GMC PD-4103 User manual

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MAINTENANCE
.MANUAL·
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GMC TRUCK, & COACH D~VISJON
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GM COACH MAINTENANCE MANUAL
USE OF MANUAL
MANUAL GROUPS
This manual is divided into major groups as indicated on the tab index at
right. Location of these groups can be readily found by the numerical black
tab on the first page of each group which corresponds to numerical tab on this
page. Some of the major groups are divided into sections, each section cover-
ing a specific unit or system, as shown in Section Index on opposite page.
PAGE AND ILLUSTRATION NUMBERS
The manual pages are numbered consecutively throughout the manual. Illus-
trations are numbered consecutively within each major group.
INDEXES
The Section Index on page 2 shows first page number of major groups, or first
page number of each section when the major group is so divided. The alpha-
betical index starting on page 5 lists important items together with Manual
page number references.
SPECIAL SECTIONS
A Trouble Shooting section, starting on page 205, is provided to facilitate
analysis and correction of improper operation of the various units and systems.
Information in this section is divided into systems or units corresponding to
manual sections.
Special Tool section, starting on page 209, lists all of the special tools referred
to throughout the manual, together with names and addresses of Vendors from
whom the tools may be obtained.
All Wiring Diagrams are folded and secured on inside of back cover.
Every effort has been made to make the contents of this manual acces-
sible, readable, and accurate. Your suggestions for further improvement
of this manual are invited.
Page 3
"
j~
Front Axle
Rear Axle
Body
Brakes
Clutch
,--~-
Cooling
Electrical
Engine
Fuel
Lubrication
Springs
Steering
Transmission
Propeller Shaft
Wheels, Hubs
and
Tires
Trouble Shooting
Special Tools

GM COACH MAINTENANCE MANUAL
GENERAL DATA
The data below includes only general information on models covered
by this manual. Specific data and specifications will be found in
"Specifications" section at end of each manual group. For conven-
ience, index of general data items is shown below:
DATA
PAGE
DATA PAGE
Cooling System Capacities . . . . . . . . . . . . . . . . . . . . . 98
Max. Engine Speed ..................... See Below
Diesel Engine Information ..................... 148
Fuel Tank Capacities . . . . . . . . . . . . . . . . . . . . . . . . . 153
Lubricant Capacities . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Rear Axle Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Transmission Ratios . . . . . . . . . . . . . . . . . .. . . . . . . . . 194
MODEL DATA
PD-4103.
Wheelbase ................................... 247"
Tire Size ........... 11:00-20 Single front-Dual rear
Diesel Engine
Model ................................... 6- 71LA39
Piston Disp.-Cu. In ........................... 425.6
Bore and Stroke ..................... .4¼ in. x 5 in.
S.A.E.
Horsepower ........................... .43.35
Governed Engine Speed (no load) ......... 2100 rpm
SERIAL NUMBER LOCATIONS
Delay and confusion can be avoided when correct serial numbers
of vehicle are specified on parts orders and correspondence.
DRIVER'S HEATER PANEL
Page 4
TP-7133
1

GM COACH MAINTENANCE MANUAL
Page 5
INDEX
A
Page
Accessories, Engine • • • • • • • • • • • • • • • • • 142
Adjustments
Bearings, Wheel •••••••••••••••••••
Brake Application Valve ••.••••••••••
Brake Shoe .................... .
Brake Treadle
Clutch ......................... .
Compressor Unloader Valve •••••••••••
Drag Link, Steering • • • • • • • • • • • • •••
Fog Lights . . . . . . . . . . . . . . . . . .....
Generator Neutral Point •••••.•••••••
Governor, Air Compressor •••••••••••
Hand Brake .................... .
Headlights ...................... .
Pressure Regulating Valve •••••••••••
Regulator, Generator •••••••••••••••
Relays ........................ .
Safety Valve •••••••••••••••••••••
Steering Gear • • • • • • • • • • • • • • • • ••••
Stop Screw, Steering Knuckle •••••••••
Tie Rod ........................ .
Windshield Wiper Valve •••••••••••••
Air Brakes •••••••••••••••••••••••
Air Cleaners, Engine ••••••••••••••••
Air Compressor and Governor •••••••••
Air Horns ....................... .
Air Intake System, Engine • • • • • • • • • • • • •
Alarm System, Tell-tale •••••••••••••
Alignment, Front End • • • • ••••••••••••
Antifreeze Chart .................. .
Application Valve, Brake •••••••••••••
Axle, Front ...................... .
Axle, Rear ...................... .
B
199
51
44
44
179
71
177
134
125
71
75
133
48
128
109
45
171
10
10
38
43
151
63
38
150
107
7
98
48
7
17
Battery • • • • • • • • • • • • • • • • • • • • • • • • • • 115
Battery Junctions •••••••••••••••••• , 106
Bearings, Wheel • • • • • • • • • • • . • • • • • • • 199
Body • • • . • • • • • • • • • • • • • • • • • • • • • • . • 29
Body Junction Panel • • • • • • • • • • • • • • • • • 104
Brake Chambers • • • • • • • • • • • . • • • • • • • 55
Brake Drums • • • • • • • • • • • • • • • • • • • • • 61
Brake, Hand • • • • • • • • • • • • • • • • • • • • • • 75
Brakes, Air . . . . . . . . . . . . . . . . . . . . . . . 43
Buzzer, Tell-tale Alarm • • • • • • • • • • • • • • 107
C
Capacity, Cooling System •••••.•••••••
Check Valve, Aux. Air System •.•••••••
Check Valve, Compressor Discharge ••••••
Chime, Passenger Signal •••••••••••••
Circuit Breaker Panel •••••••••••••••
Clutch
Compressor, Air . . ..... Cl • • •••••••••
<;ontrol Panel, Driver's ••••••••••••••
Cooling System . . . . . .............. .
98
48
46
39
102
179'""'
63
101
89
D
Page
Diesel Engine • • • • • • • • • • • • • • • • • • • • • 141
Doors and Controls • • • • • • • • • • • • • • • • • 35
Drag Link, Steering • • • • • • • • • • • • • • • • • 177
E
Electrical System •••••••••••••••••••
Electric Horn
Emergency Door .................. .
Engine Comp't. Panel •••••••••••••••
Engine Mounting •••••••••••••••••••
Engine Tune-up ••••••••••••••••••.•
Entrance Door ....... If • • • • • ••••••••
F
Fan and Water Pump ••••••••••••••••
Filter, Fuel Oil .••••••••••••••••••
Filter, Lubricating Oil • • • • • • • • • • • • •••
Front Axle •••••••••••••••••••••••
Fuel Oil Specifications •••••••••••••••
Fuel System ••••••••••••••••••••••
Gauge, Air Pressure
Gauge, Oil Pressure
G
Gauge Panel ..................... .
Generator ....................... .
Generator Regulator •••••••••••••••••
Glass Replacement ••••••••••••••••••
Governor, Air Compressor ••••••••••••
H
Hand Brake
Heating ......................... .
Horn, Electric •••••••••••••••••••••
Horns, Air •••••••••••••••••••••••
Hubs and Bearings • • • • • • • • • • • • • • • • •
99
113
35
105
145
141
35
97
149
143
7
154
149
46
142
100
121
126
36
71
75
39
113
38
199
Injector Shut-off, .Air Operated • • • • • • • • • 144
L
Lighting System ••••.•••••••••••••••
Lights, Tell-tale .••••••••••••••••••
Links, Shock Absorber •••••••••••••••
Low Air Pressure Switch •••••••••••••
Lubrication
Lubrication Chart
M
Mato-Gard ........ " .............. .
132
107
168
46
155
156
108
I

