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BRAKES CONTENTS page page ANTILOCK BRAKES ...................... 30 BASE BRAKE SYSTEM ..................... 1 BASE BRAKE SYSTEM INDEX page page DESCRIPTION AND OPERATION BRAKE HOSES AND LINES ................. 6 BRAKE PEDAL ........................... 2 BRAKE SYSTEM ......................... 2 COMBINATION VALVE ..................... 4 FRONT DISC BRAKES ..................... 4 MASTER CYLINDER ...................... 3 PARKING BRAKE ......................... 5 POWER BRAKE BOOSTER ................. 2 REAR DRUM BRAKE ...................... 5 RED BRAKE WARNING LAMP ............... 2 SERVICE WARNINGS & CAUTIONS .......... 2 STOP LAMP SWITCH ...................... 2 DIAGNOSIS AND TESTING BASE BRAKE SYSTEM .................... 6 BRAKE DRUM .......................... 10 BRAKE FLUID CONTAMINATION ............ 11 BRAKE LINE AND HOSES ................. 11 COMBINATION VALVE ..................... 9 DISC BRAKE ROTOR ..................... 10 MASTER CYLINDER/POWER BOOSTER ....... 8 PARKING BRAKE ........................ 11 RED BRAKE WARNING LAMP ............... 8 STOP LAMP SWITCH ...................... 8 SERVICE PROCEDURES BASE BRAKE BLEEDING .................. 12 BRAKE DRUM MACHINING ................ 13 BRAKE FLUID LEVEL ..................... 11 BRAKE TUBE FLARING ................... 13 DISC ROTOR MACHINING ................. 13 MASTER CYLINDER BLEEDING ............. 11 REMOVAL AND INSTALLATION BRAKE PEDAL .......................... 15 COMBINATION VALVE .................... 15 DISC BRAKE CALIPER ................... 17 DISC BRAKE ROTOR ..................... 19 DISC BRAKE SHOES ..................... 18 DRUM BRAKE SHOES .................... 19 MASTER CYLINDER ..................... 16 PARKING BRAKE HAND LEVER ............ 21 POWER BRAKE BOOSTER ................ 16 REAR PARKING BRAKE CABLE ............. 21 STOP LAMP SWITCH ..................... 14 WHEEL CYLINDER ...................... 20 DISASSEMBLY AND ASSEMBLY DISC BRAKE CALIPER ................... 23 MASTER CYLINDER RESERVOIR ........... 22 WHEEL CYLINDER ...................... 25 CLEANING AND INSPECTION CALIPER .............................. 26 REAR DRUM BRAKE ..................... 26 WHEEL CYLINDER ...................... 26 ADJUSTMENTS PARKING BRAKE CABLE TENSIONER ....... 27 REAR DRUM BRAKE ..................... 27 STOP LAMP SWITCH ..................... 27 SPECIFICATIONS BRAKE COMPONENTS ................... 29 BRAKE FLUID .......................... 28 TORQUE CHART ........................ 29 SPECIAL TOOLS BASE BRAKES .......................... 29 TJ BRAKES 5-1
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1999 Jeep TJ Wrangler Service Manual - 05. Brakes

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1999 Jeep TJ Wrangler Service Manual - 05. Brakes
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Page 1: 1999 Jeep TJ Wrangler Service Manual - 05. Brakes

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TJ BRAKES 5 - 1

BRAKES

CONTENTS

page page

NTILOCK BRAKES . . . . . . . . . . . . . . . . . . . . . . 30

page

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BASE BRAKE SYSTEM . . . . . . . . . . . . . . . . . . . . . 1

BASE BRAKE SYSTEM

INDEX

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ESCRIPTION AND OPERATIONBRAKE HOSES AND LINES . . . . . . . . . . . . . . . . . 6BRAKE PEDAL . . . . . . . . . . . . . . . . . . . . . . . . . . . 2BRAKE SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . 2COMBINATION VALVE . . . . . . . . . . . . . . . . . . . . . 4FRONT DISC BRAKES . . . . . . . . . . . . . . . . . . . . . 4MASTER CYLINDER . . . . . . . . . . . . . . . . . . . . . . 3PARKING BRAKE . . . . . . . . . . . . . . . . . . . . . . . . . 5POWER BRAKE BOOSTER . . . . . . . . . . . . . . . . . 2REAR DRUM BRAKE . . . . . . . . . . . . . . . . . . . . . . 5RED BRAKE WARNING LAMP . . . . . . . . . . . . . . . 2SERVICE WARNINGS & CAUTIONS . . . . . . . . . . 2STOP LAMP SWITCH . . . . . . . . . . . . . . . . . . . . . . 2IAGNOSIS AND TESTINGBASE BRAKE SYSTEM . . . . . . . . . . . . . . . . . . . . 6BRAKE DRUM . . . . . . . . . . . . . . . . . . . . . . . . . . 10BRAKE FLUID CONTAMINATION . . . . . . . . . . . . 11BRAKE LINE AND HOSES . . . . . . . . . . . . . . . . . 11COMBINATION VALVE . . . . . . . . . . . . . . . . . . . . . 9DISC BRAKE ROTOR . . . . . . . . . . . . . . . . . . . . . 10MASTER CYLINDER/POWER BOOSTER . . . . . . . 8PARKING BRAKE . . . . . . . . . . . . . . . . . . . . . . . . 11RED BRAKE WARNING LAMP . . . . . . . . . . . . . . . 8STOP LAMP SWITCH . . . . . . . . . . . . . . . . . . . . . . 8ERVICE PROCEDURESBASE BRAKE BLEEDING . . . . . . . . . . . . . . . . . . 12BRAKE DRUM MACHINING . . . . . . . . . . . . . . . . 13BRAKE FLUID LEVEL . . . . . . . . . . . . . . . . . . . . . 11BRAKE TUBE FLARING . . . . . . . . . . . . . . . . . . . 13DISC ROTOR MACHINING . . . . . . . . . . . . . . . . . 13MASTER CYLINDER BLEEDING . . . . . . . . . . . . . 11

EMOVAL AND INSTALLATIONBRAKE PEDAL . . . . . . . . . . . . . . . . . . . . . . . . . . 15COMBINATION VALVE . . . . . . . . . . . . . . . . . . . . 15DISC BRAKE CALIPER . . . . . . . . . . . . . . . . . . . 17DISC BRAKE ROTOR . . . . . . . . . . . . . . . . . . . . . 19DISC BRAKE SHOES . . . . . . . . . . . . . . . . . . . . . 18DRUM BRAKE SHOES . . . . . . . . . . . . . . . . . . . . 19MASTER CYLINDER . . . . . . . . . . . . . . . . . . . . . 16PARKING BRAKE HAND LEVER . . . . . . . . . . . . 21POWER BRAKE BOOSTER . . . . . . . . . . . . . . . . 16REAR PARKING BRAKE CABLE . . . . . . . . . . . . . 21STOP LAMP SWITCH . . . . . . . . . . . . . . . . . . . . . 14WHEEL CYLINDER . . . . . . . . . . . . . . . . . . . . . . 20ISASSEMBLY AND ASSEMBLYDISC BRAKE CALIPER . . . . . . . . . . . . . . . . . . . 23MASTER CYLINDER RESERVOIR . . . . . . . . . . . 22WHEEL CYLINDER . . . . . . . . . . . . . . . . . . . . . . 25LEANING AND INSPECTIONCALIPER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26REAR DRUM BRAKE . . . . . . . . . . . . . . . . . . . . . 26WHEEL CYLINDER . . . . . . . . . . . . . . . . . . . . . . 26DJUSTMENTSPARKING BRAKE CABLE TENSIONER . . . . . . . 27REAR DRUM BRAKE . . . . . . . . . . . . . . . . . . . . . 27STOP LAMP SWITCH . . . . . . . . . . . . . . . . . . . . . 27PECIFICATIONSBRAKE COMPONENTS . . . . . . . . . . . . . . . . . . . 29BRAKE FLUID . . . . . . . . . . . . . . . . . . . . . . . . . . 28TORQUE CHART . . . . . . . . . . . . . . . . . . . . . . . . 29PECIAL TOOLSBASE BRAKES . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Page 2: 1999 Jeep TJ Wrangler Service Manual - 05. Brakes

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5 - 2 BRAKES TJ

ESCRIPTION AND OPERATION

RAKE SYSTEMPower assist front disc and rear drum brakes are

tandard equipment. Disc brake components consistf single piston calipers and ventilated rotors. Rearrum brakes are dual shoe units with cast brakerums.The parking brake mechanism is lever and cable

perated. The cables are attached to levers on theear drum brake secondary shoes. The parkingrakes are operated by a hand lever.A dual diaphragm vacuum power brake booster is

sed for all applications. All models have an alumi-um master cylinder with plastic reservoir.All models are equipped with a combination valve.

he valve contains a pressure differential valve andwitch and a fixed rate rear proportioning valve.Factory brake lining on all models consists of an

rganic base material combined with metallic parti-les. The original equipment linings do not containsbestos.

ERVICE WARNINGS & CAUTIONS

ARNING: DUST AND DIRT ACCUMULATING ONRAKE PARTS DURING NORMAL USE MAY CON-AIN ASBESTOS FIBERS FROM AFTERMARKETININGS. BREATHING EXCESSIVE CONCENTRA-IONS OF ASBESTOS FIBERS CAN CAUSE SERI-US BODILY HARM. EXERCISE CARE WHENERVICING BRAKE PARTS. DO NOT CLEANRAKE PARTS WITH COMPRESSED AIR OR BYRY BRUSHING. USE A VACUUM CLEANER SPE-IFICALLY DESIGNED FOR THE REMOVAL OFSBESTOS FIBERS FROM BRAKE COMPONENTS.

F A SUITABLE VACUUM CLEANER IS NOT AVAIL-BLE, CLEANING SHOULD BE DONE WITH AATER DAMPENED CLOTH. DO NOT SAND, ORRIND BRAKE LINING UNLESS EQUIPMENT USED

S DESIGNED TO CONTAIN THE DUST RESIDUE.ISPOSE OF ALL RESIDUE CONTAINING ASBES-OS FIBERS IN SEALED BAGS OR CONTAINERSO MINIMIZE EXPOSURE TO YOURSELF AND OTH-RS. FOLLOW PRACTICES PRESCRIBED BY THECCUPATIONAL SAFETY AND HEALTH ADMINIS-RATION AND THE ENVIRONMENTAL PROTECTIONGENCY FOR THE HANDLING, PROCESSING, ANDISPOSITION OF DUST OR DEBRIS THAT MAYONTAIN ASBESTOS FIBERS.

AUTION: Never use gasoline, kerosene, alcohol,otor oil, transmission fluid, or any fluid containingineral oil to clean the system components. These

luids damage rubber cups and seals. Use only

fresh brake fluid or Mopar brake cleaner to clean orflush brake system components. These are the onlycleaning materials recommended. If system contam-ination is suspected, check the fluid for dirt, discol-oration, or separation into distinct layers. Alsocheck the reservoir cap seal for distortion. Drainand flush the system with new brake fluid if con-tamination is suspected.

CAUTION: Use Mopar brake fluid, or an equivalentquality fluid meeting SAE/DOT standards J1703 andDOT 3. Brake fluid must be clean and free of con-taminants. Use fresh fluid from sealed containersonly 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 onthe backing plates. Use multi-mileage grease or GE661 or Dow 111 silicone grease on caliper slide pinsto ensure proper operation.

BRAKE PEDALA suspended-type brake pedal is used, the pedal

pivots on a shaft mounted in the pedal supportbracket. The bracket is attached to the dash panel.

The brake pedal is a serviceable component. Thepedal, pedal bushings, shaft and pedal bracket are allreplaceable parts.

