2002 JEEP LIBERTY brake fluid

OPERATION - REAR DRUM BRAKE
When the brake pedal is depressed hydraulic pres-
sure pushes the rear brake wheel cylinder pistons
outward. The wheel cylinder push rods then push the
brake shoes outward against the brake drum. When
the brake pedal is released return springs attached
to the brake shoes pull the shoes back to there orig-
inal position (Fig. 9).
REMOVAL
REMOVAL - FRONT BRAKE PADS
(1) Raise and support the vehicle.
(2) Remove the front wheel and tire assembly.
(3) Drain a small amount of fluid from the master
cylinder brake reservoir with acleansuction gun.(4) Bottom the caliper pistons into the caliper by
prying the caliper over.
(5) Remove the caliper mounting bolts.
(6) Remove the disc brake caliper from the mount.
CAUTION: Never allow the disc brake caliper to
hang from the brake hose. Damage to the brake
hose will result. Provide a suitable support to hang
the caliper securely.
(7) Remove the inboard and outboard pads.
REMOVAL - DRUM BRAKE SHOES
(1) Raise the vehicle and remove the rear wheels.
(2) Remove and discard the spring nuts securing
drums to wheel studs.
(3) Remove the brake drums. If drums prove diffi-
cult to remove, retract brake shoes. Remove the
access hole plug at the rear of backing plate and
back off adjuster screw with brake tool and screw-
driver.
(4) Clean the individual brake components, includ-
ing the support plate and wheel cylinder exterior,
with a find mist of water. Then wipe the brake com-
ponents clean with a dampened cloth.
(5) Remove the primary and secondary return
springs from anchor pin with the brake spring pliers.
(6) Remove the U-clip and washer securing
adjuster cable to the parking brake lever.
(7) Remove the hold-down springs, retainers and
pins with standard retaining spring tool.
(8) Remove the parking brake strut and cable
guide.
(9) Remove the adjuster lever, adjuster screw and
spring.
(10) Remove the adjuster cable.
(11) Remove the brake shoes.
(12) Disconnect the cable from the parking brake
lever and remove the lever ( if needed).
INSTALLATION
INSTALLATION - FRONT BRAKE PADS
(1) Install the inboard and outboard pads.
(2) Install the caliper (Refer to 5 - BRAKES/HY-
DRAULIC/MECHANICAL/DISC BRAKE CALIPERS
- INSTALLATION).
(3) Install the tire and wheel assembly. (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
INSTALLATION - DRUM BRAKE SHOES
Bonded linings should be replaced when worn to a
thickness of 1.6 mm (1/16 in.).
Fig. 9 BRAKE COMPONENTS
1 - SECONDARY SHOE
2 - SHOE GUIDE PLATE
3 - PRIMARY SHOE
4 - HORSE SHOE RETAINING CLIP
5 - PRIMARY RETURN SPRING
6 - PARK BRAKE STRUT
7 - HOLD DOWN SPRING AND RETAINERS
8 - SHOE RETURN SPRING
9 - ADJUSTER SCREW ASSEMBLY
10 - ADJUSTER LEVER
11 - ADJUSTER CABLE
12 - SECONDARY RETURN SPRING
13 - CABLE GUIDE
14 - WHEEL CYLINDER
15 - PARK BRAKE STRUT AND SPRING
16 - SUPPORT PLATE
KJBRAKES - BASE 5 - 11
BRAKE PADS / SHOES (Continued)

OPERATION
When the brakes are applied fluid pressure is
exerted against the caliper piston. The fluid pressure
is exerted equally and in all directions. This means
pressure exerted against the caliper piston and
within the caliper bore will be equal (Fig. 14).
Fluid pressure applied to the piston is transmitted
directly to the inboard brake shoe. This forces the
shoe lining against the inner surface of the disc
brake rotor. At the same time, fluid pressure within
the piston bore forces the caliper to slide inward on
the mounting bolts. This action brings the outboard
brake shoe lining into contact with the outer surface
of the disc brake rotor.
In summary, fluid pressure acting simultaneously
on both piston and caliper, produces a strong clamp-
ing action. When sufficient force is applied, friction
will attempt to stop the rotors from turning and
bring the vehicle to a stop.
Application and release of the brake pedal gener-
ates 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 not
retract an appreciable distance from the rotor. In
fact, 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 rotor
surface clear each revolution.
The caliper piston seal controls the amount of pis-
ton extension needed to compensate for normal lining
wear.
