GM PD-4107 User manual

MAINTENANCE

MANUAL

GM

GENERAL

MOTORS

CORPORATION

C01\CIIES

COACH MODEL

PD-4107

X-6614

INDEX

Front

Axle

Rear

Axle

Body

Brakes

Clutch

Cooling

Electrical

Engine

Fuel

------------------------•

Lubrication

GMC TRUCK & COACH

DIVISION

GENERAL MOTORS CORPORATION

Pontiac, Michigan

55020

COACH INFORMATION NETWORK

Air -

Suspension A

--

Steering

-

------

Transmission

Propeller

Shaft

------

a

www.coachinfo.com Hubs,

Wheels,"!!al

_______

and

Tires

~

©

1

966

GENERAL MOTORS

CORPORATION

GMC

TRUCK

&

COACH

DIVISION

X-6614

3M

1

-66

Printed

in

U.S.A.

Air

~

Conditioning

~

NOTICE:

THIS

IS

A PHOTOCOPY

REPRODUCTION OF A

PUBLICATION THAT

IS

OUT OF PRINT.

THEREFORE SOME

DEGRADATION OF COPY

IS

TO BE EXPECTED.

INTRODUCTION

This

manual

contains

complete

service,

maintenance,

and

repair

information

on

GM

Inter-City

Coach

Model

PD-4107.

Information

in

this

manual

pertains

to

standard

equipment

and

the

most

commonly

used

special

equipment.

Operation

of

the

vehicle

from

the

standpoint

of

the

driver

is

contained

in

a

separate

Operating

Manual.

For

information

on

the

Diesel

Engine,

refer

to

the

current

Diesel

Engine

Maintenance

Manual.

Every

effort

has

been

made

to

include

timely

and

adequate

information

on

the

various

units

and

systems

used

on

the

PD-4107

Coach.

The

maintenance

and

repair

procedures

in

the

various

manual

sections

are

the

result

of

extensive

service

experience.

This

information

should

serve

not

only

as

a

reference

for

the

experienced

mechanical

force,

but

also

as

a

comprehensive

text

for

training

purposes.

All

information

contained

in

this

manual

is

based

on

the

latest

product

information

available

at

the

time

of

publication

approval.

GMC

Truck

and

Coach

Division

reserves

the

right

to

make

product

changes

at

any

time.

GENERAL

INFORMATION

ABOUT THIS

MANUAL

ARRANGEMENT

This

manual

is

divided

into

major

sections

in

the

sequence

shown

on

the

margin

of

the

title

page. A

black

tab

bearing

the

major

section

number

is

placed

on

the

first

page

of

each

major

section

which

indexes

with

the tab

on

the

title

page.

Many

of

the

major

sections

are

divided

into

sub-sections,

each

sub-section

containing

important

and

specific

information

on

or

components.

When

a

major

section

is

divided

into

sub-sections,

a

section

index

appears on

the

first

page

of

the

major

section.

PAGE AND

ILLUSTRATION

NUMBERS

The

manual

pages

are

numbered

consecutively

throughout

the

manual.

Illustrations

are

num-

bered

consecutively

within

each

section,

or

within

each

sub-section

when

the

major

section

is so

divided.

SPECIFICATIONS

Service

data,

fits,

and

tolerances

are

listed

at

the

end

of

most

sections

or

sub-sections

under

the

heading

"Specifications."

Manufacturers

model

or

part

numbers

are

used

in

many

instances

in

the

"Specifications"

tabulation.

These

numbers

are

provided

primarily

for

unit

identification

and

should

be

referred

to

when

ordering

parts.

All

detail

service

part

numbers

must

be

obtained

from

the

applicable

Parts

Book.

SPECIAL

TOOLS

Special

tools

and

equipment

are

mentioned,

and

in

many

instances

illustrated,

throughout

the

text.

These

tools

are

specially

designed

to

accomplish

certain

operations

efficiently

and

readily.

Such

tools

are

identified

in

the

text

by

tool

vendor's

numbers.

These

tools

are

not

offered

for

sale

by

GMC

Truck

and

Coach

Division.

Information

regarding

availability

of

these

tools

can

be

obtained

from

your

GM

Coach

Service

Representative

or

from

the

Factory.

