2003 JEEP GRAND CHEROKEE Brake components

CONDITION POSSIBLE CAUSES CORRECTION
VEHICLE PULLS TO ONE
SIDE DURING BRAKING1. Uneven tire pressure. 1. Adjust tire pressure.
2. Worn brake components. 2. Repair brakes as necessary.
3. Air in brake line. 3. Repair as necessary.
VEHICLE LEADS OR
DRIFTS FROM STRAIGHT
AHEAD DIRECTION ON
UNCROWNED ROAD1. Radial tire lead. 1. Cross front tires.
2. Brakes dragging. 2. Repair brake as necessary.
3. Weak or broken spring. 3. Replace spring.
4. Uneven tire pressure. 4. Adjust tire pressure.
5. Wheel Alignment. 5. Align vehicle.
6. Loose or worn steering or
suspension components.6. Repair as necessary.
7. Cross caster out of spec. 7. Align vehicle.
KNOCKING, RATTLING
OR SQUEAKING1. Worn shock bushings. 1. Replace shock.
2. Loose, worn or bent steering/
suspension components.2. Inspect, tighten or replace components
as necessary.
3. Shock valve. 3. Replace shock.
IMPROPER TRACKING 1. Loose, worn or bent track bar. 1. Inspect, tighten or replace component as
necessary.
2. Loose, worn or bent steering/
suspension components.2. Inspect, tighten or replace components
as necessary.
2 - 2 SUSPENSIONWJ
SUSPENSION (Continued)

DIAGNOSIS AND TESTING - REAR
SUSPENSION
CONDITION POSSIBLE CAUSES CORRECTION
VEHICLE INSTABILITY 1. Loose or worn wheel bearings. 1. Replace wheel bearings.
2. Loose, worn or bent suspension
components.2. Inspect, tighten or replace components
as necessary.
3. Tire pressure. 3. Adjust tire pressure.
VEHICLE PULLS TO ONE
SIDE1. Weak or broken spring. 1. Replace spring.
2. Alignment. 2. Align vehicle to specifications.
3.Tires. 3. Replace tires.
4. Brakes. 4. Repair as necassary.
KNOCKING, RATTLING
OR SQUEAKING1. Worn shock bushings. 1. Replace shock.
2. Loose shock mounting. 2. Tighten to specifications.
3. Shock valve. 3. Replace shock.
4. Loose upper ball joint. 4. Replace ball joint.
5. Loose, worn or bent suspension
components.5. Inspect, tighten or replace components
as necessary.
IMPROPER TRACKING 1. Loose, worn or bent suspension
components.1. Inspect, tighten or replace components
as necessary.
2. Bent axle. 2.Replace axle.
SPECIFICATIONS
TORQUE CHART
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Shock Absorber Upper Nut 108 80 Ð
Shock Absorber Lower Nut 115 85 Ð
Suspension Arm Upper Ball Joint Nut 142 105 Ð
Suspension Arm Upper Frame Bolts 100 74 Ð
Ball Joint Plate Bolts 136 100 Ð
Suspension Arms Lower Axle Bracket Nut 163 120 Ð
Suspension Arms Lower Frame Bracket Nut 156 115 Ð
Stabilizer Bar Retainer Bolts 54 40 Ð
Stabilizer Bar Bar Link Nut 54 40 Ð
Stabilizer Bar Bracket Link Nut 92 68 Ð
2 - 18 REARWJ
REAR (Continued)

Condition Possible Causes Correction
Axle Noise 1. Insufficient lubricant. 1. Fill differential with the correct
fluid type and quantity.
2. Improper ring gear and pinion
adjustment.2. Check ring gear and pinion
contact pattern.
3. Unmatched ring gear and pinion. 3. Replace gears with a matched
ring gear and pinion.
4. Worn teeth on ring gear and/or
pinion.4. Replace ring gear and pinion.
5. Loose pinion bearings. 5. Adjust pinion bearing pre-load.
6. Loose differential bearings. 6. Adjust differential bearing
pre-load.
7. Mis-aligned or sprung ring gear. 7. Measure ring gear run-out.
Replace components as necessary.
8. Loose differential bearing cap
bolts.8. Inspect differential components
and replace as necessary. Ensure
that the bearing caps are torqued
tot he proper specification.
9. Housing not machined properly. 9. Replace housing.
VARI-LOKT
(1) Park the vehicle on a level surface or raise
vehicle on hoist so that the vehicle is level.
(2) Remove the axle fill plug.
(3) Verify that the axle fluid level is correct. The
fluid level is correct if the fluid is level with the bot-
tom of the fill hole.
