piston ring JEEP GRAND CHEROKEE 2003 WJ / 2.G Workshop Manual

(7) Install Piston Guides 8504 into the input clutch
retainer (Fig. 74) and onto the input clutch hub to
guide the inner and outer underdrive piston seals
into position.
(8) Install the underdrive piston into the input
clutch retainer and over the input clutch hub (Fig.
73).
(9) Install the UD/OD balance piston return spring
pack into the input clutch retainer.
(10) Install Piston Guide 8252 into the input
clutch retainer (Fig. 75) to guide the UD/OD balance
piston seal into position inside the underdrive piston.(11) Install the UD/OD balance piston into the
input clutch retainer and the underdrive piston.
(12) Using Spring Compressor 8251, compress the
UD/OD return spring pack and secure the piston in
place with the snap-ring (Fig. 76).
Fig. 74 Install Underdrive Piston Using Tool 8504
1 - TOOL 8504
Fig. 75 Install Balance Piston Using Tool 8252
1 - TOOL 8252
Fig. 76 Compressing UD/OD Balance Piston Using
Tool 8251
1 - PRESS
2 - TOOL 8251
3 - BALANCE PISTON
WJAUTOMATIC TRANSMISSION - 545RFE 21 - 241
INPUT CLUTCH ASSEMBLY (Continued)

LOW/REVERSE CLUTCH
DISASSEMBLY
(1) Remove the inner overrunning clutch snap-ring
from the low/reverse clutch retainer (Fig. 84).
(2) Remove the outer low/reverse reaction plate
flat snap-ring (Fig. 84).
(3) Remove the low/reverse clutch and the over-
running clutch from the low/reverse clutch retainer
as an assembly (Fig. 84).
(4) Separate the low/reverse clutch from the over-
running clutch.(5) Remove the overrunning clutch snap-ring (Fig.
85).
(6) Remove the spacer from the overrunning clutch
(Fig. 85).
(7) Separate the inner and outer races of the over-
running clutch (Fig. 85).
(8) Remove the overrunning clutch lower snap-ring
(Fig. 85).
(9) Using Spring Compressor 8285 and a suitable
shop press (Fig. 86), compress the low/reverse piston
Belleville spring and remove the split retaining ring
Fig. 84 Low/Reverse Clutch Assembly
1 - SNAP-RING (SELECT) 8 - SEAL
2 - REACTION PLATE 9 - BELLEVILLE SPRING
3 - DISC 10 - RETAINER
4 - PLATE 11 - SNAP-RING
5 - L/R CLUTCH RETAINER 12 - OVERRUNNING CLUTCH
6 - SEAL 13 - SNAP-RING
7 - PISTON
21 - 246 AUTOMATIC TRANSMISSION - 545RFEWJ

holding the Belleville spring into the low/reverse
clutch retainer.
(10) Remove the low/reverse clutch Belleville
spring and piston from the low/reverse clutch
retainer. Use 20 psi of air pressure to remove the pis-
ton if necessary.
CLEANING
Clean the overrunning clutch assembly, clutch cam,
and low-reverse clutch retainer. Dry them with com-
pressed air after cleaning.
INSPECTION
Inspect condition of each clutch part after cleaning.
Replace the overrunning clutch roller and spring
assembly if any rollers or springs are worn or dam-
aged, or if the roller cage is distorted, or damaged.
Replace the cam if worn, cracked or damaged.
Replace the low-reverse clutch retainer if the
clutch race, roller surface or inside diameter is
scored, worn or damaged.
ASSEMBLY
(1) Check the bleed orifice to ensure that it is not
plugged or restricted.
(2) Install a new seal on the low/reverse piston.
Lubricate the seal with MopartATF +4, type 9602,
prior to installation.
(3) Install the low/reverse piston into the low/re-
verse clutch retainer.
(4) Position the low/reverse piston Belleville spring
on the low/reverse piston.
(5) Using Spring Compressor 8285 and a suitable
shop press (Fig. 86), compress the low/reverse piston
Belleville spring and install the split retaining ring
to hold the Belleville spring into the low/reverse
clutch retainer.
(6) Install the lower overrunning clutch snap-ring
(Fig. 85).
(7) Assemble the inner and outer races of the over-
running clutch (Fig. 85).
(8) Position the overrunning clutch spacer on the
overrunning clutch.
(9) Install the upper overrunning clutch snap-ring
(Fig. 85).
(10) Assemble and install the low/reverse clutch
pack into the low/reverse clutch retainer (Fig. 84).
(11) Install the low/reverse reaction plate into the
low/reverse clutch retainer (Fig. 84). The reaction
plate is directional and must be installed with the
flat side down.
(12) Install the low/reverse clutch pack snap-ring
(Fig. 84). The snap-ring is selectable and should be
chosen to give the correct clutch pack clearance.
(13) Measure the low/reverse clutch pack clearance
and adjust as necessary. The correct clutch clearance
is 1.00-1.74 mm (0.039-0.075 in.).
(14) Install the overrunning clutch into the low/re-
verse clutch retainer making sure that the index
splines are aligned with the retainer.
(15) Install the overrunning clutch inner snap-
ring.
Fig. 85 Overrunning Clutch
1 - SNAP-RING
2 - OUTER RACE
3 - OVERRUNNING CLUTCH
4 - SPACER
Fig. 86 Compress Low/Reverse Belleville Spring
Using Tool 8285
1 - PRESS
2 - TOOL 8285
3 - BELLEVILLE SPRING
WJAUTOMATIC TRANSMISSION - 545RFE 21 - 247
LOW/REVERSE CLUTCH (Continued)

