Mugen Seiki MRX4 Rear Brake Disc MRX4-21/GO by 3Racing  [MRX4-21/GO]

MRX4 Series Brake Rotor

This brake disc is an RC-scale replacement part intended for use with Mugen Seiki MRX4 and MRX4-R chassis, supplied under part number MRX4-21/GO. It is offered as a direct-fit spare to restore or modify rear braking components on 1/10 on-road models that use the MRX4 family mounting pattern.

Installation notes: confirm rotor alignment at the hub and torque fasteners to match your existing hardware recommendations, swapping worn screws or washers as needed. Fit one side first, check rotor runout, then install the opposite side and verify free rotation before reassembling the drivetrain. Standard hex drivers and hand tools used on MRX4 assemblies are sufficient for fitment.

Tuning role: changing discs alters pedal feel and brake modulation at the hub, which influences brake bias and diff setup on track. Fit matched pairs and make incremental tests on short runs to judge stopping response and corner entry behaviour.