During brake application, the seal is deflected out-
ward by fluid pressure and piston movement (Fig.
15). When the brakes (and fluid pressure) are
released, the seal relaxes and retracts the piston.
The amount of piston retraction is determined by
the amount of seal deflection. Generally the amount
is just enough to maintain contact between the pis-
ton and inboard brake shoe.
REMOVAL
(1) Install prop rod on the brake pedal to keep
pressure on the brake system.
(2) Raise and support vehicle.
(3) Remove front wheel and tire assembly.
(4) Drain small amount of fluid from master cylin-
der brake reservoir with suction gun.
(5) Remove the brake hose banjo bolt if replacing
caliper (Fig. 16).
(6) Remove the caliper mounting slide pin bolts
(Fig. 16).
(7) Remove the caliper from vehicle.
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 during
removal (Fig. 17).
Fig. 14 Brake Caliper Operation
1 - CALIPER
2 - PISTON
3 - PISTON BORE
4 - SEAL
5 - INBOARD SHOE
6 - OUTBOARD SHOE
Fig. 15 Lining Wear Compensation By Piston Seal
1 - PISTON
2 - CYLINDER BORE
3 - PISTON SEAL BRAKE PRESSURE OFF
4 - CALIPER HOUSING
5 - DUST BOOT
6 - PISTON SEAL BRAKE PRESSURE ON
5 - 14 BRAKES - BASEKJ
DISC BRAKE CALIPERS (Continued)

(4) Remove caliper piston withshort burstsof
low pressure compressed air. Direct air through fluid
inlet port and ease piston out of bore (Fig. 18).
CAUTION: Do not blow the piston out of the bore
with sustained air pressure. This could result in a
cracked piston. Use only enough air pressure to
ease the piston out.
WARNING: NEVER ATTEMPT TO CATCH THE PIS-
TON AS IT LEAVES THE BORE. THIS MAY RESULT
IN PERSONAL INJURY.(5) Remove caliper piston dust boot with suitable
pry tool (Fig. 19).
(6) Remove caliper piston seal with wood or plastic
tool (Fig. 20). Do not use metal tools as they will
scratch piston bore.
(7) Remove caliper mounting bolt bushings and
boots (Fig. 21).
Fig. 16 DISC BRAKE CALIPER
1 - DISC BRAKE CALIPER
2 - CALIPER SLIDE MOUNTING BOLTS
3 - BRAKE HOSE
4 - BANJO BOLT
5 - CALIPER ADAPTER MOUNTING BOLT
Fig. 17 PADDING CALIPER INTERIOR - TYPICAL
1 - SHOP TOWELS OR CLOTHS
2 - CALIPER
Fig. 18 CALIPER PISTON REMOVAL - TYPICAL
1 - AIR GUN
2 - CALIPER PISTON
3 - PADDING MATERIAL
Fig. 19 CALIPER PISTON DUST BOOT REMOVAL -
TYPICAL
1 - COLLAPSE BOOT WITH PUNCH OR SCREWDRIVER
2 - PISTON DUST BOOT
KJBRAKES - BASE 5 - 15
DISC BRAKE CALIPERS (Continued)

CLEANING
Clean the caliper components with clean brake
fluid or brake clean only. Wipe the caliper and piston
dry with lint free towels or use low pressure com-
pressed air.
CAUTION: Do not use gasoline, kerosene, thinner,
or similar solvents. These products may leave a
residue that could damage the piston and seal.
INSPECTION
The piston is made from a phenolic resin (plastic
material) and should be smooth and clean.
The piston must be replaced if cracked or scored.
Do not attempt to restore a scored piston surface by
sanding or polishing.
CAUTION: If the caliper piston is replaced, install
the same type of piston in the caliper. Never inter-
change phenolic resin and steel caliper pistons.The pistons, seals, seal grooves, caliper bore and
piston tolerances are different.
The bore can belightlypolished with a brake
hone to remove very minor surface imperfections
(Fig. 22). The caliper should be replaced if the bore is
severely corroded, rusted, scored, or if polishing
would increase bore diameter more than 0.025 mm
(0.001 inch).
ASSEMBLY
CAUTION: Dirt, oil, and solvents can damage cali-
per seals. Insure assembly area is clean and dry.
(1) Lubricate caliper piston bore, new piston seal
and piston with clean brake fluid.
(2) Lubricate caliper bushings and interior of
bushing boots with silicone grease.
