parking brake DODGE TRUCK 1993 Service User Guide

•

BRAKES
BRAKES
5 - 1

CONTENTS

page

BENDIX
DISC
BRAKE
37

BRAKE
ADJUSTMENTS-BRAKE BLEEDING .. 7

BRAKE
DIAGNOSIS
3

CHRYSLER
DISC
BRAKE
27
DRUM
BRAKES-ELEVEN
INCH 46
DRUM
BRAKES-TWELVE
INCH 50

GENERAL
INFORMATION 1
MASTER
CYLINDER-COMBINATION
page

VALVE-BRAKE
LINES 10

PARKING
BRAKES
56

POWER
BRAKE
BOOSTER-BRAKE
PEDAL .. 20

POWER
BRAKE
VACUUM PUMP-DIESEL
ENGINE
...22

REAR
WHEEL ANTILOCK (RWAL)
BRAKES
.. 59

SPECIFICATIONS
65

GENERAL INFORMATION
INDEX

page

Antilock
Rear
Wheel
Brakes
1
Brake
Components 1

BRAKE
COMPONENTS
AD models are equipped with front disc and rear
drum brakes. Power assist brakes and rear wheel an­
tilock brakes are standard equipment on all models. A dual reservoir master cylinder and single or dual
diaphragm, vacuum operated power brake booster is
used for all applications. Models with the Cummins
diesel engine option are also equipped with a vacuum
pump assembly to operate the power brake booster. Front disc brake units consist of single piston, slid-
ing-type calipers with semi metallic brakeshoe lin­ ing. Vented disc brake rotors are used on all models. Bendix calipers are used on 4-wheel drive models
and on diesel engine models. Chrysler disc brake cal­
ipers are used for all other applications. Rear drum brakes are dual shoe units with an au­
tomatic adjustment mechanism. Bendix and Chrysler drum brake assemblies are used. A combination valve is used on all models. The
valve consists of a front brake metering (hold-off)
valve and a front/rear pressure differential switch. A red, brake indicator and warning light is used to
alert the driver if a pressure differential exists be­
tween the front and rear hydraulic systems. The light also alerts the driver when the parking brakes
are applied. The light is located at the left side of the
instrument cluster. An additional indicator light is used for the anti-
lock system. This light is amber and is located in the
page

Brake
Fluid/Lubricants/Cleaning
Solvents
1

Brake
Safety Precautions 2
same side of the instrument cluster as the red indi­
cator light. The antilock light alerts the driver if a system fault occurs.

ANTILOCK
REAR
WHEEL
BRAKES
All AD models are equipped with antilock rear
brakes. The system is designed to retard wheel lockup during periods of high wheel slip when brak­
ing. Retarding wheel lockup is accomplished by modu­
lating fluid pressure to the wheel brake units. Refer
to the Rear Wheel Anti-Lock Brake section for oper­ ation and service information.

BRAKE
FLUID/LUBRICANTS/CLEANING SOLVENTS Recommended fluid for all AD models is Mopar
brake fluid or equivalent meeting SAE J1703 and DOT 3 standards. Use Mopar multi mileage grease to lubricate cali­
per slide surfaces, drum brake pivot pins and shoe contact points on the backing plates. Use GE 661 or
Dow 111 silicone grease (or equivalent) on caliper
bushings and slide pins. Use fresh brake fluid or Mopar brake cleaner to
clean or flush brake system components. These are
the only cleaning materials recommended.

•

BRAKES
i - 3 BRAKE DIAGNOSIS

INDEX

page

Brake
Warning Lights
3

Diagnosing
Brake Problems .................
4

Diagnosis
Procedures
3

Low
Vacuum
Switch—Diesel
Models
3
page

Master
Cylinder/Power Booster Test
5

Power
Booster
Check
Valve Test .............
6

Power
Booster
Vacuum
Test .................
6

Testing Diesel
Engine
Vacuum
Pump
Output
.... 6

DIAGNOSIS
PROCEDURES
Brake diagnosis involves determining
if the
prob­
lem
is
related
to a
mechanical, hydraulic
or
vacuum
operated component.
A
preliminary check, road test­
ing
and
component inspection
can all be
used
to de­

termine
a
problem cause. Road testing will either verify proper brake opera­
tion
or
confirm
the
existence
of a
problem. Compo­ nent inspection will,
in
most cases, identify
the
actual part causing
a
problem. The first diagnosis step
is the
preliminary check. This
involves inspecting fluid level, parking brake action,
wheel
and
tire condition, checking
for
obvious leaks
or

component damage
and
testing brake pedal response. A road test will confirm
the
existence
of a
problem.
Final diagnosis procedure involves road test analysis and
a
visual inspection
of
brake components.

