YZ-4 Rear Narrow Pulley & Belt Upgrade for YZ-4 - Z4-309C by Yokomo  [Z4-309C]

YZ-4 Aluminum Narrow Rear Pulley and Belt

The Yokomo Z4-309C kit narrows the rear belt path on YZ-4 4WD off-road models to cut driveline friction and reduce rotational load. The aluminum components target lower mechanical loss on low-power setups, where drivetrain efficiency is more important than added torque.

Installation centers on the rear belt run: the pulley and belt pieces replace the stock rear routing parts to create a narrower span. Basic RC workshop skills are enough; typical steps include accessing the rear pulley area, removing the existing belt components, and reassembling with correct belt alignment and tension to prevent binding.

Tuning note: reducing friction in the belt section helps the drivetrain draw less current under load, which can be useful for stock-class or other limited-power categories. Treat this kit as a drivetrain efficiency tweak rather than a power upgrade, and pair it with careful belt alignment for best results.

Choose the Z4-309C when you want a straightforward way to reduce rear belt friction on YZ-4 platforms; verify belt tension and alignment after fitting to maximize the intended efficiency gains.