STOP LAMP SWITCHThe plunger type stop lamp switch is mounted on a

bracket attached to the brake pedal support. Theswitch can be adjusted when necessary.

RED BRAKE WARNING LAMPA red warning lamp is used for the service brake

portion of the hydraulic system. The lamp is locatedin the instrument cluster. The red warning lightalerts the driver if a pressure differential existsbetween the front and rear hydraulic systems or theparking brakes are applied.

The lamp is turned on momentarily when the igni-tion switch is turn to the on position. This is a selftest to verify the lamp is operational.

POWER BRAKE BOOSTERThe booster assembly consists of a housing divided

into separate chambers by two internal diaphragms.The outer edge of each diaphragm is attached to thebooster housing. The diaphragms are connected tothe booster primary push rod.

Page 3: 1999 Jeep TJ Wrangler Service Manual - 05. Brakes

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TJ BRAKES 5 - 3

DESCRIPTION AND OPERATION (Continued)

Two push rods are used in the booster. The pri-ary push rod connects the booster to the brake

edal. The secondary push rod connects the boostero the master cylinder to stroke the cylinder pistons.

The atmospheric inlet valve is opened and closedy the primary push rod. Booster vacuum supply ishrough a hose attached to an intake manifold fittingt one end and to the booster check valve at thether. The vacuum check valve in the booster housings a one-way device that prevents vacuum leak back.

Power assist is generated by utilizing the pressureifferential between normal atmospheric pressurend a vacuum. The vacuum needed for booster oper-tion is taken directly from the engine intake mani-old. The entry point for atmospheric pressure ishrough a filter and inlet valve at the rear of theousing (Fig. 1).

Fig. 1 Power Brak

The chamber areas forward of the booster dia-phragms are exposed to vacuum from the intakemanifold. The chamber areas to the rear of the dia-phragms, are exposed to normal atmospheric pres-sure of 101.3 kilopascals (14.7 pounds/square in.).

Brake pedal application causes the primary pushrod to open the atmospheric inlet valve. This exposesthe area behind the diaphragms to atmospheric pres-sure. The resulting pressure differential provides theextra apply force for power assist.

MASTER CYLINDERThe master cylinder has a removable nylon reser-

voir. The cylinder body is made of aluminum andcontains a primary and secondary piston assembly.The cylinder body including the piston assembliesare not serviceable. If diagnosis indicates an internalproblem with the cylinder body, it must be replaced

ooster–Typical

Page 4: 1999 Jeep TJ Wrangler Service Manual - 05. Brakes

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DESCRIPTION AND OPERATION (Continued)

s an assembly. The reservoir and grommets are thenly replaceable parts on the master cylinder.

OMBINATION VALVEThe combination valve contains a pressure differ-

ntial valve and switch and a rear brake proportion-ng valve. The valve is not repairable and must beeplaced as an assembly if diagnosis indicates this isecessary.

RESSURE DIFFERENTIAL VALVEThe pressure differential switch is connected to the

rake warning light. The switch is actuated by move-ent of the switch valve. The switch monitors fluid

ressure in the separate front/rear brake hydraulicircuits.A decrease or loss of fluid pressure in either

ydraulic circuit will cause the switch valve to shut-le to the low pressure side. Movement of the valveushes the switch plunger upward. This action closeshe switch internal contacts completing the electricalircuit to the red warning light. The switch valve willemain in an actuated position until repairs to therake system are made.

ROPORTIONING VALVEThe proportioning valve is used to balance front-

ear brake action at high decelerations. The valvellows normal fluid flow during moderate braking.he valve only controls fluid flow during high decel-rations brake stops.

RONT DISC BRAKESThe calipers are a single piston type. The calipers

re free to slide laterally, this allows continuous com-ensation for lining wear.When the brakes are applied fluid pressure is

xerted against the caliper piston. The fluid pressures exerted equally and in all directions. This meansressure exerted against the caliper piston andithin the caliper bore will be equal (Fig. 2).Fluid pressure applied to the piston is transmitted

irectly to the inboard brake shoe. This forces thehoe lining against the inner surface of the discrake rotor. At the same time, fluid pressure withinhe piston bore forces the caliper to slide inward onhe mounting bolts. This action brings the outboardrake shoe lining into contact with the outer surfacef the disc brake rotor.In summary, fluid pressure acting simultaneously

n both piston and caliper, produces a strong clamp-ng action. When sufficient force is applied, frictionill attempt to stop the rotors from turning andring the vehicle to a stop.Application and release of the brake pedal gener-

tes only a very slight movement of the caliper and

piston. Upon release of the pedal, the caliper and pis-ton return to a rest position. The brake shoes do notretract an appreciable distance from the rotor. Infact, clearance is usually at, or close to zero. The rea-sons for this are to keep road debris from gettingbetween the rotor and lining and in wiping the rotorsurface clear each revolution.

The caliper piston seal controls the amount of pis-ton extension needed to compensate for normal liningwear.

During brake application, the seal is deflected out-ward by fluid pressure and piston movement (Fig. 3).When the brakes (and fluid pressure) are released,the seal relaxes and retracts the piston.

The amount of piston retraction is determined bythe amount of seal deflection. Generally the amountis just enough to maintain contact between the pis-ton and inboard brake shoe.

Fig. 2 Brake Caliper Operation

Fig. 3 Lining Wear Compensation By Piston Seal

Page 5: 1999 Jeep TJ Wrangler Service Manual - 05. Brakes

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TJ BRAKES 5 - 5

DESCRIPTION AND OPERATION (Continued)

EAR DRUM BRAKEThe brake systems use a leading shoe (primary)

nd trailing shoe (secondary). The mounting hard-are is similar but not interchangeable (Fig. 4).When the brake pedal is depressed hydraulic pres-

ure pushes the rear brake wheel cylinder pistonsutward. The wheel cylinder push rods then push therake shoes outward against the brake drum. Whenhe brake pedal is released return springs attachedo the brake shoes pull the shoes back to there orig-nal position.

ARKING BRAKEParking brake adjustment is controlled by a cable

ensioner mechanism. The cable tensioner, oncedjusted at the factory, should not need furtherdjustment under normal circumstances. Adjustmentay be required if a new tensioner, or cables are

nstalled, or disconnected.

ARKING BRAKE OPERATIONA hand operated lever in the passenger compartment

s the main application device. The front cable is con-ected between the hand lever and the tensioner. Theensioner rod is attached to the equalizer which is theonnecting point for the rear cables (Fig. 5).

The rear cables are connected to the actuatingever on each secondary brake shoe. The levers arettached to the brake shoes by a pin either pressednto, or welded to the lever. A clip is used to securehe pin in the brake shoe. The pin allows each levero pivot independently of the brake shoe.

Fig. 4 Brake

To apply the parking brakes, the hand lever ispulled upward. This pulls the rear brake shoe actu-ating levers forward, by means tensioner and cables.As the actuating lever is pulled forward, the parkingbrake strut (which is connected to both shoes), exertsa linear force against the primary brake shoe. Thisaction presses the primary shoe into contact with thedrum. Once the primary shoe contacts the drum,force is exerted through the strut. This force is trans-ferred through the strut to the secondary brake shoecausing it to pivot into the drum as well.

A gear type ratcheting mechanism is used to holdthe lever in an applied position. Parking brakerelease is accomplished by the hand lever releasebutton.

mponents

Fig. 5 Parking Brake Components

Page 6: 1999 Jeep TJ Wrangler Service Manual - 05. Brakes

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DESCRIPTION AND OPERATION (Continued)

A parking brake switch is mounted on the parkingrake lever and is actuated by movement of theever. The switch, which is in circuit with the redarning light in the dash, will illuminate the warn-

ng light whenever the parking brakes are applied.

RAKE HOSES AND LINESFlexible rubber hose is used at both front brakes

nd at the rear axle junction block. Double walledteel tubing is used to connect the master cylinder tohe major hydraulic braking components and then tohe flexible rubber hoses.

IAGNOSIS AND TESTING

ASE BRAKE SYSTEMBase brake components consist of the brake shoes,

alipers, wheel cylinders, brake drums, rotors, brakeines, master cylinder, booster, and parking brakeomponents.Brake diagnosis involves determining if the prob-

em is related to a mechanical, hydraulic, or vacuumperated component.The first diagnosis step is the preliminary check.

RELIMINARY BRAKE CHECK(1) Check condition of tires and wheels. Damagedheels and worn, damaged, or underinflated tires

an cause pull, shudder, vibration, and a conditionimilar to grab.(2) If complaint was based on noise when braking,

heck suspension components. Jounce front and rearf vehicle and listen for noise that might be causedy loose, worn or damaged suspension or steeringomponents.(3) Inspect brake fluid level and condition. Note

hat the front disc brake reservoir fluid level willecrease in proportion to normal lining wear. Alsoote that brake fluid tends to darken over time.his is normal and should not be mistaken forontamination.

(a) If fluid level is abnormally low, look for evi-dence of leaks at calipers, wheel cylinders, brakelines, and master cylinder.

(b) If fluid appears contaminated, drain out asample. System will have to be flushed if fluid isseparated into layers, or contains a substanceother than brake fluid. The system seals and cupswill also have to be replaced after flushing. Useclean brake fluid to flush the system.(4) Check parking brake operation. Verify freeovement and full release of cables and pedal. Alsoote if vehicle was being operated with parkingrake partially applied.

(5) Check brake pedal operation. Verify that pedaldoes not bind and has adequate free play. If pedallacks free play, check pedal and power booster forbeing loose or for bind condition. Do not road testuntil condition is corrected.

(6) If components checked appear OK, road testthe 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 remainfirm under constant foot pressure.

(3) During road test, make normal and firm brakestops 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.

PEDAL FALLS AWAYA brake pedal that falls away under steady foot

pressure is generally the result of a system leak. Theleak point could be at a brake line, fitting, hose, orcaliper/wheel cylinder. Internal leakage in the mastercylinder caused by worn or damaged piston cups,may also be the problem cause.

If leakage is severe, fluid will be evident at or aroundthe leaking component. However, internal leakage inthe master cylinder may not be physically evident.

LOW PEDALIf a low pedal is experienced, pump the pedal sev-

eral times. If the pedal comes back up, worn lining,rotors, or drums are the most likely causes.

SPONGY PEDALA spongy pedal is most often caused by air in the

system. However, thin brake drums or substandardbrake lines and hoses can also cause a spongy pedal.The proper course of action is to bleed the system, orreplace thin drums and suspect quality brake linesand hoses.

HARD PEDAL OR HIGH PEDAL EFFORTA hard pedal or high pedal effort may be due to

lining that is water soaked, contaminated, glazed, orbadly worn. The power booster or check valve couldalso be faulty.

PEDAL PULSATIONPedal 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 areloose wheel bearings or calipers and worn, damagedtires.

Page 7: 1999 Jeep TJ Wrangler Service Manual - 05. Brakes

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DIAGNOSIS AND TESTING (Continued)

OTE: Some pedal pulsation may be felt duringBS activation.

RAKE DRAGBrake drag occurs when the lining is in constant

ontact with the rotor or drum. Drag can occur at oneheel, all wheels, fronts only, or rears only.Drag is a product of incomplete brake shoe release.rag can be minor or severe enough to overheat the

inings, rotors and drums.Minor drag will usually cause slight surface char-

ing of the lining. It can also generate hard spots inotors and drums from the overheat-cool down pro-ess. In most cases, the rotors, drums, wheels andires are quite warm to the touch after the vehicle istopped.Severe drag can char the brake lining all the way

hrough. It can also distort and score rotors andrums to the point of replacement. The wheels, tiresnd brake components will be extremely hot. Inevere cases, the lining may generate smoke as ithars from overheating.Possible causes for brake drag condition are:• Seized or improperly adjusted parking brake

ables.• Loose/worn wheel bearing.• Seized caliper or wheel cylinder piston.• Caliper binding on corroded bushings or rusted

lide surfaces.• Loose caliper mounting bracket.• Drum brake shoes binding on worn/damaged

upport plates.• Mis-assembled components.If brake drag occurs at all wheels, the problemay be related to a blocked master cylinder return

ort, or faulty power booster (binds-does not release).