Page 6 GM COACH MAINTENANCE MANUAL
p
Painting
Pressure Regulating Valve, Air
Propeller Shaft
Q
Quick Release Valve
R
Radiator and Surge Tank
Radiator Shutter ••••••
Rear Axle .......... .
Rectifier, Alarm System
Regulator, Generator
Relays
Relay Valve
Safety Valve
Sash and Glass
Shock Absorbers
Shutter, Radiator
Slack Adjusters
Solenoid
Emergency Stop
Engine Stop
s
Reverse, Transmission
Solenoids •••
Special Tools
Speedometer
Spring Suspension
Starter ••••••
Starting System •••
......
.......
.
.......
Page
29
47
195
52
95
95
17
108
126
109
53
45
36
166
95
56
144
144
182
112
209
113
163
117
116
S (CONT'D.>
Steering Gear •••••••••
Strainer, Lubricating Oil
Surge Tank •••••••••••
Sway Bar ••••••••••••
Switch, Low Air Pressure
Switch, Low Oil Pressure
Switch Panel •••••••
T
Tell-tale
Alarm System
Tell-tale
Lights
Thermostat, Engine
Thermostat, Radiator
Shutter.
Thermostat, Water Overheat
Tie Rod, Front Axle
Tires
Tools, Special
....
.. .
.
..
Transmission ••
......
Trouble
Shooting
Tune-up,
Engine ••
V
Valve, Air Pressure
Regulating
Valve, Brake Application
......
Valve, Quick Release
Valve, Relay
.......
Ventilation • • • • • • • ••
w
Wheels
and Tires
.......
Windshield Wipers
•o•••••
......
Wiring and Misc. Electrical
Page
171
142
95
169
46
142
101
107
107
89
96
91
11
202
209
179
205
141
47
48
52
53
40
202
38
99

GM COACH MAINTENANCE MANUAL
Sec. 1
Page 7
This group includes instructions on Front End Alignment
and Maintenance and Repair on Front Axle Assembly.
Proper alignment of front wheels must be
maintained to insure efficient steering and satis-
factory tire life. The most important factors of
front end alignment are: Wheel camber, axle cas-
ter, and wheel toe-in.
Front end alignment should be checked at reg-
ular intervals, and particularly after front axle
has been subjected to heavy impacts such as a
collision or a hard curb bump. Before checking
alignment, wheel bearings must be properly ad-
justed since loose bearings will affect instrument
readings when checking camber, king pin inclina-
tion, and toe-in.
When checking alignment, instructions outlined
in this section should be followed carefully, as
well as instructions covering related units such
as brakes, springs, steering gear, hubs and bear-
ings, and wheels and tires which are given in
other sections of this manual.
Front end alignment chart (fig. 1) indicates
points from which alignment dimensions are tak-
en. "Specifications," at end of this section, lists
correct alignment data for each model. This
data should be followed when checking alignment,
and checking should be done with precision equip-
ment and instruments.
ALIGNMENT FACTORS
Front wheel toe-in, front wheel camber, axle
caster, king pin inclination, and steering geometry
are all factors of alignment and may be defined
as follows:
Wheel Toe-In - Distance front wheels are closer
together at front than at rear of axle. (See "J"
and "H" on chart).
Wheel Camber - The amount of wheel inclination
from a vertical position.
Positive Camber - Outward inclination of wheels
at top. (See "c" on chart.)
Zero Camber - No inclination - wheels are held
in vertical position.
Negative or Reverse Camber - Inward inclination
of wheels at top.
Axle Caster - Inclination of king pin from the
vertical in the fore and aft direction of the vehicle.
Positive Caster - Inclination of king pins toward
rear of vehicle. (See "N" on chart.)
Zero Caster -King pins are held in a vertical
position.
Negative or Reverse Caster - Inclination of king
pins
toward front of vehicle.
King Pin Inclination - The slant of the king pin
toward the center of the vehicle at the top, and
outward at the bottom. (See "D" on chart.)
Steering Geometry - The mechanics of keeping
front wheels in proper relative alignment as
wheels are turned to extreme right or left.
FRONT WHEEL TOE-IN
Toe-in offsets the effect of camber, thus pre-
venting cross wear on tires. Since camber and
toe-in are related items, both should be checked
at the same time.
Where maximum allowable camber exists, tie
rod should be adjusted to give wheels maximum
allowable toe-in.
Before checking toe-in and camber, wheels
must be in straight ahead position and correctly
installed, and tires must be properly inflated.
Measure toe-in from centers of tire treads at
height of wheel centers (see "I" and "H" on chart),
using an accurate toe-in gauge.
FRONT WHEEL CAMBER
Camber ("C" on chart) offsets wheel ,deflec-
tion, due to wear of front axle parts, and prevents
a reverse camber condition.
If camber is excessively positive or negative
or is unequal, improper steering and excessive
tire _wear will result.
Camber variations may be caused by wear at
wheel bearings and steering knuckle bushings, or
by a bent steering knuckle or axle center.
CHECKING CAMBER
Before checking camber, check wear at wheel
bearings and king pins as follows:
Jack up front of vehicle, pull bottom of wheel

Sec. 1
Page 8
GM COACH MAINTENANCE MANUAL
FRONT END ALIGNMENT
CAMBER, PIN INCLINATION, ARM AND ROD LOCATIONS
TOE-IN,
ROD AND ARM LOCATIONS
B Minus A ...••.. Camber (Inches)
C
•.••..•..•••.. Camber (Degrees)
D
.....•.....••. King Pin Inclination
E
.•.••..•...••. Bottom of Steering Arm
Above Axle
F
.•............ Top of Tie Rod Below
Spring Seat
G • • .
.•..•..••• Tire Overhang
J Minus H .....•• Toe-In
K • • . • • • . • . . . . . . Relation of Steering Arm
to Center of Axle
FRONT AXLE CASTER
AXLE CENTER TWIST AND PIN INCLINATION
L •• • • • • ••••• • • • •
M
•••••••.•••••••
N ••••• • •••••••••
p
R
T
u Minus S
•...••..
Minus V ...•.••.
C/L of Steering Arm to
Edge of Spring
C/ L of Tie Rod End to
Wheel Rim
Caster Angle
C/L of King Pin
Vertical
I-Beam Twist
King Pin Inclination
Refer to "Wheel Alignment Dimensions" for Numerical Values.
TP 4084-1
Figure 1-Front End Alignment Chart
outward and take a camber reading; then pull top
of wheel outward and take a camber reading. If
readings vary more than 1/4 degree, make fol-
lowing adjustments:
1. Adjust wheel bearings as directed in "HUBS
AND BEARINGS" (SEC. 19);then take camber read-
ings as previously instructed. If readings vary
over 1/4 degree, replace steering knuckle bushings
and king pins as instructed later in this section.
2. Check the wheel run-out as instructed in
"WHEELS AND TIRES" (SEC. 19). If run-out is
excessive, straighten or replace wheel.
3. Place vehicle on level floor, with full
weight on wheels, then take final camber reading.
If camber gauge is not available, readings can be
taken as shown on chart, (fig. 1). Place square
as shown and measure distances "A" and "B~"
"B" should exceed "A" by amount listed in "Spec-
ifications" at end of this section. Camber di-
mensions of right wheel should not vary over
3/32" from camber dimensions of left wheel. If

