JEEP YJ 1995 Service And Repair Manual

(2) Pad interior of caliper with minimum, 2.54 cm
(1 in.) thickness of shop towels or rags (Fig. 15). Tow-
els are needed to protect caliper piston during re-
moval.
(3) Remove caliper piston withshort burstsof low
pressure compressed air. Direct air through fluid in-
let port and ease piston out of bore (Fig. 16).
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. In addition, NEVER attempt to
catch the piston as it leaves the bore. This will re-
sult in personal injury.(4) Remove caliper piston dust boot (Fig. 17). Col-
lapse boot with suitable tool and remove and discard
boot.
(5) Remove and discard caliper piston seal with
wood or plastic tool (Fig. 18). Do not use metal tools
as they will scratch piston bore.
(6) Remove caliper mounting bolt bushings and
boots (Fig. 19).
Fig. 15 Padding Caliper Interior To Protect Piston
During Removal
Fig. 16 Removing Caliper Piston
Fig. 17 Removing Caliper Piston Dust Boot
Fig. 18 Removing Caliper Piston Seal
Fig. 19 Caliper Bushing And Boot
JDISC BRAKES 5 - 49

CALIPER CLEANING AND INSPECTION
Clean the caliper and piston with Mopar brake
cleaner, clean brake fluid, or denatured alcohol only.
Do not use gasoline, kerosene, thinner, or similar sol-
vents. These products leave a residue that will dam-
age pistons and seals.
Wipe the caliper and piston dry with lint free tow-
els or use low pressure compressed air.
Inspect the piston and piston bore. Replace the cal-
iper if the bore is corroded, rusted, pitted, or scored.
Do not hone the caliper piston bore. Replace the cal-
iper if the bore exhibits any of the aforementioned
conditions.
Inspect the caliper piston. The piston is made from
a phenolic resin and should be smooth and clean. Re-
place the piston if cracked, chipped, or scored. Do not
attempt to restore a scored, or corroded piston sur-
face by sanding or polishing. The piston must be re-
placed if damaged.
CAUTION: Never interchange phenolic resin and
steel caliper pistons. The seals, seal grooves, cali-
per bores and piston tolerances are different for
resin and steel pistons. Do not intermix these com-
ponents.
Inspect the caliper mounting bolt bushings and
boots. Replace the boots if cut or torn. Clean and lu-
bricate the bushings with GE 661 or Dow 111 silicone
grease if necessary.
Inspect condition of the caliper mounting bolts. Re-
place the bolts if corroded, rusted, or worn. Do not
reuse the bolts if unsure of their condition.
Length of the caliper mounting bolts is also ex-
tremely important.
Use the replacement bolts specified in the parts
catalog at all times. Do not use substitute bolts. Bolts
that are too long will partially apply the inboard
brakeshoe causing drag and pull. Refer to the caliper
and brakeshoe installation procedures for service de-
tails and bolt dimensions.
CALIPER ASSEMBLY
(1) Coat caliper piston bore, new piston seal and
piston with clean, fresh brake fluid.
(2) Lubricate caliper bushings and interior of bush-
ing boots with GE 661, Dow 111, or Permatex Dielec-
tric silicone grease.
(3) Install bushing boots in caliper first. Then in-
sert bushing into boot and push bushing into place
(Fig. 20).
(4) Install new piston seal in caliper bore. Press
seal into seal groove with finger (Fig. 21).
(5) Install dust boot on caliper piston (Fig. 22).
Slide boot over piston and seat boot in piston groove.(6) Start caliper piston in bore by hand (Fig. 23).
Use a turn and push motion to work piston into seal.
Once piston is started in seal, press pistononly part
wayinto bore.
(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. 24).
(9) Install caliper bleed screw if removed.
Fig. 20 Installing Bushings And Boots
Fig. 21 Installing Piston Seal
Fig. 22 Installing Dust Boot On Piston
5 - 50 DISC BRAKESJ

