ELECTRIC STARTER
5-41
EAS24790
CHECKING THE STARTER MOTOR
1. Check:
• Commutator
Dirt → Clean with 600 grit sandpaper.
2. Measure:
• Commutator diameter “1”
Out of specification → Replace the starter
motor.
3. Measure:
• Mica undercut “a”
Out of specification → Scrape the mica to the
proper measurement with a hacksaw blade
that has been grounded to fit the commutator.
The mica of the commutator must be undercut to
ensure proper operation of the commutator.
4. Measure:
• Armature assembly resistances (commutator
and insulation)
Out of specification → Replace the starter
motor.
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a. Measure the armature assembly resistances
with the pocket tester.
b. If any resistance is out of specification, re-
place the starter motor.
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5. Measure:
• Brush length “a”
Out of specification → Replace the brushes
as a set.
6. Measure:
• Brush spring force
Out of specification → Replace the brush
springs as a set.
Limit
23.5 mm (0.93 in)
Mica undercut (depth)
1.50 mm (0.06 in)
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
Armature coil
Commutator resistance “1”
0.024–0.030 Ω at 20 °C (68 °F)
Insulation resistance “2”
Above 1 MΩ at 20 °C (68 °F)
Limit
3.65 mm (0.14 in)
Brush spring force
5.28–7.92 N (538–808 gf, 19.01–
28.51 oz)
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