SERVICE BULLETINS

Service

bulletins

are

issued,

when

required,

supplementing

or

in

some

cases

superseding

infor-

mation

in

this

manual.

Information

in

these

bulletins

should

be

noted

in

the

text

and

the

bulletin

filed

for

ready

reference.

ALPHABETICAL

INDEX

Important

subjects,

with

manual

page

number

references,

are

alphabetically

listed

at

the

end

of

this

manual.

Page

iii

GENERAL DATA

The

data

listed

below

includes

only

general

information

on

the

PD-4107

Coach.

For

specific

data

and

specifications,

refer

to "Specifications"

at

end

of

each

section

or

sub-section.

MODEL

DATA

Length

(overall)

.....................................................

35

ft.

Width

(

overall)

....................................................

95¾

in.

Height

(maximum)

...............................................

1311h in.

Wheelbase

.........................................................

261

in.

Track

Front

...........................................................

79¼

in,

Rear

(center

of

dual

tires)

.......................................

701/2

in.

Turning

Radius

Wheels

(

right

and

left)

.............................................

39

ft.

Body

Corner

(

right

and

left)

.......................................

.43 ft.

Tire

Size

(standard)

.............................................

12.00/22.5

Fuel

Tank

Capacity

......................................

Standard-140

gal.

Optional-165

gal.

Cooling

System

Capacity

(including

heating

system)

.................

92

qts.

ENGINE

DATA

Engine

Model

.....................................................

8V

-71N

Displacement

..................................................

567.5 cu. in.

Bore

and

Stroke

..............................................

4¼

in. x 5 in.

Compression

Ratio

..................................................

18.7

:1

Brake

Horsepower

at

Governed

Speed

(1800

rpm)

......................

252

SERIAL NUMBER

LOCATIONS

Delay

and

confusion

can

be

avoided

when

correct

serial

numbers

of

vehicle

and

engine

are

placed

on

parts

orders

and

correspondence.

Locations

of

these

serial

numbers

are

illustrated

below.

GM

G(N[Rll

MOTORS

1

i•Xiiii

BUILT

BY

GMC.

TRUCK

ii

COAC.H

DIVISION

GENERAL

MOTORS

CORPORATION

PONTIAC..

MIC.H.

U.

5 A

TYPE

COACH

NO

PLATE

ON

RIGHT

SIDE

OF DASH

*8VA

1887

7087

4220

RIGHT

SIDE

OF CYLINDER

BLOCK

ON

BULKHEAD

IN

TOOL COMPARTMENT

Page

iv

GM

COACH

MAINTENANCE

MANUAL

Sec.

1

Page 1

This

group

is

divided

into

two

sections

covering

"FRONT

END ALIGNMENT" and

"FRONT

AXLE REPAIR."

Proper

front

end

alignment

must

be

maintained

to

insure

ease

of

steering

and

satisfactory

tire

life.

Front

end

alignment

inspections

generally

fall

into

two

groups:

(1)

Regular

service

inspections

performed

at

periodic

intervals,

and (2)

Inspections

to

determine

extent

of

damage

after

a

collision

or

severe

service.

Regular

service

inspections

are

primarily

concerned

with

toe-in,

camber,

and

caster.

With

proper

equipment

these

specifications

are

easily

checked.

Any

variation

from

these

specifications

will

indicate:

(1)

need

for

adjustment,

or

(2)

more

thorough

inspection

to

determine

if any

steering

or

front

axle

parts

are

bent

and

require

replacement.

Complete

front

end

alignment

data

is

given

under

"Front

End

Alignment

Data"

at

end

of

this

section.

DEFINITION

OF

TERMS

WHEEL

TOE-IN.

Distance

front

wheels

are

closer

together

at

front

than

at

rear

of

axle

(see

"G"

minus

"H,"

fig. 1).

WHEEL CAMBER. Amount

wheels

are

inclined

from

vertical

plane

(see

"C,"

fig. 1).

FRONT AXLE CASTER.

Inclination

of

king

from

the

vertical

in

the

fore

and

aft

direction

of

the

vehicle

(see

"X,"

fig.

1).

KING PIN INCLINATION.

The

slant

of

the

king

toward

the

center

of

the

vehicle

at

the

top and

out-

ward

at

the

bottom

(see

"D,"

fig. 1).

