Electrical System 205
Dismantled view of the brush holder assembly. Bosch
starter motor.
side and the other lead to the negative side. If there is
any indication of leakage the ohmmeter will show a
reading other than infinity. Repair or renew the brush
holder if leakage is evident.
(2) Check the brushes for adequate length.
Brushes should be renewed when their length is below
Specifications. They should be a free sliding fit in the
brush holders.
NOTE: Due to the difficulty involved in
removing and installing the brushes in the
Bosch starter motor, it is recommended that
the brush holder be renewed as an assembly.
(3) Check that the commutator is free from
pitting and burning. Clean with a petrol moistened
cloth and polish with a strip of fine glass paper.
A badly worn commutator may be repaired by
mounting in a lathe, spi nning at high speed, and
taking a light cut with a very sharp tool. After turning,
undercut the insulation between the segments.
(4) Check the armature for short circuit using an
ohmmeter.
Place one of the test lead s on the armature shaft
or core and move the other lead around the circum-
ference of the commutator. If the ohmmeter shows a
reading at any point the armature is faulty and should
be renewed.
Check the drive assembly clutch pinion teeth
for wear, scoring or chipping. A clutch in good
condition should take up the drive in one direction
only. It should rotate easily and smoothly in the
non-drive direction and the assembly should move
smoothly along the armature or drive shaft helical
splines.
Check the armature shaft bushes for wear
and renew as necessary. The old bushes must be
removed and the new ones pressed into the end
brackets using a polished mandrel of the exact diam-
eter of the armature shaft. NOTE: The new bushes must not be reamed
to size, as reaming will impair the porosity
of the bushes and cause early failure. New
bushes should be allowed to stand immersed
in clean light engine oil for one hour before
installation.
To Assemble
Assembly is a reversal of the dismantling proce-
dure with attention to the following points:
Lubricate the helix of the drive shaft lightly
with graphite grease and install the drive assembly
to
the drive shaft. Install the stop collar and snap ring, slide the
stop collar over the snap ring to lock the snap ring in
position.
Lubricate the bushes in both end brackets
sparingly with engine oil. Install the engaging lever and gear set into the
drive end bracket. Install the centre rear bracket and the engag-
ing lever seal into the drive end bracket.
Slide the brush holder assembly into position
on the commutator ensuring that the brush holders
are correctly positioned in the anchor points. Install the commutator end bracket to
the
armature, install the shims and C clip. Check that the armature end float is satisfac-
tory and adjust as necessary using shims of the correct
thickness.
Align the slot in the commutator end bracket
with the cut out on the wiring seal and install the
armature end cover to the commutator end bracket.
Install the cover retaini ng screws but do not tighten.
Ensure that the permanent magnets in the
yoke have not picked up any debris and slide the yoke
over the armature ensuring that the wiring seal locates
correctly in the slot in the yoke.
View showing the planetary gear set. Bosch starter
motor.