BRAKE
WARNING LIGHTS
The
red
brake warning light
is
connected
to the

parking brake switch
and to the
pressure differential switch
in the
combination valve. The
red
light will illuminate when
the
parking
brakes
are
applied
or
when
a
fluid pressure drop
oc­
curs
in the
front
or
rear brake circuit.
The
light will
also illuminate
for
approximately
2-4
seconds
at en­

gine start
up.
This
is a
self test feature designed
to

check bulb
and
circuit operation each time
the en­

gine
is
started. The amber antilock light
is
connected
to the
anti-
lock rear brake hydraulic valve.
The
light will illu­
minate
if a
fault occurs within
the
antilock system.

LOW VACUUM SWITCH-DIESEL MODELS
On diesel models,
the red
brake warning light
is
also
used
to
alert
the
driver
of a low
brake booster vacuum
condition.
The
warning light
is in
circuit with
a
vacuum
warning switch mounted
on the
driver side fender
panel.
The
vacuum side
of the
switch
is
connected
to the

power brake booster.
The
electrical side
of the
switch
is
connected
to the
brake warning light. The
low
vacuum switch monitors booster vacuum
level whenever
the
engine
is
running.
If
booster vac­
uum falls below
8.5
inches vacuum
for a
minimum
of
10 seconds,
the
switch completes
the
circuit
to the

warning light causing
it to
illuminate.
The
warning light
is
designed
to
differentiate between
a low
vac­
uum condition
and a
hydraulic circuit fault.

PRELIMINARY
BRAKE CHECK
(1) Check condition
of
tires
and
wheels. Damaged
wheels
and
worn, damaged,
or
underinflated tires
can
cause pull, shudder, tramp,
and a
condition similar
to
grab.

(2)
If
complaint
was
based
on
noise when braking,
check suspension components. Jounce front
and
rear
of

vehicle
and
listen
for
noise that might
be
caused
by

loose, worn
or
damaged suspension
or
steering compo­

nents.

(3) Inspect brake fluid level
and
condition. Note
that
the
front disc brake reservoir fluid level will drop
in
proportion
to
normal lining wear. Also note
that brake fluid tends
to
darken over time. This
is normal
and
should
not be
mistaken
for
con­
tamination.
If the
fluid
is
still clear
and
free
of

foreign material,
it is OK.

(a)
If
fluid level
is
abnormally
low,
look
for
evi­
dence
of
leaks
at
calipers, wheel cylinders, brake-
lines
and
master cylinder.
(b)
If
fluid appears contaminated, drain
out a

sample.
If
fluid
is
separated into layers,
or
obvi­
ously contains
oil or a
substance other than brake
fluid,
the
system seals
and
cups will have
to be re­

placed
and the
hydraulic system flushed.
(4) Check parking brake operation. Verify free
movement
and
full release
of
cables
and
pedal. Also
note
if
vehicle
was
being operated with parking
brake partially applied.
(5) Check brake pedal operation. Verify that pedal
does
not
bind
and has
adequate free play.
If
pedal
lacks free play, check pedal
and
power booster
for be­

ing loose
or for
bind condition.
Do not
road test until
condition
is
corrected.
(6)
If
components checked appear
OK,
road test
the

vehicle.

ROAD
TESTING (1)
If
complaint involved
low
brake pedal, pump
the pedal
and
note
if the
pedal comes back
up to
nor­ mal height.
(2) Check brake pedal response with transmission
in Neutral
and
engine running. Pedal should remain
firm under steady foot pressure.

5
- 4
BRAKES

• (3) During road test, make normal and firm brake
stops in 25-40 mph (40-64 Km/h) range. Note faulty
brake operation such as pull, grab, drag, noise, low
pedal, etc.
(4) Inspect suspect brake components and refer to
problem diagnosis information for causes of various
brake conditions.

