Mugen MRX-5 1st Gear 17T Alloy Pinion - MUGEN AM-MRX5-H0758  [AM-MRX5-H0758]

First-stage pinion description

The Arrowmax AM-MRX5-H0758 1st gear is an aftermarket pinion intended for the Mugen MRX-5 clutch and pinion arrangement. Produced from 7075-T6 aluminium with a hard-coated finish, this gear is aimed at reducing rotating weight and resisting wear while maintaining the factory clutch interface. Available tooth counts span 16T to 21T, giving stepped options to alter acceleration and the MRX-5 first-stage drive feel.

Installation is the same as a standard MRX-5 pinion swap: remove the stock first gear from the clutch bell, mount the Arrowmax unit onto the clutch/pinion hub, then check mesh against the spur and verify free rotation through the gearbox. After initial fitting, run a short test to check for correct mesh and acceptable running temperature.

Changing the first-stage tooth count modifies the effective final drive during engagement; lower tooth counts speed up spool-up and initial acceleration, while higher counts raise first-stage gearing for a firmer pull at low revs. Use the tooth range to tune launches and low-speed control for your setup.

Fitment compatibility

• Mugen MRX-5