1994 JEEP CHEROKEE dimensions

Brake drag also has a direct effect on fuel economy.
If undetected, minor brake drag can be misdiagnosed
as an engine or transmission/torque converter prob-
lem.
Minor drag will usually cause slight surface char-
ring of the lining. It can also generate hard spots in
rotors and drums from the overheat/cool down pro-
cess. In most cases, the rotors, drums, wheels and
tires are quite warm to the touch after the vehicle is
stopped.
Severe drag can char the brake lining all the way
through. It can also distort and score rotors and
drums to the point of replacement. The wheels, tires
and brake components will be extremely hot. In se-
vere cases, the lining may generate smoke as it chars
from overheating.
An additional cause of drag involves the use of in-
correct length caliper mounting bolts. Bolts that are
too long can cause a partial apply condition. The cor-
rect caliper bolts have a shank length of 67 mm
(2.637 in.), plus or minus 0.6 mm (0.0236 in.). Refer
to the Disc Brake service section for more detail on
caliper bolt dimensions and identification.
Some common causes of brake drag are:
²loose or damaged wheel bearing
²seized or sticking caliper or wheel cylinder piston
²caliper binding on bushings or slide surfaces
²wrong length caliper mounting bolts (too long)
²loose caliper mounting bracket
²distorted brake drum or shoes
²rear brakeshoes binding on worn/damaged support
plates
²severely rusted/corroded components
²misassembled components.
If brake drag occurs at all wheels, the problem may
be related to a blocked master cylinder compensator
port or faulty power booster (binds-does not release).
The brakelight switch can also be a cause of drag.
An improperly mounted or adjusted brakelight
switch can prevent full brake pedal return. The re-
sult will be the same as if the master cylinder com-
pensator ports are blocked. The brakes would be
partially applied causing drag.
BRAKE FADE
Brake fade is a product of overheating caused by
brake drag. However, overheating and subsequent
fade can also be caused by riding the brake pedal,
making repeated high deceleration stops in a short
time span, or constant braking on steep roads. Refer
to the Brake Drag information in this section for
causes.
PEDAL PULSATION
Pedal pulsation is caused by components that are
loose, or beyond tolerance limits.
Disc brake rotors with excessive lateral runout or
thickness variation, or out of round brake drums arethe primary causes of pulsation. Other causes are
loose wheel bearings or calipers and worn, damaged
tires.
PULL
A front pull condition could be the result of:
²contaminated lining in one caliper
²seized caliper piston
²binding caliper
²wrong caliper mounting bolts (too long)
²loose caliper
²loose or corroded mounting bolts
²improper brakeshoes
²damaged rotor
²incorrect wheel bearing adjustment (at one wheel)
A worn, damaged wheel bearing or suspension
component are further causes of pull. A damaged
front tire (bruised, ply separation) can also cause
pull. Wrong caliper bolts (too long) will cause a par-
tial apply condition and pull if only one caliper is in-
volved.
A common and frequently misdiagnosed pull condi-
tion is where direction of pull changes after a few
stops. The cause is a combination of brake drag fol-
lowed by fade at the dragging brake unit.
As the dragging brake overheats, efficiency is so
reduced that fade occurs. If the opposite brake unit is
still functioning normally, its braking effect is mag-
nified. This causes pull to switch direction in favor of
the brake unit that is functioning normally.
When diagnosing a change in pull condition, re-
member that pull will return to the original direction
if the dragging brake unit is allowed to cool down
(and is not seriously damaged).
REAR BRAKE GRAB
Rear grab (or pull) is usually caused by contami-
nated lining, bent or binding shoes and support
plates, or improperly assembled components. This is
particularly true when only one rear wheel is in-
volved. However, when both rear wheels are affected,
the master cylinder or proportioning valve could be
at fault.
BRAKES DO NOT HOLD AFTER DRIVING
THROUGH DEEP WATER PUDDLES
This condition is generally caused by water soaked
lining. If the lining is only wet, it can be dried by
driving with the brakes lightly applied for a mile or
two. However, if the lining is both wet and dirty, dis-
assembly and cleaning will be necessary.
BRAKE FLUID CONTAMINATION
There are two basic causes of brake fluid contami-
nation. The first involves allowing dirt, debris, or
other liquid materials to enter the cylinder reservoirs
JBRAKES 5 - 9

