible with our adapter for LEGO wheels and many of Tamiya’s wheels.
  • Two mounting orientations
  • Mounting holes designed to work with the Tamiya 70098 universal plate set and other Tamiya construction series products.
  • Transparent gear housing shows the internal mechanisms
  • Compact size of approximately 30 x 17 x 31 mm (1.2" x 0.7" x 1.2")

Note: The Tamiya 70190 mini motor multi-ratio gearbox (12-speed) is a kit; assembly is required.


Typical operating voltage 3 V
Gear ratio options 4.6, 5.1, 9.7, 10.8,
20.4, 22.6, 42.8, 47.5,
89.9, 99.8, 188.7, 209.7 :1
No-load motor shaft speed @ 3V 8400 rpm [1]
No-load current @ 3V 60 mA [2]
Stall current @ 3V 600 mA
Color clear
  1. A theoretical speed of the gearbox output shaft can be computed by dividing this speed by the gear ratio.
  2. This is the no-load current of the motor when disconnected from the gears in the gearbox; the no-load current of the entire gearbox with the motor connected will be slightly higher and will vary depending on the gear ratio.