RAKE FADEBrake fade is usually a product of overheating

aused by brake drag. However, brake overheatingnd resulting fade can also be caused by riding therake pedal, making repeated high deceleration stopsn a short time span, or constant braking on steep

ountain roads. Refer to the Brake Drag informationn this section for causes.

RAKE PULLPossible causes for front brake pull condition are:• Contaminated lining in one caliper.• Seized caliper piston.• Binding caliper.• Loose caliper.• Rusty adapter/caliper slide surfaces.• Improper brake shoes.• Damaged rotor.

A worn, damaged wheel bearing or suspension com-ponent 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 fewstops. 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 soreduced that fade occurs. Since the opposite brakeunit is still functioning normally, its braking effect ismagnified. This causes pull to switch direction infavor of the normally functioning brake unit.

An additional point when diagnosing a change inpull condition concerns brake cool down. Rememberthat pull will return to the original direction, if thedragging brake unit is allowed to cool down (and isnot seriously damaged).

REAR BRAKE GRAB OR PULLRear grab or pull is usually caused by improperly

adjusted or seized parking brake cables, contami-nated lining, bent or binding shoes and supportplates, or improperly assembled components. This isparticularly true when only one rear wheel isinvolved. However, when both rear wheels areaffected, the master cylinder or proportioning valvecould be at fault.

BRAKES DO NOT HOLD AFTER DRIVING THROUGH DEEPWATER PUDDLES

This condition is generally caused by water soakedlining. If the lining is only wet, it can be dried bydriving with the brakes very lightly applied for amile or two. However, if the lining is both soaked anddirt contaminated, cleaning and/or replacement willbe necessary.

BRAKE SQUEAK/SQUEALBrake 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 embeddedin the brake lining will also cause squeak/squeal.

A very loud squeak or squeal is frequently a sign ofseverely worn brake lining. If the lining has wornthrough to the brake shoes in spots, metal-to-metalcontact occurs. If the condition is allowed to continue,rotors and drums can become so scored that replace-ment is necessary.

BRAKE CHATTERBrake chatter is usually caused by loose or worn

components, or glazed/burnt lining. Rotors with hardspots can also contribute to chatter. Additional causesof chatter are out-of-tolerance rotors, brake lining notsecurely attached to the shoes, loose wheel bearingsand contaminated brake lining.

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5 - 8 BRAKES TJ

DIAGNOSIS AND TESTING (Continued)

HUMP/CLUNK NOISEThumping or clunk noises during braking are fre-

uently not caused by brake components. In manyases, such noises are caused by loose or damagedteering, suspension, or engine components. However,alipers that bind on the slide surfaces can generate

thump or clunk noise. In addition, worn out,mproperly adjusted, or improperly assembled rearrake shoes can also produce a thump noise.

RAKE LINING CONTAMINATIONBrake lining contamination is mostly a product of

eaking calipers or wheel cylinders, worn seals, driv-ng through deep water puddles, or lining that hasecome covered with grease and grit during repair.ontaminated lining should be replaced to avoid fur-

her brake problems.

HEEL AND TIRE PROBLEMSSome conditions attributed to brake componentsay actually be caused by a wheel or tire problem.A damaged wheel can cause shudder, vibration and

ull. A worn or damaged tire can also cause pull.Severely worn tires with very little tread left can

roduce a grab-like condition as the tire loses andecovers traction. Flat-spotted tires can cause vibra-ion and generate shudder during brake operation. Aire with internal damage such as a severe bruise,ut, or ply separation can cause pull and vibration.

TOP LAMP SWITCHStop lamp switch operation can be tested with an

hmmeter. The ohmmeter is used to check continuityetween the pin terminals at different plunger posi-ions (Fig. 6).

OTE: The switch wire harness must be discon-ected before testing switch continuity.

WITCH CIRCUIT IDENTIFICATION• Terminals 1 and 2 are for brake sensor circuit.• Terminals 3 and 4 are for the speed control cir-

uit if equipped.• Terminals 5 and 6 are for the stop lamp circuit.

WITCH CONTINUITY TEST(1) Check continuity between terminal pins 1 andas follows:

(a) Push in switch plunger completely.(b) Attach test leads to pins 1 and 2 and note

ohmmeter reading.(c) If continuity exists, switch is OK. Replace

switch if meter indicates lack of continuity (switchis open).(2) Check continuity between terminal pins 3 andas follows:

(a) Push in switch plunger completely.(b) Attach test leads to pins 3 and 4 and note

ohmmeter reading.(c) If continuity exists, switch is OK. Replace

switch if meter indicates lack of continuity (switchis open).(3) Check continuity between terminal pins 5 and

6 as follows:(a) Allow switch plunger to fully extend.(b) Attach test leads to pins 5 and 6 and note

ohmmeter reading.(c) If continuity exists, switch is OK. Replace

switch if meter indicates lack of continuity (switchis open).

RED BRAKE WARNING LAMPThe red brake warning lamp will illuminate under

the following conditions:• Self test at start-up.• Parking brakes are applied.• Leak in front/rear brake hydraulic circuit.If the red light remains on after start-up, first ver-

ify that the parking brakes are fully released. Thencheck pedal action and fluid level. If the lamp on andthe brake pedal is low this indicates the pressure dif-ferential switch and valve have been actuated due toa leak in the hydraulic system.

On models with ABS brakes, the amber warninglamp only illuminates during the self test and whenan ABS malfunction has occurred. The ABS lampoperates independently of the red warning lamp.

For additional information refer to Group 8W.

MASTER CYLINDER/POWER BOOSTER(1) Start engine and check booster vacuum hose

connections. A hissing noise indicates vacuum leak.Correct any vacuum leak before proceeding.

(2) Stop engine and shift transmission into Neu-tral.

Fig. 6 Stop Lamp Switch Terminal Identification

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TJ BRAKES 5 - 9

DIAGNOSIS AND TESTING (Continued)

(3) Pump brake pedal until all vacuum reserve inooster is depleted.(4) Press and hold brake pedal under light foot

ressure. The pedal should hold firm, if the pedalalls away master cylinder is faulty (internal leak-ge).(5) Start engine and note pedal action. It should

all away slightly under light foot pressure then holdirm. If no pedal action is discernible, power booster,acuum supply, or vacuum check valve is faulty. Pro-eed to the POWER BOOSTER VACUUM TEST.(6) If the POWER BOOSTER VACUUM TEST

asses, rebuild booster vacuum reserve as follows:elease brake pedal. Increase engine speed to 1500pm, close the throttle and immediately turn off igni-ion to stop engine.

(7) Wait a minimum of 90 seconds and try brakection again. Booster should provide two or more vac-um assisted pedal applications. If vacuum assist isot provided, booster is faulty.

OWER BOOSTER VACUUM TEST(1) Connect vacuum gauge to booster check valveith short length of hose and T-fitting (Fig. 7).(2) Start and run engine at curb idle speed for oneinute.(3) Observe the vacuum supply. If vacuum supply

s not adequate, repair vacuum supply.(4) Clamp hose shut between vacuum source and

heck valve.(5) Stop engine and observe vacuum gauge.(6) If vacuum drops more than one inch HG (33illibars) within 15 seconds, booster diaphragm or

heck valve is faulty.

OWER BOOSTER CHECK VALVE TEST(1) Disconnect vacuum hose from check valve.(2) Remove check valve and valve seal from

ooster.(3) Use a hand operated vacuum pump for test.(4) Apply 15-20 inches vacuum at large end of

heck valve (Fig. 8).(5) Vacuum should hold steady. If gauge on pump

ndicates vacuum loss, check valve is faulty andhould be replaced.

OMBINATION VALVE

ressure Differential Switch(1) Have helper sit in drivers seat to apply brake

edal and observe red brake warning light.(2) Raise vehicle on hoist.(3) Connect bleed hose to a rear wheel cylinder

nd immerse hose end in container partially filledith brake fluid.

(4) Have helper press and hold brake pedal to floorand observe warning light.

(a) If warning light illuminates, switch is oper-ating correctly.

(b) If light fails to illuminate, check circuit fuse,bulb, and wiring. The parking brake switch can beused to aid in identifying whether or not the brakelight bulb and fuse is functional. Repair or replaceparts as necessary and test differential pressureswitch operation again.(5) If warning light still does not illuminate,

switch is faulty. Replace combination valve assembly,bleed brake system and verify proper switch andvalve operation.

Fig. 7 Typical Booster Vacuum Test Connections

Fig. 8 Vacuum Check Valve And Seal

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5 - 10 BRAKES TJ

DIAGNOSIS AND TESTING (Continued)

ISC BRAKE ROTORThe rotor braking surfaces should not be refinished

nless necessary.Light surface rust and scale can be removed with a

athe equipped with dual sanding discs. The rotorurfaces can be restored by machining in a disc brakeathe if surface scoring and wear are light.

Replace the rotor under the following conditions:• Severely Scored• Tapered• Hard Spots• Cracked• Below Minimum Thickness

OTOR MINIMUM THICKNESSMeasure rotor thickness at the center of the brake

hoe contact surface. Replace the rotor if worn belowinimum thickness, or if machining would reduce

hickness below the allowable minimum.Rotor minimum thickness is usually specified on

he rotor hub. The specification is either stamped orast into the hub surface.

OTOR RUNOUTCheck rotor lateral runout with dial indicator-3339 (Fig. 9). Excessive lateral runout will causerake pedal pulsation and rapid, uneven wear of therake shoes. Position the dial indicator plungerpproximately 25.4 mm (1 in.) inward from the rotordge.

OTE: Be sure wheel bearing has zero end playefore checking rotor runout.

Maximum allowable rotor runout is 0.102 mm0.004 in.).

Fig. 9 Checking Rotor Runout And ThicknessVariation

ROTOR THICKNESS VARIATIONVariations in rotor thickness will cause pedal pul-

sation, noise and shudder.Measure rotor thickness at 6-to-12 points around

the rotor face (Fig. 10).Position the micrometer approximately 25.4 mm (1

in.) from the rotor outer circumference for each mea-surement.

Thickness should not vary by more than 0.013 mm(0.0005 in.) from point-to-point on the rotor. Machineor replace the rotor if necessary.

BRAKE DRUMThe maximum allowable diameter of the drum

braking surface is indicated on the drum outer edge.Generally, a drum can be machined to a maximum of1.52 mm (0.060 in.) oversize. Always replace thedrum if machining would cause drum diameter toexceed the size limit indicated on the drum.

BRAKE DRUM RUNOUTMeasure drum diameter and runout with an accu-

rate gauge. The most accurate method of measure-ment involves mounting the drum in a brake latheand checking variation and runout with a dial indi-cator.

Variations in drum diameter should not exceed0.076 mm (0.003 in.). Drum runout should not exceed0.20 mm (0.008 in.) out of round. Machine the drumif runout or variation exceed these values. Replacethe drum if machining causes the drum to exceed themaximum allowable diameter.

Fig. 10 Measuring Rotor Thickness

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TJ BRAKES 5 - 11

DIAGNOSIS AND TESTING (Continued)

ARKING BRAKE

OTE: Parking brake adjustment is controlled by aable tensioner. Once the tensioner is adjusted athe factory, it should not require further attention.owever, there are two instances when adjustmentill be required. The first is when a new tensioner,r cables have been installed. And the second, ishen the tensioner and cables are disconnected forccess to other brake components.