COMPONENT
INSPECTION
Fluid leak points and dragging brake units can usu­
ally be located without removing any components. The
area around a leak point will be wet with fluid. The
components at a dragging brake unit (wheel, tire, rotor)
will be quite warm or hot to the touch.
Other brake problem conditions will require compo­
nent removal for proper inspection. Raise the vehicle and remove the necessary wheels for better visual ac­

cess.

DIAGNOSING BRAKE
PROBLEMS

PEDAL FALLS
AWAY
A
brake pedal that falls away under steady foot
pressure is the result of a system leak. The leak
point could be at a brakeline, fitting, hose, or caliper. Internal leakage in the master cylinder caused by
worn or damaged piston cups, may also be the prob­ lem cause.
If leakage is severe, fluid will be evident at or around
the leaking component. However, internal leakage in
the master cylinder may not be physically evident. Re­ fer to the cylinder test procedure in this section.

LOW PEDAL
If a low pedal is experienced, pump the pedal sev­
eral times. If the pedal comes back up, worn lining
and worn rotors or drums are the likely causes.
A decrease in fluid level in the master cylinder res­
ervoirs may only be the result of normal lining wear.
Fluid level can be expected to decrease in proportion to wear. It is a result of the outward movement of
caliper and wheel cylinder pistons to compensate for
normal wear. Top off the reservoir fluid level and
check brake operation to verify proper brake action.
SPONGY PEDAL. A spongy pedal is most often caused by air in the sys­
tem. Thin brake drums or substandard brake lines and
hoses can also cause a spongy pedal. The proper course
of action is to bleed the system and replace thin drums and suspect quality brake lines and hoses.

HARD PEDAL
OR
HIGH
PEDAL
EFFORT
A hard pedal or high pedal effort may be due to
lining that is water soaked, contaminated, glazed, or
badly worn. The power booster or check valve could also be faulty. On diesel engine models, high pedal effort may be
the result of a low vacuum condition. If the booster and check valve are OK, the problem may be related
to a vacuum pump hose, hose connection, hose fit­
ting, pump diaphragm, or drive gear. Vacuum pump output can be checked with a standard vacuum
gauge. Vacuum output should range from 8.5 to 25 inches vacuum. If vacuum pump output is within

limits,
check the power booster and check valve as
described in this section.

BRAKE DRAG
Brake drag occurs when the lining is in constant
contact with the rotor or drum. Drag can occur at
one wheel, all wheels, fronts only, or rears only. It is a product of incomplete brakeshoe release. Drag can
be minor or severe enough to overheat the linings,
rotors and drums.
Brake drag can also effect fuel economy. If undetec­
ted, minor brake drag can be misdiagnosed as an en­ gine or transmission/torque converter problem.
Minor drag will usually cause slight surface charring
of the lining. It can also generate hard spots in rotors and drums from the overheat-cool down process. In most

cases,
the rotors, drums, wheels and tires are quite
warm to the touch after the vehicle is stopped.
Severe drag can char the brake lining all the way
through. It can also distort and score rotors and drums to the point of replacement. The wheels, tires and brake components will be extremely hot. In se­
vere cases, the lining may generate smoke as it chars
from overheating.
Some common causes of brake drag are:
• seized or improperly adjusted parking brake cables
• loose/worn wheel bearing
• seized caliper or wheel cylinder piston
• caliper binding on corroded bushings or rusted
slide surfaces
• loose caliper mounting bracket
• drum brakeshoes binding on worn or damaged sup­
port plates
• misassembled components. If brake drag occurs at all wheels, the problem may
be related to a blocked master cylinder return port, or faulty power booster that binds and does not release.

BRAKE FADE
Brake fade is a product of overheating caused by
brake drag. However, brake overheating and subse­ quent fade can also be caused by riding the brake
pedal, making repeated high deceleration stops in a short time span, or constant braking on steep moun­
tain roads. Refer to the Brake Drag information in
this section for additional causes.

PEDAL
PULSA
TION
Pedal pulsation is caused by components that are
loose, out of round, or worn beyond tolerance limits.

•

BRAKES
5 - 5 Disc brake rotors with excessive lateral runout or
thickness variation, or out of round brake drums are
the primary causes of pulsation. Other causes are loose
wheel bearings or calipers and worn, damaged tires.

