Repairing Armature

If armature commutator is worn, dirty, out of round or has high mica insulation between segments, commutator can be turned down in a lathe. Mica should then be undercut 1/32 in. deep with an undercutting machine and slots cleaned out to remove dirt or copper dust. If undercutting machine is not available, undercutting can be accomplished satisfactorily using a hacksaw blade. See Figure 5E-6, page 5E-5 for recessing mica separators.) Commutator should then be sanded lightly with No. 00 sandpaper to remove any burrs left from undercutting procedure. Armature test procedure is described in Section 5E. Inspect commutator end cover bushing. If bushing is worn, replace complete commutator end cover assembly. Inspect drive end cover and bearing and replace bearing if worn to excessive looseness.

REASSEMBLING STARTER MOTOR Reassembly is essentially the reverse of the disassembly procedure. If brushes (9 and 10) and springs (8) have been released from holder, use clips or clamps as shown in Figure 5L-13 to hold them in place while installing armature. Note that drive end of frame is notched to fit drive end cover. Line up positioning notch in the brush holder assembly with terminal insulator. Line up positioning mark on commutator end head with motor terminal. Install thru bolts and replace unit on engine. Reconnect cables to solenoid switch and battery.

1. Thru bolt

2. Washer and lockwasher (2)

3. Commutator end cover

4. Brush plate and holder assembly

5. Armature

6. Drive end cover

7. Drive end ball bearing

9. Terminal and brush assembly

10. Ground brush (2)

11. Frame and field coil assembly

Figure 5L-11. Prestolite 4-Pole Starter Motor - Exploded View

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