The parking brake switch is in circuit with the redarning lamp in the dash. The switch will cause the

amp to illuminate only when the parking brakes arepplied. If the lamp remains on after parking brakeelease, the switch or wires are faulty, or cable ten-ioner adjustment is incorrect.In most cases, the actual cause of an improperly

unctioning parking brake (too loose/too tight/won’told), can be traced to a parking brake component.The leading cause of improper parking brake oper-

tion, is excessive clearance between the parkingrake shoes and the shoe braking surface. Excessivelearance is a result of lining and/or drum wear,rum surface machined oversize, or inoperativedjuster components.Excessive parking brake lever travel (sometimes

escribed as a loose lever or too loose condition), ishe result of worn brake shoes, improper brake shoedjustment, or improperly assembled brake parts.A condition where the parking brakes do not hold,ill most probably be due to a wheel brake compo-ent.Items to look for when diagnosing a parking brake

roblem, are:• Rear brake shoe wear.• Drum surface machined oversize.• Front cable not secured to lever.• Rear cable not attached to lever.• Rear cable seized.• Brake shoes reversed.• Parking brake strut not seated in shoes.• Parking brake lever not seated.• Parking brake lever bind.• Adjuster screws seized.• Adjuster screws reversed.Parking brake adjustment and parts replacement

rocedures are described in the Parking Brake sec-ion.

RAKE LINE AND HOSESFlexible rubber hose is used at both front brakes

nd at the rear axle junction block. Inspect the hoseshenever the brake system is serviced, at everyngine oil change, or whenever the vehicle is in forervice.

Inspect the hoses for surface cracking, scuffing, orworn spots. Replace any brake hose immediately ifthe fabric casing of the hose is exposed due to cracksor abrasions.

Also check brake hose installation. Faulty installa-tion can result in kinked, twisted hoses, or contactwith 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, orother damage. Heavily corroded lines will eventuallyrust through causing leaks. In any case, corroded ordamaged 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 surethat brake line and hose mating surfaces are cleanand free from nicks and burrs. Also remember thatright and left brake hoses are not interchangeable.

Use new copper seal washers at all caliper connec-tions. Be sure brake line connections are properlymade (not cross threaded) and tightened to recom-mended torque.

BRAKE FLUID CONTAMINATIONIndications of fluid contamination are swollen or

deteriorated rubber parts.Swollen rubber parts indicate the presence of

petroleum in the brake fluid.To test for contamination, put a small amount of

drained brake fluid in clear glass jar. If fluid sepa-rates into layers, there is mineral oil or other fluidcontamination of the brake fluid.

If brake fluid is contaminated, drain and thor-oughly flush system. Replace master cylinder, propor-tioning valve, caliper seals, wheel cylinder seals,Antilock Brakes hydraulic unit and all hydraulicfluid hoses.

SERVICE PROCEDURES

BRAKE FLUID LEVELAlways clean the master cylinder reservoir and

caps before checking fluid level. If not cleaned, dirtcould enter the fluid.

The fluid fill level is indicated on the side of themaster cylinder reservoir (Fig. 11).

The correct fluid level is to the FULL indicator onthe side of the reservoir. If necessary, add fluid to theproper level.

MASTER CYLINDER BLEEDINGA new master cylinder should be bled before instal-

lation on the vehicle. Required bleeding tools include

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5 - 12 BRAKES TJ

SERVICE PROCEDURES (Continued)

leed tubes and a wood dowel to stroke the pistons.leed tubes can be fabricated from brake line.

LEEDING PROCEDURE(1) Mount master cylinder in vise.(2) Attach bleed tubes to cylinder outlet ports.

hen position each tube end into the reservoir (Fig.2).(3) Fill reservoir with fresh brake fluid.(4) Press cylinder pistons inward with wood dowel.

hen release pistons and allow them to return underpring pressure. Continue bleeding operations untilir bubbles are no longer visible in fluid.

ASE BRAKE BLEEDINGUse Mopar brake fluid, or an equivalent quality

luid meeting SAE J1703-F and DOT 3 standardsnly. Use fresh, clean fluid from a sealed container atll times.Do not pump the brake pedal at any time while

leeding. Air in the system will be compressed intomall bubbles that are distributed throughout the

Fig. 11 Master Cylinder Fluid Level - Typical

Fig. 12 Master Cylinder Bleeding

hydraulic system. This will make additional bleedingoperations necessary.

Do not allow the master cylinder to run out of fluidduring bleed operations. An empty cylinder will allowadditional air to be drawn into the system. Check thecylinder fluid level frequently and add fluid asneeded.

Bleed only one brake component at a time in thefollowing sequence:

• Master Cylinder• Combination Valve• Right Rear Wheel• Left Rear Wheel• Right Front Wheel• Left Front Wheel

MANUAL BLEEDING(1) Remove reservoir filler caps and fill reservoir.(2) If calipers, or wheel cylinders were overhauled,

open all caliper and wheel cylinder bleed screws.Then close each bleed screw as fluid starts to dripfrom it. Top off master cylinder reservoir once morebefore proceeding.

(3) Attach one end of bleed hose to bleed screwand insert opposite end in glass container partiallyfilled with brake fluid (Fig. 13). Be sure end of bleedhose is immersed in fluid.

(4) Open up bleeder, then have a helper pressdown the brake pedal. Once the pedal is down closethe bleeder. Repeat bleeding until fluid stream isclear and free of bubbles. Then move to the nextwheel.

Fig. 13 Bleed Hose Setup

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TJ BRAKES 5 - 13

SERVICE PROCEDURES (Continued)

RESSURE BLEEDINGFollow the manufacturers instructions carefullyhen using pressure equipment. Do not exceed the

ank manufacturers pressure recommendations. Gen-rally, a tank pressure of 15-20 psi is sufficient forleeding.Fill the bleeder tank with recommended fluid and

urge air from the tank lines before bleeding.Do not pressure bleed without a proper master cyl-

nder adapter. The wrong adapter can lead to leak-ge, or drawing air back into the system. Usedapter provided with the equipment or Adapter921.

ISC ROTOR MACHININGThe disc brake rotor can be machined if scored ororn. The lathe must machine both sides of the rotor

imultaneously with dual cutter heads. Equipmentapable of machining only one side at a time mayroduce a tapered rotor. A hub mounted on-vehicleathe is recommended. This type of lathe trues theotor to the vehicles hub/bearing.

AUTION: Brake rotors that do not meet minimumhickness specifications before or after machiningust be replaced.

RAKE DRUM MACHININGThe brake drums can be machined on a drum lathehen necessary. Initial machining cuts should be lim-

ted to 0.12 - 0.20 mm (0.005 - 0.008 in.) at a time aseavier feed rates can produce taper and surfaceariation. Final finish cuts of 0.025 to 0.038 mm0.001 to 0.0015 in.) are recommended and will gen-rally provide the best surface finish.Be sure the drum is securely mounted in the lathe

efore machining operations. A damper strap shouldlways be used around the drum to reduce vibrationnd avoid chatter marks.The maximum allowable diameter of the drum

raking surface is stamped or cast into the drumuter edge.

AUTION: Replace the drum if machining willause the drum to exceed the maximum allowableiameter.

BRAKE TUBE FLARINGA preformed metal brake tube is recommended and

preferred for all repairs. However, double-wall steeltube can be used for emergency repair when factoryreplacement parts are not readily available.

Special bending tools are needed to avoid kinkingor twisting of metal brake tubes. Special flaring toolsare needed to make a double inverted flare or ISOflare (Fig. 14).

DOUBLE INVERTED FLARING(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 matchestube 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. 15).

(9) Tighten tool handle until plug gauge issquarely seated on jaws of flaring tool. This will startthe inverted flare.

(10) Remove the plug gauge and complete theinverted flare.

Fig. 14 Inverted Flare And ISO Flare

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5 - 14 BRAKES TJ

SERVICE PROCEDURES (Continued)

SO FLARINGTo make a ISO flare use Snap-Ont Flaring Tool

FM-428 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.(4) Position the tube in the flaring tool flush with

he top of the tool bar (Fig. 16). Then tighten the toolar on the tube.(5) Install the correct size adaptor on the flaring

ool yoke screw.(6) Lubricate the adaptor.(7) Align the adaptor and yoke screw over the tube

Fig. 16).(8) Turn the yoke screw in until the adaptor is

quarely seated on the tool bar.

EMOVAL AND INSTALLATION

TOP LAMP SWITCH

EMOVAL(1) Remove steering column cover and lower trim

anel for switch access (if necessary).(2) Press brake pedal downward to fully applied

osition.(3) Rotate switch approximately 30° in counter-

lockwise direction to unlock switch retainer. Thenull switch rearward and out of bracket.(4) Disconnect switch wire harness and remove

witch from vehicle (Fig. 17).

Fig. 15 Inverted Flare Tools

INSTALLATION(1) Pull switch plunger all the way out to fully

extended position.(2) Connect harness wires to switch.(3) Press and hold brake pedal in applied position.(4) Install switch as follows: Align tab on switch

with notch in switch bracket. Then insert switch inbracket and turn it clockwise about 30° to lock it inplace.

(5) Release brake pedal, then pull pedal fully rear-ward. Pedal will set plunger to correct position aspedal pushes plunger into switch body. Switch willmake racheting sound as it self adjusts.

Fig. 16 ISO Flaring

Fig. 17 Stop Lamp Switch

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TJ BRAKES 5 - 15

REMOVAL AND INSTALLATION (Continued)

RAKE PEDAL

EMOVAL(1) Remove negative battery cable.(2) Remove brake lamp switch.(3) Remove ABS controller if equipped.(4) Remove retainer clip securing booster push rod

o pedal (Fig. 18) and clutch rod retainer clip ifquipped.(5) Remove bolts from brake pedal support and

ooster mounting nuts. Remove mounting stud plateuts or clutch cylinder mounting nuts if equipped.(6) Slid brake booster/master cylinder assembly

orward.(7) Remove mounting stud plate or slid clutch cyl-

nder forward if equipped.(8) Tilt the pedal support down to gain shaft clear-

nce.(9) Remove pedal shaft C–clip from passenger side

f the shaft.(10) Slide the pedal shaft toward the drivers side

nd remove the remaining C-clip.(11) Slid the shaft out of the pedal bracket and

emove the pedal.(12) Remove pedal bushings if they are to be

eplaced.

NSTALLATION(1) Install new bushings in pedal. Lubricate bush-

ngs and shaft with multi-purpose grease.(2) Position pedal in bracket and install shaft.(3) Install new pivot pin C-clip.(4) Position pedal support and install support bolts

nd tighten to 28 N·m (21 ft. lbs.).(5) Slid the booster/master cylinder assembly into

lace, install mounting nuts and tighten to 39 N·m29 ft. lbs.).

(6) Install stud plate or clutch cylinder if equippednd tighten mounting nut to 28 N·m (21 ft. lbs.).

Fig. 18 Push Rod Attachment

Install retainer clip securing booster push rod topedal (Fig. 18) and clutch rod retainer clip ifequipped.

(7) Install ABS controller if equipped.(8) Install and connect stop lamp switch.(9) Install negative battery cable.

COMBINATION VALVE

REMOVAL(1) Remove brake lines that connect master cylin-

der to combination valve (Fig. 19).(2) Disconnect brake lines that connect combina-

tion valve to front and rear brakes.(3) Disconnect wire from combination valve switch

terminal. Be careful when separating wire connectoras lock tabs are easily damaged if not fully disen-gaged.

(4) Remove nuts attaching combination valvebracket to booster studs and remove valve bracket offbooster studs (Fig. 20).

Fig. 19 Combination Valve/Master Cylinder

Fig. 20 Combination Valve Bracket

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5 - 16 BRAKES TJ

REMOVAL AND INSTALLATION (Continued)

NSTALLATION(1) Position valve bracket on booster studs and

ighten bracket attaching nuts to 24 N·m (18 ft. lbs.).(2) Align and start brake line fittings in combina-

ion valve and master cylinder by hand to avoid crosshreading.

