CAUTION: Never use gasoline, kerosene, alcohol,
motor oil, transmission fluid, or any fluid containing
mineral oil to clean the system components. These
fluids damage rubber cups and seals. Use only
fresh brake fluid or Mopar brake cleaner to clean or
flush brake system components. These are the only
cleaning materials recommended. If system contam-
ination is suspected, check the fluid for dirt, discol-
oration, or separation into distinct layers. Also
check the reservoir cap seal for distortion. Drain
and flush the system with new brake fluid if con-
tamination is suspected.
CAUTION: Use Mopar brake fluid, or an equivalent
quality fluid meeting SAE/DOT standards J1703 and
DOT 3. Brake fluid must be clean and free of con-
taminants. Use fresh fluid from sealed containers
only to ensure proper antilock component opera-
tion.
CAUTION: Use Mopar multi-mileage or high temper-
ature grease to lubricate caliper slide surfaces,
drum brake pivot pins, and shoe contact points on
the backing plates. Use multi-mileage grease or GE
661 or Dow 111 silicone grease on caliper slide pins
to ensure proper operation.
DIAGNOSIS AND TESTING - BASE BRAKE
SYSTEM
Base brake components consist of the brake shoes,
calipers, wheel cylinders, brake drums, rotors, brake
lines, master cylinder, booster, and parking brake
components.
Brake diagnosis involves determining if the prob-
lem is related to a mechanical, hydraulic, 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.
(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, wheel cylinders, brake
lines, and master cylinder.
(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
and cups will also have to be replaced after flush-
ing. Use clean brake fluid to flush the system.
(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
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 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/wheel cylinder. 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 or RWAL system may
also be the problem with no physical evidence.
LOW PEDAL
If a low pedal is experienced, pump the pedal sev-
eral times. If the pedal comes back up worn linings,
rotors, drums, or rear brakes out of adjustment are
the most likely causes. The proper course of action is
to inspect and replace all worn component and make
the proper adjustments.
KJBRAKES - BASE 5 - 3
BRAKES - BASE (Continued)
SPONGY PEDAL
A spongy pedal is most often caused by air in the
system. However, 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 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 or check valve could
also be faulty.
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, or out of round brake drums. Other causes are
loose wheel bearings or calipers 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 shoe release.
Drag can be minor or severe enough to overheat the
linings, rotors and drums.
Minor drag will usually cause slight surface char-
ring of the lining. It can also generate hard spots in
rotors and drums from the overheat-cool down pro-
cess. 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
severe cases, the lining may generate smoke as it
chars from overheating.
Common causes of brake drag are:
²Seized or improperly adjusted parking brake
cables.
²Loose/worn wheel bearing.
²Seized caliper or wheel cylinder piston.
²Caliper binding on corroded bushings or rusted
slide surfaces.
²Loose caliper mounting.
²Drum brake shoes binding on worn/damaged
support plates.
²Mis-assembled components.²Long booster output rod.
If brake drag occurs at all wheels, the problem
may be related to a blocked master cylinder return
port, or faulty power booster (binds-does not release).
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
A worn, damaged wheel bearing or suspension
component 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 GRAB OR PULL
Rear grab or pull is usually caused by improperly
adjusted or seized parking brake cables, contami-
nated lining, bent or binding shoes and support
plates, or improperly 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.
5 - 4 BRAKES - BASEKJ
BRAKES - BASE (Continued)
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 wheel cylinders, worn seals, driv-
ing through deep water puddles, or lining that has
become covered with grease and grit during repair.
Contaminated lining should be replaced to avoid fur-
ther 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.
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. A
tire with internal damage such as a severe bruise,
cut, or ply separation can cause pull and vibration.
BRAKE NOISES
Some brake noise is common with rear drum
brakes and 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 contribute 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 and drums can become so scored that replace-
ment is necessary.
BRAKE 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 causesof chatter are out-of-tolerance rotors, brake lining not
securely attached to the shoes, loose wheel bearings
and contaminated brake lining.
THUMP/CLUNK NOISE
Thumping or clunk noises during braking are fre-
quentlynotcaused by brake components. In many
cases, such noises are caused by loose or damaged
steering, suspension, or engine components. However,
calipers that bind on the slide surfaces can generate
a thump or clunk noise. In addition, worn out,
improperly adjusted, or improperly assembled rear
brake shoes can also produce a thump noise.
