GMC 4000 Series Service Manual page 129

Sec. 3D
Page 122
DESCRIPTION
Front hubs are mounted on steering knuckle
spindle on opposed tapered roller bearing as illu s­
trated in figure 1. Refer to "Service Parts Identi­
fication" decal on dash compartment door to de­
termine type of axle used on a specific vehicle.
Mounting parts (mainly bearings, spindle nuts, and
seals) shown in figure 1, are of primary import­
ance. Brake drum mounting bolts, studs, and nuts
differ in type and method of installation on various
series vehicles.
BEARING MAINTENANCE
All wheel bearings are adjustable for wear.
Satisfactory operation and long life of bearings
depend upon proper adjustment and correct lubri­
cation. If bearings are adjusted too tight, they will
F040 AXLE w / D ISC WHEELS
F070 AXLE D EM O U N TAB LE
w /DISC WHEELS
1 Hub Cap or Closure Plate
2 Bearing Adjusting Nut
3 Adjusting Nut Washer
4 Cap Screw
5 Gasket
6 Wheel Bolt
7 Outer Bearing Cup
G M C S E R V I C E M A N U A L
SECTION 3D
cJluhl and (iea'Unai.
overheat and wear rapidly. Loose adjustment will
cause pounding and will also contribute to steering
difficulties, uneven tire wear, and inefficient brakes.
Bearing adjustment should be checked at regular
inspection periods.
inspected, and lubricated whenever hubs are re­
moved, or at intervals indicated in LUBRICATION
(SEC. 0) of this manual.
servicing bearings if there is the slightest indica­
tion of wear or damage. An imperfect seal may
permit bearing lubricant to reach brake linings,
resulting in faulty brake operation and necessitat­
ing premature replacement of linings.
BEARING ADJUSTMENT CHECK
make sure brakes are fully released. Jack up the
F050 A N D F055 AXLES w /D ISC WHEELS
F070 A XLE FLANGE M O U N TED
w /DISC WHEELS
8 Outer Bearing Cone and Roller
9 Wheel Bolt Nut
10 Brake Drum
11 Hub to Brake Drum Bolt
12 Lock Nut
13 Inner Bearing Cup
14 Inner Bearing Cone and R ollers
Figure 1 — Front H ubs a n d Bearings
Front hubs and bearings should be cleaned,
New hub oil seals should be installed when
Before checking wheel bearing adjustment
F050 A N D F055 AXLES w /CA ST WHEELS
15 Oil Shield or Deflector
16 Inner Oil Seal
17 Wheel (Cast Type)
18 Steering Knuckle
19 Wheel (Budd Type)
20 Hub
21 Wheel Clamp