CALIPER INSTALLATION
(1) Install brakeshoes in caliper (Figs. 11, 12).
(2) Connect brake hose to caliper but do not
tighten fitting bolt completely at this time.Be sure
to use new gaskets on fitting bolt to avoid leaks
(Fig. 25).
(3) Install caliper. Position mounting notches at
lower end of brakeshoes on bottom mounting ledge
(Fig. 13). Then rotate caliper over rotor and seat
notches at upper end of shoes on mounting ledge
(Fig. 13).
(4) Coat caliper mounting bolts with GE 661 or
Dow 111 silicone grease. Then install and tighten
bolts to 10-20 Nzm (7-15 ft. lbs.) torque.CAUTION: If new caliper bolts are being installed,
or if the original reason for repair was a drag/pull
condition, check caliper bolt length before proceed-
ing. If the bolts have a shank length greater than
67.6 mm (2.66 in.), they may contact the inboard
brakeshoe causing a partial apply condition. Refer
to Figure 14 for the required caliper bolt length.
(5) Position front brake hose clear of all chassis
components and tighten caliper fitting bolt to 31 Nzm
(23 ft. lbs.) torque.
CAUTION: Be sure the brake hose is not twisted or
kinked at any point. Also be sure the hose is clear
of all steering and suspension components. Loosen
and reposition the hose if necessary.
(6) Install wheels. Tighten wheel lug nuts to 109-
150 Nzm (80-110 ft. lbs.) torque.
(7) Fill and bleed brake system. Refer to proce-
dures in Service Adjustments section.
ROTOR REMOVAL
(1) Raise vehicle and remove wheel.
(2) Remove caliper.
(3) Remove retainers securing rotor to hub studs
(Fig. 26).
(4) Remove rotor from hub (Fig. 26).
(5) If rotor shield requires service, remove front
hub and bearing assembly.
ROTOR INSTALLATION
(1) If new rotor is being installed, remove protec-
tive coating from rotor surfaces with Mopar carb
cleaner.It is not necessary to machine a rotor to
remove the coating. Mopar carb cleaner fol-
lowed by a rinse with brake cleaner will re-
move the coating.
(2) Install rotor on hub.
(3) Install caliper.
Fig. 23 Installing Caliper Piston
Fig. 24 Seating Caliper Piston Dust Boot
Fig. 25 Front Brake Hose And Fitting Components
JDISC BRAKES 5 - 51

(4) Install new spring nuts on wheel studs.
(5) Install wheel and lower vehicle.
DISC BRAKE ROTOR THICKNESS
Rotor minimum usable thickness is 22.7 mm (0.89
in.). This dimension is either cast, or stamped on the
rotor hub, or outer edge.
Measure rotor thickness at the center of the brake-
shoe contact surface.
Replace the rotor if worn below minimum thick-
ness. Also replace the rotor if refinishing would re-
duce thickness below the allowable minimum.
DISC BRAKE ROTOR RUNOUT
Check rotor lateral runout whenever pedal pulsa-
tion, or rapid, uneven brakelining wear has occurred.
On 4-wheel drive models, the rotor must be se-
curely clamped to the hub to ensure an accurate
runout measurement. Secure the rotor with the
wheel nuts and 4 or 5 large diameter flat washers on
each stud as shown (Fig. 27).
Use a dial indicator to check lateral runout (Fig.
27).
Maximum allowable rotor lateral runout is 0.13
mm (0.005 in.).
Check lateral runout with a dial indicator (Fig. 28).
Excessive lateral runout will cause brake pedal pul-
sation and rapid, uneven wear of the brakeshoes.
Maximum allowable rotor runout for all models is
0.12 mm (0.005 in.).
DISC BRAKE ROTOR THICKNESS VARIATION
Variations in rotor thickness will cause pedal pul-
sation, noise and shudder.
Measure rotor thickness at four to six points
around the rotor face. Position the micrometer ap-
proximately 2 cm (3/4 in.) from the rotor outer cir-
cumference for each measurement (Fig. 29).
Thickness should notvaryby more than 0.013 mm
(0.0005 in.) from point-to-point on the rotor. Refinish
or replace the rotor if necessary.
Fig. 26 Rotor And HubFig. 27 Securing4x4Rotor For Lateral Runout Check
Fig. 28 Typical Method Of Checking Rotor Lateral
Runout
Fig. 29 Measuring Rotor Thickness Variation
5 - 52 DISC BRAKESJ

