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4-9.3
Replacement of the brake drum is re-
quired if any of the following conditions exist:
a. The brake drum is cracked.
b. The brake surface is heat checked, grooved
or worn beyond the rebore limit or the maxi-
mum diameter.
c. The back plate is cracked.
d. The bolt holes are elongated.
e. The brake drum has been severely over-
heated.
f. The brake drum is out-of-round.
CAUTION
REPLACE BRAKE DRUMS IN PAIRS TO
A C H IE VE TH E SA ME BRA KI N G
POWER ON BOTH WHEELS AND MAIN-
TAIN AN EVEN BRAKING LOAD ON
THE AXLE. FAILURE TO DO THIS MAY
SIGNIFICANTLY REDUCE THE PER-
FORMANCE, SERVICE LIFE, AND/OR
SAFETY OF YOUR VEHICLE.
4-9.4
Replace the hub and drum as follows
(See Figures 4-12, 4-13, and 4-14):
a. For outboard mount hub and drum remove
the brake drum (See Figure 4-13). It may be
necessary to release the slack adjuster. For
inboard mount (See Figure 4-14) and spoke
wheel (See Figure 4-12) remove drum after
hub.
b. Remove hub cap and catch lubricant in a
pan.
c. Remove outer spindle nut, spindle locking
washer, inner spindle nut, and bearing. Re-
move hub from axle.
d. Using an appropriate driver, remove inner
bearing cone, and seal.
e. Using an appropriate driver, remove bearing
cups from hub.
f. Check that the hub cavity is clean. If the hub
is to be reused, clean it thoroughly.
g. Insert bearing cups into the hub.
h. Install the drum to the hub or wheel unless
the drum is outboard mount.
i.
Clean the mounting surfaces with a good
grade commercial cleaner and soft rag. Dry
all component parts with a clean, absorbent
cloth or paper. Lubricant will not adhere to
surfaces wet with solvent.
j.
For hub and drum, make sure the drum
seats flat against the hub flange and mates
properly with the hub pilot. There should be
no interference between the brake drum pilot
chamfer and the corner radius on the hub.
k. For spoke wheels, there should be clear-
ance between the spoke and the brake drum
or the brake drum will not function properly.
l.
Install inner bearing, cone, and seal.
IMPORTANT
DO NOT MIX NEW CUPS WITH OLD CONES OR
NEW CONES WITH OLD CUPS.
m. If studs are marked "R" or "L", right hand
(R) hubs should be installed on the curbside
of the vehicle, left hand (L) hubs should be in-
stalled on the driver side.
CAUTION
FAILURE TO USE THE CORRECT
STUD ON THE CORRECT SIDE MAY
CAUSE LOOSENING OF THE HUB
STUDS DURING OPERATION, RE-
SULTING IN LOSS OF A WHEEL.
n. Place the hub or wheel over the axle spindle
being careful to align the hub bore with the
axle. Do not damage the seal. Support the
hub assembly until the outer bearing cone
and spindle nut are installed, to avoid damag-
ing the seal.
o. Install the outer bearing cone and inner
spindle nut, tightening the nut until it is snug
against the outer bearing cone. Remove the
hub support allowing the hub to rest on the
bearings.
p. Install and adjust bearings (See Wheel
Bearing Lubrication and Adjustment).
q. Install the hub cap with the proper gasket.
Tighten the cap screws of the hub cap to 15
to 20 ft-lbs. of torque.
r. Remove the filler plug and fill the hub cavity
to the recommended level with a gear type
oil.
s. For Outboard Mounted Brake Drum (See
Figure 4-13) place the drum over the hub and
brake shoes being careful not to damage the
threads on the studs. Make sure the drum
seats flat against the hub flange and mates
properly with the hub pilot. There should be
no interference between the brake drum pilot
chamfer and the corner radius on the hub. If
interference exists, the hub will not be able to
function properly.
4-21
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