PDF Service Manual 1996 Jeep Grand Cherokee - 4 MB
This is the official service manual for the 1996 Jeep Grand Cherokee, including the supplement.
It provides comprehensive, factory-authorized procedures for repair and maintenance.
The guide covers everything from the engine and transmission to the electrical system and bodywork.
It's the same manual used by dealership technicians, making it an invaluable resource for both professional mechanics and dedicated owners.
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--- Page 1 ---
CHRYSLER
CORPORATION
SERVICE MANUAL and SUPPLEMENT
1996 JEEPT
GRAND CHEROKEE
To order the special service tools used and
illustrated, please refer to the instructions on
inside back cover.
NO PART OF THIS PUBLICATION MAY BE
REPRODUCED, STORED IN A RETRIEVAL SYS-
TEM, OR TRANSMITTED, IN ANY FORM OR BY
ANY MEANS, ELECTRONIC, MECHANICAL,
PHOTOCOPYING, RECORDING, OR OTHERWISE,
WITHOUT THE PRIOR WRITTEN PERMISSION
OF CHRYSLER CORPORATION.
Chrysler Corporation reserves the right to make changes in design or to
make additions to or improvements in its products without imposing any obli-
gations upon itself to install them on its products previously manufactured.
Litho in U.S.A. Copyright © 1995 Chrysler Corporation 15M0895
NEXT PAGE ©
--- Page 3 ---
0-2 LUBRICATION AND MAINTENANCE ZJ
GENERAL INFORMATION (Continued)
Fig. 3 NLGI Symbol
Fig. 2 API Symbol FLUID CAPACITIES
ENGINE OIL FUEL TANK
SAE GRADE RATING INDICATES ENGINE OIL VISCOSITY
All. . . . . . . . . . . . . . . . . . . . . . . . . . . .87.4 L (23 gal.)
An SAE viscosity grade is used to specify the vis-
cosity of engine oil. SAE 30 specifies a single viscos- ENGINE OIL W/FILTER CHANGE
ity engine oil. Engine oils also have multiple
viscosities. These are specified with a dual SAE vis- 4.0L . . . . . . . . . . . . . . . . . . . . . . . . . . .5.7 L (6.0 qts.)
cosity grade which indicates the cold-to-hot tempera- 5.2L . . . . . . . . . . . . . . . . . . . . . . . . . . .4.7 L (5.0 qts.)
ture viscosity range. COOLING SYSTEM
• SAE 30 = single grade engine oil.
• SAE 10W-30 = multiple grade engine oil. 4.0L . . . . . . . . . . . . . . . . . . . . . . . .11.4 L (12.0 qts.)*
5.2L . . . . . . . . . . . . . . . . . . . . . . . .14.1 L (14.9 qts.)*
API QUALITY CLASSIFICATION
*Includes 2.2 L (2.3 qts.) for coolant recovery bot-
The API Service Grade specifies the type of perfor-
tle.
mance the engine oil is intended to provide. The API
Service Grade specifications also apply to energy con- AUTOMATIC TRANSMISSION
serving engine oils.
Use engine oil that is API Service Grade Certified Dry fill capacity.*
or an oil that conforms to the API Service Grade SH
or SH/CD. MOPAR engine oils conform to all of these 42RE . . . . . . . . . . . . . . . . . . . .8.0-10.4 L (17-22 pts.)
service grades. 44RE . . . . . . . . . . . . . . . . . . . .8.0-10.4 L (17-22 pts.)
Refer to Group 9, Engine for engine oil specifica- *Depending on type and size of internal cooler,
tion. length and inside diameter of cooler lines, or use of
an auxiliary cooler, these figures may vary. Refer to
GEAR LUBRICANTS Group 21, Transmission for proper fluid fill proce-
SAE ratings also apply to multiple grade gear dure.
lubricants. In addition, API classification defines the
lubricants usage. FRONT AXLE
LUBRICANTS AND GREASES Model 30 . . . . . . . . . . . . . . . . . . . . .1.48 L (3.13 pts.)