PULL A
front pull condition could be the result of con­
taminated lining in one caliper, seized caliper piston,
binding caliper, loose caliper, loose or corroded slide

pins,
improper brakeshoes, or a damaged rotor.
A worn, damaged wheel bearing or suspension compo­
nent are further causes of pull. A damaged front tire (bruised, ply separation) can also cause pull.
A common and frequently misdiagnosed pull condi­
tion is where direction of pull changes after a few
stops.
The cause is a combination of brake drag fol­
lowed by fade at one of the brake units.
As the dragging brake overheats, efficiency is so
reduced that fade occurs. Since the opposite brake
unit is still functioning normally, its braking effect is
magnified. This causes pull to switch direction in fa­
vor of the normally functioning brake unit.
When diagnosing a change in pull condition, re­
member that pull will return to the original direction
if the dragging brake unit is allowed to cool down (and is not seriously damaged).

REAR BRAKE GRAB
OR
PULL
Rear grab or pull is usually caused by an improperly
adjusted or seized parking brake cable, contaminated
lining, bent or binding shoes and support plates, or im­
properly assembled components. This is particularly
true when only one rear wheel is involved. However,
when both rear wheels are affected, the master cylinder or proportioning valve could be at fault.

BRAKES
DO NOT
HOLD
AFTER
DRIVING
THROUGH
DEEP
WATER
PUDDLES

This condition is generally caused by water soaked
lining. If the lining is only wet, it can be dried by driv­
ing with the brakes very lightly applied for a few min­

utes.
However, if the lining is thoroughly wet and dirty,
disassembly and cleaning will be necessary.

BRAKE NOISE

Squeak/Squeal
Brake squeak or squeal may be due to linings that
are wet or contaminated with brake fluid, grease, or oil. Glazed linings and rotors with hard spots can also con­
tribute to squeak. Dirt and foreign material embedded in the brake lining can also cause squeak/squeal.
A very loud squeak or squeal is frequently a sign of
severely worn brake lining. If the lining has worn
through to the brakeshoes in spots, metal-to-metal con­
tact occurs. If the condition is allowed to continue, ro­ tors can become so scored that replacement is necessary.
Thump/Clunk

Thumping or clunk noises during braking are fre­
quently not caused by brake components. In many

cases,
such noises are caused by loose or damaged steering, suspension, or engine components. How­
ever, calipers that bind on the slide pins, or slide sur­

faces,
can generate a thump or clunk noise. Worn
out, improperly adjusted, or improperly assembled
rear brakeshoes can also produce a thump noise.

Chatter
Brake chatter is usually caused by loose or worn
components, or glazed/burnt lining. Rotors with hard
spots can also contribute to chatter. Additional
causes of chatter are out of tolerance rotors, brake
lining not securely attached to the shoes, loose wheel
bearings and contaminated brake lining.
Brakelining Contamination Brakelining contamination is usually a product of
leaking calipers or wheel cylinders, driving through
deep water puddles, or lining that has become cov­
ered with grease and grit during repair.
Wheel and
Tire
Problems Some conditions attributed to brake components
may actually be caused by a wheel or tire problem.
A damaged wheel can cause shudder, vibration and
pull. A worn or damaged tire can also cause pull.
Severely worn tires with very little tread left can
produce a grab-like condition as the tire loses and re­ covers traction. Flat-spotted tires can cause vibration and wheel
tramp and generate shudder during brake operation. A tire with internal damage such as a severe
bruise or ply separation can cause pull and vibration.

MASTER
CYLINDER/POWER BOOSTER TEST
(1) Start engine and check booster vacuum hose
connections. Hissing noise indicates a vacuum leak. Correct any leaks before proceeding. (2) Stop engine and shift transmission into Neu­
tral (3) Pump brake pedal until all vacuum reserve in
booster is depleted. (4) Press and hold brake pedal under light foot
pressure. (a) If pedal holds firm, proceed to step (5).
(b) If pedal does not hold firm and falls away,
master cylinder is faulty (internal leakage). (5) Start engine and note pedal action. (a) If pedal falls away slightly under light foot
pressure then holds firm, proceed to step (6). (b) If pedal is effort is high, or no pedal action is
discernible, power booster or vacuum check valve is
faulty. Install known good check valve and repeat steps (2) through (5).

