Motor Failure Modes and Heat Management

Common Motor Failure Modes

Bent Shaft

The most common crash-related failure. Symptoms: vibration at all throttle levels, visible wobble in the prop, motor feels rough when spun by hand. Fix: replace the shaft (on motors with replaceable shafts) or replace the motor entirely.

Worn Bearings

Bearings wear out over time and from dust ingestion. Symptoms: grinding or crunching when the motor is spun by hand, increasing vibration over time. Fix: replace bearings (cheap, fiddly) or replace the motor.

Damaged Windings

Caused by a crash that pushes the stator hard enough to nick the enamel on the windings. Symptoms: motor twitches on arm, one phase reads differently on a multimeter, ESC throws a desync error. Fix: motor replacement only.

Loose Magnets

High-speed crash can cause the rotor magnets to separate from the bell. Symptoms: motor locks up or has inconsistent resistance when spun. Fix: replacement.

Heat Management

Motors should be warm but not hot after a full pack. As a practical guide:

• Comfortable to hold (under 50°C): Good. Operating efficiently.
• Too hot to hold for more than a second (60–70°C): Investigate. Possible causes: props too aggressive, KV/cell count mismatch, high D-term.
• Burning smell: Land immediately. Winding damage likely.

Preventive Care

• After every session, spin each motor by hand and check for roughness or wobble.
• Blow out dust with compressed air every 5–10 packs.
• Check bell screws for looseness — Loctite 243 on the threads after any crash.