Lubricating grease is rated for quality and usage REAR AXLE
by the NLGI. All approved products have the NLGI
symbol (Fig. 3) on the label. At the bottom NLGI Model 44* . . . . . . . . . . . . . . . . . . . .2.24 L (4.75 pts.)
symbol is the usage and quality identification letters.
*If the vehicle is equipped with TRAC-LOK,
Wheel bearing lubricant is identified by the letter
include 0.11 L (0.25 pts.) of friction modifier.
“G”. Chassis lubricant is identified by the latter “L”.
The letter following the usage letter indicates the NOTE: Vehicles with trailer tow, must use a syn-
quality of the lubricant. The following symbols indi- thetic lubricant. Refer to Group 3, Differential and
cate the highest quality. Driveline for service procedures.
--- Page 4 ---
2-4 SUSPENSION ZJ
1996 Grand Cherokee
SERVICE PROCEDURES (Continued) Publication No. 81-370-6147
TSB 26-04-96 April, 1996
Fig. 2 Drag Link and Tie Rod Clamp
Fig. 1 Cam Adjuster
TOE POSITION
The toe position adjustment should be the last
adjustment made.
NOTE: The engine must remain running during the
entire toe position adjustment.
(1) Apply parking brakes.
(2) Start the engine and turn wheels both ways
before straightening the steering wheel. Center and Fig. 3 Steering Linkage—6 Cylinder Engine
secure the steering wheel.
(3) Loosen the adjustment sleeve clamp bolts (Fig. 2).
(4) Adjust the right wheel toe position with the
drag link (Fig. 3) and (Fig. 4). Turn the sleeve until
the right wheel is at the correct positive TOE-IN
position. Position the clamp bolts as shown (Fig. 2)
and tighten to 49Nzm (36 ft. lbs.).
NOTE: Tighten clamp bolt nearest the pitman arm
first. Make sure the toe setting does not change
during clamp tightening.
(5) Adjust the left wheel toe position with the tie rod.
Turn the sleeve until the left wheel is within .05°
TOE-IN position as the right wheel. Position the clamp
bolts as shown (Fig. 2) and tighten to:
• Vehicles with 6 cyl engine: 27 Nzm (20 ft. lbs.) Fig. 4 Steering Linkage—8 Cylinder Engine
• Vehicles with 8 cyl engine: 49 Nzm (36 ft. lbs.)
--- Page 5 ---
3-2 DIFFERENTIAL AND DRIVELINE ZJ
GENERAL INFORMATION (Continued)
Fig. 1 Front & Rear Propeller Shafts—Typical 4WD
which eliminates the need for a slip yoke. The CV
joint has a splined shaft which allows the overall
shaft length to be adjusted for optimum joint travel.
This spline shaft is locked in place with a nut. Never
attempt to adjust the shaft length. The overall
shaft length is preset during manufacturing.
Fig. 3 Single Cardan U-Joint —Rear
Fig. 2 Front Propeller Shaft PRECAUTIONS
Use exact replacement hardware for attaching the
UNIVERSAL JOINTS propeller shafts. Exact replacement will ensure safe
Three different types of universal joints are used operation. The specified torque must always be
(Fig. 3), (Fig. 4) and (Fig. 5). These joints are not applied when tightening the fasteners.
repairable if worn or damaged they must be replaced. Put reference marks on the propshaft yoke and
If a vehicle has a damaged constant velocity joint or axle or transmission yoke before service (Fig. 6). This
boot (Fig. 5), the propeller shaft must be replaced. will assure correct phasing and eliminate possible
vibration.
LUBRICATION
The slip yoke on the Type 1 front shaft is equipped CAUTION: Do not allow the propeller shaft to drop
with a lubrication fitting. Use a multi-purpose NLGI or hang from either universal joint during removal.