(3) Tighten brake line fittings at combination valveo 21 N·m (15 ft. lbs.).

(4) Tighten brake line fittings at master cylindero 15 N·m (11 ft. lbs.).

(5) Connect wire to differential pressure switch inombination valve.(6) Bleed base brake system.

ASTER CYLINDER

EMOVAL(1) Remove evaporative canister, refer to Group 25missions for service procedure.(2) Disconnect brake lines to master cylinder and

ombination valve (Fig. 21).(3) Remove combination valve bracket mounting

uts and remove valve.(4) Remove master cylinder mounting nuts and

emove master cylinder.(5) Remove cylinder cover and drain fluid.

NSTALLATION

OTE: If master cylinder is replaced, bleed cylinderefore installation.

(1) Remove protective sleeve from primary pistonhank on new master cylinder.(2) Check condition of seal at rear of cylinder body.eposition seal if dislodged. Replace seal if cut, or

orn.(3) Install master cylinder onto brake booster

tuds and tighten mounting nuts to 24 N·m (18 ft.bs.).

Fig. 21 Master Cylinder/Combination Valve

NOTE: Use only original or factory replacement nuts.(4) Install combination valve onto brake booster

studs and tighten mounting nuts to 24 N·m (18 ft.lbs.).

(5) Install brake lines to master cylinder and com-bination valve by hand to avoid cross threading.

(6) Tighten master cylinder brake lines to 15 N·m(11 ft. lbs.).

(7) Tighten combination valve brake lines to 21N·m (15 ft. lbs.).

(8) Install evaporative canister, refer to Group 25Emissions for service procedure.

(9) Bleed base brake system.

POWER BRAKE BOOSTER

REMOVAL(1) Remove combination valve and master cylinder.(2) Disconnect vacuum hose from booster check

valve.(3) Remove retaining clip that secures booster

push rod to brake pedal (Fig. 22) and slide the rod offthe pin.

(4) Remove four nuts attaching booster to frontcowl panel (Fig. 23).

(5) In engine compartment, slide booster studs outof cowl panel, and remove the booster from enginecompartment.

(6) Remove dash seal from booster.

INSTALLATION(1) Clean the booster mounting surface.(2) Install dash seal on booster.(3) Align and position booster on the front cowl

panel.(4) In passenger compartment, install nuts that

attach booster to dash panel. Tighten nuts justenough to hold booster in place.

Fig. 22 Push Rod & Clip

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REMOVAL AND INSTALLATION (Continued)

(5) Lubricate the pedal pin and bushing withopar multi-mileage grease. Then slid the booster

ush rod onto brake pedal pin and secure withetaining clip.(6) Tighten booster mounting nuts to 37 N·m (27

t. lbs.).(7) Connect vacuum hose to booster check valve.(8) Install master cylinder and combination valve.(9) Top off master cylinder fluid level and bleed

ase brakes.

ISC BRAKE CALIPER

EMOVAL(1) Raise and support vehicle.(2) Remove front wheel and tire assembly.(3) Drain small amount of fluid from master cylin-

er brake reservoir with suction gun.(4) Bottom caliper piston in bore with C-clamp.

osition clamp screw on outboard brake shoe andlamp frame on rear of caliper (Fig. 24). Do notllow clamp screw to bear directly on outboardhoe retainer spring. Use wood or metal spaceretween shoe and clamp screw.

Fig. 23 Booster Mounting Nuts

Fig. 24 Bottoming Caliper Piston With C-Clamp

(5) Remove brake hose mounting bolt and discardwashers (Fig. 25).

(6) Remove caliper mounting bolts (Fig. 26).

(7) Tilt top of caliper outward with pry tool if nec-essary (Fig. 27) and remove caliper.

(8) Remove caliper from vehicle.

INSTALLATION(1) Clean brake shoe mounting ledges with wire

brush and apply light coat of Mopar multi-mileagegrease to surfaces (Fig. 28).

(2) Install caliper by position notches at lower endof brake shoes on bottom mounting ledge. Thenrotate caliper over rotor and seat notches at upperend of shoes on top mounting ledge (Fig. 29).

Fig. 25 Brake Hose And Bolt

Fig. 26 Caliper Mounting Bolts

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REMOVAL AND INSTALLATION (Continued)

(3) Coat caliper mounting bolts with siliconerease. Then install and tighten bolts to 15 N·m (11t. lbs.).

AUTION: If new caliper bolts are being installed,r if the original reason for repair was a drag/pullondition, check caliper bolt length before proceed-ng. Bolts must not have a shank length greaterhan 67.6 mm (2.66 in.) (Fig. 30).

(4) Install brake hose to caliper with new sealashers and tighten fitting bolt to 31 N·m (23 ft.

bs.).

AUTION: Verify brake hose is not twisted orinked before tightening fitting bolt.

(5) Bleed base brake system.(6) Install wheel and tire assemblies.(7) Remove supports and lower vehicle.(8) Verify firm pedal before moving vehicle.

Fig. 27 Caliper Removal

Fig. 28 Caliper Lubrication Points

DISC BRAKE SHOES

REMOVAL(1) Raise and support vehicle.(2) Remove wheel and tire assembly.(3) Remove caliper.(4) Pressing one end of outboard shoe inward to

disengage shoe lug. Then rotate shoe upward untilretainer spring clears caliper. Press opposite end ofshoe inward to disengage shoe lug and rotate shoe upand out of caliper (Fig. 31).

(5) Grasp ends of inboard shoe and tilt shoe out-ward to release springs from caliper piston (Fig. 32)and remove shoe from caliper.

Fig. 29 Caliper Installation

Fig. 30 Mounting Bolt Dimensions

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REMOVAL AND INSTALLATION (Continued)

OTE: If original brake shoes will be used, keephem in sets left and right. They are not inter-hangeable.

(6) Secure caliper to nearby suspension part withire. Do not allow brake hose to support calipereight.(7) Wipe caliper off with shop rags or towels.

AUTION: Do not use compressed air, this cannseat dust boot and force dirt into piston bore.

NSTALLATION(1) Install inboard shoe in caliper and verify shoe

etaining is fully seated into the piston.(2) Starting one end of outboard shoe in caliper

nd rotating shoe downward into place. Verify shoeocating lugs and shoe spring are seated.

(3) Install caliper.(4) Install wheel and tire assembly.(5) Remove support and lower vehicle.

Fig. 31 Outboard Brake Shoe Removal

Fig. 32 Inboard Brake Shoe Removal

(6) Pump brake pedal until caliper pistons andbrake shoes are seated.

(7) Top off brake fluid level if necessary.

DISC BRAKE ROTOR

REMOVAL(1) Remove wheel and tire assemble.(2) Remove caliper.(3) Remove retainers securing rotor to hub studs

(Fig. 33).(4) Remove rotor from hub.(5) If rotor shield requires service, remove front

hub and bearing assembly.

INSTALLATION(1) If new rotor is being installed, remove protec-

tive coating from rotor surfaces with carburetorcleaner.

(2) Install rotor on hub.(3) Install caliper.(4) Install wheel and tire assembly.

DRUM BRAKE SHOES

REMOVAL(1) Raise vehicle and remove rear wheels.(2) Remove and discard spring nuts securing

drums to wheel studs.(3) Remove brake drums.

NOTE: If drums are difficult to remove, back offadjuster through support plate access hole withbrake tool and screwdriver.

(4) Remove U-clip and washer securing adjustercable to parking brake lever (Fig. 34).

(5) Remove primary and secondary return springsfrom anchor pin with brake spring pliers.

Fig. 33 Rotor & Hub

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5 - 20 BRAKES TJ

REMOVAL AND INSTALLATION (Continued)

(6) Remove hold-down springs, retainers and pinsith standard retaining spring tool.(7) Install spring clamps on wheel cylinders to

old pistons in place.(8) Remove adjuster lever, adjuster screw and

pring.(9) Remove adjuster cable and cable guide.(10) Remove brake shoes and parking brake strut.(11) Disconnect cable from parking brake lever and

emove lever.

NSTALLATION(1) Clean support plate with brake cleaner.(2) If new drums are being installed, remove pro-

ective coating with carburetor cleaner or brakeleaner.(3) Apply multi-purpose grease to brake shoe con-

act surfaces of support plate (Fig. 35).(4) Lubricate adjuster screw threads and pivotith spray lube.(5) Attach parking brake lever to secondary brake

hoe. Use new washer and U-clip to secure lever.(6) Remove wheel cylinder clamps.(7) Attach parking brake cable to lever.(8) Install brake shoes on support plate. Secure

hoes with new hold-down springs, pins and retain-rs.(9) Install parking brake strut and spring.(10) Install guide plate and adjuster cable on

nchor pin.(11) Install primary and secondary return springs.(12) Install adjuster cable guide on secondary

hoe.

Fig. 34 Drum Brake

(13) Lubricate and assemble adjuster screw.(14) Install adjuster screw, spring and lever and

connect to adjuster cable.(15) Adjust shoes to drum.(16) Install wheel/tire assemblies and lower vehi-

cle.(17) Verify firm brake pedal before moving vehicle.

WHEEL CYLINDER

REMOVAL(1) Remove wheel and tire assembly.(2) Remove brake drum.(3) Remove wheel cylinder brake line.(4) Remove brake shoe return springs and move

shoes out of engagement with cylinder push rods.

ponents—Typical

Fig. 35 Shoe Contact Surfaces

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REMOVAL AND INSTALLATION (Continued)

(5) Remove cylinder attaching bolts and removeylinder from support plate.

NSTALLATION(1) Apply bead of silicone sealer around cylinderounting surface of support plate.(2) Install cylinder mounting bolts and tighten to

0 N·m (7 ft. lbs.).(3) Install brake line to cylinder and tighten to 16·m (12 ft. lbs.).(4) Install brake shoe return spring.(5) Install brake drum.(6) Install wheel and tire assembly.(7) Bleed base brake system.

ARKING BRAKE HAND LEVER

EMOVAL(1) Release parking brakes.(2) Raise vehicle on hoist.(3) Remove front cable adjusting nut and disen-

age cable tensioner from equalizer. Then removeront cable from tensioner (Fig. 36).

(4) Lower vehicle.(5) Remove lever cover or center console if

quipped. Refer to Group 23 Body for procedures.(6) Disconnect parking brake switch wiring con-

ectors (Fig. 37).(7) Remove screws attaching parking brake lever

o mount (Fig. 38).(8) Disengage front cable from parking brake lever

nd remove lever assembly from vehicle.

NSTALLATION(1) Install front cable on lever assembly.(2) Install lever assembly on mounting bracket and

ighten mounting bolts to 12 N·m (9 ft. lbs.).(3) Connect parking brake switch wire.(4) Install parking lever cover.

Fig. 36 Parking Brake Cable Attachment

(5) Raise vehicle.(6) Assemble front cable, cable tensioner and cable

bracket.(7) Adjust parking brake front cable.(8) Lower vehicle.

REAR PARKING BRAKE CABLE

REMOVAL(1) Raise vehicle and loosen equalizer nuts until

rear cables are slack.(2) Disengage cable from equalizer and remove

cable (Fig. 36).(3) Remove cable bracket from upper suspension

arm (Fig. 39).(4) Remove rear wheel and brake drum.

Fig. 37 Parking Brake Lamp Switch

Fig. 38 Parking Brake Lever

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REMOVAL AND INSTALLATION (Continued)

(5) Remove secondary brake shoe and disconnectable from lever on brake shoe.(6) Compress cable retainer with worm drive hose

lamp (Fig. 40) and remove cable from backing plate.