STEERING GEOMETRY.

The

design

of

the

front

end

which

causes

the

front

wheels

to

stay

in

proper

relative

alignment

when

the

wheels

are

turned

to

right

or

left.

FRONT END INSPECTION

Before

checking

front

end

alignment,

the

fol-

lowing

front

end

inspection

should

always

be

made:

1.

Check

tires

for

proper

inflation.

2.

Check

wheel

installation

and

run-out.

3.

Check

wheel

bearing

adjustment.

4.

Check

tie

rod

and

drag

link

ends

for

loose-

ness.

5.

Check

king

pins

for

looseness.

Front

end

alignment

requires

the

vehicle

to

be

level

while

being

checked.

Full

weight

must

be

on

wheels

with

vehicle

empty.

ALIGNMENT

FRONT WHEEL

TOE-IN

Toe-in

is

measured

from

centers

of

tire

tread.

Measurements

at

both

front

and

rear

of

axle

(see

"H"

and

"G,"

fig.

1)

must

be

made

at

same

height

from

floor.

First

hoist

front

of

vehicle

and

spin

wheels

to

obtain a

center

line

on

tire

treads.

Place

wheels

in

straight-ahead

position.

Roll

the

vehicle

straight

ahead

for

several

feet

to

where

the

inspection

is

to

be

made.

This

will

remove

any

slack

caused

by

looseness

in

the

wheel

bearings

or

steering

connections.

Measure

at

point

"H"

-and

"G"

(fig. 1).

Toe-in

is

"G"

minus

"H."

Incorrect

toe-in

results

in

excessive

tire

wear

caused

by

side

slippage.

Unstable

steering

with a

tendency

to

wander

may

also

result.

Toe-in

Adjustment

NOTE: If

toe-in

has

to

be

changed

a

consider-

able

amount,

drag

link

must

be

removed,

then

re-

installed

and

readjusted

so

steering

gear

will

not

be

thrown

off high

point.

1.

Loosen

clamp

bolts

which

retain

each

tie

rod

end

on

tie

rod.

2.

Using

a

pipe

wrench,

turn

tie

rod

tube

as

required

to

obtain

correct

toe-in

measurement.

3.

After

correct

adjustment

is

obtained,

make

certain

that

both

tie

rod

ends

are

in

the

same

plane;

then

tighten

all

clamp

bolts

firmly.

4.

Recheck

toe-in

to

make

sure

adjustment

was

not

changed

when

clamp

bolts

were

tightened.

FRONT WHEEL CAMIIER

Positive

Camber

is

outward

inclination

of

wheels

at

top;

Negative

or

Reverse

Camber

is

in-

ward

inclination

of

wheels

at

top.

This

vehicle

is

designed

with

positive

camber.

Camber

variations

may

be

caused

by

wear

at

wheel

bearings

and

Sec.

1

Page

2

GM

COACH

MAINTENANCE MANUAL

FRONT

END

ALIGNMENT

B

MINUS A

C

.....

.

D

.....

.

E

G MINUS H

J

.....

.

M

.....

.

N

(MECH.)

N (POWER)

H

------+------1

Centerline

of

axle

is

marked

by

4 prick

--

-

---

punch

marks

on

rear

face

of

axle

-

With

Power

Steering

TOE-IN,

ROD

AND ARM LOCATIONS

~

H

_

Centerline

of

axle

is

marked

by

4 prick

-1-

punch marks on

rear

face

of

axle

I

j

i

I

With Mechanical Steering

TOE-IN,

ROD

AND ARM LOCATIONS

Camber

(Inches)

Camber

(Degrees)

King Pin

fnclination

(Degrees)

Top of

Tie

Rod

Tube

Below Top

of Axle

Front

Wheel

Toe-in

(Inches)

Centerline

of

Tie

Rod

End

Stud

to

Wheel

Rim

Centerline

of Axle

to

Center

of

Tie

Rod

End

Studs

Centerline

of Axle

to

Center

of

Steering

Arm

End

(At

Drag

Link)

Centerline

of Axle

to

Center

of

Extension

End

Stud

CAMBER,

PIN INCLINATIONS,

AND

ROD

LOCATIONS

~

Front-

FRONT

AXLE

CASTER

KING PIN INCLINATION

CASTER

P . . . . . . Bottom of

Tie

Rod

Arm

Boss

to

Top

of Axle Beam

S MINUS T

U MINUS

V

X

y

z

Caster

(Inches)

(Measure

at

Front

of Axle)

King Pin

Inclination

(Inches)

Caster

(Degrees)

Vertical

Centerline

of King Pin

T-2200-1

Figure

1-Front

End

Alignment

Chart

GM

COACH

MAINTENANCE MANUAL

Sec.