GM COACH MAINTENANCE MANUAL
Sec. 1
Page 9
final camber reading is incorrect, either steering
knuckle or axle center is bent.
4. To determine which part is bent, check
king pin inclination ("D" on chart). Camber plus
king pin inclination is the included angle of steer-
ing knuckle. If included angle of knuckle varies
more than 1/2 degree from value given in "Spec-
ifications," knuckle is bent and should be replaced.
AXLE CASTER
Caster ("N" on chart) provides the steering
stability necessary to keep wheels in straight
ahead position, assists in bringing vehicle out of
a
turn, and reduces tendency of wheels to shimmy.
Negative caster may cause wandering condition
or difficulty in bringing vehicle out of a turn.
Negative caster may result from sagging springs
or a bent axle.
Excessive positive caster causes wheel shim-
my and hard steering.
Uneven tightening of spring U-bolt nuts will
affect caster; therefore, tighten all U-bolt nuts
equally.
Check caster with full vehicle weight on wheels
and with vehicle empty, using an accurate gauge.
If caster angle does not agree with specified
value, check front axle components to determine
cause.
KING PIN INCLINATION
King pins are inclined ("D," figure 1) to de-
crease friction between tires and road when turn-
ing. Special instruments must be used to check
king pin inclination when axle is installed in ve-
hicle. When axle is removed, check can be made
on bench as follows:
Place two uniform blocks on level surface, then
rest spring seats on blocks as shown in figure 1.
Using square, measure "U" and "v" dimensions.
Front axle assembly is reverse Elliott type.
Axles are equipped with steering knuckles con-
structed as shown in figure 2.
Wheel bearings, springs, and brake parts which
are mounted on front axle, are described in their
respective manual sections.
Specifications and pertinent front acle service
information is given in "Specifications" at end of
section and in Front End Alignment Chart (fig. 1).
FRONT AXLE CONSTRUCTION
Front axle assembly center section is a hol-
low rectangular tube in which dowel pins are in-
stalled to locate spring seats. Outer ends of axle
FRONT AXLE REPAIR
"u" minus "V" equals king pin inclination in inches.
While axle is set up on blocks, check axle
center twist by measuring distances "S" and "T"
(fig. 1). Difference between dimensions "S" and
"T" equals axle center twist. If axle center is
twisted, refer to "Straightening Axle Center," later
in this section for corrective information.
STEERING GEOMETRY
Steering geometry is controlled by length and
angularity of steering arms and linkage. Since
a large part of driving is done with wheels in
turning position, steering geometry is a very im-
portant alignment factor.
All other alignment factors must be correct
and steering arms must be correctly installed be-
fore steering geometry is checked. Check follow-
ing points using alignment instruments. Refer to
figure 1.
1. Relative position of steering arm to axle
spring seat, "E" on chart.
2. Relative position of tie rod to axle spring
seat "F."
3. Relative position of steering arm to cen-
ter line of axle, "K" on charL
4. Center of steering arm to edge of spring,
"L" on chart.
5. Relative position of tie rod ball to wheel
rim, "M" on chart.
The important factors of front end alignment
and the methods of checking and correcting er-
rors are previously listed in this section. How-
ever, other front axle related units should be
maintained in order to obtain correct steering.
Refer to other sections of this manual for cor-
rection of such items as:
Front Wheel and Tire Balance
Front Wheel Bearing Adjustment
Front and Rear Spring Mounting
Steering Gear Adjustment
are solid forgings machined to accommodate steer-
ing knuckles and king pins.
Steering knuckles (fig. 2) are supported on
solid king pins which are tapered at center sec-
tion to fit snugly in tapered holes in axle outer
ends. Nut installed at threaded upper end of each
king pin, locks king pin bushing (3) against spacer
(4) and secures king pin in axle. King pin nuts
are secured by cotter pins.
Load is transmitted from axle center to steer-
ing knuckles through tapered roller thrust bearing
assemblies (9, figo 2). C-overs and plugs (2 and· 9,
fig. 2) exclude dust and moisture from knuckle
bushings and serve as lubricant seals. Steering
knuckle bushings can be replaced when necessary.

Sec. 1
Page 10
GM COACH MAINTENANCE MANUAL
FRONT AXLE REPAIR
1 King Pin Nut
2 King Pin Cover
3 King
Pin Bushing
4 Spacing Washer
5 Axle Center End
6 King Pin
7 Expansion Plug
8 Steering Knuckle
Bushing
9 Thrust Bearing
Assembly
10 Steering Knuckle
TP-6335
Figure 2-Steering Knuckle Cross Section
Stop screws installed at each end of center limit
turning angle of front wheels.
FRONT AXLE GENERAL MAINTENANCE
INSPECTION
Following inspection operations should be per-
formed at intervals determined by severity of
service.
L Inspect spring U-bolts for tightness. Tight-
en as directed in SPRING SUSPENSION (SEC. 15).
2.
Inspect and tighten tie rod arm and steer-
ing arm nuts. Torque specifications are shown
in "Specifications" at end of this section.
3. Inspect steering arm and tie rod arm nuts
for looseness. Tighten if necessary. Also inspect
tie rod end stud nuts for looseness and check tie
rod ends for wear.
4. When steering difficulty or abnormal tire
wear indicate necessity, check front end align-
ment as previously instructed under "Front End
Alignment."
5. Check stop screws and adjust when neces-
sary. Stop screw adjustment procedure is des-
cribed later.
6. Lubricate front axle parts as instructed
in LUBRICATION (SEC. 13).
7. When lubricating front axle parts, observe
condition of seals at steering knuckle, tie rod ends,
and drag link. If seals are found to be damaged
or missing, new seals should be installed imme-
diately.
8. Periodical inspection should be made at
steering knuckles to determine if excessive up-
and-down movement of knuckles on king pins
exists. Since excessive pounding will damage
thrust bearing (9, fig. 2) the up-and-down move-
ment of steering knuckles must be kept within
prescribed limits. Shims for use in reducing
clearance are available. Refer to "ADJUSTMENTS"
later in section for method of checking clearance
and making shim installation.
ADJUSTMENTS
A
number of difficulties found during front end
alignment check can be corrected by making ad-
justments at front axle assembly. Among these
adjustments are; wheel bearing adjustment, tie
rod and drag link adjustment, stop screw adjust-
ment and brake adjustment. All the above men-
tioned adjustment procedures except tie rod and
stop screw adjustment are covered in other sec-
tions of manual.
TIE ROD ADJUSTMENT
Tie rod adjustment is necessary whenever
front wheel toe-in is found to be incorrect. Ad-
just tie rod as follows:
1. Set front wheels in straight-ahead position.
2. Loosen clamp bolts at both ends of tie rod.
3. Use pipe wrench to turn tie rod tube as
required to correct toe in measurement. Refer
to "FRONT END ALIGNMENT" previously in this
section for method of measuring toe-in.
4. When adjustment is completed, make sure
tie rod ends are in same plane, then tighten
clamp bolts.
STOP SCREW ADJUSTMENT
Stop screws installed in front axle center limit
front wheel turning angle to right and left. Stop
screws must be set properly to give equal turn-
ing radius to the right and to left, as well as to
limit turning angle and thereby prevent interfer-
ence between front tires and other parts of coach.
Before setting stop screws, refer to STEER-
ING GEAR (SEC. 16) and be sure pitman arm is
properly installed on steering gear and be sure
steering gear drag link is properly adjusted for
length and not distorted or bent.
Adjust stop screws as follows:
1. Raise front axle until front wheels are off
floor.
2. Turn front wheels to extreme left. In this
position there should be 1 /2 inch clearance be-
tween tire and drag link. If necessary, turn stop
screw in or out to provide 1 /2 inch clearance
mentioned above. Secure stop screw setting with
lock nut.
3. With wheels turned to extreme left posi-
tion measure and record distance from left front
tire to outer edge of front spring at nearest point.

