Yokomo YZ-4 6mm Rear Drive Belt Upgrade - Z4-309-6  [Z4-309-6]

Slim 6mm rear belt for YZ-4 drivetrains

A 6mm rear drive belt made for the Yokomo YZ-4 platform, the Z4-309-6 is built to reduce drivetrain load on RC models running in low-power stock classes. Its narrower cross section reduces contact area versus wider belts, trimming transmission friction without changing chassis geometry.

In tuning terms, this belt helps cut drivetrain resistance and tightens throttle response where motor output is limited. Results are most apparent when matched with a narrow aluminium pulley like the Z4-630A, which focuses contact on a smaller diameter and can further lower drag. This setup suits tracks requiring quick bursts rather than sustained high speed.

Installation tips: confirm alignment of motor pinion, spur gear and pulleys before setting final belt tension, and avoid over-tensioning which raises bearing load. Inspect pulley grooves and running surfaces for wear and verify smooth rotation of bearings and idlers after fitting. This accessory is intended for RC-scale model use only.