1

Page 3

steering

knuckle

bushings,

or

by

bent

steering

knuckle

or

sagging

axle

center.

In

checking

camber

it

is

recommended

that

an

accurate

gauge

be

used.

If

a

camber

gauge

is

not

available,

readings

can

be

taken

as

illustrated

at

"A"

and

"B" on

chart

(fig. 1).

Place

square

as

shown

and

measure

distance

between

"A"

and

rim,

and

"B"

and

rim.

Lower

dimension

should

exceed

upper

dimension

by

amount

listed

in

"Front

End

Alignment

Data"

at

end

of

this

section.

This

dimen-

sion

on

right

wheel

should

not

vary

over

3/

32"

from

same

dimension

taken

at

left

wheel.

If

final

camber

reading

is

incorrect,

either

steering

knuckle

or

axle

center

is

bent.

To

deter-

mine

which

part

is

bent,

check

king

inclination

("D,

11

fig.

1).

Camber

plus

king

inclination

is

the

INCLUDED ANGLE of

steering

knuckle.

If

in-

cluded

angle

of

knuckle

varies

more

than

1/2

de-

gree

from

values

given

in

"Front

End

Alignment

Data,"

knuckle

is

bent.

Excessive

positive

camber

results

in

irregular

wear

of

tires

at

outer

shoulders.

Negative

or

re-

verse

camber

causes

wear

at

inner

shoulders.

Ease

of

steering

is

affected

by any

deviation

from

specified

camber.

AXLE

CASTER

Positive

Caster

is

the

inclination

of

the

king

pins

toward

rear

of

vehicle.

Negative

or

Reverse

Caster

is

the

inclination

of king

pins

toward

front

of

vehicle.

This

vehicle

is

designed

with

positive

caster.

Caster

variations

may

be

caused

by

bent

axle,

or

tilting

of

side

suspension

supports.

Precision

instruments

must

be

used

to

check

caster

angles

when

axle

is

installed

in

vehicle.

Caster

can

be

adjusted

on

vehicle

by

loosening

clamp

bolts

in

adjusting

clamp

(fig.

2)

and

turning

clamp.

Adjust

to

dimension

listed

in

"Front

End

Alignment

Data"

on

Tighten

clamp

bolts

firmly

after

adjustment.

When

axle

is

removed

from

vehicle,

check

can

be

made

on

bench

as

follows:

Place

two

uniform

blocks

on

level

surface.

Rest

suspension

support

seats

on

blocks.

Using

square,

measure

"S"

and

"T"

dimensions

(fig.

1)

at

front

side

of

axle.

"S"

minus

"T"

equals

caster

in

inches.

If

this

dimension

does

not

agree

with

specified

value,

the

axle

is

twisted.

The

purpose

of

caster

is

to

provide

steering

stability

by

keeping

the

wheels

in

a

straight-ahead

position.

Variations

from

specified

caster

values

will

affect

steering

stability

causing

wandering,

difficulty

in

pulling

out

of

curves,

and a

tendency

toward

wheel

shimmy.

FRONT

END

ALIGNMENT

Figure

2-Caster

Adjusting

Clamp

KING PIN

INCLINATION

Precision

instruments

must

be

used

to

check

king

inclination

when

axle

is

installed

in

vehicle.

When

axle

is

removed,

check

can

be

made

on

bench

as

follows:

Place

two

uniform

blocks

on

level

surface,

rest

suspension

support

seats

on

blocks.

Using

square,

measure

"U"

and

"V"

dimensions

(fig. 1).

"U"

minus

"V"

equals

king

inclination

in

inches.

If

axle

is

bent

or

twisted,

axle

center

must

be

replaced.

STEERING

GEOMETRY

(Refer

to

Fig.

