1993 DODGE TRUCK wheel bolts

•

BRAKES
5 - 13
COMBINATION VALVE OPERATION

METERING (HOLD-OFF) VALVE The metering valve is used to balance brake action
between the front disc and rear drum brakes. The
valve meters (holds-off) full apply pressure to the front disc brakes until the rear brakeshoes are in full
contact with the drums.
The valve is designed to maintain front brake fluid
pressure at 3-30 psi until the hold-off limit of 117 psi is reached. At this point, the metering valve opens completely permitting full fluid apply pressure to the
front disc brakes.
PRESSURE DIFFERENTIAL SWITCH AND VALVE The pressure differential switch is connected to the
brake warning light. The switch is triggered by movement of the switch valve. The purpose of the switch is to monitor fluid pressure in the separate
front/rear brake hydraulic circuits.
A decrease or loss of fluid pressure in either hy­
draulic circuit will cause the switch valve to shuttle
forward or rearward in response to a pressure differ­ ential.
Movement of the switch valve will push the switch
plunger upward. This closes the switch internal con­ tacts completing the electrical circuit to the warning light. The switch valve will remain in an actuated
position until repair restores system pressures to nor­ mal levels.

COMBINATION VALVE TESTING
TESTING METERING VALVE Metering valve operation can be checked visually
and with the aid of a helper.
Observe the metering valve stem while a helper
applies and releases the brakes. If the valve is oper­
ating correctly, the stem will extend slightly when
the brakes are applied and retract when the brakes are released.
If the valve is faulty, replace the entire combina­
tion valve as an assembly.
TESTING PRESSURE DIFFERENTIAL SWITCH (1) Have helper sit in drivers seat to observe brake
warning light and to operate brake pedal.
(2) Raise vehicle on hoist.
(3) Connect bleed hose to left or right rear wheel
cylinder. Then immerse hose end in glass jar par­
tially filled with brake fluid.
(4) Have helper press and hold brake pedal all the
way down and observe warning light.
(a) If warning light illuminates, switch is operat­
ing correctly. (b) If light fails to illuminate, check circuit fuse,
bulb and wiring. Repair as necessary and repeat test steps (3) and (4). (5) If warning light still fails to illuminate, check
brakelight and park brake switches (and wiring) with test lamp. Repair or replace parts as necessary and test differential pressure switch operation again.
(6) If warning light still does not illuminate,
switch is faulty. Replace combination valve, bleed
brakes and verify proper switch and valve operation.

COMBINATION VALVE REMOVAL/INSTALLATION
VALVE REMOVAL (1) Raise vehicle on hoist.
(2) Mark or tag brake lines connected to valve for
assembly reference.
(3) Disconnect lines at valve (Fig. 8).
(4) Disconnect wires from differential pressure
switch.
(5) Remove bolts attaching valve to frame bracket
and remove valve.
VALVE INSTALLATION (1) Mount new valve on bracket and tighten valve
and bracket screws/nuts securely.
(2) Connect brakelines to valve. Tighten fittings to
16 N*m (145 in. lbs.)
(3) Connect wires to pressure differential switch
terminal. (4) Bleed brakes.
(5) Lower vehicle and verify proper brake opera­
tion.

BRAKE
LINES AND
HOSES

BRAKE LINE AND HOSE INSPECTION Flexible rubber hose is used at both front brakes
and at the rear axle junction block. Inspect the hoses
whenever the brake system is serviced, at every en­ gine oil change, or whenever the vehicle is in for ser­

vice.

Inspect the hoses for surface cracking, scuffing, or
worn spots. Replace any brake hose immediately if
the fabric casing of the hose is exposed by cracks or abrasion.
Also check brake hose installation. Faulty installa­
tion can result in kinked, twisted hoses, or contact with the wheels and tires or other chassis compo­
nents.
All of these conditions can lead to scuffing,
cracking and eventual failure.
The steel brake lines should be inspected periodi­
cally for evidence of corrosion, twists, kinks, leaks, or
other damage. Heavily corroded lines will eventually
rust through causing leaks. In any case, corroded or damaged brake lines should be replaced.

•

BRAKES
5 - 29 presses the outboard shoe lining against the opposite
side of the rotor to complete braking action.
The application or release of fluid pressure causes
only a very slight movement of the caliper and pis­
ton. At brake release, the piston and caliper return
to the non-applied position.
The brakeshoes do not retract an appreciable dis­
tance from the rotor. The minimal running clearance
between the lining and rotor provides improved re­ sponse and reduced pedal travel. It also helps in pre­
venting dirt and foreign material from lodging
between the shoe and rotor surfaces.