STANDARD PROCEDURE
STANDARD PROCEDURE - PRESSURE
BLEEDING
Use Mopar brake fluid, or an equivalent quality
fluid meeting SAE J1703-F and DOT 3 standards
only. Use fresh, clean fluid from a sealed container at
all times.
Do not pump the brake pedal at any time while
bleeding. Air in the system will be compressed into
small bubbles that are distributed throughout the
hydraulic system. This will make additional bleeding
operations necessary.
Do not allow the master cylinder to run out of fluid
during bleed operations. An empty cylinder will allow
additional air to be drawn into the system. Check the
cylinder fluid level frequently and add fluid as
needed.
Bleed only one brake component at a time in the
following sequence:
²Master Cylinder
²Combination Valve
²Right Rear Wheel
²Left Rear Wheel
²Right Front Wheel
²Left Front Wheel
Follow the manufacturers instructions carefully
when using pressure equipment. Do not exceed the
tank manufacturers pressure recommendations. Gen-
erally, a tank pressure of 15-20 psi is sufficient for
bleeding.
Fill the bleeder tank with recommended fluid and
purge air from the tank lines before bleeding.
Do not pressure bleed without a proper master cyl-
inder adapter. The wrong adapter can lead to leak-
age, or drawing air back into the system. Use
adapter provided with the equipment or Adapter
6921.
KJBRAKES - BASE 5 - 5
BRAKES - BASE (Continued)
BRAKE LINES
DESCRIPTION
Flexible rubber hose is used at both front brakes
and at the rear axle junction block. Double walled
steel tubing is used to connect the master cylinder to
the major hydraulic braking components and then to
the flexible rubber hoses. Double inverted style and
ISO style flares are used on the brake lines.
DIAGNOSIS AND TESTING - BRAKE LINE AND
HOSES
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
engine oil change, or whenever the vehicle is in for
service.
Inspect the hoses for surface cracking, scuffing, or
worn spots. Replace any brake hose immediately if
the fabric casing of the hose is exposed due to cracks
or abrasions.
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.
Factory replacement brake lines and hoses are rec-
ommended to ensure quality, correct length and supe-
rior fatigue life. Care should be taken to make sure
that brake line and hose mating surfaces are clean
and free from nicks and burrs. Also remember that
right and left brake hoses are not interchangeable.
Use new copper seal washers at all caliper connec-
tions. Be sure brake line connections are properly
made (not cross threaded) and tightened to recom-
mended torque.
STANDARD PROCEDURE
STANDARD PROCEDURE - DOUBLE INVERTED
FLARING
A preformed metal brake tube is recommended and
preferred for all repairs. However, double-wall steel
tube can be used for emergency repair when factory
replacement parts are not readily available.
Special bending tools are needed to avoid kinking
or twisting of metal brake tubes. Special flaring tools
are needed to make a double inverted flare or ISO
flare.(1) Cut off damaged tube with Tubing Cutter.
(2) Ream cut edges of tubing to ensure proper
flare.
(3) Install replacement tube nut on the tube.
(4) Insert tube in flaring tool.
(5) Place gauge form over the end of the tube.
(6) Push tubing through flaring tool jaws until
tube contacts recessed notch in gauge that matches
tube diameter.
(7) Tighten the tool bar on the tube
(8) Insert plug on gauge in the tube. Then swing
compression disc over gauge and center tapered flar-
ing screw in recess of compression disc (Fig. 2).
(9) Tighten tool handle until plug gauge is
squarely seated on jaws of flaring tool. This will start
the inverted flare.
(10) Remove the plug gauge and complete the
inverted flare.
STANDARD PROCEDURE - ISO FLARING
A preformed metal brake tube is recommended and
preferred for all repairs. However, double-wall steel
tube can be used for emergency repair when factory
replacement parts are not readily available.
Special bending tools are needed to avoid kinking
or twisting of metal brake tubes. Special flaring tools
are needed to make a double inverted flare or ISO
flare.