•

BRAKES
i - 7
BRAKE
ADJUSTMENTS-BRAKE
BLEEDING

INDEX

page

Brake
Fluid and Level 7

Brake
System
Bleeding 8
Rear
Brake
Adjustment 7

BRAKE
FLUID
AND
LEWEL

RECOMMENDED
FLUID The only brake fluid recommended for AD models
is Mopar brake fluid, or an equivalent fluid meeting SAE
J1703
and DOT 3 standards.
Use new brake fluid only, to top off the master
cylinder or refill the system* Never use re­
claimed fluid, fluid not meeting the
SAE/DOT
standards, fluid marked 70R1, or fluid from a
container that has been left open for any length
of time. Using non recommended or unspecified
fluid can result in brake failure after hard pro­ longed braking.

BRAKE
FLUID
LEWEL Always clean the master cylinder cover before
checking fluid level. If not cleaned, dirt from the
cover could enter the fluid. Also check the cover seal
and replace it if torn or distorted.
Correct fluid level is to the bottom of the ring in­
dicators on models with a plastic reservoir and to
within 1/4 inch of the reservoir rim on all others. If necessary, add fluid to bring up to the proper level.
Note that on disc brake equipped vehicles, fluid level can be expected to fall as the brake pads wear.

BRAKE
FLUID
CONTAMINATION
Oil in the fluid will cause brake system rubber
seals to soften and swell. The seals may also become
porous and begin to deteriorate.
If fluid contamination is suspected, drain off a sam­
ple from the master cylinder. A suction gun or simi­ lar device can be used for this purpose.
Empty the drained fluid into a glass container.
Contaminants in the fluid will cause the fluid to sep­
arate into distinct layers. If contamination has oc­
curred, the system rubber seals, hoses and cups must
be replaced and the system thoroughly flushed with clean brake fluid.
Remember that brake fluid tends to darken
over time. Do not confuse this normal condition
with contamination.

REAR
BRAKE
ADJUSTMENT
The rear drum brakes are equipped with a self ad­
justing mechanism. Under normal circumstances, the only time adjustment is required is when the brake-
page

Stop
Light Switch Adjustment 9

Wheel
Nut Tightening 9
shoes are replaced; removed for access to other parts; or when one or both drums are replaced.
Adjustment can be performed with a standard
brake gauge or with adjusting tool C-3784.

ADJUSTMENT
WITH
STANDARD
BRAKE
GAUGE
(1) Verify that left/right automatic adjuster lever
and cable are properly connected and that parking
brakes are fully released. Be sure there is slack in cables.
(2) Insert brake gauge in drum. Expand gauge un­
til gauge inner legs contact drum braking surface. Then lock gauge in position (Fig. 1).

Fig.
1 Adjusting Gauge To Brake
Drum

(3) Reverse gauge and install it on brakeshoes
(Fig. 2). Position gauge legs at shoe centers as
shown. If gauge does not fit (too loose/too tight), ad­
just shoes. (4) Pull the shoe adjuster star wheel away from
the automatic adjuster lever.
(5) Turn the adjuster star wheel (by hand) to ex­
pand or retract the brakeshoes. Continue adjustment until the gauge outside legs are a light drag-fit on
the shoes (Fig. 2).
(6) Repeat adjustment at the opposite brakeshoe
assembly. (7) Install the brake drums and wheels and lower
the vehicle.
(8) Make final adjustment. Drive vehicle and make
one forward stop followed by one reverse stop. Repeat
procedure 8-10 times to actuate adjuster mechanism and equalize adjustment. Bring vehicle to complete

i - 8
BRAKES

•
BRAKE
SHOE'S

Fig. 2 Adjusting Brakeshoes To Gauge standstill at each stop. Incomplete, rolling stops will
not activate the automatic adjusters.

ADJUSTMENT
WITH
TOOL
C-3784
(1) Release parking brakes fully. Be sure there is
slack in cables. (2) Raise vehicle so all wheels are free to turn.
(3) Remove rubber plugs from access holes in sup­
port plates. (4) Insert adjusting Tool
0-3784
into star wheel of
adjuster screw. Turn star wheel counterclockwise
(move tool upward) until slight drag is felt when
road wheel is rotated.

