Piper COMANCHE PA-24-180 Service Manual page 586

9-78. Ovrhaul. If during the above inspection any indication of starting motor difficulty is
noted, the starting motor should be removed from the engine for cleaning and repair.
9-79. Removal. To remove the staring motor from the engine, fint disconnect the ground cable
from the battery post to prevent short circuiting. Disconnect the lead from the starting motor
terminal, then take out the mounting bolts. The motor can then be lifted off and taken to the
bench for overhaul.
9-80. DiOassembl y
a. Remove the frame screws from the commutator end head and pull end head and armature
from frame. Lift the brushes and lock in elevated position with brush springs. Use a puller to re-
move the end head from the armature. Use a special bearing puller to remove the sealed ball
bearing from the armature shaft.
b. Remove the frame screws that secure the gear housing to the frame. Rem - bolts and
nuts holding the gear housing to the pinion housing and separate the two units. Pull Bendix shaft
from pinion housing. Do not lose the steel spacer that is located on the pinion end of the shaft.
Remove reduction gear, woodruff key and steel spacer from shaft.
c. Turn the Bendix pinion until it locks in the extended position. Locate "spirol" pin and
use a punch to remove. Slide drive assembly off the shaft. Do not attempt to disassemble the
drive and do not dip it in cleaning solvent.
d. To remove the roller bearings from the gear housing, use an arbor press and the correct
bearing arbor. DO NOT HAMMER OUT. Each part should be cleaned and inspected for excessive
wear or damage Bearings should be checked for proper clearance and evidence of roughness or
galling. Oil and din should be removed from insulation and the condition of the insulation checked.
9-81. Brushes. Check the brushes to see that they slide freely in their holders and make full
contact on the commutator. If worn to half their original length or less, they should be replaced.
9-82. Armature.
a. Check the commutator for uneven wear,excessive glazing or evidence of excessive arcing.
If only slightly dirty, glazed or discolored. the commutator can be cleaned with 00 or 000 sand-
paper. If the commutator is rough or worn, it should be turned in a lathe. Refer to Figure 9-29b.
The armature shaft should be inspected for rough bearing surfaces and rough or damaged splines.
b. To test the armature for grounds, a set of test probes connected in series with a 110-volt
light should be used. Touch one probe to a commutator segment and the other to the armature
core If the test lamp lights, the armature is grounded and should be replaced.
c. To test for shored armature coils, a growler is used. (Refer to Figure 9-29c.) The anma-
ture is placed on the growler and slowly rotated by hand while a steel strip is held over the core
so that it passes over each armature core slot. If a coil is shorted, the steel strip willvibrare.
d. A quick check for opens can be made by inspecting the trailing edge (in direction of ro-
tation) of the commutator segments for excessive discoloration. This condition indicates an open
circuit.
ELECTRICAL SYSTEM
ISSUED: 8/1872
3 C16
PIPER COMANCHE SERVICE MANUAL