1)

Since

the

angularity

of

the

steering

arms

largely

controls

steering

geometry,

checking

the

alignment

of

the

steering

arms

and

linkage

is

an

important

alignment

factor.

After

making

all

other

front

end

alignment

checks,

inspect

steering

arms

for

proper

install-

ation,

then

measure

steering

arm

angles

as

follows:

1.

Position

of

top

of

tie

rod

tube

below

top

of

axle

("E").

2.

Distance

of

center

of

tie

rod

end

studs

to

edge

of

wheel

rims

("J").

3.

Distances

of

center

of

tie

rod

end

studs

to

centerline

of

axle

("M").

4.

Distance

from

centerline

of

axle

to

center

of

steering

arm

end

(at

drag

link) ("N") (Mech.

Steering).

5.

Distance

from

centerline

of

axle

to

center

of

extension

end

stud

(at

steering

arm)

(N")

(Power

Steering).

If

these

dimensions

are

not

within

specified

values,

the

steering

arms

or

steering

linkage

are

bent

and

should

be

replaced.

Refer

to

for

"Front

End

Alignment

Data."

Sec.

1

Page

4

GM

COACH

MAINTENANCE MANUAL

FRONT

AXLE

REPAIR

POINTS

ON

CHART

B

MINUS

A

C

D

E

G

MINUS

H

J

M

N

(MECH.)

N

(POWER)

p

S

MINUS

T

(MECH.)

S

MINUS

T

(POWER)

U

MINUS

V

X

(MECH.)

X

(POWER)

1 King

Nut

FRONT END ALIGNMENT DATA

(Refer

To

Front

End

Alignment

Chart, Figure 1)

Wheel

Camber

(Inches)

Wheel

Camber

(Degrees)

King

Inclination

(Degrees)

Top

of

Tie

Rod

Tube

Below

Top

of

Axle

(Inches)

Front

Wheel

Toe-in

(Inches)

DIMENSIONS

1½2

1

8

5½

plus

or

minus½

Oto

½G

Centerline

of

Tie

Rod

End

Stud

to

Wheel

Rim

(Inches)

*Centerline

of

Axle

to

Center

of

Tie

Rod

End

Studs

(Inches)

2

1

5/22

32½2

3l2½2

32%

*Centerline

of

Axle

to

Center

of

Steering

Arm

End

(At

Drag

Link)

(Inches)

*Centerline

of

Axle

to

Center

of

Extension

End

Stud

(Inches)

Bottom

of

Tie

Rod

Arm

Boss

to

Top

of

Axle

Beam

(Inches)

Caster

(Inches)

(Measured

at

Front

of

Axle)

5

%

o/J.6

l½

l½-2

3

Caster

(Inches)

(Measured

at

Front

of

Axle)

.

King

Inclination

(Inches)

Caster

(Degrees)

Caster

(Degrees)

Front

Wheel

Track

at

Ground

(Inches)

79¼

*Centerline

of

Axle

is

Prick-punched

on

Face

of

Axle

Beam

7

Expansion

Plug

CONSTRUCTION

Front

axle

assembly

is

Reverse

Elliott

type.

Axles

are

equipped

with

steering

knuckles

con-

structed

as

shown

in

figure

1.

Wheel

bearings,

air

suspension,

steering

gear

housing,

and

brake

parts

which

are

mounted

on

front

axle

are

described

in

their

respective

sec-

tions

in

this

manual.

Specifications

and

pertinent

front

axle

service

information

are

given

in

"Specifications"

at

end

of

this

section.

2

King Pin Cover 8

Steering

Knuckle

Bushing

Front

axle

assembly

center

section

is

a hollow

rectangular

tube

in

which

dowel

pins

are

installed

to

locate

air

suspension

supports.

Outer

ends

of

axle

are

solid

forgings

machined

to

accommodate

steering

knuckles

and

king

pins.

3

King

Bushing

4

Spacing Washer

5 Axle Center End

6

King

9

Thrust

Bearing

Assembly

10

Steering

Knuckle

TP-6335-1

Figure

1-Steering

Knuckle

Assembly

Steering

knuckles

(fig. 1)

are

supported

on

solid

king

pins

which

are

tapered

at

center

section

to

fit

snugly

in

tapered

holes

in

axle

outer

ends.