(4) Shift the transfer case into the 4WD full-time
position.
(5) Drive the vehicle in a tight circle for 2 minutes
at 5mph to fully prime the pump.
(6) Block the tires opposite the axle to be tested to
prevent the vehicle from moving.
(7) Shift the transfer case into the 4WD Low posi-
tion and the transmission into the Park position.
(8) Raise both the wheels of the axle to be tested
off of the ground.
(9) Rotate the left wheel by hand at a minimum of
one revolution per second while an assistant rotates
the right wheel in the opposite direction.
(10) The left wheel should spin freely at first and
then increase in resistance within 5 revolutions until
the wheels cannot be continuously rotated in opposite
directions.
(11) The Vari-loktdifferential has engaged prop-
erly if the wheels cannot be rotated in opposite direc-
tions for a moment. After the wheels stop rotating for
a moment, the fluid pressure will drop in the differ-
ential and the wheels begin to rotate once again.
(12) If the system does not operate properly,
replace the Vari-loktdifferential.
REMOVAL
(1) Raise and support the vehicle.
(2) Position a suitable lifting device under the
axle.
(3) Secure axle to lift.
(4) Remove the wheels and tires.
(5) Remove the brake calipers and rotors (Refer to
5 - BRAKES/HYDRAULIC/MECHANICAL/ROTORS
- REMOVAL) from the axle.
(6) Disconnect the wheel sensor wiring harness
from the vehicle wiring harness.
(7) Disconnect the vent hose from the axle shaft
tube.
(8) Mark propeller shaft and yoke/pinion flange for
installation alignment reference.
(9) Remove propeller shaft.
(10) Disconnect stabilizer bar links at the axle.
(11) Disconnect shock absorbers from axle brack-
ets.
(12) Disconnect track bar.
(13) Disconnect the tie rod and drag link from the
steering knuckle.
(14) Disconnect the steering damper from the axle
bracket.
(15) Disconnect the upper and lower suspension
arms from the axle brackets.
(16) Lower the lifting device enough to remove the
axle. The coil springs will drop with the axle.
(17) Remove the coil springs from the axle.
3 - 20 FRONT AXLE - 186FBIWJ
FRONT AXLE - 186FBI (Continued)

Condition Possible Causes Correction
Axle Noise 1. Insufficient lubricant. 1. Fill differential with the correct
fluid type and quantity.
2. Improper ring gear and pinion
adjustment.2. Check ring gear and pinion
contact pattern.
3. Unmatched ring gear and pinion. 3. Replace gears with a matched
ring gear and pinion.
4. Worn teeth on ring gear and/or
pinion.4. Replace ring gear and pinion.
5. Loose pinion bearings. 5. Adjust pinion bearing pre-load.
6. Loose differential bearings. 6. Adjust differential bearing
pre-load.
7. Mis-aligned or sprung ring gear. 7. Measure ring gear run-out.
Replace components as necessary.
8. Loose differential bearing cap
bolts.8. Inspect differential components
and replace as necessary. Ensure
that the bearing caps are torqued
tot he proper specification.
9. Housing not machined properly. 9. Replace housing.
VARI-LOKT
(1) Park the vehicle on a level surface or raise
vehicle on hoist so that the vehicle is level.
(2) Remove the axle fill plug.
(3) Verify that the axle fluid level is correct. The
fluid level is correct if the fluid is level with the bot-
tom of the fill hole.
(4) Shift the transfer case into the 4WD full-time
position.
(5) Drive the vehicle in a tight circle for 2 minutes
at 5mph to fully prime the pump.
(6) Block the tires opposite the axle to be tested to
prevent the vehicle from moving.
(7) Shift the transfer case into the 4WD Low posi-
tion and the transmission into the Park position.
(8) Raise both the wheels of the axle to be tested
off of the ground.
(9) Rotate the left wheel by hand at a minimum of
one revolution per second while an assistant rotates
the right wheel in the opposite direction.
(10) The left wheel should spin freely at first and
then increase in resistance within 5 revolutions until
the wheels cannot be continuously rotated in opposite
directions.
(11) The Vari-loktdifferential has engaged prop-
erly if the wheels cannot be rotated in opposite direc-tions for a moment. After the wheels stop rotating for
a moment, the fluid pressure will drop in the differ-
ential and the wheels begin to rotate once again.
(12) If the system does not operate properly,
replace the Vari-loktdifferential.
REMOVAL
(1) Raise and support the vehicle.
(2) Position a lifting device under the axle and
secure axle.