Grade 2 EP lubricant.The factory installed U-joints Attach it to the vehicle underside with wire to pre-
are lubricated for the life of the vehicle and do not vent damage to the universal joints.
need lubrication. All U-joints should be inspected for
leakage and damage each time the vehicle is ser-
viced. If seal leakage or damage exists, the U–joint CAUTION: It is very important to protect the
should be replaced. machined, external surface of the slip yoke from
damage after propeller shaft removal. If damaged,
the transmission extension seal could be damaged
and cause a leak.
--- Page 6 ---
3 - 16 DIFFERENTIAL AND DRIVELINE ZJ
GENERAL INFORMATION (Continued)
• The factory installed lubricant quantity for the
non–disconnect type axle is 1.48 L (3.13 pts.).
• The factory installed lubricant quantity for the
vacuum–disconnect type axle is 1.65 L (3.76 pts.).
Refer to Group 0, Lubrication and Maintenance for
additional information regarding temperature range,
viscosity and fluid level.
CAUTION: If axle is submerged in water, lubricant
must be replaced immediately to avoid possible
premature axle failure.
PINION GEAR DEPTH INFORMATION
Ring and pinion gears are supplied as matched
sets only. The identifying numbers for the ring and
pinion gear are etched into the face of each gear (Fig. Fig. 2 Pinion Gear Head
1). A plus (+) number, minus (–) number or zero (0) is
etched into the face of the pinion gear. This number and the thickness included with the total shim
is the amount (in thousandths of an inch) the depth pack.
varies from the standard depth setting of a pinion
etched with a (0). The standard setting from the cen-
terline of the ring gear to the back face of the pinion
is 92.1 mm (3.625 inches) for Model 30 axles (Fig. 2).
The standard depth provides the best teeth contact
pattern.
Fig. 3 Shim Locations
Fig. 1 Pinion Gear ID Numbers
New gear set: note the depth variance etched
THE BUTTON END ON THE PINION GEAR
into both the original and the replacement pin-
HEAD IS NO LONGER A MACHINED–TO– SPECI-
ion gear. Add or subtract the thickness of the
FICATIONS SURFACE. DO NOT USE THIS SUR-
original depth shims to compensate for the dif-
FACE FOR PINION DEPTH SET–UP OR
ference in the depth variances. Refer to the
CHECKING (Fig. 2).
Depth Variance charts.
Compensation for depth variance is achieved by a
Note where Old and New Pinion Marking columns
selected thickness oil slinger (production) or shims
intersect. Intersecting figure represents plus or
(service). The slinger is placed between the inner pin-
minus amount needed.
ion bearing cone and gear head (Fig. 3). The shim
For example, if old pinion is plus (+) 1 and the new
pack is placed under the inner (rear) bearing cup for
pinion is minus (–) 3, intersecting figure is (+) 0.004
service. To change the pinion adjustment, shims are
in. (0.10 mm). Add this amount to the original shim.
available in thicknesses of 0.003, 0.005, and 0.010
Or if the old pinion is (–) 3 and the new pinion is (–)
inch. The oil slinger or baffle must be measured
--- Page 7 ---
3 - 30 DIFFERENTIAL AND DRIVELINE ZJ
REMOVAL AND INSTALLATION (Continued)
(8) Install the yoke washer and old nut on the • Original Bearings: 1 to 3 N·m (10 to 20 in. lbs.).
pinion gear. Use Holder 6958 to retain the yoke (Fig. • New Bearings: 2 to 5 N·m (15 to 35 in. lbs.).
28). Tighten nut to 216– 352 N·m (160–260 ft. lbs.) (10) If rotating torque is high, add shims to
torque. decrease torque. If rotating torque is low, remove
shims to increase torque.
DISASSEMBLY AND ASSEMBLY
AXLE SHAFT—CARDAN U-JOINT
DISASSEMBLY
Single cardan U–joints are not serviceable. If defec-
tive, they must be replaced as a unit. If the bearings,
seals, spider or bearing caps are damaged or worn,
replace the complete U–joint.
CAUTION: Clamp only the forged portion of the
yoke in the vise. Also, to avoid distorting the yoke,
do not over tighten the vise jaws.