(5)
Insert thin screwdriver or length of welding rod
into support plate access hole and push adjuster lever
out of engagement with star wheel (Fig. 3). Do not
bend lever or distort lever spring.
(6) Hold adjuster lever away from star wheel. Then
back off star wheel until shoe drag on drum is elim­ inated.
(7) Repeat above adjustment at opposite wheel. Be
sure adjustment is equal. (8) Install access hole plugs in support plate.
(9) Adjust the parking brake after wheel brake ad­
justment.
(10) Make final adjustment. Drive vehicle and
make one forward stop followed by one reverse stop.
Repeat procedure 8-10 times to actuate adjuster
mechanism and equalize adjustment. Bring vehicle to
complete standstill at each stop. Incomplete, rolling stops will not activate adjuster mechanism.

CHECKING DRUM
BRAKE ADJUSTER
OPERATION

(1) Place vehicle on hoist, with helper in driver
seat to apply brakes.
(2) Remove access plugs from support plates.
(3) Back off adjuster screw star wheel approxi­
mately 20-30 notches. (4) Observe adjuster screw star wheel and spin
drum and road wheel rapidly in a reverse direction. Fig. 3 Rear Brake Adjustment With Tool
C-3784

(5) Have helper apply brakes firmly. Firm applica­
tion will cause secondary shoe to move and engage rotating drum.
(6) Normal shoe "wrap-up" effect should move sec­
ondary shoe enough to cause adjuster cable to pull adjuster lever up and turn star wheel.

BRAKE
SYSTEM BLEEDING
The brake system can be bled manually or with
pressure equipment. Manual bleeding requires the aid of a helper. Pressure equipment allows the sys­
tem to be bled by one person. All models are equipped with a front brake meter­
ing (hold off) valve. The metering valve is located
within the combination valve. The metering valve balances brake action between the front disc and
rear drum brakes during initial brake application. The metering valve is designed to hold off fluid
flow to the front disc brakes at pressures between 3 and 135 psi (20.68 and 930.8 kPa). Pressures generated by gravity or manual type
bleeding techniques will not affect the valve. How­ ever, pressure bleeding equipment will generate
enough fluid pressure (20 to 30 psi) to close the valve and prevent fluid flow to the front brakes. As a re­
sult, the valve must be held open with special tool
C-4121 when using pressure bleeding equipment.
BLEEDING PROCEDURE (1) If new or overhauled master cylinder will be used,
be sure to bleed cylinder before installation. Refer to
bleeding procedure in Master Cylinder section. (2) If master cylinder has not been serviced, clean
master cylinder and cover to prevent dirt entering
reservoirs. Then remove cover.
(3) If pressure bleeding tank C-3496-B will be
used, install adapter C-4578 on master cylinder.
Then prepare tank for bleeding according to instruc­
tions provided by supplier. Be sure to purge air from
tank lines before use.

i - 46
BRAKES

• DRUM
BRAKES—ELEVEN
INCH

INDEX
page
Brake Drum Inspection
and
Refinishing
........ 48

Brake Drum
Installation
.................... 48

Brake Drum Removal
46

Brake
Shoe
Installation
. 47

Brake Support
Plate
Installation
49
Brake Support
Plate
Removal
............... 49
page
Brakeshoe Removal
...................... 46

Cleaning
and
Inspection
47

General
Information
46

Wheel Cylinder
Installation
50
Wheel Cylinder Overhaul
49

Wheel Cylinder Removal
49

GENERAL
INFORMATION
Chrysler eleven inch rear drum brakes are used on
D and W150 models (Fig. 1). All applications are two
shoe,
internal expanding units with a self adjuster
mechanism. A single wheel cylinder is used to ex­
pand the dual brakeshoes. The lower ends of the
brake shoes are connected by a star wheel adjusting screw which is part of the self adjusting mechanism.

SUPPORT PLATE PARKING

BRAKE

STRUT
AND
SPRING RETURN
SPRING ANCHOR
PLATE RETURN CABLE
SPRING GUJDE
PRIMARY
SHOE
AND
LINING

SHOE SPRING
ADJUSTER SCREW
ASSEMBLY
ADJUSTER
LEVER LEVER
SPRING PARKING

BRAKE
LEVER
ADJUSTER CABLE AND
SPRING
SHOE
RETAINER, SPRING
AND
PIN

SECONDARY SHOE
AND
LINING
J9005-62

Fig.
1 Eleven
Inch
Drum
Brake
Assembly

BRAKE
DRUM REMOVAL
(1) Raise and support vehicle. (2) Remove wheel and tire.
(3) Remove clip nuts securing brake drum to wheel

studs.
(4) If drum is difficult to remove, retract brake-
shoes as follows: (a) Remove rear plug from access hole in support
plate. (b) Insert a thin screwdriver into access hole and push self adjusting lever away from adjuster screw
star wheel. (c) Insert Tool C-3784 into brake adjusting hole
and rotate adjuster screw star wheel to retract
brakeshoes.
(5) Remove brake drum.
(6) Inspect brakelining for wear, alignment, or ev­
idence of leakage from axle or wheel cylinder.

