GMC 4000 Series Service Manual page 131

Sec. 3D
Page 124
FRONT HUBS A N D BEARINGS
damage. Non-demountable brake drums can be re­
finished while mounted on hubs. (NOTE: Refer to
"HYDRAULIC BRAKES" (SEC. 5A) under "Brake
Drums.") If necessary to replace demountable
brake drum refer to "Repair" later in this section.
4. Examine wheel studs or rim clamp studs
for damaged threads and replace, if necessary, as
directed later under "Repair."
5. Discard old oil seals and obtain new oil
seals to be used at assem bly.
REPAIR
Bearing Cup Replacement
1. Bearing cups are removed by using a mild
steel rod through opposite end of hub and driving
against inner edge of bearing cup. Alternately
drive on opposite sides of cup to avoid cocking cup
and damaging inside of hub.
2. To install new cups, position cup in hub
and drive into place, using a suitable driver or by
using a mild steel rod against outer edge of cup.
If drift is used, alternately drive against opposite
sides to assure driving cup in squarely. Cups must
seat against shoulder in hub.
Brake Drum Replacement
1. Demountable Type. The demountable type
drum may be separated from the hub and removed
from the vehicle without disturbing the hub. The
drum is held to the hub by countersunk, slotted
screw s, which are easily removed with a screw ­
driver.
2. Non-Demountable Type. Non-demountable
type hub and drum assembly is such that replace­
ment cannot be accomplished with the hub assem ­
bly installed on the vehicle.
G M C S E R V I C E M A N U A L
the drum-to-hub retaining bolts, hub stud nuts, or
by pressing out the wheel studs, as applicable.
ing certain that all drain holes are in alignment.
pound to the hub oil deflector contact surface, and
position deflector to drum.
stud nuts, or press wheel studs into drum.
Wheel Bolt Replacement
swaged in place; however, replacement procedure
remains the same for both types of installation.
P ress bolts out of hub flange, using suitable p ress,
then press new bolts into place, making sure bolts
are a tight fit. If all bolts were removed, be sure
that hub oil deflector is in position under bolt heads.
single stud failure caused by a loose running wheel,
all studs should be replaced.
stud to break, but several more studs may become
fatigued to the point, of failure, but not actually
breaking. Replacing only the one broken stud and
remounting wheel will then set the stage for a
second and possibly more serious failure. If holes
in wheel have become elongated, or enlarged, re­
place wheel.
Hub Stud Replacement
using a conventional stud remover and replacer.
Make sure that studs are firmly bottomed in holes
and that threads are not damaged during installation.
a. Separate the drums and hub by removing
b. Position brake drum to hub assembly, mak­
c. Apply a light, even coating of sealing com­
d. Install drum-to-hub retaining bolts, hub
Wheel bolts are serrated and may also be
IMPORTANT: If any one wheel experiences a
A loose running wheel may cause only one
Hub studs can be removed and replaced by