(3) Install bushing boots in caliper, then insert
bushing into boot and push bushing into place (Fig.
23).
(4) Install new piston seal into seal groove with
finger (Fig. 24).
(5) Install new dust boot on caliper piston and seat
boot in piston groove (Fig. 25).
(6) Press piston into caliper bore by hand, use a
turn and push motion to work piston into seal (Fig.
26).
(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. 27).
(9) Replace caliper bleed screw if removed.
Fig. 20 PISTON SEAL REMOVAL - TYPICAL
1 - REMOVE SEAL WITH WOOD PENCIL OR SIMILAR TOOL
2 - PISTON SEAL
Fig. 21 MOUNTING BOLT BUSHING AND BOOT -
TYPICAL
1 - CALIPER SLIDE BUSHING
2 - BOOT
Fig. 22 POLISHING PISTON BORE - TYPICAL
1 - SPECIAL HONE
2 - CALIPER
3 - PISTON BORE
5 - 16 BRAKES - BASEKJ
DISC BRAKE CALIPERS (Continued)

(4) Install the brake hose to the caliper withnew
seal washersand tighten fitting bolt to 31 N´m (23
ft. lbs.).
CAUTION: Verify brake hose is not twisted or
kinked before tightening fitting bolt.
(5) Remove the prop rod from the vehicle.
(6) Bleed the base brake system,(Refer to 5 -
BRAKES - STANDARD PROCEDURE) OR (Refer to
5 - BRAKES - STANDARD PROCEDURE).
(7) Install the wheel and tire assemblies (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
(8) Remove the supports and lower the vehicle.
(9) Verify a firm pedal before moving the vehicle.
DISC BRAKE CALIPER
ADAPTER
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the front wheel and tire assembly.
(3) Drain a small amount of fluid from master cyl-
inder brake reservoir with acleansuction gun.
(4) Bottom the caliper pistons into the caliper by
prying the caliper over.
(5) Remove the caliper mounting bolts (Fig. 16).
(6) Remove the disc brake caliper from the mount.
CAUTION: Never allow the disc brake caliper to
hang from the brake hose. Damage to the brake
hose will result. Provide a suitable support to hang
the caliper securely.
(7) Remove the inboard and outboard brake pads.
(Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/
BRAKE PADS/SHOES - REMOVAL).
(8) Remove the caliper adapter mounting bolts
(Fig. 16).
INSTALLATION
(1) Install the caliper adapter mounting bolts.
Tighten the mounting bolts to 135 N´m (100 ft.lbs).
(2) Install the inboard and outboard pads. (Refer
to 5 - BRAKES/HYDRAULIC/MECHANICAL/
BRAKE PADS/SHOES - INSTALLATION).
(3) Install the caliper mounting bolts.
(4) Install the tire and wheel assembly. (Refer to
22 - TIRES/WHEELS/WHEELS - STANDARD PRO-
CEDURE).
ROTORS
DIAGNOSIS AND TESTING - DISC BRAKE
ROTOR
The rotor braking surfaces should not be refinished
unless necessary.
Light surface rust and scale can be removed with a
lathe equipped with dual sanding discs. The rotor
surfaces can be restored by machining in a disc brake
lathe if surface scoring and wear are light.
Replace the rotor under the following conditions:
²severely scored
²tapered
²hard spots
²cracked
²below minimum thickness
ROTOR MINIMUM THICKNESS
Measure rotor thickness at the center of the brake
shoe contact surface. Replace the rotor if worn below
minimum thickness, or if machining would reduce
thickness below the allowable minimum.
Rotor minimum thickness is usually specified on
the rotor hub. The specification is either stamped or
cast into the hub surface.
ROTOR RUNOUT
Check rotor lateral runout with dial indicator
C-3339 (Fig. 28). Excessive lateral runout will cause
brake pedal pulsation and rapid, uneven wear of the
brake shoes. Position the dial indicator plunger
approximately 25.4 mm (1 in.) inward from the rotor
edge. The dial indicator should be positioned in the
center of the rotor surface. Maximum allowable rotor
runout is 0.102 mm (0.004 in.).
ROTOR THICKNESS VARIATION
Variations in rotor thickness will cause pedal pul-
sation, noise and shudder.
Measure rotor thickness at 6 to 12 points around
the rotor face (Fig. 29).
Position the micrometer approximately 25.4 mm (1
in.) from the rotor outer circumference for each mea-
surement.