(1) Remove the bearing cap retaining snap rings
(Fig. 30).
Fig. 28 Tightening Pinion Nut
(9) Check bearing rotating torque with an inch
pound torque wrench (Fig. 29). If torque to rotate is
within specification, remove old nut and install new
nut. The torque necessary to rotate the pinion gear
should be;
Fig. 30 Axle Shaft Outer U–Joint
It can be helpful to saturate the bearing caps
with penetrating oil prior to removal.
(2) Locate a socket that is larger in diameter than
the bearing cap. Place the socket (receiver) against
the yoke and around the perimeter of the bearing cap
to be removed. Locate a socket that is smaller in
diameter than the bearing cap. Place the socket
(driver) against the opposite bearing cap. Position the
yoke with the sockets in a vise (Fig. 31).
(3) Compress the vise jaws to force the bearing cap
into the larger socket (receiver).
Fig. 29 Check Pinion Gear Torque
--- Page 8 ---
3 - 44 DIFFERENTIAL AND DRIVELINE ZJ
GENERAL INFORMATION (Continued)
CAUTION: If axle is submerged in water, lubricant
must be replaced immediately to avoid possible
premature axle failure.
DESCRIPTION AND OPERATION
AXLES
The Model 35 axle is standard for XJ vehicles. The
8 1/4 axle is available in XJ vehicles without ABS
brakes.
The Model 35 and 8 1/4 axle housings has a cast
iron center section. Two steel axle shaft tubes are
pressed into the differential housing and welded.
It is not necessary to remove the axle from the
vehicle for service. A removable differential cover is
provided for routine vehicle service. If the differential
housing is damaged, the complete axle assembly can
be removed.
For complete drive axle assembly removal and
installation refer to Drive Axle Assembly Replace-
ment in this Group. Fig. 1 Model 35 Differential Cover
IDENTIFICATION
Model 35 axle has the assembly part number and
gear ratio listed on a tag. The tag is attached to the
left side of the housing cover (Fig. 1). Build date
identification codes on axles are stamped on the axle
shaft tube cover side. The Model 35 axle has a flat
housing cover gasket flange at the outer edge (Fig.
1).
The 8 1/4 axle has the build date code and gear
ratio tags attached to the housing cover (Fig. 2). The
housing cover gasket has a rolled gasket flange at
the outer edge (Fig. 2).
• The Model 35 axle has shaft tubes that are
2.625 inch (66.67 mm) in diameter.
• The 8 1/4 axle has axle shaft tubes that are
3.0–inch (76.2 mm) in diameter.
STANDARD DIFFERENTIAL OPERATION
The differential gear system divides the torque
between the axle shafts. It allows the axle shafts to
rotate at different speeds when turning corners.
Each differential side gear is splined to an axle
shaft. The pinion gears are mounted on a pinion Fig. 2 Differential Cover–8 1/4
mate shaft and are free to rotate on the shaft. The • The side gears (splined to the axle shafts) rotate
pinion gear is fitted in a bore in the differential case the shafts
and is positioned at a right angle to the axle shafts. During straight- ahead driving, the differential
In operation, power flow occurs as follows: pinion gears do not rotate on the pinion mate shaft.
• The pinion gear rotates the ring gear This occurs because input torque applied to the gears
• The ring gear (bolted to the differential case) is divided and distributed equally between the two
rotates the case side gears. As a result, the pinion gears revolve with
• The differential pinion gears (mounted on the the pinion mate shaft but do not rotate around it
pinion mate shaft in the case) rotate the side gears (Fig. 3).
--- Page 9 ---
3 - 58 DIFFERENTIAL AND DRIVELINE ZJ
REMOVAL AND INSTALLATION (Continued)
(8) Remove the collapsible preload spacer (Fig. 29). PINION GEAR INSTALLATION
(1) Install the pinion rear bearing cup with
Installer C—4308 and Driver Handle C–4171 (Fig.
31). Ensure cup is correctly seated.