GM COACH MAINTENANCE MANUAL
Sec. 1
Page 11
4. Turn wheels to extreme right position and
measure distance from right front tire to outer
edge vf front spring at nearest point. If this di-
FRONT AXLE REPAIR
mension is not same as the corresponding dimen-
sion at left-hand side of coach, adjust right stop
screw to provide same dimensions.
FRONT AXLE OVERHAUL
Steering knuckes, king pins, and bushings can
be replaced, and minor axle straightening can be
performed, without removing front axle assembly
from vehicle. However, when front axle assembly
requires a complete overhaul, the assembly may
be removed, overhauled and installed, as described
below.
Certain preliminary inspections can be made,
while axle is still mounted on vehicle, which will
aid in determining the amount of repair work
necessary. Check front end alignment as directed
in "Front End Alignment" previously in this sec-
tion. Inability to align front end correctly indi-
cates that axle center or steering knuckle has
been distorted, steering arms have been bent, or
bushings in steering knuckle yokes are worn be-
yond limits. Repair procedures on such items as,
brakes, shock absorbers, wheel bearings, and
steering gear are covered in respective sections of
this manual.
FRONT AXLE REMOVAL
1. Loosen wheel nuts, then raise front of ve-
hicle with jack or chain hoist and block vehicle
behind front axle.
2. Disconnect drag link from steering arm
by removing drag link end stud nut and driving
tapered stud out of arm at steering knuckle.
3. Disconnect air lines at brake chambers.
4. Disconnect shock absorbers and both ends
of each front spring in manner described in
SPRING SUSPENSION (SEC. 15).
NOTE: U-bolts which clamp springs onto axle
may be removed to permit removal of axle as-
sembly without removing front springs. Refer to
SPRING SUSPENSION (SEC. 15) for details of
spring installation.
5. After axle assembly has been completely
detached from coach, roll the assembly out from
under vehicle.
TIE ROD REPAIR
Tie rod assembly used is three-piece type
comprised of a rod and two end assemblies. Tube
is threaded into ends and locked with clamp bolts.
Right-and left-hand threads are provided on tie
rod to facilitate toe-in adjustment.
Tie rod ends (fig. 3) are constructed so as to
automatically compensate for wear on bearing
surfaces. Tie rod end stud is held in contact
with bearing surfaces by tension of spring which
holds seat firmly against inner end of stud. Tie
rod end parts are held in place by an end plug
retained by lock ring.
Normal wear on bearing surface in tie rod
end, will cause increase in overall height of as-
sembly. If excessive play is noted, the parts
which are worn must be replaced, or a new
tie rod end assembly must be installed.
TIE ROD DISASSEMBLY (Fig. 4)
1. Remove cotter pins and nuts from tie rod
ends, support steering arm to prevent bending then
drive tie rod end tapered stud out of steering arm.
Remove spring (2), dust cover (3 ), seal (4), and
retainer (5) from stud.
2. Loosen clamp bolts, then remove tie rod
end assembly from tube.
3. Pry end plug lock (15) out of groove in
body (7); then remove plug (14), seat and spring
(12 and 13), and grease retainer (11). Stud and
bearing assembly can now be removed from body.
INSPECTION
Clean all parts of tie rod end then inspect
parts for wear and check tension of spring (13,
fig.
4). Discard worn parts and replace spring
if broken or weak.
ASSEMBLING TIE ROD ENDS (Fig. 4)
1. Lubricate parts with lubricant specified in
LUBRICATION (SEC. 13) before assembling tie
rod ends.
TP 0082
Figure 3-Tie Rod End Construction

Sec. 1
Page 12
GM COACH MAINTENANCE MANUAL
FRONT AXLE REPAIR
Tie Rod End Stud Nut
2 Dust Cover Retainer
Spring
3 Tie Rod End Dust Cover
4 Tie Rod End Dust Seal
5 Tie Rod End Dust Seal
Retainer
6 Tie Rod End Clamp Bolt
7 Tie Rod End Body
8 Clamp Bolt Lock Washer
9 Clamp Bolt Nut
10 Tie Rod End Stud and
Bearing Assembly
11 Tie Rod End Oil Retaining
Felt
12 Tie Rod End Stud Seat
13 Tie Rod End Stud Seat
Spring
14 Tie Rod End Plug
15 Tie Rod End Plug Lock
16 Tie Rod Tube
TP 1705
Figure 4-Disassembled View of Tie Rod End
2. Insert end stud and bearing assembly (10)
into tie rod end body (7), place oil retaining felt
(11) over end of end stud seat (12), then position
seat (12) in body (7).
3.
Place stud seat spring (13) inside seat
(12), lay end plug (14) on spring, then compress
spring (13) and install end plug lock (15) in groove
in body (7).
4. Thread tie rod end assemblies on tie rod
tube (16), install clamp bolts (6), new lock wash-
ers (8), and nuts (9). Do not tighten nuts (9) at
this time.
5. Carefully clean tapered portion of tie rod
end studs (1), then install dust seal retainers (5),
dust seals (4), dust covers (3), and dust retainer
springs (2) on end studs in order named.
6. Clean tapered holes in steering tie rod
arms, position complete tie rod assembly on
steering arms, then thread stud nuts (1) on end
studs (10). Tighten stud nuts to minimum torque
given in "Specifications" at end of this section,
then tighten nuts until next castellation on nut
lines up with cotter pin holes in studs. Install
new cotter pin full size of hole.
STEERING KNUCKLE DISASSEMBLY
If desired, steering knuckles may be removed
from front axle without removing front axle as-
sembly from the vehicle. To remove steering
knuckles from axle after axle has been removed
from vehicle, proceed as follows:
1. Remove tie rod and ends assembly from
steering tie ·rod arms as directed under "Tie Rod
Repair" covered previously in this section.
2. Remove front wheels and hubs, as directed
in HUBS, WHEELS, AND TIRES (SEC. 19).
3. Remove brake mechanism, including brake
chambers, slack adjusters and brake shoes as
directed in AIR BRAKES (SEC. 4).
4. Remove nuts and washers from studs which
attach brake spider to steering knuckle flange;
then remove spider and camshaft as an assembly.
5. Remove cotter pins, nuts, and washers
from steering tie rod arms, then drive arms out
of steering knuckles using a lead hammer. Also
remove drag link arm from left-hand knuckle.
6. Remove cap screws which attach dust cap
to steering knuckle, then remove dust cap and
gasket. Discard gasket.
7. Remove lock ring from knuckle lower yoke,
and
remove plug (7, fig. 2). Remove nut from
top of king pin, then using large brass drift, drive
king pin out of axle and knuckle.
8. Remove knuckle and thrust bearing and
spacing washer from axle. King pin bushing will
remain in knuckle upper yoke and can be lifted
from yoke as soon as king pin is removed.
CLEANING
Wash steering knuckle parts in cleaning solu-
tion, being sure to remove all dirt and lubricant,
If necessary, soak thrust bearings in cleaner
until all old lubricant is dissolved; then slush
bearing in cleaning solution until all grit is re-
moved from races.
INSPECTION AND REPAIR
STEERING KNUCKLES
After steering knuckles have been cleaned
thoroughly, examine knuckles for distortion, dam-
age, cracks or fractures. If Magna Flux inspec-
tion equipment is available, use this method to
inspect steering knuckles and king pins for minute
cracks, checks, or fractures, which otherwise
would not be visible to the naked eyeo
AXLE CENTER
There are two conditions which, if either exists,
will necessitate replacement of axle center.
1. If king pin holes in axle center ends are
worn to such an extent that a new pin fits loosely,

