Parts Replacement & Testing: Bushings

Armature shaft is supported by three bushings. Commutator and driving end brackets each carry porous bronze bushings, while intermediate bracket carries a graphite-impregnated brass bushing. Bushings which are worn to the extent that they allow excessive side play of the armature must be replaced.
The drive end bushing and intermediate bracket bushings can be pressed out. The commutator end bracket bushing is removed by inserting a suitable tap and withdrawing the tap with the bushing attached. New bushings are installed using a shouldered highly polished mandrel of same diameter as shaft to be fitted in the bushing.
CAUTION: Do not ream bronze bushings, as the porosity of the bushing may be altered.
Before installing a new porous bronze bushing, it should be immersed in clean engine oil for 24 hours. This process can be speeded up in case of an emergency, by heating oil to 212°F (100°C) and allowing bushing to soak for two hours. Allow oil to cool before removing bushings from oil.