Commutator Inspection

Inspect commutator for dirt or signs of burning. If dirt or burning is present, sand lightly with No. 300-400 sand paper or lathe as necessary to clean surface.
Using a dial indicator, check commutator for runout. Standard runout is .0019" (.05 mm). Maximum runout is .015" (.4 mm). If runout exceeds the maximum limit, replace commutator.
Using a micrometer, measure diameter of brush end of commutator. Standard measurement is 1.16" (29.4 mm). Minimum measurement is 1.13" (28.8 mm). If measurement is less than minimum, replace commutator.
Measure depth of grooves between commutator segments and insulators. See Fig 1. Standard depth is .0196-.0314" (.5-.8 mm). Minimum depth is .0078" (.2 mm). If less than minimum depth, replace commutator.

Fig 1: Measuring Depth of Commutator Segment Grooves

Courtesy of SUZUKI OF AMERICA, INC.