BRAKESHOE
REMOVAL
(1) Remove rear wheel and drum.
(2) Remove shoe return springs with Tool C-3785
(Fig. 2).
SHOE
RETURN SPRING SPECIAL
TOOL

(REMOVING
AND
INSTALLING)
SHOE
TO SHOE

SPRING LEVER
SPRING
ADJUSTING
LEVER
RH225A

Fig.
2 Removing/Installing
Shoe
Return
Springs
(3) Remove adjuster cable. Slide cable eye off an­
chor pin and remove cable from adjuster lever.
(4) Remove cable guide from secondary shoe and
remove anchor plate from anchor pin. (5) Remove adjuster lever. Disengage lever from
spring by sliding lever forward to clear pivot and
work lever out from under spring.
(6) Remove adjuster lever spring from pivot.
(7) Disengage and remove shoe spring from brake-

shoes.

BRAKES
5 - 47
(8) Disengage and remove adjuster screw assembly
from brakeshoes.
(9) Remove brake shoe retainers, springs and pins
with Tool C-4070, (Fig. 3). Fig. 3 Removing/Installing Shoe Retainers, Springs
and Pins (10) Remove secondary brakeshoe from support
plate. (11) Remove strut and anti rattle spring (Fig. 4).
Fig. 4 Removing/Installing Strut And Spring
(12) Remove parking brake lever from secondary

shoe.

(13) Remove primary shoe from support plate.
(14) Disengage parking brake lever from parking
brake cable.

CLEANING AND INSPECTION
Clean the brake components, including the support
plate and wheel cylinder exterior, with a water dampened cloth or with Mopar brake cleaner. Do not
use any other cleaning agents and do not use com­
pressed air to remove dirt and dust. Replace the brakeshoes if worn to within 1.5 mm
(1/16 in.) of the rivet heads or if bonded lining is less
than 4 mm (3/16 in.) thick. Examine the lining con­
tact pattern to determine if the shoes are bent or the drum is tapered. The lining should exhibit contact across the entire width. Shoes exhibiting contact only
on one side should be replaced and the drum checked
for runout or taper.
Clean and inspect the adjuster screw assembly. Re­
place the assembly if the star wheel threads are damaged, or the components are severely rusted or corroded.
Discard the brake springs and retainer components
if worn distorted, or collapsed. Also replace the springs if a brake drag condition had occurred. Over­
heating will distort and weaken the springs. Inspect the brakeshoe contact surfaces on the sup­
port plate (Fig. 5). Remove light rust and scale from
these surfaces with 180 grit emery cloth or sandpa­
per. However, replace the support plate if any of the contact surfaces are worn or rusted through. Also re­
place the plate if it is bent or distorted.
Fig. 5 Shoe Contact Surfaces

BRAKE
SHOE INSTALLATION
(1) Lubricate anchor pin and brakeshoe contact
pads on support plate (Fig. 5) with Mopar multi-pur­

pose,
or high temperature grease. (2) Lubricate adjuster screw socket, nut, button
and screw thread surfaces with Mopar multi purpose,
or high temperature grease. (3) Attach parking brake cable to lever. Then con­
nect lever to secondary shoe. (4) Install primary shoe on support plate. Secure
shoe with new spring retainers and pin (Fig. 6). (5) Install spring on parking brake strut and en­
gage strut in primary shoe (Fig. 6). (6) Install secondary shoe on support plate (Fig. 6).
Insert strut in shoe and guide shoe onto anchor pin.
Temporarily secure shoe with retaining pin. (7) Install anchor plate and adjuster cable eyelet
on support plate anchor pin.