Thickness should notvaryby more than 0.013 mm
(0.0005 in.) from point-to-point on the rotor. Machine
or replace the rotor if necessary.
5 - 18 BRAKES - BASEKJ
DISC BRAKE CALIPERS (Continued)

JUNCTION BLOCK
DESCRIPTION
The junction block and a rear brake proportioning
valve. The valve is not repairable and must be
replaced as an assembly if diagnosis indicates this is
necessary.
OPERATION
PROPORTIONING VALVE
The proportioning valve is used to balance front-
rear brake action at high decelerations. The valve
allows normal fluid flow during moderate braking.
The valve only controls fluid flow during high decel-
erations brake stops. If the primary brake hydraulic
circuit cannot build pressure a by-pass feature is
activated allowing full flow and pressure to the rear
brakes.
DIAGNOSIS AND TESTING - PROPORTIONING
VALVE
The valve controls fluid flow. If fluid enters the
valve and does not exit the valve the combination
valve must be replaced.
REMOVAL
(1) Install prop rod on the brake pedal to keep
pressure on the brake system.
(2) Remove the brake lines from the junction
block.
(3) Remove mounting nuts and bolt and remove
the junction block (Fig. 31).
INSTALLATION
(1) Install the junction block on the mounting
studs.
(2) Install mounting nuts and bolt. Tighten to 14
N´m (125 in. lbs.).
(3) Install brake lines to the junction block and
tighten to 20 N´m (180 in. lbs.).
(4) Bleed ABS brake system (Refer to 5 - BRAKES
- STANDARD PROCEDURE).
PEDAL
DESCRIPTION
A suspended-type brake pedal is used, the pedal
pivots on a shaft mounted in the steering coloumn
support bracket. The bracket is attached to the dash
panel. The unit is serviced as an assembly, except for
the pedal pad.
OPERATION
The brake pedal is attached to the booster push
rod. When the pedal is depressed, the primary
booster push rod is depressed which move the booster
secondary rod. The booster secondary rod depress the
master cylinder piston.
REMOVAL
(1) Remove the knee blocker under the steering
column,(Refer to 23 - BODY/INSTRUMENT PANEL/
KNEE BLOCKER - REMOVAL).
(2) Remove the retainer clip securing the booster
push rod to pedal (Fig. 32).
(3) Remove the brake lamp switch,(Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
BRAKE LAMP SWITCH - REMOVAL).
(4) Remove the nuts securing the pedal to the col-
umn bracket.
(5) Remove the pedal from the vehicle.
INSTALLATION
(1) Install the pedal into the vehicle.
(2) Install the nuts securing the pedal to the col-
umn bracket.
(3) Tighten the nuts to 22.6 N´m (200 in. lbs.).
(4) Lubricate the brake pedal pin and bushings
with Mopar multi-mileage grease.
(5) Install the booster push rod on the pedal pin
and install a new retainer clip (Fig. 32).
(6) Install the brake lamp switch,(Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
BRAKE LAMP SWITCH - INSTALLATION).
(7) Install the knee blocker,(Refer to 23 - BODY/
INSTRUMENT PANEL/KNEE BLOCKER - INSTAL-
LATION).
Fig. 31 JUNCTION BLOCK
1 - JUNCTION BLOCK
2 - MOUNTING NUT
5 - 20 BRAKES - BASEKJ

(4) Apply 15-20 inches vacuum at large end of
check valve (Fig. 35).
(5) Vacuum should hold steady. If gauge on pump
indicates vacuum loss, check valve is faulty and
should be replaced.
REMOVAL
(1) Disconnect the wire to the fluid level switch at
the bottom of the reservoir.(2) Remove the master cylinder (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/MASTER
CYLINDER - REMOVAL).
(3) Disconnect vacuum hose from booster check
valve.
(4) Remove the brake lines from the master cylin-
der and the HCU (abs vehicles only) or the junction
block for clearence.
(5) Disconnect the HCU from the mounts and
move to the side for clearence of the booster.
Fig. 33 Power Brake Booster±Typical
1 - VACUUM CHECK VALVE
2 - FRONT DIAPHRAGM
3 - REAR DIAPHRAGM
4 - HOUSING
5 - SEAL
6 - AIR FILTER7 - PRIMARY PUSH ROD (TO BRAKE PEDAL)
8 - ATMOSPHERIC INLET VALVE ASSEMBLY
9 - BOOSTER MOUNTING STUDS (4)
10 - SECONDARY PUSH ROD (TO MASTER CYLINDER)
11 - MASTER CYLINDER MOUNTING STUD (2)
12 - SPRING
5 - 22 BRAKES - BASEKJ
POWER BRAKE BOOSTER (Continued)

(4) Tighten booster mounting nuts to 22.6 N´m
(200 ft. lbs.).
