By Bruce Santucci
Updated Mar 24, 2022
RC hobbyists know that a motor’s health directly impacts a vehicle’s performance. Neglect can lead to premature wear, but a systematic rebuild can restore or even improve power, efficiency, and lifespan. Follow this expert guide for a clean, reliable motor restoration.
Remove the motor’s end bell first, then carefully unscrew the springs with a Phillips screwdriver. Pull the old brushes out by their wire ends before disconnecting the end bell. Keep the order of removal in mind; you’ll need to reassemble in the same sequence.
Twist and gently pull the end bell apart. Pay close attention to the screw locations relative to the magnets. The timing is often set during manufacturing; changing it can affect heat and RPM. Mark the position of any washers or spacers so you can return them to the exact spot during reassembly.
Mount the motor on your lathe following the manufacturer’s instructions. Use a Sharpie marker to ink the commutator surface; this reveals high spots after the first pass and helps gauge when the surface is truly flat. The ink also provides a light lubricant for the copper.
Turn the lathe in small increments (e.g., 0.01”) and cut from the outer edge toward the center. Work the same setting once before increasing the depth. When the commutator regains roundness, wipe grooves with an X‑Acto knife to remove debris. Avoid scoring the copper, which can impair contact.
Reinsert the armature into the motor housing and tighten the screws, mirroring the original arrangement. Proper screw placement is critical for timing and heat management. Aim for a balance between high RPM and efficient operation.
Secure the new brush wires to the end bell using a soldering iron. Hold the tip with pliers to prevent solder from flowing up the wire, which would stiffen the brush and reduce efficiency. Ensure the brushes are firm but flexible.
Slide the brushes into the brush hood, which is the recessed section of the end bell. They should fit smoothly without resistance. Reattach the springs, keeping the wires untangled. Tangled springs can cause arcing, raising motor temperature and shortening life.
Reconnect the motor to a 2–3 V supply and run it for about 10 minutes. This breaks in the brushes and ensures a firm electrical contact. Once the motor runs smoothly, it’s ready for service.
