1995 JEEP YJ service

(6) Disconnect both flex brakelines at HCU (Fig. 18).
(7) Disconnect HCU solenoid harness from main
harness (Fig. 19).
(8) Disconnect HCU pump motor harness (Fig. 20).(9) If HCU mounting bracket will be left in place,
it will be necessary to remove HCU solenoid harness
connecter from mounting bracket. Remove connecter
fasteners, by squeezing them closed with needle nose
pliers; then pulling them out of bracket.
(10) Disconnect lines to front/rear brakes at lower
left side of HCU (Fig. 21).
(11) Remove HCU as follows:
(a) If only the HCU will be removed, remove
three shoulder bolts attaching HCU to mounting
bracket and remove HCU (Fig. 22).
(b) If HCU and bracket will be removed as as-
sembly, remove three nuts attaching HCU to stud
plate and remove HCU and bracket as assembly.
Fig. 18 Disconnecting Flex Lines From HCU
Fig. 19 Disconnecting HCU Solenoid Harness
Fig. 20 Disconnecting HCU Pump Harness
Fig. 21 HCU Front/Rear Brakeline Connections
Fig. 22 HCU Assembly
5 - 42 ABS OPERATION AND SERVICEJ

HCU INSTALLATION (XJ)
(1) Install HCU as follows:
(a) If only the HCU was removed, position HCU
in mounting bracket. Then install and tighten
three shoulder bolts that attach HCU to bracket
(Figs. 23 and 24). One bolt is used at forward end
of bracket and two at rear as shown.
(b) If HCU and bracket were removed as assem-
bly, position bracket on studs and install attaching
nuts. Tighten nuts to 10-13 Nzm (92-112 in. lbs.)
torque.
(c) On right hand drive models, If brackets were
removed, assemble brackets. Then position lower
bracket on body studs and install attaching nuts
and the one attaching bolt (Fig. 25).
(2) If HCU mounting bracket was not removed,
press solenoid harness connecter fasteners into
mounting bracket.
(3) Connect HCU pump motor and solenoid har-
nesses (Figs. 19 and 20).
(4) Connect brakelines from front/rear brakes to
HCU. Start brakeline fittings in HCU ports by handto avoid cross threading (Fig. 26). Then tighten line
fittings snug but not to required torque at this time.
(5) Connect flex lines to HCU (Fig. 18). Start
brakeline fittings in flex line ports by hand to avoid
cross threading. Then tighten line fittings snug but
not to required torque at this time.
(6) Bleed brakes. Refer to procedure in Brake Flu-
id-Brake Bleeding-Brakelines And Hoses section.
(7) Tighten brakeline fittings to following torques
after brake bleeding: 15- 18 Nzm (130-160 in. lbs.) at
HCU and master cylinder and 18-24 Nzm (160-210 in.
lbs.) at combination valve.
(8) Install engine air cleaner assembly and hoses.
(9) Connect vacuum lines to manifold fittings.
(10) Check brake pedal action before moving vehi-
cle. Bleed brakes again if pedal is not firm (feels soft/
spongy).
Fig. 23 Installing HCU Front Shoulder Bolt
Fig. 24 Installing HCU Rear Shoulder Bolts
Fig. 25 HCU And Bracket Mounting (RHD Models)
Fig. 26 Starting Brakelines In HCU (By Hand)
JABS OPERATION AND SERVICE 5 - 43

HCU REMOVAL (YJ)
(1) Place shop towels under master cylinder and
HCU brakelines.
(2) Disconnect flex lines at upper part of HCU.
(3) Disconnect solenoid and pump harness wires at
HCU harness connecters.
(4) Disconnect lines to front/rear brakes at lower
part of HCU.
(5) Remove shoulder bolts attaching HCU to
mounting bracket and remove HCU.
HCU INSTALLATION (YJ)
(1) Position HCU in mounting bracket (Fig. 27).
(2) Install shoulder bolts that attach HCU to
bracket.
(3) Connect brakelines to HCU. Start brakeline fit-
tings by hand to avoid cross threading. Tighten fit-
tings snug but not to torque at this time.
(4) Connect HCU pump and solenoid harness wires
to engine compartment harness.
(5) Fill and bleed brake system.
(6) Tighten brakeline fittings to 15-18 Nzm
(130-160 in. lbs.) at HCU and master cylinder, and to
18-24 Nzm (160-210 in. lbs.) at combination valve.
Fig. 27 HCU Mounting (YJ)
5 - 44 ABS OPERATION AND SERVICEJ

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

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

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

PARKING BRAKES
INDEX
page page
General Service Information................. 60
Parking Brake Cable Tensioner Adjustment (XJ/YJ).. 68
Parking Brake Cable Tensioner Replacement (XJ) . 65
Parking Brake Front Cable Replacement (YJ).... 67
Parking Brake Lever Installation (XJ with Full
Console).............................. 64
Parking Brake Lever Installation (XJ with Mini
Console).............................. 63
Parking Brake Lever Installation (XJ Without
Console).............................. 65Parking Brake Lever Removal (XJ with Full Console).63
Parking Brake Lever Removal (XJ with Mini
Console).............................. 62
Parking Brake Lever Removal (XJ Without Console).64
Parking Brake Operation.................... 60
Parking Brake Pedal Installation (YJ)........... 66
Parking Brake Pedal Removal (YJ)............ 66
Parking Brake Rear Cable Replacement (XJ)..... 66
Parking Brake Rear Cable Replacement (YJ)..... 68
Parking Brake Switch...................... 68
GENERAL SERVICE INFORMATION
Parking brake adjustment is controlled by a cable ten-
sioner mechanism.
The cable tensioner, once adjusted at the factory,
should not need further adjustment under normal
circumstances. There are only two instances when
adjustment is required. The first is when a new ten-
sioner, or cables have been installed. And the second,
is when the tensioner and cables are disconnected for
access to other brake components.
PARKING BRAKE OPERATION
The rear brakes are utilized for the parking brake
function. They are actuated hydraulically during nor-
mal brake operation but are mechanically actuated
for parking brake operation.
Parking Brake Components
The rear brakeshoes are applied by a system of le-
vers and cables for parking brake operation. A foot or
hand operated lever in the passenger compartment is
the main application device. Actuating levers on the
Fig. 1 Parking Brake Components (YJ)
5 - 60 PARKING BRAKESJ