GM COACH MAINTENANCE MANUAL
Sec. 1
Page 13
axle center must be replaced.
2. If axle center has been twisted or bent
more than 5 degrees from original shape, the
center should be replaced. As a general rule,
when an extreme bent condition exists, minute
fractures which may be invisible will occur, and
failure under ordinary operating conditions will
result.
CHECKING AXLE CENTER
Check axle center for twist with alignment
instruments, or on a bench as illustrated in front
alignment chart (fig. 1). If equipment is available,
use Magna-Flux method to check axle center for
minute fractures.
STRAIGHTENING AXLE CENTER
The straightening of axle forgings must be
performed by mechanics who are thoroughly fa-
miliar with such operations and the use of special
straightening tools. ALWAYS STRAIGHTEN FORG-
INGS COLD -- UNDER NO CIRCUMSTANCES
SHOULD HEAT BE
APPLIED. Application of heat
to facilitate straightening weakens the material
strength of all forgings.
THRUST BEARING
Examine thrust bearings for excessive wear,
pitting, or other damage. If these conditions are
evident, discard bearing and install new part when
assembling axle. If bearing retainers are bent or
damaged, bearings should be replaced.
BUSHING REPLACEMENT
Steering knuckle bushings should be replaced
if inspection reveals that they are scored, worn,
or otherwise damaged; or if results given under
"Checking Camber" in "Front End Alignment",
previously in this section.
Bushing dimensions are given in specifications.
Replace bushings if not within limits.
Removal
1. Clamp steering knuckle securely in vise
equipped with soft jaws.
2. Thread tap, of suitable size, into bushing
if bushing driver is not available.
3. Using soft metal rod, slightly smaller than
bushing and long enough to extend about 1-1/2
inches through opposite knuckle yoke; drive tap
and bushing out of knuckle bore.
4. Repeat process to remove remaining steer-
ing knuckle bushing.
Installation
1. Clean the steering knuckle bushing bores,
then round off all sharp edges of new bushings,
slightly.
2. Position bushing so that oil hole in bushing
FRONT AXLE REPAIR
will line up with lubrication fitting hole in steer-
ing knuckle yoke, and so that bushing will enter
knuckle bore straight when pressed into yoke.
3. Press bushing into knuckle bore, using
arbor press or suitable driver, until positioned
as shown in figure 1. NEVER ATTEMPT TO
DRIVE BUSHINGS WITH HAMMER.
4. Burnish or ream bushings to diameter given
in "Specifications" at end of this section, using
either a two step reamer or a burnishing tool.
Tool used must have a long pilot bar or be long
enough to finish both upper and lower bushings at
the same time.
5. Clean cuttings out of oil grooves, then
round off all sharp edges in grooves,
KING PIN
Check diameter of king pin, at upper and low-
er bearing surfaces, against dimensions given in
"Specifications" at end of this section. If wear
exceeds limits given, replace with new king pin.
King pins
should also be inspected for minute
cracks or other damage. Any burrs or grooves
may be honed out provided such honing will not
reduce diameter of pin below limits given in
"Specifications" at end of this section.
STEERING KNUCKLE INSTALLATION
The importance of cleanliness, when assembling
steering knuckle parts, can not be over-stressed.
If king pins and bushings are installed with parti-
cles of dirt or metal between bearing surfaces,
excessive wear will result necessitating prema-
ture replacement of parts.
Install steering knuckles and king pins in the
following manner: Key numbers in text refer to
figure 2.
1. Position steering knuckle (10) on axle cen-
ter end (5), then slide thrust bearing assembly
(9) into place between lower face of axle center
and steering knuckle lower yoke. Make sure re-
tainer is on top of bearing with lip of retainer
down. Align king pin holes in steering knuckle
yokes with king pin hole in axle center end.
2. With axle center held rigidly, place a jack
under knuckle yoke and raise knuckle sufficiently
to take up all clearance between lower yoke, thrust
bearing, and lower face of axle center end.
3.
Check clearance between top face of axle
center end and lower face of steering knuckle
yoke, then select shim and spacing washer com-
bination which will reduce clearance to limits giv-
en in "Specifications" at end of this section. Shim
and spacing washer thicknesses available are given
in "Specifications" at end of this section.
4. Make certain king pin hole in axle center
(5), king pin (6), and nut (1), are carefully cleaned
and dry. King pin nut (1) should screw on king