(8) Install and tighten caliper mounting 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 will contact the inboard
brakeshoe causing a partial apply condition. Refer
to Figure 14 for required caliper bolt length.
(9) Install wheels. Tighten lug nuts to 102 Nzm (75
ft. lbs.) torque.
(10) Pump brake pedal until caliper pistons and
brakeshoes are seated.
(11) Top off brake fluid level if necessary. Use Mo-
par brake fluid or equivalent meeting SAE J1703
and DOT 3 standards only.
CALIPER REMOVAL
(1) Raise vehicle and remove front wheels.
(2) Remove caliper mounting bolts (Fig. 4).(3) Rotate caliper rearward by hand or with pry
tool (Fig. 5). Then rotate caliper and brakeshoes off
mounting ledges.
(4) Remove caliper hose fitting bolt and disconnect
front brake hose at caliper. Discard fitting bolt wash-
ers. They are not reusable and should be replaced.
(5) Remove caliper from vehicle.
CALIPER DISASSEMBLY
(1) Remove brakeshoes from caliper.
(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).
Fig. 11 Installing Inboard Brakeshoe
Fig. 12 Installing Outboard Brakeshoe
Fig. 13 Caliper Installation
Fig. 14 Caliper Mounting Bolt Dimensions
JBRAKES 5 - 27

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 (plastic material) and should be
smooth and clean. Replace the piston if cracked,
chipped, or scored. Do not attempt to restore a
scored, or corroded piston surface by sanding or pol-
ishing. The piston must be replaced 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 sili-
cone grease if necessary.
Inspect condition of the caliper mounting bolts. Re-
place the bolts if corroded, rusted, or worn. Do not re-
use 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 in-
board brakeshoe causing drag and pull. Refer to the
caliper and brakeshoe installation procedures for ser-
vice details 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) Apply light coat of GE 661, Dow 111, or Per-
matex silicone grease to indicated areas (circumfer-
Fig. 20 Installing Bushings And Boots
Fig. 21 Installing Piston Seal
Fig. 22 Installing Dust Boot On Piston
Fig. 23 Installing Caliper Piston
JBRAKES 5 - 29

ENGINE STARTER MOTOR SERVICE PROCEDURES
INDEX
page page
2.5L Starter General Information.............. 4
2.5L Starter Motor Removal/Installation......... 5
4.0L Starter General Information.............. 6
4.0L Starter Motor Removal/Installation......... 6General Information........................ 4
Park/Neutral Position Switch................. 6
Starter Relay Replacement.................. 4
GENERAL INFORMATION
This section will cover the starting system compo-
nent service procedures only. For diagnostic proce-
dures, refer to Group 8A - Battery/Starting/Charging
Systems Diagnostics.
Starting system components: battery, starter mo-
tor, starter relay, starter solenoid, ignition switch,
connecting wires and battery cables. A park/neutral
position switch is used with automatic transmissions.
STARTER RELAY REPLACEMENT
The starter relay is located in the Power Distribu-
tion Center (Figs. 1 and 2). Refer to underside of
Power Distribution Center cover for relay location.
(1) Disconnect negative cable from battery.
(2) Replace relay.
(3) Connect negative cable to battery.
(4) Test relay operation.
2.5L STARTER GENERAL INFORMATION
The 2.5L engine starter motor incorporates several
features to create an efficient, lightweight unit.
A planetary gear system (intermediate transmis-
sion) between the electric motor and pinion shaftmakes it possible to reduce the dimensions of the
starter. This also makes it possible to obtain a higher
rotational speed to produce the same torque at the
pinion.
The permanent magnet field consists of six two-
component high strength magnets. The magnets are
aligned according to their polarity and are perma-
nently fixed in the starter frame.
The brush holder plate consists of a plastic base-
plate with four tubular brush holders.
This unit is highly sensitive to hammering, shocks
and external pressure.
CAUTION: The starter motor MUST NOT BE
CLAMPED in a vise by the starter frame. Doing so
may damage the magnets. It may be clamped by the
mounting flange ONLY.
CAUTION: Do not connect starter motor incorrectly
when tests are being performed. The magnets may
be damaged and rendered unserviceable.
²Ensure cleanliness when performing repairs.
Fig. 1 Power Distribution CenterÐXJ
Fig. 2 Power Distribution CenterÐYJ
8B - 4 BATTERY/STARTER/GENERATOR SERVICEJ

