MG321T/0.5M 0.5M Module 21T Motor Pinion for RC Applications by GPM  [MG321T/0.5M]

This GPM MG321T/0.5M motor gear is a compact pinion aimed at scale RC drivetrains that require a 21-tooth, 0.5mm module pinion. The item is made from 40Cr steel with a hardened black surface finish to provide improved durability compared with non-hardened replacements.

Primary dimensions are listed so you can confirm fitment: 21T tooth count, 0.5mm module, and motor tooth diameter 3.175mm with a round motor bore. The pinion fastens to the motor shaft with two 3x3 set screws; check shaft style and pinion spacing prior to installation for correct mesh.

For typical replacement and modest tuning the pinion keeps mesh geometry predictable, the hardened steel resists premature wear in normal RC loading, and the round bore with dual set screws simplifies alignment on common motor shafts. Confirm mesh clearance after fitting and before operation.