(3) Remove the wheels and tires.
(4) Remove brake calipers and rotors.
(5) Disconnect parking brake cables from brackets
and lever.
(6) Remove wheel speed sensors.
(7) Remove brake hose at the axle junction block.
Do not disconnect the brake hydraulic lines at the
calipers.
(8) Disconnect the vent hose from the axle shaft
tube.
(9) Mark propeller shaft and yokes for installation
reference.
(10) Remove propeller shaft.
(11) Disconnect stabilizer bar links.
(12) Remove upper suspension arm rear axle ball
joint nut.
WJREAR AXLE - 198RBI 3 - 55
REAR AXLE - 198RBI (Continued)

BRAKES
TABLE OF CONTENTS
page page
BRAKES - BASE........................... 1BRAKES - ABS........................... 41
BRAKES - BASE
TABLE OF CONTENTS
page page
BRAKES - BASE
DESCRIPTION..........................2
DIAGNOSIS AND TESTING - BASE BRAKE
SYSTEM.............................2
STANDARD PROCEDURE
STANDARD PROCEDURE - MANUAL
BLEEDING............................5
STANDARD PROCEDURE - PRESSURE
BLEEDING............................5
SPECIFICATIONS
BRAKE COMPONENTS..................6
TORQUE CHART......................6
SPECIAL TOOLS
BASE BRAKES........................7
BRAKE FLUID LEVEL SWITCH
REMOVAL.............................7
INSTALLATION..........................7
RED BRAKE WARN INDICATOR SWITCH
DESCRIPTION..........................7
OPERATION............................7
DIAGNOSIS AND TESTING - RED BRAKE
WARNING LAMP.......................7
ADJUSTABLE PEDAL SWITCH
REMOVAL.............................8
INSTALLATION..........................8
BRAKE LINES
DESCRIPTION..........................8
DIAGNOSIS AND TESTING - BRAKE HOSES
AND LINES...........................8
STANDARD PROCEDURE
STANDARD PROCEDURE - DOUBLE
INVERTED FLARING....................9
STANDARD PROCEDURE - ISO FLARING . . . 9
BRAKE PADS / SHOES
DESCRIPTION
DESCRIPTION - FRONT DISC BRAKE
SHOES.............................10DESCRIPTION - REAR DISC BRAKE SHOES . 10
OPERATION
OPERATION - FRONT DISC BRAKE SHOES . 10
OPERATION - REAR DISC BRAKE SHOES . . 10
REMOVAL
REMOVAL- FRONT DISC BRAKE SHOES . . . 11
REMOVAL - REAR DISC BRAKE SHOES....12
INSTALLATION
INSTALLATION - FRONT DISC BRAKE
SHOES.............................13
INSTALLATION - REAR DISC BRAKE
SHOES.............................14
DISC BRAKE CALIPERS
REMOVAL
REMOVAL - FRONT DISC BRAKE CALIPER . 14
REMOVAL - REAR DISC BRAKE CALIPER . . 15
DISASSEMBLY
DISASSEMBLY - FRONT DISC BRAKE
CALIPER............................17
DISASSEMBLY - REAR DISC BRAKE
CALIPER............................18
CLEANING - DISC BRAKE CALIPER.........19
INSPECTION - DISC BRAKE CALIPER.......19
ASSEMBLY
ASSEMBLY - FRONT DISC BRAKE CALIPER . 20
ASSEMBLY - REAR DISC BRAKE CALIPER . 21
INSTALLATION
INSTALLATION - FRONT DISC BRAKE
CALIPER............................22
INSTALLATION - REAR DISC BRAKE
CALIPER............................22
FLUID
DIAGNOSIS AND TESTING - BRAKE FLUID
CONTAMINATION.....................22
SPECIFICATIONS
BRAKE FLUID........................23
FLUID RESERVOIR
REMOVAL.............................23
WJBRAKES 5 - 1

INSTALLATION.........................23
MASTER CYLINDER
DESCRIPTION.........................23
OPERATION...........................24
DIAGNOSIS AND TESTING - MASTER
CYLINDER/POWER BOOSTER...........24
STANDARD PROCEDURE - MASTER
CYLINDER BLEEDING PROCEDURE......25
REMOVAL.............................25
INSTALLATION.........................25
PEDAL
DESCRIPTION
DESCRIPTION - STANDARD PEDAL.......25
DESCRIPTION - ADJUSTABLE PEDALS....25
OPERATION...........................26
REMOVAL
REMOVAL - NON-ADJUSTABLE PEDAL....26
REMOVAL - ADJUSTABLE PEDALS........27
INSTALLATION
INSTALLATION - NON-ADJUSTABLE PEDAL . 28
INSTALLATION - ADJUSTABLE PEDALS....28
PEDAL MOTOR
REMOVAL.............................28
INSTALLATION.........................28
POWER BRAKE BOOSTER
DESCRIPTION.........................29
OPERATION...........................29
REMOVAL.............................31
INSTALLATION.........................31
ROTORS
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - FRONT DISC
BRAKE ROTOR.......................31DIAGNOSIS AND TESTING - REAR DISC