Fig. 29 Collapsible Spacer
(9) Remove the inner bearing from the pinion with
Puller C–293PA and Adapter C–293–39 (Fig. 30). Fig. 31 Pinion Rear Bearing Cup Installation
Place adapter rings so they do not damage
the bearing cage. (2) Install the pinion front bearing cup with
Installer D–129 and Handle C–4171 (Fig. 32).
Fig. 32 Pinion Front Bearing Cup Installation
Fig. 30 Inner Bearing Removal
(10) Remove the depth shims from the pinion gear
shaft. Record the thickness of the depth shims.
--- Page 10 ---
3 - 72 DIFFERENTIAL AND DRIVELINE ZJ
SPECIAL TOOLS (Continued)
Dial Indicator—C-3339 Arbor, Pinion—W-115-3
Installer—D-130
Driver—C-3716-A
Installer—D-146
Handle—C-4171
Remover—D-147
Trac-lok Tool—C-4487
--- Page 11 ---
3 - 86 DIFFERENTIAL AND DRIVELINE ZJ
REMOVAL AND INSTALLATION (Continued)
(5) Separate the housing enough to remove the (6) Install case in the housing. Tap the differential
case from the housing. Measure the distance with the case to ensure the bearings are fully seated (Fig. 18).
dial indicator (Fig. 16). Remove the spreader.
(6) Remove the dial indicator.
(7) Pry the differential case loose from the hous-
ing. To prevent damage, pivot on housing with the
end of the pry bar against spreader (Fig. 17).
Fig. 18 Differential Installation
(7) Install the bearing caps at their original loca-
tions (Fig. 19). Tighten the bearing cap bolts to 77
N·m (57 ft. lbs.) torque.
Fig. 17 Differential Removal
(8) Remove the case from housing. Mark or tag
bearing cups and outboard shim/spacer (selected
thickness) indicating which side they were removed.
DIFFERENTIAL INSTALLATION
(1) Position Spreader W–129–B with the tool dowel
pins seated in the locating holes (Fig. 16). Install the
hold down clamps and tighten the tool turnbuckle
finger–tight.
(2) Install a pilot stud at the left side of the differ-
ential housing. Attach Dial Indicator to housing pilot
stud. Load the indicator plunger against the opposite
side of the housing (Fig. 16) and zero the indicator.
CAUTION: Do not spread over 0.38 mm (0.015 in). If
the housing is over–separated, it could be distorted
or damaged. Fig. 19 Differential Bearing Cap Reference Letters
(3) Separate the housing enough to install the case
in the housing. Measure the distance with the dial
indicator (Fig. 16).
(4) Remove the dial indicator.
(5) Install differential and outboard shim/spacer
(selected thickness) in housing.
--- Page 12 ---
3 - 100 DIFFERENTIAL AND DRIVELINE ZJ
ADJUSTMENTS (Continued)
The differential bearings must be preloaded
to compensate for heat and load during opera-
tion.
(9) Add an additional 0.004–in. (0.1 mm) to each
outboard shim/spacer for bearing preload.
(10) Remove differential from axle housing.
(11) Remove dummy bearings.
(12) Install new side bearing cones and cups.
(13) Install ring gear.
(14) Install differential and verify gear lash and
contact pattern.
(15) Proceed to Final Assembly paragraph in this
section.
GEAR BACKLASH AND CONTACT PATTERN
ANALYSIS
After installing new side bearings or ring and pin-
ion set adjusting the bearing perload and gear mash
backlash will be necessary.
(1) Rotate assembly several revolutions to seat
bearings. Measure backlash at three equally spaced
locations around the perimeter of the ring gear with
a dial indicator (Fig. 63). Fig. 64 Backlash Shim Adjustment
(2) Apply a thin coat of hydrated ferric oxide, or
equivalent, to the drive and coast side of the ring
gear teeth.
(3) Rotate the ring gear one complete revolution in
both directions while a load is being applied. Insert a
pry bar between the differential housing and the case
flange. This will produce distinct contact patterns on
both the drive side and coast side of the ring gear
teeth.