SIDE CLEARANCE MEASUREMENT
Slide snug-fitting feeler gauge between the con-
necting rod and crankshaft journal flange. Refer to
Engine Specifications for the proper clearance. Re-
place the connecting rod if the side clearance is not
within specification.
PISTON FITTING
MICROMETER METHOD
(1) Measure the inside diameter of the cylinder
bore at a point 58.725 mm (2-5/16 inches) below top
of bore.
(2) Measure outside diameter of the piston. Be-
cause pistons are cam ground, measure at right an-
gle to piston pin at center line of pin (Fig. 8).
The difference between cylinder bore diameter and
piston diameter is piston-to-bore clearance.
FEELER GAUGE METHOD
(1) Remove the rings from the piston.
(2) Insert a long 0.025 mm (0.001 inch) feeler
gauge into the cylinder bore.
(3) Insert the piston, top first, into cylinder bore
alongside the feeler gauge. With entire piston in-
serted into cylinder bore, the piston should not bind
against feeler gauge.
(4) Repeat steps with a long 0.051 mm (0.002 inch)
feeler gauge. The piston should bind.
(5) If the piston binds on 0.025 mm (0.001 inch)
feeler gauge, the piston is too large or cylinder bore
is too small. If the piston does not bind on 0.051 mm
(0.002 inch) feeler gauge, the piston is too small for
cylinder bore. Pistons up to 0.102 mm (0.004 inch)undersize may be enlarged by knurling or shot-peen-
ing. Replace pistons that are 0.102 mm (0.004 inch)
or more undersize.
PISTON PIN
REMOVAL
Piston pins are press-fitted into the connecting rods
and require no locking device.
(1) Position the piston and connecting rod assem-
bly on an arbor press.
(2) Apply force to a piloted driver and press the
pin completely out of the connecting rod and piston
assembly (Fig. 9). Note position of the pin through
the gauge window of removal support tool.
INSPECTION
(1) Inspect the piston pin and pin bore in the con-
necting rod for nicks and burrs. Remove as neces-
sary. Never reuse a piston pin after it has been
installed in and removed from a connecting rod.
(2) With the pin removed from the piston and con-
necting rod, clean and dry piston pin bores and the
replacement piston pin.
(3) Position the piston so that the pin bore is in
vertical position. Insert the pin in bore. At room tem-
perature, the replacement pin should slide com-
pletely through the pin bore in piston by force of
gravity.
(4) Replace piston if pin jams in the pin bore.
INSTALLATION
(1) Insert the piston pin pilot through the piston
and connecting rod pin bores. Ensure that the arrow
on the piston crown is pointing up (Fig. 10).
Fig. 8 Piston Dimensions
Fig. 9 Piston Pin Removal/Installation
J2.5L ENGINE 9 - 37

The difference between cylinder bore diameter and
piston diameter is piston-to-bore clearance.
FEELER GAUGE METHOD
(1) Remove the rings from the piston.
(2) Insert a long 0.025 mm (0.001 inch) feeler
gauge into the cylinder bore.
(3) Insert the piston, top first, into cylinder bore
alongside the feeler gauge. With entire piston in-
serted into cylinder bore, the piston should not bind
against feeler gauge.
(4) Repeat steps with a long 0.051 mm (0.002 inch)
feeler gauge. The piston should bind.
(5) If the piston binds on 0.025 mm (0.001 inch)
feeler gauge, the piston is too large or cylinder bore
is too small. If the piston does not bind on 0.051 mm
(0.002 inch) feeler gauge, the piston is too small for
cylinder bore. Pistons up to 0.102 mm (0.004 inch)
undersize may be enlarged by knurling or shot-peen-
ing. Replace pistons that are 0.102 mm (0.004 inch)
or more undersize.
PISTON PIN
REMOVAL
Piston pins are press-fitted into the connecting rods
and require no locking device.
(1) Position the piston and connecting rod assem-
bly on an arbor press.
(2) Apply force to a piloted driver and press the
pin completely out of the connecting rod and piston
assembly (Fig. 9). Note position of the pin through
the gauge window of removal support tool.INSPECTION
(1) Inspect the piston pin and pin bore in the con-
necting rod for nicks and burrs. Remove as neces-
sary. Never reuse a piston pin after it has been
installed in and removed from a connecting rod.
(2) With the pin removed from the piston and con-
necting rod, clean and dry piston pin bores and the
replacement piston pin.
(3) Position the piston so that the pin bore is in
vertical position. Insert the pin in bore. At room tem-
perature, the replacement pin should slide com-
pletely through the pin bore in piston by force of
gravity.
(4) Replace piston if pin jams in the pin bore.
INSTALLATION
(1) Insert the piston pin pilot through the piston
and connecting rod pin bores. Ensure that the arrow
on the piston crown is pointing up (Fig. 10).
(2) Position the pin pilot, piston and connecting
rod on a support with the squirt hole of the connect-
ing rod to the left-hand side (Fig. 10).
(3) Insert piston pin through the upper piston pin
bore and into the connecting rod pin bore.
(4) Position the piloted driver inside the piston pin
(Fig. 9).
(5) Using an arbor press, press the piston pin
through the connecting rod and piston bores until pin
pilot indexes with mark on the support. The piston
pin requires a 8 900 N (2,000 pounds) press-fit. If lit-
tle effort is required to install piston pin in a con-
necting rod, or if the rod moves laterally on the pin,
the connecting rod must be replaced.
Fig. 8 Piston Dimensions
Fig. 9 Piston Pin Removal/Installation
J4.0L ENGINE 9 - 77

