Starter Motor Assembly: Inspection: Commutator

Support the armature with a pair of V block and turn it to measure the runout of the surface not rubbed by the brushes using a dial gauge.
Standard value: 0.05 mm (0.002 inch) or less

Limit: 0.1 mm (0.004 inch)

Fig 1: Measuring Runout Of Commutator Surface
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Measure the diameter of the commutator.
Standard value: 29.4 mm (1.157 inch)

Limit: 28.8 mm (1.134 inch)

Fig 2: Measuring Outer Diameter Of Commutator
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Measure the depth of the undercut between segments.
Standard value: 0.5 mm (0.002 inch)

Limit: 0.2 mm (0.008 inch)

Fig 3: Identifying Undercut Depth
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.