(5) Install the knee blocker,(Refer to 23 - BODY/
INSTRUMENT PANEL/KNEE BLOCKER - INSTAL-
LATION).
(6) If original master cylinder is being installed,
check condition of seal at rear of master cylinder.
Replace seal if cut, or torn.
(7) Clean cylinder mounting surface of brake
booster. Use shop towel wetted with brake cleaner for
this purpose. Dirt, grease, or similar materials will
prevent proper cylinder seating and could result in
vacuum leak.
(8) Align and install master cylinder on the
booster studs. Install mounting nuts and tighten to
22.6 N´m (200 in. lbs.).
(9) Connect vacuum hose to booster check valve.
(10) Remount the HCU. Tighten bracket mounting
nuts to 22.6 N´m (200 in. lbs.).
(11) Connect and secure the brake lines to HCU or
junction block and master cylinder. Start all brake
line fittings by hand to avoid cross threading.
(12) Connect the wire to fluid level switch at the
bottom of the reservoir.
(13) Fill and bleed base brake system,(Refer to 5 -
BRAKES - STANDARD PROCEDURE).
(14) Verify proper brake operation before moving
vehicle.
MASTER CYLINDER
DESCRIPTION
The master cylinder has a removable nylon reser-
voir. The cylinder body is made of aluminum and
contains a primary and secondary piston assembly.
The cylinder body including the piston assemblies
are not serviceable. If diagnosis indicates an internal
problem with the cylinder body, it must be replaced
as an assembly. The reservoir and grommets are the
only replaceable parts on the master cylinder.
OPERATION
The master cylinder bore contains a primary and
secondary piston. The primary piston supplies
hydraulic pressure to the front brakes. The secondary
piston supplies hydraulic pressure to the rear brakes.
The master cylinder reservoir stores reserve brake
fluid for the hydraulic brake circuits.
DIAGNOSIS AND TESTING - 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.
(3) Pump brake pedal until all vacuum reserve in
booster is depleted.
(4) Press and hold brake pedal under light foot
pressure. The pedal should hold firm, if the pedal
falls away master cylinder is faulty (internal leak-
age).
(5) Start engine and note pedal action. It should
fall away slightly under light foot pressure then hold
firm. If no pedal action is discernible, power booster,
vacuum supply, or vacuum check valve is faulty. Pro-
ceed to the POWER BOOSTER VACUUM TEST.
(6) If the POWER BOOSTER VACUUM TEST
passes, rebuild booster vacuum reserve as follows:
Release brake pedal. Increase engine speed to 1500
rpm, close the throttle and immediately turn off igni-
tion to stop engine.
(7) Wait a minimum of 90 seconds and try brake
action again. Booster should provide two or more vac-
uum assisted pedal applications. If vacuum assist is
not provided, booster is faulty.
POWER BOOSTER VACUUM TEST
(1) Connect vacuum gauge to booster check valve
with short length of hose and T-fitting (Fig. 38).
(2) Start and run engine at curb idle speed for one
minute.
(3) Observe the vacuum supply. If vacuum supply
is not adequate, repair vacuum supply.
(4) Clamp hose shut between vacuum source and
check valve.
(5) Stop engine and observe vacuum gauge.
(6) If vacuum drops more than one inch HG (33
millibars) within 15 seconds, booster diaphragm or
check valve is faulty.
POWER BOOSTER CHECK VALVE TEST
(1) Disconnect vacuum hose from check valve.
(2) Remove check valve and valve seal from
booster.
(3) Use a hand operated vacuum pump for test.
(4) Apply 15-20 inches vacuum at large end of
check valve (Fig. 39).
(5) Vacuum should hold steady. If gauge on pump
indicates vacuum loss, check valve is faulty and
should be replaced.
STANDARD PROCEDURE - MASTER CYLINDER
BLEEDING
A new master cylinder should be bled before instal-
lation on the vehicle. Required bleeding tools include
bleed tubes and a wood dowel to stroke the pistons.
Bleed tubes can be fabricated from brake line.
(1) Mount master cylinder in vise.
5 - 24 BRAKES - BASEKJ
POWER BRAKE BOOSTER (Continued)