NSTALLATION

(1) Install new cable in backing plate. Be sureable retainer is seated.(2) Attach cable to lever on brake shoe and install

rake shoe on backing plate.(3) Adjust brake shoes to drum with brake gauge.(4) Install brake drum and wheel.(5) Install cable/bracket on upper suspension arm.(6) Engage cable in equalizer and install equalizer

uts.(7) Adjust parking brakes.

Fig. 39 Parking Brake Cable Bracket

Fig. 40 Cable Retainer

DISASSEMBLY AND ASSEMBLY

MASTER CYLINDER RESERVOIR

REMOVAL(1) Remove reservoir cap and empty fluid into

drain container.(2) Remove pins that retain reservoir to master

cylinder. Use hammer and pin punch to remove pins(Fig. 41).

(3) Clamp cylinder body in vise with brass protec-tive jaws.

(4) Loosen reservoir from grommets with pry tool(Fig. 42).

(5) Remove reservoir by rocking it to one side andpulling free of grommets (Fig. 43).

(6) Remove old grommets from cylinder body (Fig.44).

Fig. 41 Reservoir Retaining Pins

Fig. 42 Loosening Reservoir

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DISASSEMBLY AND ASSEMBLY (Continued)

NSTALLATION

AUTION: Do not use any type of tool to install therommets. Tools may cut, or tear the grommets cre-ting a leak problem after installation. Install therommets using finger pressure only.

(1) Lubricate new grommets with clean brake fluidnd Install new grommets in cylinder body (Fig. 45).se finger pressure to install and seat grommets.

(2) Start reservoir in grommets. Then rock reser-oir back and forth while pressing downward to seatt in grommets.

Fig. 43 Reservoir Removal

Fig. 44 Grommet Removal

Fig. 45 Grommet Installation

(3) Install pins that retain reservoir to cylinderbody.

(4) Fill and bleed master cylinder on bench beforeinstallation in vehicle.

DISC BRAKE CALIPER

DISASSEMBLY(1) Remove brake shoes from caliper.(2) Drain brake fluid out of caliper.(3) Take a piece of wood and pad it with one-inch

thickness of shop towels. Place this piece in the out-board shoe side of the caliper in front of the piston.This will cushion and protect caliper piston duringremoval (Fig. 46).

(4) Remove caliper piston with short bursts oflow pressure compressed air. Direct air through fluidinlet port and ease piston out of bore (Fig. 47).

CAUTION: Do not blow the piston out of the borewith sustained air pressure. This could result in acracked piston. Use only enough air pressure toease the piston out.

WARNING: NEVER ATTEMPT TO CATCH THE PIS-TON AS IT LEAVES THE BORE. THIS MAY RESULTIN PERSONAL INJURY.

(5) Remove caliper piston dust boot with suitablepry tool (Fig. 48).

(6) Remove caliper piston seal with wood or plastictool (Fig. 49). Do not use metal tools as they willscratch piston bore.

(7) Remove caliper mounting bolt bushings andboots (Fig. 50).

Fig. 46 Padding Caliper Interior

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DISASSEMBLY AND ASSEMBLY (Continued)

SSEMBLY

AUTION: Dirt, oil, and solvents can damage cali-er seals. Insure assembly area is clean and dry.

(1) Lubricate caliper piston bore, new piston sealnd piston with clean brake fluid.(2) Lubricate caliper bushings and interior of

ushing boots with silicone grease.(3) Install bushing boots in caliper, then insert

ushing into boot and push bushing into place (Fig.1).(4) Install new piston seal into seal groove with

inger (Fig. 52).

Fig. 47 Caliper Piston Removal

Fig. 48 Caliper Piston Dust Boot Removal

(5) Install new dust boot on caliper piston and seatboot in piston groove (Fig. 53).

(6) Press piston into caliper bore by hand, use aturn and push motion to work piston into seal (Fig.54).

(7) Press caliper piston to bottom of bore.(8) Seat dust boot in caliper with Installer Tool

C-4842 and Tool Handle C-4171 (Fig. 55).(9) Replace caliper bleed screw if removed.

Fig. 49 Piston Seal Removal

Fig. 50 Mounting Bolt Bushing And Boot

Fig. 51 Bushings And Boots Installation

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DISASSEMBLY AND ASSEMBLY (Continued)

HEEL CYLINDER

ISASSEMBLY(1) Remove push rods and boots (Fig. 56).(2) Press pistons, cups and spring and expander

ut of cylinder bore.(3) Remove bleed screw.

Fig. 52 Piston Seal Installation

Fig. 53 Dust Boot On Piston

Fig. 54 Caliper Piston Installation

ASSEMBLY(1) Lubricate wheel cylinder bore, pistons, piston

cups and spring and expander with clean brake fluid.(2) Install first piston in cylinder bore. Then

install first cup in bore and against piston. Be surelip of piston cup is facing inward (towardspring and expander) and flat side is againstpiston.

(3) Install spring and expander followed byremaining piston cup and piston.

(4) Install boots on each end of cylinder and insertpush rods in boots.

(5) Install cylinder bleed screw.

Fig. 55 Piston Dust Boot Installation

Fig. 56 Wheel Cylinder Components–Typical

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LEANING AND INSPECTION

ALIPER

LEANINGClean the caliper components with clean brake

luid or brake clean only. Wipe the caliper and pistonry with lint free towels or use low pressure com-ressed air.

AUTION: Do not use gasoline, kerosene, thinner,r similar solvents. These products may leave aesidue that could damage the piston and seal.

NSPECTIONThe piston is made from a phenolic resin (plasticaterial) and should be smooth and clean.The piston must be replaced if cracked or scored.o not attempt to restore a scored piston surface by

anding or polishing.

AUTION: If the caliper piston is replaced, installhe same type of piston in the caliper. Never inter-hange phenolic resin and steel caliper pistons.he pistons, seals, seal grooves, caliper bore andiston tolerances are different.

The bore can be lightly polished with a brakeone to remove very minor surface imperfectionsFig. 57). The caliper should be replaced if the bore iseverely corroded, rusted, scored, or if polishingould increase bore diameter more than 0.025 mm

0.001 inch).

EAR DRUM BRAKE

LEANINGClean the individual brake components, including

he support plate and wheel cylinder exterior, with aater dampened cloth or with brake cleaner. Do not

Fig. 57 Polishing Piston Bore

use any other cleaning agents. Remove light rust andscale from the brake shoe contact pads on the sup-port plate with fine sandpaper.

INSPECTIONAs a general rule, riveted brake shoes should be

replaced when worn to within 0.78 mm (1/32 in.) ofthe rivet heads. Bonded lining should be replacedwhen worn to a thickness of 1.6 mm (1/16 in.).

Examine the lining contact pattern to determine ifthe shoes are bent or the drum is tapered. The liningshould exhibit contact across its entire width. Shoesexhibiting contact only on one side should bereplaced and the drum checked for runout or taper.

Inspect the adjuster screw assembly. Replace theassembly if the star wheel or threads are damaged,or the components are severely rusted or corroded.

Discard the brake springs and retainer componentsif worn, distorted or collapsed. Also replace thesprings if a brake drag condition had occurred. Over-heating will distort and weaken the springs.

Inspect the brake shoe contact pads on the supportplate, replace the support plate if any of the pads areworn or rusted through. Also replace the plate if it isbent or distorted (Fig. 58).

WHEEL CYLINDER

CLEANINGClean the cylinder and pistons with clean brake

fluid or brake cleaner only. Do not use any othercleaning agents.

Dry the cylinder and pistons with compressed air.Do not use rags or shop towels to dry the cylindercomponents. Lint from cloth material will adhere tothe cylinder bores and pistons.

Fig. 58 Shoe Contact Surfaces

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CLEANING AND INSPECTION (Continued)

NSPECTIONInspect the cylinder bore. Light discoloration and

ark stains in the bore are normal and will notmpair cylinder operation.

The cylinder bore can be lightly polished but onlyith crocus cloth. Replace the cylinder if the bore is

cored, pitted or heavily corroded. Honing the bore toestore the surface is not recommended.Inspect the cylinder pistons. The piston surfaces

hould be smooth and free of scratches, scoring andorrosion. Replace the pistons if worn, scored, or cor-oded. Do attempt to restore the surface by sandingr polishing.Discard the old piston cups and the spring and

xpander. These parts are not reusable. The originalust boots may be reused but only if they are in goodondition.

DJUSTMENTS

TOP LAMP SWITCH(1) Press and hold brake pedal in applied position.(2) Pull switch plunger all the way out to fully

xtended position.(3) Release brake pedal. Then pull pedal fully rear-ard. Pedal will set plunger to correct position asedal pushes plunger into switch body. Switch willake ratcheting sound as it self adjusts.

ARKING BRAKE CABLE TENSIONER

OTE: Parking brake adjustment is only necessaryhen the tensioner, or a cable has been replaced orisconnected for service. When adjustment is nec-ssary, perform the following procedure for properarking brake operation.

DJUSTMENT(1) Raise vehicle.(2) Back off tensioner adjusting nut to create slack

n cables.(3) Remove rear wheel/tire assemblies and remove

rake drums.(4) Check rear brake shoe adjustment with stan-

ard brake gauge. Excessive shoe-to-drum clear-nce, or worn brake components will result inaulty parking brake adjustment and operation.

(5) Verify that parking brake cables operate freelynd are not binding, or seized. Replace faulty cables,efore proceeding.(6) Reinstall brake drums and wheel/tire assem-

lies after brake shoe adjustment is complete.(7) Lower vehicle enough for access to parking

rake lever. Then fully apply parking brakes. Leaverakes applied until adjustment is complete.

(8) Raise vehicle and mark tensioner rod 6.5 mm(1/4 in.) from tensioner bracket (Fig. 59).

(9) Tighten adjusting nut at equalizer until markon tensioner rod moves into alignment with tensionerbracket.

(10) Lower vehicle until rear wheels are 15-20 cm(6-8 in.) off shop floor.

(11) Release parking brake lever and verify thatrear wheels rotate freely without drag.

(12) Lower vehicle.

NOTE: Do not loosen/tighten equalizer adjustingnut for any reason after completing adjustment.

REAR DRUM BRAKEThe rear drum brakes are equipped with a self-ad-

justing mechanism. Under normal circumstances, theonly time adjustment is required is when the shoesare replaced, removed for access to other parts, orwhen one or both drums are replaced.

Adjustment can be made with a standard brakegauge or with adjusting tool. Adjustment is per-formed with the complete brake assembly installedon 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. 60).

(5) Reverse gauge and install it on brake shoes.Position gauge legs at shoe centers as shown (Fig.61). If gauge does not fit (too loose/too tight), adjustshoes.

(6) Pull shoe adjuster lever away from adjusterscrew star wheel.

Fig. 59 Tensioner Rod Measurement

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ADJUSTMENTS (Continued)

(7) Turn adjuster screw star wheel (by hand) toxpand or retract brake shoes. Continue adjustmentntil gauge outside legs are light drag-fit on shoes.(8) Install brake drums and wheels and lower

ehicle.(9) Drive vehicle and make one forward stop fol-

owed by one reverse stop. Repeat procedure 8-10imes to operate automatic adjusters and equalizedjustment.

OTE: Bring vehicle to complete standstill at eachtop. Incomplete, rolling stops will not activateutomatic adjusters.

DJUSTMENT WITH ADJUSTING TOOL(1) Be sure parking brake lever is fully released.(2) Raise vehicle so rear wheels can be rotated

reely.(3) Remove plug from each access hole in brake

upport plates.

Fig. 60 Adjusting Gauge On Drum

Fig. 61 Adjusting Gauge On Brake Shoes

(4) Loosen parking brake cable adjustment nutuntil there is slack in front cable.

(5) Insert adjusting tool through support plateaccess hole and engage tool in teeth of adjustingscrew star wheel (Fig. 62).