DISC
BRAKE
LINING WEAR COMPENSATION
Normal lining wear is compensated for by extension
of the caliper piston and by lateral movement of the cal­
iper in the adapter. Piston position is also determined
in part by the square cut piston seal (Fig. 4).
Normal disc brake lining wear will cause the cali­
per piston to extend enough to maintain proper pedal height and brake response. The caliper bore will re­ceive the extra fluid needed to compensate for the ad­
ditional piston extension.
As the piston extends during brake application, the
square-cut seal is deflected outward (Fig. 4). When
brake pressure is released, the seal straightens and
returns to a normal relaxed position. Although the amount of seal movement is quite small, it is enough
to retract the piston to the necessary minimum run­
ning clearance.
As lining wear occurs, the fluid level in the front
brake reservoir will decrease. This is a normal con­ dition and only requires adding enough fluid to re­store proper level. However, when the brakeshoes are
replaced and the caliper pistons bottomed in the

bores,
the added fluid must be compensated for to avoid overfill and overflow. Removing a small
amount of fluid from the front brake reservoir before­
hand will prevent this condition.
PISTON CALIPER
DUST BOOT
RN102

Fig.
4 Caliper
Piston
Seal
Operation

DISC
BRAKE INSPECTION
Inspect the disc brake components whenever the
caliper and brakeshoes are removed during service
operations or routine maintenance. Check condition of the rotor, brakeshoe lining, caliper
and brake hoses. Front wheel bearing adjustment and
condition can also be checked at this time. The bearings
should be repacked and adjusted if necessary.

Brakeshoes
With the caliper and brakeshoes on the vehicle,
check running clearance between the rotor and
brakeshoes. The shoe lining should either be in very light contact with the rotor or have a maximum of
0.127 mm (0.005 in.) running clearance. If clearance
exceeds the stated amount, apply the brakes several
times and recheck clearance. If clearance is still ex­ cessive, either the shoes are severely worn or the cal­
iper piston could be binding in the bore.

Hoses
And Adapter Inspect condition of the brake lines and hoses. Re­
place either front hose if cut, torn, or the reinforcing
fabric is visible. Check condition of the metal brake-
lines.
Replace any line that is badly rusted, leaking
or damaged in any way.
Clean and lubricate the slide surfaces of the caliper
and adapter. Use Mopar high temperature grease for
this purpose. Also verify that the caliper adapter
bolts are secure and tightened to proper torque.
Fluid Level Check the master cylinder fluid level. Maintain
fluid level to the bottom of the indicator rings on the
reservoir. Note that front disc brake fluid level can
be expected to drop slightly as normal lining wear occurs. Use Mopar brake fluid or equivalent meeting SAE and DOT standards J1703 and DOT 3. Use
clean brake fluid from a sealed container only.

Rotors
Check the rotor surfaces for excessive wear, discol­
oration, scoring, rust, scale, or cracks. Also look for
damaged or severely rusted ventilating segments. If
pedal pulsation was experienced, check wheel bear­ ing adjustment and condition. If the bearings are OK, also check rotor runout and thickness variation.

DISC
BRAKESHOE
REMOVAL
(1) If front brakeshoes are to be replaced, remove
approximately 1/3 of fluid from master cylinder front
brake reservoir with suction gun. (2) Raise and support vehicle.
(3) Remove front wheels.
(4) Press caliper pistons to bottom of bore with
large C-clamp. Position clamp screw on outboard
brakeshoe and position clamp frame on rear of cali­
per. (5) Remove bolts securing caliper retainer clips to
caliper. Then remove clips and anti-rattle springs (Fig. 5).

BRAKES
5 - 39
DISC BRAKE LINING WEAR COMPENSATION
Normal lining wear is compensated for by exten­
sion of the caliper piston and by lateral movement of
the caliper in the adapter. Piston position is also de­ termined in part by the square cut piston seal (Fig.
4).

Normal disc brake lining wear will cause the cali­
per piston to extend enough to maintain proper pedal height and brake response. The caliper bore will re­ceive the extra fluid needed to compensate for the ad­
ditional piston extension.
As the piston extends during brake application, the
square-cut seal is deflected outward (Fig. 4). When
brake pressure is released, the seal straightens and returns to a normal relaxed position. Although the amount of seal movement is quite small, it is enough
to retract the piston to the necessary minimum run­ ning clearance. Fluid level in the front brake reservoir will de­
crease as lining wear occurs, the. This is a normal
condition and only requires adding enough fluid to
restore proper level. However, when the brakeshoes are replaced and the caliper pistons bottomed in the

bores,
the added fluid must be compensated for. This is necessary to avoid overfill and overflow. Removing a small amount of fluid from the front brake reser­
voir beforehand will prevent this condition.

Fig.
4 Caliper
Piston
Seal
Operation

DISC
BRAKE INSPECTION
Inspect the disc brake components whenever the
caliper and brakeshoes are removed during service
operations or routine maintenance. Check condition of the rotor, brakeshoe lining, cal­
iper and brake hoses. Front wheel bearing adjust­
ment and condition can also be checked at this time.
The bearings should be repacked and adjusted if nec­ essary.

