Starter Armature: Testing and Inspection
INSPECTION1. Remove the starter.
2. Disassemble the starter as shown at the beginning of this procedure.
3. Inspect the armature for wear or damage from contact with the permanent magnet. If there is wear or damage, replace the armature.
4. Check the commutator (A) surface. If the surface is dirty or burnt, resurface with emery cloth or a lathe within the following specifications, or recondition with #500 or #600 sandpaper (B).
5. Check the commutator diameter. If the diameter is below the service limit, replace the armature.
Commutator diameter
Standard (New)
M/T: 29.9-30.0 mm (1.177-1.181 in.)
A/T: 28.0-28.1 mm (1.102-1.106 in.)
Service limit
M/T: 29.0 mm (1.142 in.)
A/T: 27.5 mm (1.083 in.)
6. Measure the commutator (A) runout.
- If the commutator runout is within the service limit, check the commutator for carbon dust or brass chips between the segments.
- If the commutator runout is not within the service limit, replace the armature.
Commutator Runout
Standard (New): 0.02 mm (0.001 in.) max.
Service limit: 0.05 mm (0.002 in.)
7. Check the mica depth (A). If the mica is too high (B), undercut the mica with a hacksaw blade to the proper depth. Cut away all the mica (C) between the commutator segments. The undercut should not be too shallow, too narrow, or V-shaped (D).
Commutator mica depth
Standard (New)
M/T: 0.5-0.8 mm (0.020-0.031 in.)
A/T: 0.4-0.5 mm (0.016-0.020 in.)
Service limit
M/T: 0.2 mm (0.008 in.)
A/T: 0.15 mm (0.006 in.)
8. Check for continuity between the segments of the commutator. If an open circuit exists between any segments, replace the armature.
9. Check with an ohmmeter that no continuity exists between the commutator (A) and armature coil core (B), and between the commutator and armature shaft (C). If continuity exists, replace the armature.