PISTONS
DESCRIPTION
There are several sizes and types of pistons used in
an automatic transmission. Some pistons are used to
apply clutches. They all have in common the fact
that they are round or circular in shape, located
within a smooth walled cylinder, which is closed at
one end and converts fluid pressure into mechanical
movement. The fluid pressure exerted on the piston
is contained within the system through the use of
piston rings or seals.
OPERATION
The principal which makes this operation possible
is known as Pascal's Law. Pascal's Law can be stated
as: ªPressure on a confined fluid is transmitted
equally in all directions and acts with equal force on
equal areas.º
PRESSURE
Pressure (Fig. 98) is nothing more than force (lbs.)
divided by area (in or ft.), or force per unit area.
Given a 100 lb. block and an area of 100 sq. in. on
the floor, the pressure exerted by the block is: 100
lbs. 100 in or 1 pound per square inch, or PSI as it is
commonly referred to.
PRESSURE ON A CONFINED FLUID
Pressure is exerted on a confined fluid (Fig. 99) by
applying a force to some given area in contact with
the fluid. A good example of this is a cylinder filled
with fluid and equipped with a piston that is closely
fitted to the cylinder wall. If a force is applied to the
piston, pressure will be developed in the fluid. Of
course, no pressure will be created if the fluid is not
confined. It will simply ªleakº past the piston. There
must be a resistance to flow in order to create pres-
sure. Piston sealing is extremely important in
hydraulic operation. Several kinds of seals are used
to accomplish this within a transmission. These
include but are not limited to O-rings, D-rings, lip
seals, sealing rings, or extremely close tolerances
between the piston and the cylinder wall. The force
exerted is downward (gravity), however, the principle
remains the same no matter which direction is taken.
The pressure created in the fluid is equal to the force
applied, divided by the piston area. If the force is 100
lbs., and the piston area is 10 sq. in., then the pres-
sure created equals 10 PSI. Another interpretation of
Pascal's Law is that regardless of container shape or
size, the pressure will be maintained throughout, as
long as the fluid is confined. In other words, the
pressure in the fluid is the same everywhere within
the container.
Fig. 98 Force and Pressure Relationship
Fig. 99 Pressure on a Confined Fluid
21 - 256 AUTOMATIC TRANSMISSION - 545RFEWJ