DISC BRAKE ROTOR REFINISHING
When To Refinish
Rotor braking surfaces can be refinished by sand-
ing and/or machining in a disc brake lathe. However,
the rotor should be cleaned and inspected before-
hand. Careful inspection will avoid refinishing rotors
with very little service life left in them.
Pay particular attention to rotors that are heavily
rusted, or corroded. Accumulated rust/corrosion on
braking surfaces and ventilating ribs may extend to
a depth beyond acceptable limits. This can be espe-
cially true on: (a) high mileage vehicles; (b) vehicles
regularly exposed to road salt during winter months;
(c) vehicles operated in coastal regions where salt air/
road splash is a factor; (d) and vehicles used for ex-
tensive off-road operation.
New rotors have a protective coating that should be
removed before installation.It is not necessary to
machine a rotor to remove this coating. The
coating is easily removed with Mopar carb
cleaner followed by a rinse with Mopar brake
cleaner. A scotch brite pad, or steel wool can
also be used to help loosen and remove the
coating if desired.
Recommended Refinishing Equipment
The brake lathe must be capable of machining both
rotor surfaces simultaneously with dual cutter heads
(Fig. 30).Equipment capable of machining only
one side at a time will produce a tapered rotor.
The lathe should also be equipped with a grinder at-
tachment, or dual sanding discs for final cleanup or
light refinishing.
Refinishing Techniques
If the rotor surfaces only need minor cleanup of
rust, scale, or scoring, use abrasive sanding discs to
clean up the rotor surfaces. However, when a rotor is
scored or worn, machining with cutting tools will be
required.
Light cuts are recommended when machining the
rotor surfaces. Heavy feed rates are not recom-
mended and may result in chatter marks, or taper.
CAUTION: Never refinish a rotor if machining would
cause the rotor to fall below minimum allowable
thickness.
The final finish on the rotor should be a non-direc-
tional, cross hatch pattern (Fig. 31). Use sanding
discs to produce this finish.
Fig. 30 Rotor Refinishing Equipment
JDISC BRAKES 5 - 53

WHEEL NUT TIGHTENING
The wheel attaching nuts must be tightened prop-
erly to ensure efficient brake operation. Overtighten-
ing the nuts or tightening them in the wrong
sequence can cause distortion of the brake rotors and
drums. Impact wrenches are not really recommended
for tightening wheel nuts. A torque wrench should be
used for this purpose.
A light coat of LPS Anti-Corrosion spray lube
around the hub face and on the studs will cut down
on rust/corrosion formation.The correct tightening sequence is important in
avoiding rotor and drum distortion. The correct se-
quence is in a diagonal crossing pattern (Fig. 32).
Recommended torque range for XJ/YJ wheel nuts
is 108-149 Nzm (80-110 ft. lbs.). Preferred set-to
torque is 129 Nzm (95 ft. lbs.) torque.
Seat the wheel and install the wheel nuts finger
tight. Tighten the nuts in the sequence to 1/2 the re-
quired torque. Then repeat the tightening sequence
to final specified torque.
Fig. 31 Preferred Rotor Surface Finish
Fig. 32 Wheel Nut Tightening Sequence
5 - 54 DISC BRAKESJ

