d. Wheel Bearings Replacement (fig. 4-6). Drain
b. The trailer axle uses a positive bearing
as much oil from the unit as possible by removing plug
adjustment feature. When the wheel and parts are
in side of hub cap and rotate the hole to the bottom.
assembled into position, the proper bearing adjustment
Replace plug when all oil is out.
is obtained automatically by tightening the retaining nuts
against the shoulder on the axle spindle. The bearing
(1) Loosen and remove the six cap screws
adjustment will range from .005 inches .007 inches
and lockwashers securing the hub cap.
loose. Both the inner (adjusting) and outer (jam ) nuts
are tightened to 250-300 ft.-lb. The adjustment can in
(2) Remove hub cap and its gasket.
time become looser, especially when the bearing wear is
(3) Remove bearing jam nut,
accelerated by contaminated lubricant.
lockwasher, and wheel bearing adjusting nut.
c. The after-service adjustment condition can be
(4) Remove hub and outer and inner bearings
checked by means of a dial indicator.
with brake drum from axle spindle.
(1) Loosen and remove the six capscrews
and lockwashers fastening hub cap. Drain oil first.
When removing hub the brake
drum will come with it. Do not let
(2) Remove hub cap and gasket.
brake drum drag across brake
(3) Attach indicator base to end of the axle
shoes or drop down on axle
spindle and the stem should bear against the outer
machined face of the wheel hub. (A magnetic base
indicator is easier and faster to mount).
(5) Remove bearings from hub.
(4) Watch the indicator while pushing inward
(6) Remove seal from hub.
on the wheel assembly and roll it back and forth until the
indicator stops changing. Make note of this reading.
(7) Remove wiper from spindle journal.
(5) Pull outward and roll the wheel assembly
(8) Clean hub cavity and spindle journal
until the indicator again stops changing. Make note of
removing all nicks and burrs.
(9) Install new wiper.
(6) The difference between the two readings
taken in (4) and (5) above is the adjustment condition.
(10) Install new oil seal in hub. (See f of this
(7) If the difference is .040 inches loose or
greater, the bearings should be replaced even though
(11) Install hub with the new oil seal and
they may appear satisfactory.
bearings on axle spindle.
(8) If the difference is greater than .012
(12) Install wheel bearing adjustment nut and
inches loose but less than .040 inches loose see h. of
tighten with a torque wrench to 250-300 ft.-lb., while
rotating hub back and forth.
(13) Install pierced locking washer.
(14) Install outer jam nut and tighten with a
torque wrench to 250-300 ft.-lb.
(15) Install hub cap. (See g of this paragraph
(16) Fill hub with recommended oil to level
indicated on hub cap. Rotate wheel and re-check oil