To make a ISO flare use a ISO brake flaring tool or
equivalent.
(1) Cut off damaged tube with Tubing Cutter.
(2) Remove any burrs from the inside of the tube.
(3) Install tube nut on the tube.
Fig. 2 Inverted
5 - 8 BRAKES - BASEKJ
OPERATION - REAR DRUM BRAKE
When the brake pedal is depressed hydraulic pres-
sure pushes the rear brake wheel cylinder pistons
outward. The wheel cylinder push rods then push the
brake shoes outward against the brake drum. When
the brake pedal is released return springs attached
to the brake shoes pull the shoes back to there orig-
inal position (Fig. 9).
REMOVAL
REMOVAL - FRONT BRAKE PADS
(1) Raise and support the vehicle.
(2) Remove the front wheel and tire assembly.
(3) Drain a small amount of fluid from the master
cylinder brake reservoir with acleansuction gun.(4) Bottom the caliper pistons into the caliper by
prying the caliper over.
(5) Remove the caliper mounting bolts.
(6) Remove the disc brake caliper from the mount.
CAUTION: Never allow the disc brake caliper to
hang from the brake hose. Damage to the brake
hose will result. Provide a suitable support to hang
the caliper securely.
(7) Remove the inboard and outboard pads.
REMOVAL - DRUM BRAKE SHOES
(1) Raise the vehicle and remove the rear wheels.
(2) Remove and discard the spring nuts securing
drums to wheel studs.
(3) Remove the brake drums. If drums prove diffi-
cult to remove, retract brake shoes. Remove the
access hole plug at the rear of backing plate and
back off adjuster screw with brake tool and screw-
driver.
(4) Clean the individual brake components, includ-
ing the support plate and wheel cylinder exterior,
with a find mist of water. Then wipe the brake com-
ponents clean with a dampened cloth.
(5) Remove the primary and secondary return
springs from anchor pin with the brake spring pliers.
(6) Remove the U-clip and washer securing
adjuster cable to the parking brake lever.
(7) Remove the hold-down springs, retainers and
pins with standard retaining spring tool.
(8) Remove the parking brake strut and cable
guide.
(9) Remove the adjuster lever, adjuster screw and
spring.
(10) Remove the adjuster cable.
(11) Remove the brake shoes.
(12) Disconnect the cable from the parking brake
lever and remove the lever ( if needed).
INSTALLATION
INSTALLATION - FRONT BRAKE PADS
(1) Install the inboard and outboard pads.
(2) Install the caliper (Refer to 5 - BRAKES/HY-
DRAULIC/MECHANICAL/DISC BRAKE CALIPERS
- INSTALLATION).
(3) Install the tire and wheel assembly. (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
INSTALLATION - DRUM BRAKE SHOES
Bonded linings should be replaced when worn to a
thickness of 1.6 mm (1/16 in.).
Fig. 9 BRAKE COMPONENTS
1 - SECONDARY SHOE
2 - SHOE GUIDE PLATE
3 - PRIMARY SHOE
4 - HORSE SHOE RETAINING CLIP
5 - PRIMARY RETURN SPRING
6 - PARK BRAKE STRUT
7 - HOLD DOWN SPRING AND RETAINERS
8 - SHOE RETURN SPRING
9 - ADJUSTER SCREW ASSEMBLY
10 - ADJUSTER LEVER
11 - ADJUSTER CABLE
12 - SECONDARY RETURN SPRING
13 - CABLE GUIDE
14 - WHEEL CYLINDER
15 - PARK BRAKE STRUT AND SPRING
16 - SUPPORT PLATE
KJBRAKES - BASE 5 - 11
BRAKE PADS / SHOES (Continued)
Examine the lining contact pattern to determine if
the shoes are bent or the drum is tapered. The lining
should exhibit contact across its entire width. Shoes
exhibiting contact only on one side should be
replaced and the drum checked for runout or taper.
Inspect the adjuster screw assembly. Replace the
assembly if the star wheel or 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 brake shoe contact pads on the support
plate, replace the support plate if any of the pads are
worn or rusted through. Also replace the plate if it is
bent or distorted.
(1) Clean support plate with brake cleaner.
