ARRMA ARA-2628 Pinion Gear 13T 0.5 MOD

This ARRMA CNC-machined 13-tooth pinion gear in MOD 0.5 pitch with a 2.3mm bore is a replacement and gearing-tune option for the GROM platform. The pinion is the small gear on the motor shaft that drives the spur — the single cheapest way to change how a truck accelerates and tops out.

CNC machining from metal delivers precise tooth geometry for a smooth, quiet mesh with the GROM's 0.5 MOD spur gears, and far better wear life than molded pinions. The 2.3mm bore matches the GROM motor shaft, secured with the setscrew.

As the smallest pinion in the GROM range (13T–21T), this is the torque option: harder acceleration, better wheelie response, and cooler motor temperatures at the cost of top speed — the right pick for tight spaces and grass.

Fitment is the ARRMA GROM platform including the Quake GROM. The package includes one 13T MOD 0.5 CNC pinion gear.