(6) Rotate adjuster screw star wheel (move toolhandle upward) until slight drag can be felt whenwheel is rotated.

(7) Push and hold adjuster lever away from starwheel with thin screwdriver.

(8) Back off adjuster screw star wheel until brakedrag is eliminated.

(9) Repeat adjustment at opposite wheel. Be sureadjustment is equal at both wheels.

(10) Install support plate access hole plugs.(11) Adjust parking brake cable and lower vehicle.(12) Drive vehicle and make one forward stop fol-

lowed by one reverse stop. Repeat procedure 8-10times to operate automatic adjusters and equalizeadjustment.

NOTE: Bring vehicle to complete standstill at eachstop. Incomplete, rolling stops will not activateautomatic adjusters.

SPECIFICATIONS

BRAKE FLUIDThe brake fluid used in this vehicle must conform

to DOT 3 specifications and SAE J1703 standards.No other type of brake fluid is recommended orapproved for usage in the vehicle brake system. Useonly Mopar brake fluid or an equivalent from atightly sealed container.

Fig. 62 Brake Adjustment

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SPECIFICATIONS (Continued)

AUTION: Never use reclaimed brake fluid or fluidrom an container which has been left open. Anpen container will absorb moisture from the airnd contaminate the fluid.

AUTION: Never use any type of a petroleum-ased fluid in the brake hydraulic system. Use ofuch type fluids will result in seal damage of theehicle brake hydraulic system causing a failure ofhe vehicle brake system. Petroleum based fluidsould be items such as engine oil, transmission

luid, power steering fluid, etc.

RAKE COMPONENTS

isc Brake Caliper

Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SlidingDisc Brake Rotor

Type . . . . . . . . . . . . . . . . . . . . . . . . . . . VentilatedSize . . . . . . . . . 279.4 x 23.876 mm (11 x 0.94 in.)Max. Runout . . . . . . . . . . . . . 0.12 mm (0.005 in.)Max. Thickness Variation . . 0.013 mm (0.0005 in.)Min. Thickness . . . . . . . . . . . 22.7 mm (0.8937 in.)

Brake DrumSize . . . . . . . . . . . . . 228.6 x 63.5 mm (9 x 2.5 in.)

Brake BoosterType . . . . . . . . . . . . . . . . . . . Tandem Diaphragm

ORQUE CHART

DESCRIPTION TORQUEBrake Pedal

Support Bolt . . . . . . . . . . . . . . 28 N·m (21 ft. lbs.)Brake Booster

Mounting Nuts . . . . . . . . . . . . 39 N·m (29 ft. lbs.)Master Cylinder

Mounting Nuts . . . . . . . . . . . . 24 N·m (18 ft. lbs.)Brake Lines . . . . . . . . . . . . . . . 15 N·m (11 ft. lbs.)

Combination ValveMounting Nuts . . . . . . . . . . . . 24 N·m (18 ft. lbs.)Brake Lines . . . . . . . . . . . . . . 21 N·m (15 ft. lbs.)

CaliperMounting Bolts . . . . . . . . . . . . 15 N·m (11 ft. lbs.)Brake Hose Bolt . . . . . . . . . . . 31 N·m (23 ft. lbs.)

Wheel CylinderMounting Bolts . . . . . . . . . . . . . 10 N·m (7 ft. lbs.)Brake Line . . . . . . . . . . . . . . . 16 N·m (12 ft. lbs.)

Parking BrakeLever Bolts . . . . . . . . . . . . . . . . 12 N·m (9 ft. lbs.)Lever Bracket Bolts . . . . . . . . . 12 N·m (9 ft. lbs.)Cable Retainer Nut . . . . . . . . 1.5 N·m (14 in. lbs.)

SPECIAL TOOLS

BASE BRAKES

Installer Caliper Dust Boot C-4842

Handle C-4171

Adaptor Cap Pressure Bleeder 6921

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ANTILOCK BRAKES

INDEX

page page

ESCRIPTION AND OPERATIONABS SYSTEM RELAYS . . . . . . . . . . . . . . . . . . . . 33ABS WARNING LAMP . . . . . . . . . . . . . . . . . . . . 33ACCELERATION SWITCH . . . . . . . . . . . . . . . . . 32ANTILOCK BRAKE SYSTEM . . . . . . . . . . . . . . . 30COMBINATION VALVE . . . . . . . . . . . . . . . . . . . . 32CONTROLLER ANTILOCK BRAKES . . . . . . . . . . 30HYDRAULIC CONTROL UNIT . . . . . . . . . . . . . . . 31WHEEL SPEED SENSORS AND TONE WHEEL . . 31IAGNOSIS AND TESTING

ANTILOCK BRAKES . . . . . . . . . . . . . . . . . . . . . . 33

SERVICE PROCEDURESBLEEDING ABS BRAKE SYSTEM . . . . . . . . . . . 33

REMOVAL AND INSTALLATIONACCELERATION SWITCH . . . . . . . . . . . . . . . . . 36COMBINATION VALVE . . . . . . . . . . . . . . . . . . . . 35CONTROLLER ANTILOCK BRAKES . . . . . . . . . . 33FRONT WHEEL SENSOR . . . . . . . . . . . . . . . . . . 34HYDRAULIC CONTROL UNIT . . . . . . . . . . . . . . . 33REAR WHEEL SPEED SENSOR . . . . . . . . . . . . 35

SPECIFICATIONS

T0RQUE CHART . . . . . . . . . . . . . . . . . . . . . . . . 37

ESCRIPTION AND OPERATION

NTILOCK BRAKE SYSTEMThe purpose of the antilock system is to preventheel lockup during periods of high wheel slip. Pre-enting lockup helps maintain vehicle braking actionnd steering control.The antilock CAB activates the system whenever

ensor signals indicate periods of high wheel slip.igh wheel slip can be described as the point whereheel rotation begins approaching 20 to 30 percent ofctual vehicle speed during braking. Periods of highheel slip occur when brake stops involve high pedalressure and rate of vehicle deceleration.Battery voltage is supplied to the CAB ignition ter-inal when the ignition switch is turned to Run posi-

ion. The CAB performs a system initializationrocedure at this point. Initialization consists of atatic and dynamic self check of system electricalomponents.The static check occurs after the ignition switch is

urned to Run position. The dynamic check occurshen vehicle road speed reaches approximately 30ph (18 mph). During the dynamic check, the CABriefly cycles the pump and solenoids to verify oper-tion.If an ABS component exhibits a fault during ini-

ialization, the CAB illuminates the amber warningight and registers a fault code in the microprocessor

emory.

ORMAL BRAKINGDuring normal braking, the master cylinder, power

ooster and wheel brake units all function as theyould in a vehicle without ABS. The HCU compo-ents are not activated.

ANTILOCK BRAKINGThe antilock system prevents lockup during high

slip conditions by modulating fluid apply pressure tothe wheel brake units.

Brake fluid apply pressure is modulated accordingto wheel speed, degree of slip and rate of decelera-tion. A sensor at each wheel converts wheel speedinto electrical signals. These signals are transmittedto the CAB for processing and determination ofwheel slip and deceleration rate.

The ABS system has three fluid pressure controlchannels. The front brakes are controlled separatelyand the rear brakes in tandem. A speed sensor inputsignal indicating a high slip condition activates theCAB antilock program.

Two solenoid valves are used in each antilock con-trol channel. The valves are all located within theHCU valve body and work in pairs to either increase,hold, or decrease apply pressure as needed in theindividual control channels.

The solenoid valves are not static during antilockbraking. They are cycled continuously to modulatepressure. Solenoid cycle time in antilock mode can bemeasured in milliseconds.

CONTROLLER ANTILOCK BRAKESThe CAB is located under the instrument panel to

the right side of the steering column. It is mountedto bracket with one bolt. The bracket is mounted tothe front upper cowl panel.

The CAB operates the ABS system (Fig. 1) and isseparate from other vehicle electrical circuits. CABvoltage source is through the ignition switch in theRUN position.

The CAB contains dual microprocessors. A logicblock in each microprocessor receives identical sensor

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DESCRIPTION AND OPERATION (Continued)

ignals. These signals are processed and comparedimultaneously.The CAB contains a self check program that illu-inates the ABS warning light when a system fault

s detected. Faults are stored in a diagnostic programemory and are accessible with the DRB scan tool.ABS faults remain in memory until cleared, or

ntil after the vehicle is started approximately 50imes. Stored faults are not erased if the battery isisconnected.

YDRAULIC CONTROL UNITThe hydraulic control unit (HCU) consists of a

alve body, pump body, accumulators, pump motor,nd wire harnesses (Fig. 2).The pump, motor, and accumulators are combined

nto an assembly attached to the valve body. Theccumulators store the extra fluid released to theystem for ABS mode operation. The pump provideshe fluid volume needed and is operated by a DCype motor. The motor is controlled by the CAB.

The valve body contains the solenoid valves. Thealves modulate brake pressure during antilock brak-ng and are controlled by the CAB.

The HCU provides three channel pressure controlo the front and rear brakes. One channel controlshe rear wheel brakes in tandem. The two remaininghannels control the front wheel brakes individually.During antilock braking, the solenoid valves are

pened and closed as needed. The valves are nottatic. They are cycled rapidly and continuously toodulate pressure and control wheel slip and decel-

ration.During normal braking, the HCU solenoid valves

nd pump are not activated. The master cylinder andower booster operate the same as a vehicle withoutn ABS brake system.During antilock braking, solenoid valve pressureodulation occurs in three stages, pressure increase,

Fig. 1 Controller Antilock Brakes

pressure hold, and pressure decrease. The valves areall contained in the valve body portion of the HCU.

Pressure DecreaseThe outlet valve is opened and the inlet valve is

closed during the pressure decrease cycle.A pressure decrease cycle is initiated when speed

sensor signals indicate high wheel slip at one ormore wheels. At this point, the CAB opens the outletvalve, which also opens the return circuit to the accu-mulators. Fluid pressure is allowed to bleed off(decrease) as needed to prevent wheel lock.

Once the period of high wheel slip has ended, theCAB closes the outlet valve and begins a pressureincrease or hold cycle as needed.

Pressure HoldBoth solenoid valves are closed in the pressure

hold cycle. Fluid apply pressure in the control chan-nel is maintained at a constant rate. The CAB main-tains the hold cycle until sensor inputs indicate apressure change is necessary.

Pressure IncreaseThe inlet valve is open and the outlet valve is

closed during the pressure increase cycle. The pres-sure increase cycle is used to counteract unequalwheel speeds. This cycle controls re-application offluid apply pressure due to changing road surfaces orwheel speed.

WHEEL SPEED SENSORS AND TONE WHEELA speed sensor is used at each wheel. The front

sensors are mounted to the steering knuckles. Therear sensors are mounted to the rear brake backingplate.

The sensors convert wheel speed into a small ACelectrical signal. This signal is transmitted to theCAB. The CAB convert the AC signal into a digital

Fig. 2 Hydraulic Controller Unit

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DESCRIPTION AND OPERATION (Continued)

ignal for each wheel. This voltage is generated byagnetic induction when a tone wheel passes by the

tationary magnetic of the wheel speed sensor.A gear type tone ring serves as the trigger mecha-

ism for each sensor. The tone rings are mounted athe outboard ends of the front and rear axle shafts.

Different sensors are used at the front and rearheels (Fig. 3). The front/rear sensors have the

ame electrical values but are not interchangeable.he sensors have a resistance between 900 and 1300hms.