(4) Note patterns in compound. Refer to (Fig. 65)
for interpretation of contact patterns and adjust
accordingly.
SPECIFICATIONS
MODEL 44 AXLE
Fig. 63 Ring Gear Backlash Measurement
The ring gear backlash must be within 0.12 – DESCRIPTION SPEC.
0.20 mm (0.005 – 0.008 in.). It cannot vary more Type . . . . . . . . . . . . . . . . . . . . .Semi-floating Hypoid
than 0.05 mm (0.002 in.) between the points Axle Ratios. . . . . . . . . . . . . . . . . . . . . . . . .3.55/3.73
checked. Ring Gear Diameter . . . . . . . . . . .216 mm (8.5 in.)
If backlash must be adjusted, spacers are available Gear Backlash . . . .0.13–0.20 mm (0.005–0.008 in.)
in various thicknesses. Adjust the backlash accord- Pinion Depth . . . . . . . . . . . . .109.52 mm (4.312 in.)
ingly (Fig. 64). Do not increase the total shim Brg. Perload, Pinion (New) . . . . . . .2.26–4.52 N·m
pack thickness, excessive bearing preload and (20–40 in. lbs.)
damage will occur. Maximum Carrier Spread. . . . .0.51 mm (0.020 in.
The ring gear teeth contact patterns will show if
the pinion gear depth shim(s) have the correct thick-
ness. It will also show if the ring gear backlash has
been adjusted correctly. The backlash must be main-
tained within the specified limits until the correct
tooth contact patterns are obtained.
--- Page 13 ---
3 - 10 DIFFERENTIAL AND DRIVELINE ZJ
REMOVAL AND INSTALLATION (Continued)
COLLAPSIBLE SPACER
REMOVAL W/PINION INSTALLED
(1) Raise and support the vehicle.
(2) Remove wheel and tire assemblies.
(3) Remove rear brake rotors and calipers. Refer to
Group 5, Brakes, for proper procedures.
(4) Mark the propeller shaft and pinion yoke for
installation reference.
(5) Remove the propeller shaft from the yoke.
(6) Rotate the pinion gear three or four times.
(7) Measure the amount of torque necessary to
rotate the pinion gear with an in. lbs. dial-type
torque wrench. Record the torque reading for instal-
lation reference.
(8) Using a short piece of pipe and Holder 6958 to
hold the pinion yoke, remove the pinion nut and Fig. 14 Pinion Yoke Removal
washer (Fig. 13).
(9) Use Remover C-452 and Wrench C-3281 to
remove the pinion yoke (Fig. 14).
(10) Use Remover 7794-A and slide hammer to
remove the pinion shaft seal (Fig. 15).
(11) Remove the front pinion bearing using a pair
of suitable pick tools to pull the bearing straight off
the pinion gear shaft. It may be necessary to lightly
tap the end of the pinion gear with a rawhide or rub-
ber mallet if the bearing becomes bound on the pin-
ion shaft.
(12) Remove the collapsible spacer.
Fig. 15 Seal Removal
(8) Remove differential assembly from axle hous-
ing.
(9) Using Holder 6958 to hold yoke and a short
length of 1 in. pipe, remove the pinion yoke nut and
washer (Fig. 13).
(10) Using Remover C–452 and Wrench C–3281,
remove the pinion yoke from pinion shaft (Fig. 14).
Fig. 13 Pinion Yoke Holder (11) Remove the pinion gear from housing (Fig.
16). Catch the pinion with your hand to prevent it
REMOVAL W/PINION REMOVAL from falling and being damaged.
(1) Raise and support the vehicle. (12) Remove collapsible spacer from pinion shaft.
(2) Remove wheel and tire assemblies.
(3) Remove rear brake rotors and calipers. Refer to INSTALLATION
Group 5, Brakes, for proper procedures. (1) Install a new collapsible preload spacer on pin-
(4) Mark the propeller shaft and pinion yoke for ion shaft (Fig. 17).
installation reference. (2) If pinion gear was removed, install pinion gear
(5) Remove the propeller shaft from the yoke. in housing.