DRUM BRAKES
INDEX
page page
Brake Drum Refinishing.................... 58
Drum Brake Adjustment.................... 57
Drum Brakeshoe Installation................. 55
Drum Brakeshoe Removal................... 55
Support Plate Replacement.................. 58Wheel Cylinder Installation.................. 58
Wheel Cylinder Overhaul.................... 57
Wheel Cylinder Removal.................... 57
Wheel Nut Tightening...................... 59
DRUM BRAKESHOE REMOVAL (Figs. 1 and 2)
(1) Raise vehicle and remove rear wheels.
(2) Remove and discard spring nuts securing
drums to wheel studs.
(3) Remove brake drums. If drums prove difficult
to remove, retract brakeshoes. Remove access plug at
the rear of backing plate and back off adjuster screw
with brake tool and screwdriver.
(4) Remove U-clip and washer securing adjuster
cable to parking brake lever.
(5) Remove primary and secondary return springs
from anchor pin with Brake Spring Plier Tool 8078.
(6) Remove holddown springs, retainers and pins
with standard retaining spring tool.
(7) Install spring clamps on wheel cylinders to hold
pistons in place.
(8) Remove adjuster lever, adjuster screw and
spring.
(9) Remove adjuster cable and cable guide.
(10) Remove brakeshoes and parking brake strut.(11) Disconnect cable from parking brake lever and
remove lever.
DRUM BRAKESHOE INSTALLATION
(1) Clean support plate with Mopar brake cleaner.
Replace support plate if worn, or rusted through at
any point. Do not attempt to salvage, or reuse a dam-
aged support plate.
(2) If new drums are being installed, remove pro-
tective coating with Mopar Carb cleaner followed by
final rinse with Mopar brake cleaner. A scotch brite
pad, or steel wool can also be used to help loosen and
remove coating if desired.It is not necessary to
machine drums to remove the coating.
(3) Clean and lubricate anchor pin with light coat
of Mopar multi-mileage grease.
(4) Apply Mopar multi-mileage grease to brakeshoe
contact surfaces of support plate (Figs. 3 and 4).
(5) Lubricate adjuster screw threads and pivot
with Mopar spray lube.
Fig. 1 Nine Inch Drum Brake Components
JDRUM BRAKES 5 - 55

(6) Attach parking brake lever to secondary brake-
shoe. Use new washer and U-clip to secure lever.
(7) Remove wheel cylinder clamps.
(8) Attach parking brake cable to lever.
(9) Install brakeshoes on support plate. Secure
shoes with new holddown springs, pins and retainers.
(10) Install parking brake strut and spring.
(11) Install guide plate and adjuster cable on an-
chor pin.
(12) Install primary and secondary return springs.
(13) Install adjuster cable guide on secondary shoe.
(14) Lubricate and assemble adjuster screw (Fig.
5).
(15) Install adjuster screw, spring and lever and
connect to adjuster cable.(16) Adjust shoes to drum as described in following
procedure.
(17) Install wheel/tire assemblies and lower vehi-
cle.
(18) Verify firm brake pedal before moving vehicle.
Fig. 2 Ten Inch Drum Brake Components
Fig. 3 Shoe Contact Surfaces (9-Inch Support Plate)
Fig. 4 Shoe Contact Surfaces (10-Inch Support
Plate)
5 - 56 DRUM BRAKESJ

DRUM BRAKE ADJUSTMENT
Rear drum brakes are equipped with a self adjust-
ing mechanism. Under normal circumstances, the
only time adjustment is required is when the shoes
are replaced, removed for access to other parts, or
when one or both drums are replaced.
The only tool needed for adjustment is a standard
brake gauge.
Adjustment is performed with the brakeshoes in-
stalled on the support plate. Procedure is as follows:
ADJUSTMENT PROCEDURE
(1) Raise and support vehicle rear end and remove
wheels and brake drums.
(2) Verify that left/right automatic adjuster lever
and cable are properly connected.
(3) Insert brake gauge in drum. Expand gauge un-
til gauge inner legs contact drum braking surface.
Then lock gauge in position (Fig. 6).
(4) Reverse gauge and install it on brakeshoes
(Fig. 6). Position gauge legs at shoe centers as
shown. If gauge does not fit (too loose or tight), ad-
just shoes.
(5) Pull shoe adjuster star wheel away from ad-
juster lever.(6) Turn adjuster star wheel (by hand) to expand
or retract brakeshoes. Continue adjustment until
gauge outside legs are light drag-fit on shoes (Fig. 7).
(7) Repeat adjustment at opposite brakeshoe as-
sembly.
(8) Install brake drums and wheels and lower ve-
hicle.
(9) Make final adjustment as follows:
(a) Drive vehicle and make one forward stop fol-
lowed by one reverse stop.
(b) Repeat procedure 8-10 times to actuate self
adjuster components and equalize adjustment.
(c)Bring vehicle to complete standstill at
each stop. Incomplete, rolling stops will NOT
activate adjuster mechanism.
WHEEL CYLINDER REMOVAL
(1) Raise vehicle and remove wheel.
(2) Disconnect brakeline at wheel cylinder.If cyl-
inder brakeline fitting is hard to break loose,
spray generous amount of Mopar Rust Pene-
trant between fitting and line and around fit-
ting threads in wheel cylinder. Note that it may
require a few minutes for penetrant to work.
(3) Remove brakeshoes.
(4) Remove bolts attaching wheel cylinder to sup-
port plate and remove cylinder.
WHEEL CYLINDER OVERHAUL (Figs. 8 and 9)
(1) Remove links.
(2) Remove dust boots.
(3) Remove cups and pistons. Discard cups.
(4) Remove and discard spring and expander.
(5) Remove bleed screw.
(6) Clean cylinder, pistons and links with Mopar
brake cleaner.
(7) Inspect cylinder bore and pistons. Light discol-
oration of bore is acceptable. However, replace cylin-
der if bore and pistons are scored, pitted, or corroded.
Fig. 5 Adjuster Screw Components (9-Inch Brake)
Fig. 6 Adjusting Gauge To Brake Drum
Fig. 7 Adjusting Brakeshoes To Gauge
JDRUM BRAKES 5 - 57