•

BRAKES
5 - 49 (2) Adjust brake shoes to drum with a brake
gauge. (3) Install and secure drum to wheel studs with
new retaining nuts/clips.
(4) Install rubber access plugs in support plate if
removed.
(5) Install wheel and tire.

BRAKE
SUPPORT PLATE REMOVAL
(1) Remove wheel and tire and brake drum.
(2) Remove axle shaft and retainer. Refer to Group
3 for procedures. (3) Remove primary brakeshoe for access to park­
ing brake cable if necessary. (4) Compress parking brake cable retainer tabs
with a hose clamp (Fig. 9). Then push retainer and cable through and out of support plate.
AIRCRAFT TYPE

HOSE
CLAMP
RB763

Fig.
9
Removing
Parking Brake Cable From
Support
Plate
(5) Disconnect brake line at wheel cylinder.
(6) Remove wheel cylinder and brakeshoes from
support plate.
(7) Remove bolts attaching support plate to axle
and remove support plate.

BRAKE
SUPPORT PLATE INSTALLATION
(1) If new support plate is being installed, apply
bead of Mopar silicone sealer around wheel cylinder mounting surface. Then transfer wheel cylinder to
new support plate. (2) Apply bead of Mopar silicone sealer around
axle mounting surface of support plate. (3) Install support plate on axle flange. Tighten at­
taching bolts to 47-68 N-m (35-50 ft. lbs.). (4) Install parking brake cable in support plate.
(5) Install axle shaft and retainer.
(6) Start brakeline in wheel cylinder and install
cylinder on support plate. Tighten brakeline fitting after cylinder installation. (7) Connect parking brake cable to lever on sec­
ondary shoe and install brakeshoes on support plate.
(8) Adjust brakeshoes to drum with brake gauge.
(9) Install brake drum and wheel and tire.
(10) Bleed brake system.

WHEEL CYLINDER REMOVAL
(1) Raise vehicle and remove wheel and brake
drum. (2) Disconnect wheel cylinder brakeline.
(3) Remove brakeshoe return springs and move
shoes out of engagement with cylinder push rods. (4) Remove cylinder attaching bolts and remove
cylinder from support plate.

WHEEL
CYLINDER OVERHAUL
WHEEL
CYLINDER DISASSEMBLY
(1) Remove push rods and boots (Fig. 10).
(2) Press pistons, cups and spring and expander
out of cylinder bore.
(3) Remove bleed screw.
SPRING

CYLINDER PISTON
CUP
CUP

EXPANDERS
BOOT
PISTON
'

BLEED
SCREW PUSH
ROD '
J9005-66

Fig.
10
Wheel
Cylinder
Components
CLEANING
AND
INSPECTION

Clean the cylinder and pistons with fresh brake
fluid or brake cleaner only. Do not use any other cleaning agents. Dry the cylinder and pistons with
compressed air. Do not use rags or shop towels to dry
the cylinder components. Lint from such materials
can adhere to the cylinder bores and pistons.
Inspect the cylinder bore. Light discoloration and
dark stains in the bore are normal and will not im­
pair cylinder operation. If desired, the bore can be lightly polished but only with crocus cloth. Replace
the cylinder if the bore is scored, pitted or heavily
corroded. Honing the bore to restore the surface is
not recommended.
Inspect the cylinder pistons. The piston surfaces
should be smooth and free of scratches, scoring and
corrosion. Replace the pistons if worn, scored, or cor­
roded. Do attempt to restore the surface by sanding or polishing.

SHOE
HOLD-

DOWN
PIN

WHEEL
CYLINDER PRIMARY SHOE UPPER
SHOE-TO-SHOE SPRING

SHOE
HOLD-DOWN SPRING
LOWER-SHOE-TO-SHOE
SPRING

ANTI-RATTLE
SPRING

FLAT
WASHER
ANCHOR BOLT WHEEL CYLINDER BOLTS
ADJUSTING
HOLE COVER ANCHOR
BOLT NUT
SHOE
HOLD-

DOWN
PIN
BACKING PLATE

AUTOMATIC
ADJUSTER
CABLE

ADJUSTER LEVER
PIVOT
PIN

SECONDARY
SHOE
PARKING

BRAKE
LEVER ADJUSTER LEVER
RETURN SPRING

AUTOMATIC

ADJUSTER LEVER
RN326A

Fig. 1
Twelve
Inch
Drum
Brake
Assembly