(2) If new drums are being installed, remove pro-
tective coating with carburetor cleaner followed by
final rinse with brake cleaner.
(3) Clean and lubricate anchor pin with light coat
of Mopar multi-mileage grease.
(4) Apply Mopar multi-mileage grease to brake
shoe contact surfaces of support plate (Fig. 10).
(5) Lubricate the adjuster screw threads and pivot
with spray lube.
(6) Attach parking brake lever to secondary brake
shoe. Use new washer and U-clip to secure lever.
(7) Attach the parking brake cable to lever (if
removed).
(8) Install the brake shoes on support plate.
Secure shoes with new hold-down springs, pins and
retainers.
(9) Install the parking brake strut and spring.(10) Install the guide plate and adjuster cable on
anchor pin.
(11) Install the adjuster cable guide on the shoe.
(12) Install the primary and secondary return
springs.
(13) Lubricate and assemble adjuster screw.
(14) Install the adjuster screw, spring and lever
and connect to adjuster cable.
(15) Adjust the shoes to the drum (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/BRAKE
PADS/SHOES - ADJUSTMENTS).
(16) Install the brake drum.
(17) Install the wheel/tire assemblies and lower
vehicle (Refer to 22 - TIRES/WHEELS/WHEELS -
STANDARD PROCEDURE).
(18) Verify firm brake pedal before moving vehicle.
ADJUSTMENTS
ADJUSTMENT - REAR DRUM BRAKE
The rear drum brakes are equipped with a self-ad-
justing mechanism. Under normal circumstances, the
only time adjustment is required is when the shoes
are replaced, removed for access to other parts, or
when one or both drums are replaced.
Adjustment can be made with a standard brake
gauge or with adjusting tool. Adjustment is per-
formed with the complete brake assembly installed
on the backing plate.
ADJUSTMENT WITH BRAKE GAUGE
(1) Be sure parking brakes are fully released.
(2) Raise rear of vehicle and remove wheels and
brake drums.
(3) Verify that left and right automatic adjuster
levers and cables are properly connected.
(4) Insert brake gauge in drum. Expand gauge
until gauge inner legs contact drum braking surface.
Then lock gauge in position (Fig. 11).
(5) Reverse gauge and install it on brake shoes.
Position gauge legs at shoe centers as shown (Fig.
12). If gauge does not fit (too loose/too tight), adjust
shoes.
(6) Pull shoe adjuster lever away from adjuster
screw star wheel.
(7) Turn adjuster screw star wheel (by hand) to
expand or retract brake shoes. Continue adjustment
until gauge outside legs are light drag-fit or 30 thou-
sands of an inch clearence on the shoes.
(8) Install brake drums and wheels and lower
vehicle.
(9) Drive vehicle and make one forward stop fol-
lowed by one reverse stop. Repeat procedure 8-10
times to operate automatic adjusters and equalize
adjustment.
Fig. 10 Shoe Contact Surfaces
1 - ANCHOR PIN
2 - SUPPORT PLATE
3 - SHOE CONTACT SURFACES
5 - 12 BRAKES - BASEKJ
BRAKE PADS / SHOES (Continued)
(4) Install the brake hose to the caliper withnew
seal washersand tighten fitting bolt to 31 N´m (23
ft. lbs.).
CAUTION: Verify brake hose is not twisted or
kinked before tightening fitting bolt.
(5) Remove the prop rod from the vehicle.
(6) Bleed the base brake system,(Refer to 5 -
BRAKES - STANDARD PROCEDURE) OR (Refer to
5 - BRAKES - STANDARD PROCEDURE).
(7) Install the wheel and tire assemblies (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
(8) Remove the supports and lower the vehicle.
(9) Verify a firm pedal before moving the vehicle.
DISC BRAKE CALIPER
ADAPTER
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the front wheel and tire assembly.
(3) Drain a small amount of fluid from master cyl-
inder brake reservoir with acleansuction gun.
(4) Bottom the caliper pistons into the caliper by
prying the caliper over.
(5) Remove the caliper mounting bolts (Fig. 16).
(6) Remove the disc brake caliper from the mount.
CAUTION: Never allow the disc brake caliper to
hang from the brake hose. Damage to the brake
hose will result. Provide a suitable support to hang
the caliper securely.
