Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Starting Motor Inspection: Armature
- Check commutator for dirt or burn. Correct commutator with sandpaper or lathe if necessary.
- Check commutator for uneven wear with armature (1) supported on V-blocks (2) by using dial gauge (4). If dial gauge (4) deflection exceeds the limit, repair commutator or replace armature.
Commutator out of round
Standard: 0.05 mm (0.002 in.) or less
Limit: 0.4 mm (0.02 in.)
- Check commutator for wear and measure diameter of commutator. If diameter of commutator is lower than the limit, replace armature.
Commutator outside diameter
Standard: 29.4 mm (1.16 in.)
Limit: 28.8 mm (1.13 in.)
- Check commutator (1) for insulator (2) depth. Correct insulator depth if it is lower than the limit.
Commutator insulator depth "a"
Standard: 0.5 mm (0.020 in)
Limit: 0.2 mm (0.008 in.)
- Check insulation between commutator and armature core. If there is continuity, replace armature.
- Check for continuity between segments. If there is no continuity at any test point, replace armature
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.