Nut

installed

at

threaded

upper

end

of

each

king

locks

king

bushing

(3,

fig.

1)

against

washer

(4,

fig.

1)

and

secures

king

in

axle.

King pin

nuts

are

secured

by

cotter

pins.

GM

COACH

MAINTENANCE MANUAL

Sec.

1

Page 5

Load

is

transmitted

from

axle

center

to

steer-

ing

knuckles

through

tapered

roller

thrust

bearing

assemblies

(9,

fig.

1).

Covers

and

plugs

(2

and

7,

fig.

1)

exclude

dust

and

moisture

from

knuckle

bushings

and

serve

as

lubricant

seals.

Steering

knuckle

bushings

can

be

replaced

when

necessary.

Stop

screws

installed

at

each

end

of

axle

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.

1.

Inspect

air

suspension

support

stud

nuts

and

U-bolt

nuts.

Tighten

as

directed

in

AIR SUS-

PENSI0N (SEC. 14).

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

alignment

as

previously

instructed

under

"FRONT

END

ALIGNMENT."

5.

Check

stop

screws

and

adjust

when

nec-

essary.

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

immediately.

8.

Periodic

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

bear-

ing

(9,

fig.

1),

the

up-and-down

movement

of

steer-

FRONT

AXLE

REPAIR

ing

knuckles

must

be

kept

within

prescribed

limits.

Shims

for

use

in

reducing

clearance

are

available.

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

turning

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.

Also,

make

sure

air

suspension

is

pressur-

ized.

Adjust

stop

screws

as

follows:

1.

Raise

front

axle

until

front

wheels

are

off

floor.

2.

Turn

front

wheels

to

extreme

left,

measure

and

record

distance

from

left

front

tire

to

nearest

point

on

coach.

In

this

position

there

should

be

a

3/

4

to

1-inch

clearance.

3.

If

not

within

3/

4

to

1-inch,

turn

stop

screw

in

or

out

until

proper

clearance

is

obtained.

Secure

stop

screw

setting

with

lock

nut, and

recheck

to

make

sure

dimension

was

not

changed

when

lock

nut

was

tightened.

4.

Turn

wheels

to

extreme

right

position

and

repeat

procedure

mentioned

above

at

right

front

tire.

If

this

dimension

is

not

same

as

the

corres-

ponding

dimension

at

left-hand

side

of

coach,

ad-

just

right

stop

screw

to

provide

same

dimension.

5. When

adjustment

is

completed,

road

test

coach

and

note

if any

interference

takes

place

be-

tween

tires

and

other

parts

of

coach

while

making

sharp

turns

in

either

direction.

FRONT

AXLE

REPLACEMENT

Refer

to

AIR SUSPENSION (SEC. 14)

for

pro-

cedures

necessary

to

remove

and

install

front

axle

assembly.

FRONT

AXLE

OVERHAUL

Steering

knuckles,

king

pins,

and

bushings

may

be

replaced

without

removing

front

axle

as-

sembly

from

vehicle.

However,

when

front

axle

assembly

requires

a

complete

overhaul,

the

as-

sembly

may

be

removed.

Certain

preliminary

inspections

can

be

made,

while

axle

is

still

mounted

on

vehicle,

which

will

aid

in

determining

the

amount

of

repair

work

nec-

essary.

Check

front

end

alignment

as

previously

directed

in

"FRONT

END ALIGNMENT"

section.

Inability

to

align

front

end

correctly

indicates

that

axle

center

or

steering

knuckle

is

distorted,

steer-

ing

arms

are

bent,

or

bushings

in

steering

knuckle

yokes

are

worn

beyond

limits.

Repair

procedures

on

such

items

as

brakes,

wheel

bearings,

and

steering

gear

are

covered

in

respective

sections

of

this

manual.

STEERING

KNUCKLE

REMOVAL

If

desired,

steering

knuckles

may

be

removed

from

front

axle

without

removing

front

axle

as-

sembly

from

the

vehicle.

To

remove

steering

Sec.

1

Page 6

GM

COACH

MAINTENANCE MANUAL

FRONT AXLE

REPAIR

knuckles

from

the

axle

either

with

or

without

re-

moving

the

front

axle

assembly

from

vehicle,

proceed

as

follows:

1.