Brakeshoes
With the caliper and brakeshoes on the vehicle,
check running clearance between the rotor and
brakeshoes. The shoe lining should either be in very light contact with the rotor or a maximum of 0.127
mm (0.005 in.) running clearance. If clearance ex­ceeds the stated amount, apply the brakes several times and recheck clearance. If clearance is still ex­
cessive, either the shoes are severely worn or the cal­
iper piston could be binding in the bore.

Hoses
And Adapter Inspect condition of the brake lines and hoses. Re­
place either front hose if cut, torn, or the reinforcing
fabric is visible. Check condition of the metal brake-
lines.
Replace any line that is badly rusted, leaking
or damaged in any way.
Clean and lubricate the adapter slide surfaces. Use
Mopar multi-mileage or high temperature grease for
this purpose. Also verify that the caliper adapter
bolts are secure and tightened to proper torque.
Fluid Level Check the master cylinder fluid level. Maintain
fluid level to the bottom of the indicator rings on the
reservoir. Note that front brake fluid level can be ex­
pected to drop slightly as normal lining wear occurs.
Use Mopar brake fluid or equivalent meeting SAE and DOT standards J1703 and DOT 3. Use clean
brake fluid from a sealed container only.

Rotors
Check rotor surfaces for excessive wear, discolora­
tion, scoring, rust, scale, or cracks. Also look for damaged or severely rusted ventilating segments. If
pedal pulsation was experienced, check wheel bear­ ing adjustment and condition. If the bearings are OK, also check rotor runout and thickness variation.

DISC
BRAKESHOE REMOVAL
(1) Remove approximately 1/3 of fluid from master
cylinder front brake reservoir with a suction gun. (2) Raise and support vehicle.
(3) Remove wheel and tire assemblies.
(4) Press caliper pistons to bottom of bore with
large C-clamp (Fig. 5). Position clamp screw on out­
board shoe and clamp frame or rear of caliper hous­ ing. (5) Remove support key retaining screw (Fig. 6).
(6) Remove caliper support key and spring. Use
pin punch or drift to tap key out of caliper (Fig. 7). (7) Lift caliper out of adapter. (8) Remove outboard shoe from caliper (Fig. 8).
(9) Secure caliper to convenient chassis component
with wire. Do not allow brake hose to support caliper weight. (10) Remove inboard shoe and anti-rattle spring
from caliper adapter (Fig. 9). Note position of spring
for installation reference.
CLEANING AND INSPECTION Inspect the shoe lining for wear. Replace riveted
shoes if the lining is worn to within 1.5 mm (1/16 in.)
of the rivet heads. Replace bonded lining if thickness is 3 mm (3/16 in.) or less.

•

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.

5
- 50
BRAKES

• Discard
the old
piston cups
and the
spring
and ex­

pander. These parts
are not
reusable.
The
original
dust boots
may be
reused
but
only
if
they
are in
good condition.

ASSEMBLING
WHEEL
CYLINDER
(1) Lubricate wheel cylinder bore, pistons, piston
cups
and
spring
and
expander with clean brake fluid. (2) Install first piston
in
cylinder bore. Then
in­

stall
cup in
bore
and
against piston.
Be
sure
lip of

piston
cup is
facing inward (toward spring
and

expander)
and
flat side
is
against piston.
(3) Install spring
and
expanders followed
by re­
maining piston
cup and
piston.
(4) Install boots
on
each
end of
cylinder
and
insert
push rods
in
boots.

(5)
Install cylinder bleed screw.

WHEEL
CYLINDER INSTALLATION
(1) Apply bead
of
Mopar silicone sealer around cyl­
inder mounting surface
of
support plate. (2) Connect brake line
to
cylinder. Mount cylinder
on support plate
and
install cylinder attaching bolts. (3) Install wheel brake components.
(4) Install brake drum
and
wheel
and
bleed
brakes.

DRUM
BRAKES—TWELVE INCH

INDEX

page

Brake Drum
Installation
54

Brake Drum Removal
52

Brake Drum Service
54

Brake
Shoe
Installation
53

Brakeshoe
Removal
52

Cleaning
and
Inspection
52

GENERAL
INFORMATION
Twelve inch rear drum brakes
are
used
on D and

W 250/350 models
(Fig. 1). All
applications
are
dual
shoe,
internal expanding units with
a
self adjusting
mechanism.
A
single wheel cylinder
is
used
to ex-
page
General
Information
50

Support
Plate
Installation
55

Support
Plate
Removal
55

Wheel
Cylinder
Installation
55
Wheel
Cylinder
Overhaul
...................
54

Wheel
Cylinder
Removal
. 54

pand
the
dual brakeshoes.
The
lower ends
of the

brake shoes
are
connected
by a
star wheel adjuster screw which
is
part
of the
self adjusting mechanism
(Fig.
1).

