Hardened 40Cr 21T Motor Pinion MG321T/0.5M for RC motors by GPM  [MG321T/0.5M]

This GPM MG321T/0.5M motor gear is a compact pinion made for scale RC drivetrains that need a 21-tooth, 0.5mm module gear. It is manufactured from 40Cr steel with a hardened black finish to give better wear resistance and a longer service life than untreated replacement gears.

Key dimensions are provided so you can confirm fitment: 21T tooth count, 0.5mm module, and a motor tooth diameter of 3.175mm with a round motor bore. The pinion fastens to the motor shaft using two 3x3 set screws; check your motor shaft style and pinion spacing before installation to ensure correct mesh.

For routine replacement and light tuning this pinion keeps mesh geometry predictable, the hardened steel reduces early wear under normal RC loads, and the round bore plus dual set screws simplifies alignment on common motor shafts. Always verify gear parameters and mesh clearance after fitting and before running.