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

MRX-5 first-stage pinion overview

The Arrowmax AM-MRX5-H0758 1st gear is an aftermarket pinion created for use with the Mugen MRX-5 clutch and pinion assembly. Machined from 7075-T6 aluminum and finished with a hard surface treatment, this pinion aims to reduce rotating mass while improving wear resistance without changing the clutch interface. Tooth options from 16T through 21T let you adjust acceleration and initial drive feel on the MRX-5 drivetrain.

Fitting follows the standard MRX-5 pinion swap routine: remove the original 1st gear from the clutch bell, mount the Arrowmax pinion onto the clutch/pinion hub, then check mesh to the spur and confirm smooth rotation through the gearbox. Make small mesh tweaks and run a short test to monitor temperature and noise before extended operation.

From a tuning perspective, selecting a lower tooth count quickens spool-up and launch response, while higher tooth counts will raise first-stage gearing slightly for a firmer initial drive. Use the 16T-21T range to dial in launch behaviour and low-speed traction for your track setup.

Vehicle compatibility

• Mugen MRX-5