TM 10-3930-641-34-1
STARTER MOTOR TESTING (CONT)
(Sheet 5 of 6)
LOCATION/ITEM
ACTION
REMARKS
12. Armature (46)
Check for ground with a multimeter. Check
Replace if necessary.
for shorts with a growler. Check for out of
round conditions on the commutator by
installing the armature in a vise. If the surface
of the commutator is damaged or out of
round it must be resurfaced or replaced. The
mica should be cut 0.025-0.032 in. (6.35-
8.13 mm) below the commutator surface.
13. Commutator resurfacing
Rotate armature at 8000 rpm in a lathe.
Take very light cuts across the commutator
finishing with a cut of no more than 0.002 in.
(.05 mm) Do not cut smaller than 2.1930 in.
(55.7022 mm). Check the mica for proper
undercut. Use either a power undercutting
tool or cut it by hand.
NOTE
The mica undercut of 0.025-0.032 in.
(6.35-8.13 mm) is very critical. Do not
widen the commutator slots as you cut, but
do not leave mica on the edges in a radius
form.
TA 099068
Go on to Sheet 6
3-204