Sec. 1
Page 14 GM
COACH MAINTENANCE MANUAL
FRONT AXLE REPAIR
pin freely without binding in any manner. These
precautions should be taken to assure king pin
being securely locked in place, when installation
is completed.
5. Insert king pin (6) through bottom yoke of
steering knuckle (10), then drive king pin into
place with lead hammer.
6. Place king pin bushing (3) over threaded
end of king pin (6), then press bushing into place.
Be sure king pin bushing is installed squarely on
king pin.
7. Make sure threads on king pin nut are
clean and dry, then install king pin nut (1 ). Tight-
en nut, with torque wrench, to minimum torque
given in "Specifications" at end of this section,
then tighten nut until next castellation on nut lines
up with cotter pin hole through king pin. Install
new cotter pin, full size of cotter pin hole.
8. Position new dust cap gasket on steering
knuckle upper yoke, place dust cap (2) on gasket,
then secure cap with attaching screws.
9. Install new plug (7) in lower yoke, then
install lock ring to retain plug. Install plug with
concave side toward lock ring so edge of plug
contacts ring.
10. Check turning torque of assembled steer-
ing knuckle. Place torque wrench on nut and meas-
ure torque required to turn knuckle. If reading
is not within limits given in "Specifications" at
end of this section, disassemble steering knuckle
and recheck all parts until cause is found.
NOTE:
Turning torque can also be
measured by use of a spring scale. Attach
scale at extreme end of steering knuckle
spindle, pull on scale and note reading
when knuckle is in motion. Multiply read-
ing by distance in feet, from end of spin-
dle to center line of king pin.
11. Place arm keys in keyways machined in
steering arm and steering tie rod arms. After
making sure tapered holes in knuckle yoke and
tapered ends of arms are clean and dry, insert
arms in yokes. Place lock washers and nuts on
steering tie rod arms, tighten nuts to minimum
torque given in "Specifications" at end of this
section, then tighten nut until next castellation on
nut lines up with cotter pin hole in arm. Install
new cotter pin full size of hole. Place brake
chamber bracket on steering arm, using dowel in
steering knuckle upper yoke to locate bracket cor-
rectly, then install new lock washer and nut.
Tighten nut to minimum torque given in "Specifi-
cations" at end of this section, then tighten nut
until next castellation on nut lines up with cotter
pin hole in arm. Install new cotter pin.
12. Position brake spider and camshaft, as
an assembly, on steering knuckle; then install new
lock washers and nuts. Tighten nuts securely.
13. Install front brake shoes as instructed
under "Brake Shoe Installation" in AIR BRAKES
(SEC. 4).
14.
Connect and adjust brake chamber push
rods at slack adjusters as directed in AIR BRAKES
(SEC. 4).
15.
Install wheel bearings, hubs and brake
drums, following instructions in HUBS, WHEELS,
AND TIRES.
16. Install tie rod assembly with the tie rod
end with right-hand thread toward right-hand side
of axle.
FRONT AXLE INSTALLATION
1. Install spring assemblies on axle as di-
rected in SPRING SUSPENSION (SEC. 15); then
roll the complete assembly into place under coach.
2. Attach springs at brackets and shackles
referring to SPRING SUSPENSION (SEC. 15)for
instructions. Also connect shock absorbers to
axle.
3. Connect air lines to brake chambers, then
check and adjust brakes. Refer to AIR BRAKES
(SEC. 4).
4. Connect drag link to steering arm.
5. Remove blocking and lower vehicle to floor,
then re-check wheel nuts and spring U-bolt nuts.
6r Lubricate front axle assembly as instructed
in LUBRICATION (SEC. 13).
7.
Check front end alignment and adjust front
wheel toe-in. Refer to "Front End Alignment"
Chart (fig. 1) and "Specifications" at end of sec-
tion for alignment and toe-in dimensions.

GM COACH MAINTENANCE MANUAL
Sec. 1
Page 15
FRONT AXLE SPECIFICATIONS
(New Limits)
WHEEL ALIGNMENT DIMENSIONS
B-A
C
(Refer to Alignment Chart, Fig.
Wheel Camber (Inches)
Wheel Camber (Degrees)
Loose Axle
Axle Installed
King Pin Inclination (Degrees)
1)
13/32
11
1° ± 1/4°
1/2°
D
E
F
Bottom of Steering Arm Above Axle (Spring Seat)
Top of Tie Rod Below Spring Seat
5-1/2°
3-5/16
11
1-1/2
11
1/16
11
to l/8
11
7/8
11
Ahead
Toe-In
Relation of Steering Arm to Axle Center
Line
J-H
K
L
Center of Steering Arm to Edge of Spring
2-3/4
11
3-1/8
11
3-1/2
11
M
N
T-S
U-V
Tubular Axle .
Center of Tie Rod End to Wheel Rim
Caster Angle
Axle Center Twist
King Pin Inclination (Inches).
STEERING KNUCKLE
Spindle Diameter
At Inner Wheel Bearing
At Outer Wheel Bearing
Steering Knuckle Bushings
Inner Diameter .
Length .•.........•.
King Pin Bushings
Inner Diameter
Outer Diameter
Length .•.•...
KING PIN
Diameter at Top of Pin
Diameter at Bottom of Pin
Length (Overall) ••....
FITS AND TOLERANCES
Clearance Between
King Pin Bushing and Knuckle Bushing
King Pin and Lower Knuckle Bushing
King Pin and King Pin Bushing
Steering Knuckle Thrust
Thrust Adjustment .•...
Shim Thickness Available - l@
Spacing Washer Thickness Available
Equal
. • 1-1/32
11
2.5613-2.5623
11
2.1243-2.1248
11
1.7965-1.7975
11
2-3/16
11
1.310-1.311
11
1. 7950-1.7960
11
2-15/32"
1.309-1.310
11
1. 7950-1. 7960
11
10-25/ 32
11
0.0005-0.0025
11
0. 0005-0, 0025 II
0.000-0.002
11
. • 0.015
11
Maximum
With Shims and Spacers
0. 015 II
0.093
11
, 0.125
11
, & 0.156
11

Sec. 1
Page 16
GM COACH MAINTENANCE MANUAL
FRONT AXLE
TORQUE SPECIFICATIONS
King Pin Nuts ......•.•.•••........•..•...•
Steering Arm Nuts ...•...•..•••.•..•.•...•..
Steering Tie Rod Arm Nuts .•.•.••..•..••.•.•..
Tie Rod End Stud Nuts . • . . . . • . . . . . . • • . •
Assembled Steering Knuckle (Turning Torque) .•.•...
TIE ROD END
3 00-400 ft. lbs.
5 00-55 0 ft. lbs.
500-550 ft. lbs.
255-380 ft. lbs.
8-50 ft. lbs.
End Stud Seat Spring Free Length . • . . • . . . . . • • • . . . . • 1-1/4"
Resistance When Compressed to 1/2" . . • • • • • • • . • . . . . . 235-265 lbs.
Solid Height . . • • • . . . . . . . • . . . • . . . • . • . • . • • • . • • 13/16"
AXLE CENTER
Maximum Allowable Twist End to End •.
Distance Between Centerlines
Spring Seat Dowels (Top) . • • • . • . • • • . . • • . • . • • . • • . . • 45"
Spring Seat Dowels (Bottom) • • • • • • • • . • . . • • . • . . . . . • • • . 40"
SERVICE BULLETINS
Service Bulletins are issued, whenever required, supplementing information
in this section. The information contained in these bulletins should be noted
in the text and bulletin filed for future reference -Make note of bulletin
number in space below:
NOTES