PEED SENSOR AIR GAP

ront SensorFront sensor air gap is fixed and not adjustable.nly rear sensor air gap is adjustable.Although front air gap is not adjustable, it can be

hecked if diagnosis indicates this is necessary. Frontir gap should be 0.40 to 1.3 mm (0.0157 to 0.051n.). If gap is incorrect, the sensor is either loose, oramaged.

ear SensorA rear sensor air gap adjustment is only neededhen reinstalling an original sensor. Replacement

ensors have an air gap spacer attached to the sensorickup face. The spacer establishes correct air gaphen pressed against the tone ring during installa-

ion. As the tone ring rotates, it peels the spacer offhe sensor to create the required air gap. Rear sensorir gap is 0.28-1.5 mm (0.011-0.059 in.).Sensor air gap measurement, or adjustment proce-

ures are provided in this section. Refer to the front,r rear sensor removal and installation procedures asequired.

Fig. 3 Typical Wheel Speed Sensors

COMBINATION VALVEThe combination valve contains a pressure differ-

ential valve and switch and a rear brake proportion-ing valve. The valve is not repairable and must bereplaced as an assembly if diagnosis indicates this isnecessary.

PRESSURE DIFFERENTIAL VALVEThe pressure differential switch is connected to the

brake warning light. The switch is actuated by move-ment of the switch valve. The switch monitors fluidpressure in the separate front/rear brake hydrauliccircuits.

A decrease or loss of fluid pressure in eitherhydraulic circuit will cause the switch valve to shut-tle to the low pressure side. Movement of the valvepushes the switch plunger upward. This action closesthe switch internal contacts completing the electricalcircuit to the red warning light. The switch valve willremain in an actuated position until repairs to thebrake system are made.

PROPORTIONING VALVEThe proportioning valve is used to balance front-

rear brake action at high decelerations. The valveallows normal fluid flow during moderate braking.The valve only controls fluid flow during high decel-erations brake stops.

ACCELERATION SWITCHThe acceleration switch is located in front of the

console/shifter mounted to a bracket on the floor pan.The switch (Fig. 4), provides an additional vehicle

deceleration reference during 4-wheel drive opera-tion. The switch is monitored by the CAB at alltimes. The switch reference signal is utilized by theCAB when all wheels are decelerating at the samespeed.

Fig. 4 Acceleration Switch

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DESCRIPTION AND OPERATION (Continued)

BS SYSTEM RELAYSThe ABS brakes has two relays, which are the sys-

em and pump motor relays. The ABS system relay issed for the solenoid valves and CAB. The systemelay is connected to the CAB at the power controlelay terminal. The pump motor relay is used for theump motor only. The pump motor relay starts/stopshe pump motor when signaled by the CAB.

The relays are located in the power distributionox in the engine compartment.

BS WARNING LAMPThe amber ABS warning lamp is located in the

nstrument cluster. The lamp illuminates at start-upo perform a self check. The lamp goes out when theelf check program determines the system is operat-ng normal. If an ABS component exhibits a fault theAB will illuminate the lamp and register a troubleode in the microprocessor. The lamp is controlled byhe CAB. The CAB controls the lamp sending a mes-age to the instrument cluster.

IAGNOSIS AND TESTING

NTILOCK BRAKESThe ABS brake system performs several self-tests

very time the ignition switch is turned on and theehicle is driven. The CAB monitors the systemsnput and output circuits to verify the system is oper-ting correctly. If the on board diagnostic systemenses that a circuit is malfunctioning the systemill set a trouble code in its memory.

OTE: An audible noise may be heard during theelf-test. This noise should be considered normal.

OTE: The MDS or DRB III scan tool is used toiagnose the ABS system. For additional informa-

ion refer to the Antilock Brake section in GroupW. For test procedures refer to the Chassis Diag-ostic Manual.

ERVICE PROCEDURES

LEEDING ABS BRAKE SYSTEMABS system bleeding requires conventional bleed-

ng methods plus use of the DRB scan tool. The pro-edure involves performing a base brake bleeding,ollowed by use of the scan tool to cycle and bleed theCU pump and solenoids. A second base brake bleed-

ng procedure is then required to remove any airemaining in the system.

(1) Perform base brake bleeding. Refer to basebrake section for procedure.

(2) Connect scan tool to the Data Link Connector.(3) Select ANTILOCK BRAKES, followed by MIS-

CELLANEOUS, then ABS BRAKES. Follow theinstructions displayed. When scan tool displays TESTCOMPLETE, disconnect scan tool and proceed.

(4) Perform base brake bleeding a second time.Refer to base brake section for procedure.

(5) Top off master cylinder fluid level and verifyproper brake operation before moving vehicle.

REMOVAL AND INSTALLATION

CONTROLLER ANTILOCK BRAKES

REMOVAL(1) Remove negative battery terminal.(2) Remove the harness connector from the CAB

located underneath the instrument panel (Fig. 5).(3) Remove mounting bolt and remove the CAB.

INSTALLATION(1) Install the controller and install the mounting

bolt.(2) Tighten the mounting bolt to 7-9 N·m (60-80 in.

lbs.).(3) Plug in the harness connector into the controller.(4) Install negative battery cable.

HYDRAULIC CONTROL UNIT

REMOVAL(1) Disconnect and isolate the negative battery ter-

minal.(2) Disconnect the HCU harness connectors.

Fig. 5 Controller Antilock Brakes

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REMOVAL AND INSTALLATION (Continued)

(3) Remove all the brake lines from the HCU (Fig.).(4) Remove HCU mounting bolts and remove HCU

Fig. 7).(5) Remove bolts from mount and remove mount

rom HCU.

NSTALLATION(1) Install mounting bracket on HCU and tighten

o 6.5 N·m (57 in. lbs.).(2) Install HCU and tighten mounting bolts to 9-13·m (80-115 in. lbs.).(3) Align and start brake line fittings by hand to

void cross threading.(4) Tighten brake lines to 15-18 N·m (130-160 in.

bs.).(5) Connect HCU harness.(6) Connect negative battery terminal.(7) Bleed complete brake system.

Fig. 6 HCU Brake Lines

Fig. 7 HCU Mount

FRONT WHEEL SENSOR

REMOVAL(1) Raise vehicle and turn wheel outward to access

the sensor.(2) Disconnect sensor wire connector at harness

plug.(3) Remove sensor wire from mounting retainers.(4) Clean sensor and surrounding area with shop

towel before removal.(5) Remove bolt attaching sensor to steering

knuckle and remove sensor (Fig. 8).

INSTALLATION(1) If original sensor will be installed, wipe all

traces of old spacer material off sensor pickup face.Use a dry shop towel for this purpose.

(2) Apply Mopar Lock N’ Seal or Loctitet 242 onolt that secures sensor in steering knuckle. Use newensor bolt if original bolt is worn or damaged.(3) Position sensor on steering knuckle. Seat sen-

or locating tab in hole in knuckle and install sensorttaching bolt finger tight.(4) Tighten sensor attaching bolt to 4-6 N·m (34-50

n. lbs.).(5) If original sensor has been installed, check sen-

or air gap. Air gap should be 0.40 to 1.3 mm (0.0157o 0.051 in.). If gap is incorrect, sensor is either loose,r damaged.(6) Route sensor wire and install into mounting

etainers.(7) Connect sensor wire to harness.

Fig. 8 Front Wheel Speed Sensor

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REMOVAL AND INSTALLATION (Continued)

EAR WHEEL SPEED SENSOR

EMOVAL(1) Disconnect sensors at rear harness connectors.(2) Remove wheel and tire assembly.(3) Remove brake drum.(4) Remove clips securing sensor wires to brake

ines, rear axle and, brake hose.(5) Unseat sensor wire support plate grommet.(6) Remove bolt attaching sensor to bracket (Fig.

) and remove sensor.

NSTALLATION(1) If original sensor is being installed, remove

ny remaining pieces of cardboard spacer from sen-or pickup face. Use dry shop towel only to removeld spacer material.(2) Insert sensor wire through support plate hole.

hen seat sensor grommet in support plate.(3) Apply Mopar Lock N’ Seal or Loctitet 242 to

riginal sensor bolt. Use new bolt if original is wornr damaged.(4) Install sensor bolt finger tight only at this

ime.(5) If original rear sensor was installed, adjust

ensor air gap to 0.28-1.5 mm (0.011-0.059 in.). Useeeler gauge to measure air gap (Fig. 10). Tightenensor bolt to 12-14 N·m (106-124 in. lbs.).(6) If new sensor was installed, push cardboard

pacer on sensor face against tone ring (Fig. 11).hen tighten sensor bolt to 12-14 N·m (106-124 in.

bs.). Correct air gap will be established as tone ringotates and peels spacer off sensor face.(7) Secure the rear sensor wires to the retainer

lips. Verify that wire is clear of rotating components.(8) Connect sensor wire to harness connector.(9) Install brake drum and wheel and tire assembly.(10) Lower vehicle.(11) Connect sensor wire to harness connector.

Fig. 9 Wheel Speed Sensor

COMBINATION VALVE

REMOVAL(1) Remove brake lines that connect master cylin-

der to combination valve (Fig. 12).(2) Disconnect brake lines that connect combina-

tion valve to HCU.(3) Disconnect wire from combination valve switch

terminal. Be careful when separating wire connectoras lock tabs are easily damaged if not fully disen-gaged.

(4) Remove nuts attaching combination valvebracket to booster studs and valve bracket off boosterstuds (Fig. 13).

INSTALLATION(1) Position valve bracket on booster studs and

tighten bracket attaching nuts to 17 N·m (13 ft. lbs.).(2) Align and start brake line fittings in combina-

tion valve, master cylinder and HCU by hand toavoid cross threading.

(3) Tighten brake line fittings at combination valveto 21 N·m (15 ft. lbs.).

(4) Tighten brake line fittings at master cylinderto 15 N·m (11 ft. lbs.).

Fig. 10 Setting Air Gap On Original Rear Sensor

Fig. 11 New Rear Sensor

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REMOVAL AND INSTALLATION (Continued)

(5) Tighten brake line fittings at HCU to 16 N·m12 ft. lbs.).

(6) Connect wire to differential pressure switch inombination valve.(7) Bleed base brake system.

CCELERATION SWITCH

EMOVAL(1) From the drivers side lift carpet back in front

f the console/shifter.(2) Disconnect harness for switch.(3) Remove mounting bolts and remove switch

Fig. 14).

NSTALLATION

AUTION: The mercury switch (inside the accelera-ion switch), will not function properly if the switchs installed incorrectly. Verify that the switch locat-

Fig. 12 Combination Valve Brake Lines

Fig. 13 Combination Valve Bracket

ing arrow is pointing to the front of the vehicle (Fig.15).

(1) Position switch on mounting bracket.(2) Install mounting bolts and tighten to 4-5 N·m

(35-45 in. lbs.).(3) Connect harness to switch.(4) Place carpet back into position.

Fig. 14 Acceleration Switch

Fig. 15 Acceleration Switch Position Indicator

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PECIFICATIONS

0RQUE CHART

DESCRIPTION TORQUEAcceleration Sensor

Sensor Bolt . . . . . . . . . . . . 4-5 N·m (35-45 in. lbs.)Bracket Bolt . . . . . . . . . 8-13 N·m (75-115 in. lbs.)

Hydraulic Control UnitBracket to HCU Bolts . . . . . . 6.5 N·m (57 in. lbs.)Body Bracket Bolts . . . . . . . . . . . . . . . 16-24 N·m

(142-212 in. lbs.)HCU to Body Bracket Bolts . . . . . . . . . . 9-13 N·m

(80-115 in. lbs.)Brake Lines . . . . . . . 15-18 N·m (130-160 in. lbs.)

Controller Anitlock BrakesMounting Bolt . . . . . . . . . 7-9 N·m (60-80 in. lbs.)

Wheel Speed SensorsFront Mounting Bolt . . . . . . . . 4-6 (34-50 in. lbs.)Rear Mounting Bolt . . . . . . . . . . . . . . . 12-14 N·m

(106-124 in. lbs.)

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