Remove

cotter

pins

and

nuts

from

tie

rod

end

studs,

then

using

a

soft

plastic

hammer,

tap

studs

until

tie

rod

is

loose;

remove

tie

rod.

2.

On

vehicles

equipped

with

mechanical

steer-

ing,

remove

drag

link

from

steering

arm.

On

ve-

hicles

equipped

with

power

steering,

remove

ex-

tension

and

end

socket

assembly

from

steering

arm

as

directed

in

STEERING

(SEC. 16) of

this

manual.

3.

Remove

front

wheels,

hubs,

and

bearings.

Refer

to

HUBS,

WHEELS, AND

TIRES

(SEC. 19).

4.

Remove

air

brake

mechanism

and

brake

shoes.

Detach

brake

shoe

spider

from

knuckle

and

remove

spider,

camshaft,

and

slack

adjuster

as

an

assembly.

5.

Remove

nuts

from

steering

tie

rod

arms

and

drive

arms

out

of

steering

knuckles.

6.

Remove

cover

(2,

fig.

1)

from

top of

knuckle

to

expose

king

nut.

Remove

snap

ring

from

knuckle

lower

yoke

and

remove

expansion

plug.

7.

Remove

cotter

pin,

then

remove

nut

from

upper

end

of king

pin.

Using

suitable

brass

drift,

drive

king

downward

out of

axle

and

knuckle.

Remove

knuckle,

thrust

bearing,

and

spacing

wash-

er

from

axle.

King

bushing

can

be

lifted

out

of

knuckle

upper

yoke.

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

removed

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

in-

spect

steering

knuckles

and

king

pins

for

minute

cracks,

checks,

or

fractures

which

otherwise

would

not

be

visible

to

the

naked

eye.

AXLE

CENTER

There

are

two

conditions

which, if

either

exists,

will

necessitate

replacement

of

axle

center.

1.

If

king

holes

in

axle

center

ends

are

worn

to

such

an

extent

that

a

new

fits

loosely,

axle

center

must

be

replaced.

2.

If

axle

center

has

been

twisted

or

bent

more

than

5

degrees

from

original

shape,

the

cen-

ter

should

be

replaced.

When

an

extreme

bent

condition

exists,

minute

invisible

fractures

may

occur

and

cause

failure

under

ordinary

operating

conditions.

Checking

Axle

Center

Check

axle

center

for

twist

with

alignment

instruments,

or

on a

bench

as

illustrated

in

front

end

alignment

chart

(fig. 1

in

"FRONT

END ALIGN-

MENT"

section).

If

equipment

is

available,

use

Magna-Flux

method

to

check

axle

center

for

min-

ute

fractures.

THRUST BEARINGS

Examine

thrust

bearings

for

excessive

wear,

pitting,

or

other

damage.

If

these

conditions

are

evident

or

if

bearing

retainers

are

bent

or

damag-

ed,

bearings

should

be

replaced.

BUSHING

REPLACEMENT

Steering

knuckle

bushings

should

be

replaced

if

inspection

reveals

that

they

are

scored,

worn,

or

otherwise

damaged.

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

at

least

1-1/2"

through

opposite

knuckle

yoke,

drive

tap

and

bush-

ing

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

will

line

up

with

lubrication

fitting

hole

in

steering

knuckle

yoke,

and

so

that

bushing

will

enter

knuckle

bore

straight

when

pressed

into

yoke.

3.

Using

arbor

press

and

suitable

installer,

press

bushing

(8,

fig.

1)

into

knuckle

bore

until

positioned

as

shown

in

figure

1.

NEVERATTEMPT

TO

DRIVE

BUSHINGS WITH HAMMER.

4.

Ream

or

hone

bushings

to

diameter

given

in

"Specifications"

at

end

of

this

section.

5.

Clean

cuttings

out of

oil

grooves,

then

round

off

all

sharp

edges

in

grooves.

KING PIN

Check

diameter

of

king

at

upper

and

lower

bearing

surfaces

against

dimensions

given

in

"Specifications"

at

end

of

this

section.

If

wear

ex-

ceeds

limits

given,

replace

with

new

king

pin.

King

pins

should

also

be

inspected

for

minute

cracks

or

other

damage.

GM PD-4107 User manual

Popular Automobile manuals by other brands