GM COACH MAINTENANCE MANUAL
Sec, 2
Page 17
Rear axle is full-floating type, using a one
piece axle housing with housing bowl cover welded
to housing. Housing bowl is located to the left of
axle center line.
As shown in figure 3, drive pinion assembly
is mounted at an angle to drive gear, thus in-
creasing the tooth contact area between drive gear
and drive pinion gear teeth. Drive is transmitted
from transmission angle drive unit through pro-
peller shaft to spiral bevel gears, axle housing,
and springs, then to vehicle underframe.
Differential and drive pinion assemblies are
both provided with facilities for adjustment of
bearings and gear tooth contact.
DIFFERENTIAL CARRIER
Differential assembly, drive pinion, and pm10n
cage assembly, are mounted in differential car"rier.
After axle shafts have been removed, and propeller
shaft has been disconnected, differential carrier
can be removed for inspection and adjustment
without removing axle housing from vehicle.
DIFFERENTIAL ASSEMBLY
Conventional four-pinion type differential is
carried in two-piece case mounted on tapered
roller bearings. Bevel drive gear is bolted to
flanged half of differential case. Drive gear and
pinion are furnished in matched, lapped sets, and
should always be installed as such to assure sat-
isfactory operation.
Thrust washers are used between differential
side gears and case and between differential pin-
ions and case. Each pinion contains an aluminum-
bronze bushing. When bushings become worn, pin-
ions must be replaced. Differential case halves
are held together with special bolts and slotted
nuts, locked in place with lock wire.
DIFFERENTIAL SIDE BEARINGS
Differential case is supported in tapered roller
bearings which take thrust as well as radial loads.
Bearings are mounted in machined supports in
differential carrier with thrust loads taken by ad-
justing rings threaded into carrier supports and •
bearing caps. Adjusting rings bear against bearing
cups and are locked in position by adjusting ring .
locks bolted to each bearing cap.
PINION AND CAGE ASSEMBLY
Bevel drive pinion is installed at an angle in
differential carrier. Pinion is straddle mounted
in two opposed tapered roller bearings at outer
end, and one straight roller bearing at inner end.
Tapered roller bearing cups are installed in
pinion cage (fig. 3), and are separated by a ma-
chined shoulder in pinion cage assembly.
Pinion bearings are adjusted on shaft by se-
lecting correct spacer combination as described
later in this section, under "Pinion and Cage As-
sembly."
Straight roller bearing at inner end of drive
pinion, is secured in place with retainer and a bolt.
Shims of various thicknesses are used between
bearing cage and differential carrier to adjust
drive pinion tooth contact and gear backlash.
Pinion shaft and cage assembly cannot be re-
moved from carrier until differential case assem-
bly including drive gear has been removed from
carrier.
AXLE SHAFT AND HOUSING
Axle shafts are full floating type. Drive flange
at outer ends have external teeth which mesh with
similar internal teeth on hub drive plate. Drive
plate is doweled to hub with dowel pins and held
in place, together with plate cover, with ten hub
studs and nuts as illustrated in figure 1.
Axle housing is one-piece design with differ-
ential located off center. Housing is equipped with
removable outer end tubes which are threaded to
accommodate wheel bearing adjusting nuts.
AXLE MAINTENANCE ON VEHICLE
The following maintenance operations should be
accomplished at regular inspection and lubrication
intervals.
LUBRICATION
Lubrication intervals, method of filling and
draining, also type of lubricant for axle is covered
in LUBRICATION (SEC. 13).
Check for lubricant leaks at differential hous-
ing, at pinion bearing oil seal and at cover plate
at outer end of hubs. Eliminate leaks by tightening
nuts or bolts or by replacing gaskets or oil seal.

Sec. 2
Page 18
GM COACH MAINTENANCE MANUAL
REAR AXLE
1 Drive Cover Plate
2 Axle Shaft Flange
3 Drive
Plate
4 Drive Plate Dowel Pin
5 Gasket
6 Drive Ring
8 7 Drive
Plate
Stud
8 Spring
7 6
TP 4086
Figure 1-Axle Shaft and Drive Plate Installation
MOUNTING
Check rear spring U-bolts for tightness at reg-
ular intervals as directed in SPRING SUSPENSION
(SEC. 15).
Rear springs are used to hold rear axle in
alignment, therefore when rear axle alignment dif-
ficulties occur, the rear spring suspension units
should be checked before checking axle assembly.
Refer to TROUBLE SHOOTING (SEC. 21) for sug-
gestions on how to determine alignment difficulties.
AXLE SHAFT DRIVE PLATE AND COVER
(Refer to Figure 1)
Rear axle shafts are installed as shown in fig-
ure 1. Drive plate (3) and cover plate (1) are held
on hub with ten drive studs and nuts and dowel
pins (4). Three gaskets (5), to prevent lubricant
leaks, are used between parts as shown.
Spring (8) prevents endwise movement of axle
shaft. Keep stud nuts tight to prevent drive plate
loosening on dowels and to prevent lubricant leaks.
Rear axle outer oil seal assembly is installed
between drive ring (6) and hub. HUBS, WHEELS,
AND
TIRES (SEC. 19) contains complete oil seal
information.
AXLE SHAFT REPLACEMENT
Axle shaft splines at inner end are free fit in
differential side gears; and teeth at flange on outer
end of shaft also are free in drive plate. A suit-
able handle for removing and installing axle shafts
can be provided by attaching slide hammer assem-
bly (J -2 654) to outer end of axle shaft. Axle shaft
flange has hole tapped with 1 /2 x 13 N. C. thread
and the above tool can be screwed into this hole
to provide means of withdrawing axle shaft from
housing. Above tool also provides a handle which
can be used to support axle shaft while guiding
inner end into differential side gear splines during
installation.
AXLE SHAFT REMOVAL (Fig. 1)
1. Remove stud nuts holding drive plate (3)
and cover (1) on hub.
2. Remove cover (1), spring (8), and outer
gasket (5). Screw threaded end of slide hammer
(J-2654) into tapped hole in axle shaft flange; then
pull axle shaft out of housing.
3. Drive plate (3) has three tapped holes into
which puller screws can be installed for removing
plate from hub. To remove plate, turn puller
screws alternately until plate is free from dowels.
Drive ring (6) and gaskets may be removed after
drive plate is removed.
AXLE SHAFT INSTALLATION
1. If drive plate (3) and ring (6) h:we been
removed, install ring using one gasket on each
side; then install drive plate over studs and dowels.
Use a stud nut and washer on stud at each dowel
pin to draw plate (3) into place. Tighten stud nuts
alternately to draw plate squarely into place.
2. Lubricate splines on axle shaft, then guide
axle shaft into housing so that splines enter dif-
ferential side gear, and teeth on flange mate with
teeth on drive plate.
3. Place outer gasket (5) at hub; then install
spring (8) and cover (1). Install studs nuts with
new lock washers. Tighten studs nuts to 55 to 66
foot pounds using torque wrench.
REAR AXLE OVERHAUL
Rear axle assembly may be disassembled while the housing remains at-
tached to springs if proper equipment is available for handling differential
assembly. Information on propeller shaft, rear springs, hubs anct bearings,
brakes and wheels and tires will be found in other sections of this manual.
REAR AXLE REMOVAL
1. Block coach in raised position and remove
rear wheels.
2. Disconnect air lines at brake chambers.
3. Disconnect propeller shaft at axle flange.
4. Remove rear spring U-bolts, disconnect
sway bar and shock absorbers (if used).
5. Support axle assembly on dolly jack, then
disconnect rear springs at rear shackles. Refer
to SPRING SUSPENSION (SEC. 15) for details on
spring and shackle construction.
6. Remove rea:::- axle assembly from coach.