BRAKE ROTOR.......................32
STANDARD PROCEDURE - DISC ROTOR
MACHINING..........................33
REMOVAL
REMOVAL - FRONT DISC BRAKE ROTOR . . 33
REMOVAL - REAR DISC BRAKE ROTOR . . . 33
INSTALLATION
INSTALLATION - FRONT DISC BRAKE
ROTOR .............................34
INSTALLATION - REAR DISC BRAKE
ROTOR .............................34
PARKING BRAKE
OPERATION...........................34
DIAGNOSIS AND TESTING - PARKING BRAKE . 34
CABLES
REMOVAL
REMOVAL - FRONT PARKING BRAKE
CABLE..............................35
REMOVAL - REAR PARKING BRAKE
CABLES............................36
INSTALLATION
INSTALLATION - FRONT PARKING BRAKE
CABLE..............................37
INSTALLATION - REAR PARKING BRAKE
CABLES............................37
LEVER
REMOVAL.............................38
INSTALLATION.........................39
SHOES
REMOVAL.............................39
INSTALLATION.........................39
ADJUSTMENTS - PARKING BRAKE SHOE....40
BRAKES - BASE
DESCRIPTION
Dual piston disc brake calipers are used on the
front. Single piston disc brake calipers are used on
the rear. Ventilated disc brake rotors are used on the
front and solid rotors are used on the rear.
Power brake assist is supplied by a vacuum oper-
ated, dual diaphragm power brake booster. The mas-
ter cylinder used for all applications has an
aluminum body and nylon reservoir with single filler
cap. A fluid level indicator is mounted to the side of
the reservoir.
The braking force of the rear wheels is controlled
by electronic brake distribution (EBD). The EBD
functions like a rear proportioning valve. The EBD
system uses the ABS system to control the slip of the
rear wheels in partial braking range. The braking
force of the rear wheels is controlled electronically by
using the inlet and outlet valves located in the HCU.
Factory installed brake linings on all models con-
sists of organic base material combined with metallic
particles.
DIAGNOSIS AND TESTING - BASE BRAKE
SYSTEM
Base brake components consist of the brake shoes,
calipers, rear park brake drums/rotors, front brake
rotors, brake lines, master cylinder, booster, HCU
and parking brake shoes.
Brake diagnosis involves determining if the prob-
lem is related to a mechanical, hydraulic, electrical
or vacuum operated component.
The first diagnosis step is the preliminary check.
PRELIMINARY BRAKE CHECK
(1) Check condition of tires and wheels. Damaged
wheels and worn, damaged, or underinflated tires
can cause pull, shudder, vibration, and a condition
similar to grab.
5 - 2 BRAKES - BASEWJ

(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
components.
(3) Inspect brake fluid level and condition. Note
that the brake reservoir fluid level will decrease 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 contam-
ination.
(a) If fluid level is abnormally low, look for evi-
dence of leaks at calipers, brake lines, master cyl-
inder, and HCU.
(b) If fluid appears contaminated, drain out a
sample to examine. System will have to be flushed
if fluid is separated into layers, or contains a sub-
stance other than brake fluid. The system seals,
cups, hoses, master cylinder, and HCU will also
have to be replaced after flushing. Use clean brake
fluid to flush the system.
(4) Check parking brake operation. Verify free
movement and full release of cables and lever. 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
being loose or for bind condition. Do not road test
until condition is corrected.
(6) Check booster vacuum check valve and hose.
(7) If components checked appear OK, road test
the vehicle.
ROAD TESTING
(1) If complaint involved low brake pedal, pump
pedal and note if it comes back up to normal height.
(2) Check brake pedal response with transmission
in neutral and engine running. Pedal should remain
firm under constant foot pressure.
(3) During road test, make normal and firm brake
stops in 25-40 mph range. Note faulty brake opera-
tion such as low pedal, hard pedal, fade, pedal pulsa-
tion, pull, grab, drag, noise, etc.
(4) Attempt to stop the vehicle with the parking
brake only (do not exceed 25 mph) and note grab,
drag, noise, etc.