(6) Rotate the pinion gear three or four times. (3) Install pinion front bearing. Apply a light coat-
(7) Measure the amount of torque necessary to ing of gear lubricant on the lip of pinion seal. Install
rotate the pinion gear with an in. lbs. dial-type seal with Installer D–163 and Handle C–4171 (Fig.
torque wrench. Record the torque reading for instal- 18).
lation reference.
--- Page 14 ---
3 - 24 DIFFERENTIAL AND DRIVELINE ZJ
DISASSEMBLY AND ASSEMBLY (Continued)
Fig. 62 Side Gear & Clutch Disc Removal Fig. 64 Clutch Discs & Lower Side Gear Installation
Fig. 65 Upper Side Gear & Clutch Disc Pack
Installation
Fig. 63 Clutch Disc Pack tighten the forcing screw in order to install the pin-
ion gears.
(7) Hold assembly in position. Insert Threaded
(12) Tighten forcing screw to 122 N·m (90 ft. lbs.)
Adapter C–4487–3 into top side gear.
to compress the Belleville springs.
(8) Insert Forcing Screw C–4487–2.
(13) Lubricate and install thrust washers behind
(9) Tighten forcing screw tool to slightly compress
pinion gears and align washers with a small screw
clutch discs.
driver. Insert mate shaft into each pinion gear to ver-
(10) Place pinion gears in position in side gears
ify alignment.
and verify that the pinion mate shaft hole is aligned.
(14) Remove forcing screw, threaded adapter, and
(11) Rotate case with Turning Bar C–4487–4 until
step plate.
the pinion mate shaft holes in pinion gears align
(15) Install pinion gear mate shaft and align holes
with holes in case. It may be necessary to slightly
in shaft and case.
--- Page 15 ---
5-4 BRAKES ZJ
DESCRIPTION AND OPERATION (Continued)
Fig. 2 Master Cylinder
pressure in the separate front/rear brake hydraulic
circuits.
A decrease or loss of fluid pressure in either
hydraulic circuit will cause the switch valve to shut-
tle to the low pressure side. Movement of the valve
pushes the switch plunger upward. This action closes
the switch internal contacts completing the electrical Fig. 3 Brake Caliper Operation
circuit to the red warning light. The switch valve will Application and release of the brake pedal gener-
remain in an actuated position until repairs are ates only a very slight movement of the caliper and
made. piston. Upon release of the pedal, the caliper and pis-
The rear proportioning valve is used to balance ton return to a rest position. The brakeshoes do not
front-rear brake action. The valve allows normal retract an appreciable distance from the rotor. In
fluid flow during moderate effort brake stops. The fact, clearance is usually at, or close to zero. The rea-
valve only controls (meters) fluid flow during high sons for this are to keep road debris from getting
effort brake stops. between the rotor and lining and in wiping the rotor
surface clear each revolution.
FRONT DISC BRAKES The caliper piston seal controls the amount of pis-
The calipers are a single piston type. The calipers ton extension needed to compensate for normal lining
are free to slide laterally, this allows continuous com- wear.
pensation for lining wear. During brake application, the seal is deflected out-
When the brake are applied fluid pressure is ward by fluid pressure and piston movement (Fig. 4).
exerted against the caliper piston. The fluid pressure When the brakes (and fluid pressure) are released,
is exerted equally and in all directions. This means the seal relaxes and retracts the piston.
pressure exerted against the caliper piston and The amount of piston retraction is determined by
within the caliper bore will be equal (Fig. 3). brakelining wear. Generally the amount is just
Fluid pressure applied to the piston is transmitted enough to maintain contact between the piston and
directly to the inboard brakeshoe. This forces the inboard brakeshoe.
shoe lining against the inner surface of the disc
brake rotor. At the same time, fluid pressure within REAR DISC BRAKES