GM COACH MAINTENANCE MANUAL
Sec. 2
Page 19
REAR AXLE REPAIR
The following instructions provide procedures
for complete disassembly, cleaning, inspection, re-
pair, and reassembly of rear axle. Axle housing
may be checked for bent condition before axle as-
sembly is removed from coach. The following re-
pair procedure is based on the operations neces-
sary when axle is removed from coach.
AXLE HOUSING CHECK
At regular inspection intervals, or if conditions
indicate that rear axle housing might be bent, hous-
ing should be checked, usin_g the following method.
This check can be made before or after axle is
removed from coach to determine if axle housing
is sprung. Conventional camber and toe-in gauges
can be used to perform inspection.
1. Support axle in level position using blocks
at each spring seat; then check rear wheel bear-
ing adjustment referring to HUBS, WHEELS, AND
BEARINGS (SEC. 19) for bearing information.
2. Check run-out at each rear wheel and re-
place wheels having run-out in excess of 3/32 inch.
3. Check for toe-in and camber at rear wheels.
Rear wheels should not toe in or out more than
1/8 inch, and camber should be zero, plus or minus
1/4 degree. If measurements are not within the
above dimensions, bent or sprung axle housing is
indicated. Make notation of the existing conditions
for use when making corrections later.
4. In cases where bent axle housings are in-
dicated, further checks to determine exact location
of bend should be made after rear axle has been
disassembled; and necessary steps taken to cor-
rect the condition. Any straightening should be
done with axle housing COLD, UNDER NO CIR-
CUMSTANCES SHOULD HEAT BE APPLIED.
AXLE DISASSEMBLY
(Key Numbers in Text Refer to Fig. 3)
Before and during disassembly operations, per-
form following inspections and check all adjust-
ments to determine repairs required.
1. Visually inspect exterior of housing for
leaks and damage; then clean outside of housing
using suitable cleaning equipment.
2. After differential assembly is removed
from housing, check pinion bearings for end
play. Check differential case assembly run-out
and backlash before removal of differential and
make note of same for later reference during re-
pair.
DIFFERENTIAL CARRIER REMOVAL (Fig. 3)
1. Remove axle shafts as previously instructed
under "Axle Shaft Replacement" in this section.
2. Remove drain plug and drain lubricant from
REAR AXLE
housing, then loosen differential carrier stud
nuts.
3. Remove stud nuts (34) and lock washers
(35) from differential carrier studs (33).
4. Be certain that differential carrier is sup-
ported solidly, then proceed to pull complete car-
rier assembly out of housing.
DIFFERENTIAL REMOVAL FROM CARRIER
(Fig. 3)
1. Remove lock wire from bolts (6) which lock
adjusting rings (38).
2. Remove nuts from differential side bearing
cap studs. Make certain that bearing caps (41)
and carrier are marked before removal; then re-
move side bearing caps (41) and cups (40). Lift
out differential assembly including drive gear (1)
and side bearings (39). Remove side bearing ad-
justing rings (38).
DIFFERENTIAL CASE DISASSEMBLY (Fig. 3)
1. Mark both halves of case (11) so halves
may be reassembled in original positions (fig. 2).
2. Remove side bearings (39) from each half
of case, using special bearing puller CS-1047 as
shown in figure 4.
3. Remove lock wire and nuts (4) from bolts
(43) which hold the two halves of differential case
(11) together; then separate halves of case (11).
4.
Remove side gears (9), thrust washers (10)
and (3), spider (2), and pinions (42) from differ-
ential case (11).
5. If either drive gear (1) or drive pinion (29)
TP 0750
Figure 2-Differenfial Case Alignment Marks

Sec" 2
Page 20
REAR AXLE
36
35
34
33
GM COACH MAINTENANCE MANUAL
43 2 3 4
4
I
24
23 22
21
20
19
Figure 3-Sectional View of Rear A1e

GM COACH MAINTENANCE MANUAL
Sec. 2
Page 21
1 Drive Gear
2 Differential Spider
3 Differential Pinion Thrust
Washer
4 Differential Case Bolt Nut
5 Adjusting Ring
Lock
6 Adjusting Ring Lock Bolt
7 Axle Shaft (Right Hand)
8
Differential Carrier Gasket
9 Differential Side Gear
10 Differential Side Gear
Thrust Washer
11 Differential Case Assembly
12 Drive Gear Bolt Lock Wire
13 Drive Gear Bolt
14 Differential Carrier
Assembly
15 Pinion Cage Shims
16 Lock Washer
17 Pinion Cage Stud Nut
18 Pinion
Cage Stud
19
Drive Pinion Nut Washer
20 Drive Pinion Nut
21 Propeller Shaft Flange
22 Oil Seal Assembly
23 Pinion Cage and Bearing
Cup Assembly
24 Drive Pinion Outer Bearing
Cone
25
Outer Bearing Cup
26 Drive Pinion Bearing
Spacer
27 Inner Bearing Cup
28
Drive Pinion Inner Bearing
Cone
29 Drive Pinion
Legend for Figure 3
REAR AXLE
30 Pinion Bearing Inner Race
(Part of Item 31)
31 Drive Pinion Inner Bearing
32 Inner Bearing Retainer Ring
33
Differential Carrier Stud
34
Differential Carrier Stud
Nut
35 Lock
Washer
36 Axle Shaft (Left Hand)
37 Axle Housing
Assembly
38 Differential Bearing
Adjusting Ring
39
Differential Side Bearing
Cone
40
Differential Side Bearing Cup
41 Differential Bearing Cap
42 Differential Pinion
43 Differential Case Bolt
TP-4085-lB
are worn or damaged, both must be replaced as
a matched set. Never replace drive pinion or
drive gear separately.
CLEANING, INSPECTION, AND
REPAIR
PINION CAGE REMOVAL
AND DISASSEMBLY
(Refer to Fig. 3)
1. Mark pinion cage (23) and differential car-
rier (14) so parts can be reassembled in the same
relative position. Remove nuts (17) and lock
washers (16) which secure pinion cage (23) on dif-
ferential carrier (14).
2. Install puller screws and tighten alternately
and evenly to pull cage (23) out of carrier; then
noting quantity, remove shim pack (15) from pinion
cage studs (18). Tie shims (15) together so same
shim pack may be used at reassembly.
3. Remove retainer ring (32) which secures
inner bearing (31) on drive pinion (29). Remove
inner bearing (31) from drive pinion (29) with a
suitable puller.
4. Clamp propeller shaft flange (21) in vise
equipped with padded jaws. Remove cotter pin,
nut (20),
and washer (19) from drive pinion (29).
5.
Place cage and drive pinion assembly in
an arbor press and press drive pinion (29) out of
flange (21) and pinion cage. Outer bearing (24)
will remain in pinion cage.
6. Remove spacer (26) from drive pinion (29).
Using special bearing puller (CS-1047) remove in-
ner bearing (28) from drive pinion (29). Remove
oil seal (22). Inspect bearing cups (25) and (27).
If bearing cups must be removed from cage (23),
use brass drift and carefully drive cws out of
pinion cage.
CLEANING BEARINGS
The importance of proper bearing cleaning can-
not be over-emphasized. Bearings should always
be cleaned separately from other rear axle parts.
When cleaning bearings, be sure to perform all of
the following steps.
1. Soak differential and drive pinion bearings
in clean kerosene or Diesel fuel oil.
Figure 4-Differential Side Bearing Removal