PEDAL FALLS AWAY
A brake pedal that falls away under steady foot
pressure is generally the result of a system leak. The
leak point could be at a brake line, fitting, hose, or
caliper. If leakage is severe, fluid will be evident at
or around the leaking component.Internal leakage (seal by-pass) in the master cylin-
der caused by worn or damaged piston cups, may
also be the problem cause.
An internal leak in the ABS system may also be
the problem with no visual fluid leak.
LOW PEDAL
If a low pedal is experienced, pump the pedal sev-
eral times. If the pedal comes back up, the most
likely causes are worn linings, rotors, or calipers are
not sliding on the slide pins. The proper course of
action is to inspect and replace all worn component.
SPONGY PEDAL
A spongy pedal is most often caused by air in the
system. However substandard brake hoses can cause
a spongy pedal. The proper course of action is to
bleed the system, and replace substandard quality
brake hoses if suspected.
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, check valve, check
valve seal/grommet or vacuum leak could also cause
a hard pedal or high pedal effort.
PEDAL PULSATION
Pedal pulsation is caused by components that are
loose, or beyond tolerance limits.
The primary cause of pulsation are disc brake
rotors with excessive lateral runout or thickness vari-
ation. Other causes are loose wheel bearings or cali-
pers and worn, damaged tires.
NOTE: Some pedal pulsation may be felt during
ABS activation.
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.
Drag is a product of incomplete brake release.
Drag can be minor or severe enough to overheat the
linings, rotors and park brake drums.
Minor drag will usually cause slight surface charring
of the lining. It can also generate hard spots in rotors
and park brake drums from the overheat-cool down pro-
cess. In most cases, the rotors, 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 to the
point of replacement. The wheels, tires and brake
components will be extremely hot. In severe cases,
the lining may generate smoke as it chars from over-
heating.
WJBRAKES - BASE 5 - 3
BRAKES - BASE (Continued)

Common causes of brake drag are:
²Parking brake partially applied.
²Loose/worn wheel bearing.
²Seized caliper.
²Caliper binding.
²Loose caliper mounting.
²Mis-assembled components.
²Damaged brake lines.
If brake drag occurs at the front, rear or all
wheels, the problem may be related to a blocked mas-
ter cylinder return port, faulty power booster (binds-
does not release) or the ABS system.
BRAKE FADE
Brake fade is usually a product of overheating
caused by brake drag. However, brake overheating
and resulting 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
mountain roads. Refer to the Brake Drag information
in this section for causes.
BRAKE PULL
Front brake pull condition could result from:
²Contaminated lining in one caliper
²Seized caliper piston
²Binding caliper
²Loose caliper
²Rusty caliper slide surfaces
²Improper brake shoes
²Damaged rotor
²Wheel alignment.
²Tire pressure.
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
favor of the normally functioning brake unit.
An additional point when diagnosing a change in
pull condition concerns brake cool down. Remember
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 DRAG OR PULL
Rear drag or pull may be caused by improperly
adjusted park brake shoes or seized parking brake
cables, contaminated lining, bent or binding shoes or
improperly assembled components. This is particu-
larly true when only one rear wheel is involved.However, when both rear wheels are affected, the
master cylinder or ABS system 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
driving with the brakes very lightly applied for a
mile or two. However, if the lining is both soaked and
dirt contaminated, cleaning and or replacement will
be necessary.
BRAKE LINING CONTAMINATION
Brake lining contamination is mostly a product of
leaking calipers or worn seals, driving through deep
water puddles, or lining that has become covered with
grease and grit during repair. Contaminated lining
should be replaced to avoid further brake problems.
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.
NOTE: Propshaft angle can also cause vibration/
shudder.
Severely worn tires with very little tread left can
produce a grab-like condition as the tire loses and
recovers traction. Flat-spotted tires can cause vibra-
tion and generate shudder during brake operation.
Tire damage such as a severe bruise, cut, ply separa-
tion, low air pressure can cause pull and vibration.
BRAKE NOISES
Some brake noise is common on some disc brakes
during the first few stops after a vehicle has been
parked overnight or stored. This is primarily due to
the formation of trace corrosion (light rust) on metal
surfaces. This light corrosion is typically cleared from
the metal surfaces after a few brake applications
causing the noise to subside.
BRAKE 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 will 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 brake shoes in spots, metal-to-metal
contact occurs. If the condition is allowed to continue,
rotors may become so scored that replacement is nec-
essary.
5 - 4 BRAKES - BASEWJ
BRAKES - BASE (Continued)