Fig. 2 Frame Alignment Reference DimensionsÐXJ Vehicles
13 - 2 FRAME AND BUMPERSJ

CONSTRUCTION
The frame is constructed of high-strength channel
steel siderails and crossmembers. The crossmembers
join the siderails and retain them in alignment in re-
lation to each other. This provides resistance to
frame twists and strains.
FRAME ALIGNMENT
INCORRECT ALIGNMENT
Incorrect frame alignment is usually a result of:
²collision impact, or
²the vehicle being operated with excessive loads, or
²loads not positioned in a properly distributed man-
ner on the vehicle.
A mis-aligned frame will affect front axle and/or
rear axle alignment. It can cause excessive wear and
mechanical failures in the powertrain. Window glass
cracks and door opening/closing problems. Vehicle
performance can also be impaired.
RE-ALIGNMENT
With collision damage, it is important that the ex-
istence of any frame alignment damage be deter-
mined. If necessary, the frame should be correctly re-
aligned. Refer to the reference dimensions listed on
frame alignment dimension chart (Fig. 4).
FRAME INSPECTION/MEASUREMENTS
INSPECTION
Before proceeding with measurements, inspect all
components for visible damage and other metal dam-
age. Also, inspect all connections for loose and miss-
ing hardware.
All damaged areas must be repaired and/or the
components replaced, as necessary.
MEASUREMENTS
Measure the frame for mis-alignment with the
body attached to the frame. Figure 4 provides the
alignment reference dimensions. The following infor-
mation applies to all measurements.
(1) Place the vehicle on a level surface.
(2) If the vehicle is loaded, ensure that the vehicle
weight plus the payload does not exceed the gross ve-
hicle weight rating. Also, ensure that the load is dis-
tributed in the vehicle as evenly as possible.
(3) Measure the tire inflation pressures and adjust
the pressure, if necessary.
HORIZONTAL OR DIAGONAL FRAME MEASUREMENTS
Determine the frame horizontal non-square devia-
tion(s) according to the following procedure.
(1) Select several reference points along one frame
siderail, preferably at the crossmember junctions.(2) Transfer these reference points to the surface/
floor with a plumb bob. Paper sheets can be attached
to the surface below the reference points for better
measurement accuracy.
(3) Locate the reference points on the other frame
siderail and transfer them to the surface/floor with
the same procedure as above.
(4) Move the vehicle away and measure between
all the reference points diagonally from and parallel
to the siderails (Fig. 5). The measurements should
not differ by more than 6 mm (1/4 in).
(5) Measure the distance between the two front
reference points and the distance between the two
rear reference points. Divide each distance in half
and indicate the two half-way points on the surface/
floor. Designate the front point as ``1'' and the rear
point as ``2'' (Fig. 5).
(6) Place a chalk-line between points 1 and 2 and
``snap'' the string.
(7) Determine how close the center line is to the
diagonal intersection points A, B, C, D, E, and F in
Figure 5.
(8) The reference marks on the surface/floor will
provide an illustrated indication of the degree of
frame misalignment.
(9) A reference point transferred from one frame
siderail may be 3 mm (1/8 in) ahead or behind the
reference point from the opposite siderail.
(10) Frame bow to the side should not exceed 3
mm per 2,540 mm (1/8 inch per 100 inches) in
length.
(11) The overall width of the frame should not
vary more than 3 mm (1/8 in) from reference point-
to-reference point.
(12) Repeat steps (1) through (11) after straighten-
ing the frame to evaluate the effectiveness.
TWIST AND PARALLEL FRAME MEASUREMENTS
Determine the amount of frame twist and siderail
deviation according to the following procedure.
(1) Mark the vertical measurement reference
points under the frame siderails at 305-mm (12-in)
intervals starting at the rear frame crossmember.
(2) Measure the vertical distance up from a level
surface to each reference point located under the left
and right frame siderails.
(3) The distance to a reference point under one
frame siderail should be 3 mm (1/8 in) greater or less
than the point under the opposite siderail.
(4) Plot the measured vertical distances to scale on
a sheet of graph paper. Plot the distances so that the
frame siderails are located adjacent to each other.
Join the vertical distance points.
13 - 10 FRAME AND BUMPERSJ