deterioration of lubricant, will produce a reddish-brown
coating and small etched holes over outer and exposed
surfaces of the race. Corrosive oxides also act as
Bearing fits on rotating shafts are usually specified as
tight. Excessive looseness-even .001"-under a load,
produces a creeping or slipping of the inner race on the
rotating shaft. The result is that surface metal of the
shafts scrub or wear off. The force causing the inner
race to rotate disappears when the bearing fits properly.
Installation and Removal of Bearings
Improper installation or removal of bearings, especially
hammering the bearing on the shaft with off-center
blows, can result in brinelling. Since such damage is
seldom visible, it does not become known until after
failure or complete disassembly. The correct drivers
(preferably under an arbor press) and pullers should be
Removing bearings is more difficult than installing them.
In most cases, it is necessary to remove the bearing by
pulling on the outer race, which can damage the balls or
races. Therefore, it is a good Idea to replace bearings
during an overhaul, to prevent problems. However, if a
bearing is not going to be replaced, avoid removal during
low mileage rebuilds.
All ball bearings, whether manufactured here or abroad,
dimensions, tolerances, and fits. However, for a given
shaft size there are standard bearings for light, medium,
and heavy duty service.
Numbers and symbols stamped on inner and outer races
of bearings designate size and type. Note that the
numbering systems of different bearing manufacturers
have not been standardized. Consult interchangeable
tables and use the proper bearings for replacement