Do not hone cylinder bores or polish pistons.
Replace cylinder as an assembly if bore is dam-
aged.
(8) Install bleed screw.
(9) Coat cylinder bore, pistons, cups and expander
with brake fluid and reassemble cylinder compo-
nents. Be sure piston cup lips face expander.
WHEEL CYLINDER INSTALLATION
(1) Apply small bead of silicone sealer around cyl-
inder mounting surface of support plate.
(2) Start brakeline in wheel cylinder fitting by
hand.
(3) Align and seat wheel cylinder on support plate
(Fig. 10).
(4) Install cylinder mounting bolts (Fig. 10).
Tighten bolts to 10 Nzm (90 in. lbs.) torque.(5) Tighten brakeline fitting to 15 Nzm (132 in.
lbs.) torque.
(6) Install brakeshoes. Adjust shoes to drum with
brake gauge.
(7) Install brake drums and lower vehicle.
(8) Fill master cylinder and bleed brakes.
SUPPORT PLATE REPLACEMENT
The support plate should cleaned and inspected
whenever the drum brake components are being ser-
viced.
Check the support plate for wear, or rust through
at the contact pads and replace the plate if necessary.
Be sure to lubricate the contact pads with Mopar
multi-mileage grease before shoe installation. Lubri-
cation will avoid noisy operation and shoe bind.
(1) Raise vehicle and remove wheel/tire assembly.
(2) Remove brake drum, brakeshoes, and wheel
cylinder.
(3) Remove axle shaft as described in Group 3.
(4) Remove support plate attaching nuts and re-
move support plate.
(5) Clean axle tube flange. If gasket is not used on
flange, apply thin bead of silicone adhesive/sealer to
flange.
(6) Position new support plate on axle tube flange.
(7) Apply Mopar Lock N9Seal, or Loctite 242 to
support plate attaching nuts. Then install and
tighten nuts.
(8) Apply light coat of Mopar multi-mileage grease
to contact pads of new support plate.
(9) Install wheel cylinder and brakeshoes.
(10) Adjust brakeshoes to drums. Refer to proce-
dure in this section.
(11) Bleed brakes.
(12) Install wheel and tire assembly.
(13) Adjust parking brake cable tensioner. Refer to
procedure in Parking Brake section.
(14) Lower vehicle and verify proper service brake
and parking brake operation.
BRAKE DRUM REFINISHING
Brake drums can be machined to restore the brak-
ing surface. Use a brake lathe to clean up light scor-
ing and wear.
CAUTION: Never refinish a brake drum if machining
will cause the drum to exceed maximum allowable
brake surface diameter.
Brake drums that are warped, distorted, or se-
verely tapered should be replaced. Do not refinish
drums exhibiting these conditions. Brake drums that
are heat checked or have hard spots should also be
replaced.
Fig. 8 Wheel Cylinder (9-Inch Brake)
Fig. 9 Wheel Cylinder (10-Inch Brake)
Fig. 10 Wheel Cylinder Mounting
5 - 58 DRUM BRAKESJ