(7) Remove the inboard and outboard brake pads.
(Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/
BRAKE PADS/SHOES - REMOVAL).
(8) Remove the caliper adapter mounting bolts
(Fig. 16).
INSTALLATION
(1) Install the caliper adapter mounting bolts.
Tighten the mounting bolts to 135 N´m (100 ft.lbs).
(2) Install the inboard and outboard pads. (Refer
to 5 - BRAKES/HYDRAULIC/MECHANICAL/
BRAKE PADS/SHOES - INSTALLATION).
(3) Install the caliper mounting bolts.
(4) Install the tire and wheel assembly. (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
ROTORS
DIAGNOSIS AND TESTING - DISC BRAKE
ROTOR
The rotor braking surfaces should not be refinished
unless necessary.
Light surface rust and scale can be removed with a
lathe equipped with dual sanding discs. The rotor
surfaces can be restored by machining in a disc brake
lathe if surface scoring and wear are light.
Replace the rotor under the following conditions:
²severely scored
²tapered
²hard spots
²cracked
²below minimum thickness
ROTOR MINIMUM THICKNESS
Measure rotor thickness at the center of the brake
shoe contact surface. Replace the rotor if worn below
minimum thickness, or if machining would reduce
thickness below the allowable minimum.
Rotor minimum thickness is usually specified on
the rotor hub. The specification is either stamped or
cast into the hub surface.
ROTOR RUNOUT
Check rotor lateral runout with dial indicator
C-3339 (Fig. 28). Excessive lateral runout will cause
brake pedal pulsation and rapid, uneven wear of the
brake shoes. Position the dial indicator plunger
approximately 25.4 mm (1 in.) inward from the rotor
edge. The dial indicator should be positioned in the
center of the rotor surface. Maximum allowable rotor
runout is 0.102 mm (0.004 in.).
ROTOR THICKNESS VARIATION
Variations in rotor thickness will cause pedal pul-
sation, noise and shudder.
Measure rotor thickness at 6 to 12 points around
the rotor face (Fig. 29).
Position the micrometer approximately 25.4 mm (1
in.) from the rotor outer circumference for each mea-
surement.
Thickness should notvaryby more than 0.013 mm
(0.0005 in.) from point-to-point on the rotor. Machine
or replace the rotor if necessary.
5 - 18 BRAKES - BASEKJ
DISC BRAKE CALIPERS (Continued)
STANDARD PROCEDURE - DISC BRAKE
ROTOR
The disc brake rotor can be machined if scored or
worn. The lathe must machine both sides of the rotor
simultaneously with dual cutter heads. The rotor
mounting surface must be clean before placing on the
lathe. Equipment capable of machining only one side
at a time may produce a tapered rotor. A hub
mounted on-vehicle lathe is recommended. This type
of lathe trues the rotor to the vehicles hub/bearing.CAUTION: Brake rotors that do not meet minimum
thickness specifications before or after machining
must be replaced.
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the tire and wheel assembly.
(3) Remove the caliper adapter (Fig. 30). (Refer to
5 - BRAKES/HYDRAULIC/MECHANICAL/DISC
BRAKE CALIPER ADAPTER - REMOVAL).
CAUTION: Never allow the disc brake caliper to
hang from the brake hose. Damage to the brake
hose will result. Provide a suitable support to hang
the caliper securely.
(4) Remove the disc brake rotor.
INSTALLATION
(1) Install the disc brake rotor to the hub.
(2) Install the caliper mounting adapter. (Refer to
5 - BRAKES/HYDRAULIC/MECHANICAL/DISC
BRAKE CALIPER ADAPTER - INSTALLATION).
(3) Install the tire and wheel assembly. (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
Fig. 28 Checking Rotor Runout And Thickness
Variation
1 - DIAL INDICATOR
Fig. 29 Measuring Rotor Thickness
1 - MICROMETER
2 - ROTOR
Fig. 30 DISC BRAKE ROTOR
1 - DISC BRAKE ROTOR
2 - CALIPER ADAPTER
3 - DISC BRAKE CALIPER
4 - SHOES
KJBRAKES - BASE 5 - 19
ROTORS (Continued)