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

5
- 54
BRAKES

• (11) Attach adjuster cable to adjuster lever. Be
sure cable is properly routed.
(12) Adjust brakeshoes to drum with brake gauge.

BRAKE
DRUM INSTALLATION
(1) Position drum on axle housing.
(2) Install bearing and inner nut. Adjust bearing
as described in Group 3. (3) Install locking washer and outer nut. Bend
locking washer to secure it. (4) Place new gasket on hub and install axle shaft,

cones,
lock washers and nuts. (5) Install wheel and tire assembly.
(6) Remove support stands and lower vehicle.

BRAKE
DRUM
SERVICE
BRAKE DRUM REFINISHING The brake drums can be resurfaced on a drum
lathe when necessary. Initial machining cuts should
be limited to 0.12 - 0.20 mm (0.005 - 0.008 in.) at a time as heavier feed rates can produce taper and sur­
face variation. Final finish cuts of 0.025 to 0.38 mm (0.001 to 0.0015 in) are recommended and will gen­
erally provide the best surface finish.
Be sure the drum is securely mounted in the lathe
before machining operations. A damper strap should always be used around the drum to reduce vibration
and avoid chatter marks.
BRAKE DRUM REFINISH LIMITS The maximum allowable diameter of the drum
braking surface is stamped or cast into the drum outer edge (Fig. 9). Generally, a drum can be ma­
chined to a maximum of 1.5 mm (0.060 in.) oversize.
Always replace the drum if machining would cause
drum diameter to exceed indicated size limit.
BRAKE DRUM RUNOUT Measure drum diameter and runout with an accu­
rate gauge. The most accurate method of measure­
ment involves mounting the drum in a brake lathe and checking variation and runout with a dial indi­
cator.
Variations in drum diameter should not exceed
0.076 mm (0.003 in). Drum runout should not exceed
0.20 mm (0.008 in.) out of round. Refinish the drum
if runout or variation exceed these values.

WHEEL
CYLINDER REMOVAL
(1) Raise and support vehicle.
(2) Remove brake drum and brakeshoes as de­
scribed in this section. (3) Remove anchor bolt and nut and remove
washer, spring, parking brake lever, adjuster cable, cam plate and anchor pin bushing. (4) Loosen brakeline at wheel cylinder.
(5) Remove wheel cylinder bolts. Fig. 9 Location Of Brake
Drum
Maximum Allowable
Diameter (6) Disconnect brakeline and remove wheel cylin­
der.

WHEEL
CYLINDER OVERHAUL

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

Fig.
10
Wheel
Cylinder
Components

CLEANING AND INSPECTION Clean the cylinder and pistons with clean 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.

•

BRAKES
5 - 55 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.
Discard the old piston cups and the spring and ex­
pander. These parts are not reusable. The original
dust boots may be reused but only if they are in good condition.

ASSEMBLING
WHEEL CYLINDER
(1) Lubricate wheel cylinder bore, pistons, piston
cups and spring and expander with ^clean brake fluid. (2) Install first piston in cylinder bore. Then in­
stall cup in bore and against piston. Be sure lip of
piston cup is facing inward (toward spring and
expander) and flat side is against piston.
(3) Install spring and expanders followed by re­
maining piston cup and piston.
(4) Install boots on each end of cylinder and insert
push rods in boots.

(5)
Install cylinder bleed screw.

WHEEL
CYLINDER INSTALLATION
(1) Start brakeline into cylinder.
(2) Position cylinder on support plate and install
cylinder attaching bolts. (3) Tighten brakeline fitting and cylinder attach­
ing bolts. (4) Install anchor pin bushing, cam plate, adjuster
cable, parking brake lever, spring washer and anchor
bolt and nut.
(5) Install brakeshoes and brake drum as described
in this section. (6) Install axle shaft.
(7) Install wheel and tire.
(8) Remove supports and lower vehicle.

SUPPORT
PLATE REMOVAL
(1) Raise and support vehicle.
(2) Remove wheel and tire.
(3) Remove axle shaft.
(4) Remove brake drum, brake shoes and wheel
cylinder as described in this section. (5) Remove bolts/nuts attaching support plate to
axle and remove support plate.

SUPPORT PLATE INSTALLATION
(1) Transfer wheel cylinder and parking brake le­
ver components to replacement support plate. (2) Position support plate on axle and install at­
taching bolts/nuts. (3) Lubricate shoe contact surfaces of support plate
with Mopar multi-purpose, or high temperature bear­ ing grease. (4) Install brakeshoes. Adjust shoes to drum with
brake gauge. (5) Install brake drum.
(6) Install axle shaft.
(7) Install wheel and tire.
(8) Remove supports and lower vehicle.