MR-03 Platform Upgrade Guide

The MR-03 is the benchmark for 1/28 RWD racing. It’s the platform most serious indoor racers run, and for good reason — the chassis is well-engineered, parts availability is excellent, and the tuning depth is substantial.

This guide covers the core upgrade path from stock to competitive.

Chassis Foundation

Start with bearings and T-plate as described in the First 5 guide. For MR-03 specifically, the rear T-plate choice matters a lot. The platform is sensitive to rear flex stiffness.

For high-grip RCP surfaces, run a stiffer carbon T-plate. For carpet or lower-grip surfaces, a medium flex gives better traction.

Motor and Electronics

The stock brushed motor will get you started, but a brushless conversion is where the performance ceiling rises significantly. The MR-03 EVO accepts brushless motors in the stock motor mount.

Popular options include the Atomic brushless system and PN Racing’s brushless conversion kit. These require a brushless-compatible ESC — most modern ESCs handle both.

Suspension Tuning

The MR-03 has a relatively simple suspension setup, but the details matter. Front spring rate, knuckle offset, and toe settings all affect how the car turns in and tracks through corners.

Start neutral and adjust one thing at a time. Front springs: stiffer helps high-speed stability, softer helps low-speed rotation. Rear toe: slight toe-in increases straight-line stability.