Prestolite And Hitachi Starter Motors


Due to the internal wiring and connections of the Prestolite frame and field assembly, there is no satisfactory field test to determine grounded or shorted field coils. If field coils are required on either Prestolite or Hitachi motors it is necessary, due to the method of installing field coils in this assembly, to replace the frame and field assembly. To tesl for field coils, using a test lamp, place one probe of test light against the frame. Place the other probe against each of the brushes attached to the field coils to indicate open or closed circuit.


If commutator is dirty it can be cleaned by polishing with No. 00 sandpaper — not emery cloth. If commutator is worn, 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. Commutator should then be sanded lightly with No. 00 sandpaper to remove any burrs left from undercutting procedure. 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.


To replace the Prestolite insulated brushes (9, figure 5-27) remove the terminal and brush assembly from slot in frame and install new terminal and brush assembly. To replace brushes attached to the field coils, first cut off old brush lead wire where it is attached to the field coil lead. Thoroughly clean coil lead by filing off old connection. Insulation on field coil lead should be removed only as far back as necessary to make new solder connection. Usinc resin flux, solder brush lead to field coil lead, making certain brush lead is in the same position as the original brush lead. On Hitachi model negative brush leads must be unsoldered from brush holder to replace. Do not overheat brush leads or solder will run on wire strands and brush leads will no longer be flexible. Before reassembling motor, check brush connections for sufficient clearance from frame and from armature.

Replace brushes when worn down close to the following minimum lengths.

Prestolite - 1/4 inch

Hitachi - 7/16 inch

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  • genet
    How to replace brushes in a prestolite 4 pole starter?
    5 years ago

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