A solenoid can also be described by the method by
which it is controlled. Some of the possibilities
include variable force, pulse-width modulated, con-
stant ON, or duty cycle. The variable force and pulse-
width modulated versions utilize similar methods to
control the current flow through the solenoid to posi-
tion the solenoid plunger at a desired position some-
where between full ON and full OFF. The constant
ON and duty cycled versions control the voltage
across the solenoid to allow either full flow or no flow
through the solenoid's valve.
OPERATION
When an electrical current is applied to the sole-
noid coil, a magnetic field is created which produces
an attraction to the plunger, causing the plunger to
move and work against the spring pressure and the
load applied by the fluid the valve is controlling. The
plunger is normally directly attached to the valve
which it is to operate. When the current is removed
from the coil, the attraction is removed and the
plunger will return to its original position due to
spring pressure.
The plunger is made of a conductive material and
accomplishes this movement by providing a path for
the magnetic field to flow. By keeping the air gap
between the plunger and the coil to the minimum
necessary to allow free movement of the plunger, the
magnetic field is maximized.
TORQUE CONVERTER
DESCRIPTION
The torque converter (Fig. 109) is a hydraulic
device that couples the engine crankshaft to the
transmission. The torque converter consists of an
outer shell with an internal turbine, a stator, an
overrunning clutch, an impeller and an electronically
applied converter clutch. The converter clutch pro-vides reduced engine speed and greater fuel economy
when engaged. Clutch engagement also provides
reduced transmission fluid temperatures. The con-
verter clutch engages in third gear. The torque con-
verter hub drives the transmission oil (fluid) pump
and contains an o-ring seal to better control oil flow.
The torque converter is a sealed, welded unit that
is not repairable and is serviced as an assembly.
CAUTION: The torque converter must be replaced if
a transmission failure resulted in large amounts of
metal or fiber contamination in the fluid. If the fluid
is contaminated, flush the fluid cooler and lines.
Fig. 109 Torque Converter Assembly
1 - TURBINE ASSEMBLY
2-STATOR
3 - CONVERTER HUB
4 - O-RING
5 - IMPELLER ASSEMBLY
6 - CONVERTER CLUTCH PISTON
7 - TURBINE HUB
21 - 264 AUTOMATIC TRANSMISSION - 545RFEWJ
SOLENOIDS (Continued)

STATOR
The stator assembly (Fig. 112) is mounted on a sta-
tionary shaft which is an integral part of the oil
pump. The stator is located between the impeller and
turbine within the torque converter case (Fig. 113).
The stator contains an over-running clutch, which
allows the stator to rotate only in a clockwise direc-
tion. When the stator is locked against the over-run-
ning clutch, the torque multiplication feature of the
torque converter is operational.
TORQUE CONVERTER CLUTCH (TCC)
The TCC (Fig. 114) was installed to improve the
efficiency of the torque converter that is lost to the
slippage of the fluid coupling. Although the fluid cou-
pling provides smooth, shock-free power transfer, it is
natural for all fluid couplings to slip. If the impeller
and turbine were mechanically locked together, a
zero slippage condition could be obtained. A hydraulic
piston with friction material was added to the tur-
bine assembly to provide this mechanical lock-up.
In order to reduce heat build-up in the transmission
and buffer the powertrain against torsional vibrations,
the TCM can duty cycle the L/R-CC Solenoid to achieve
a smooth application of the torque converter clutch.
This function, referred to as Electronically Modulated
Converter Clutch (EMCC) can occur at various times
depending on the following variables:
²Shift lever position
²Current gear range
²Transmission fluid temperature
²Engine coolant temperature
²Input speed
²Throttle angle
²Engine speed
Fig. 112 Stator Components
1 - CAM (OUTER RACE)
2 - ROLLER
3 - SPRING
4 - INNER RACE
Fig. 113 Stator Location
1-STATOR
2 - IMPELLER
3 - FLUID FLOW
4 - TURBINE
Fig. 114 Torque Converter Clutch (TCC)
1 - IMPELLER FRONT COVER
2 - THRUST WASHER ASSEMBLY
3 - IMPELLER
4-STATOR
5 - TURBINE
6 - PISTON
7 - FRICTION DISC
WJAUTOMATIC TRANSMISSION - 545RFE 21 - 267
TORQUE CONVERTER (Continued)

OPERATION
The converter impeller (Fig. 115) (driving member),
which is integral to the converter housing and bolted
to the engine drive plate, rotates at engine speed.
The converter turbine (driven member), which reacts
from fluid pressure generated by the impeller, rotates
and turns the transmission input shaft.
TURBINE
As the fluid that was put into motion by the impel-
ler blades strikes the blades of the turbine, some of
the energy and rotational force is transferred into the
turbine and the input shaft. This causes both of them
(turbine and input shaft) to rotate in a clockwise
direction following the impeller. As the fluid is leav-
ing the trailing edges of the turbine's blades it con-
tinues in a ªhinderingº direction back toward the
impeller. If the fluid is not redirected before it strikes
the impeller, it will strike the impeller in such a
direction that it would tend to slow it down.
STATOR
Torque multiplication is achieved by locking the
stator's over-running clutch to its shaft (Fig. 116).
Under stall conditions (the turbine is stationary), the
oil leaving the turbine blades strikes the face of the
stator blades and tries to rotate them in a counter-
clockwise direction. When this happens the over-run-ning clutch of the stator locks and holds the stator
from rotating. With the stator locked, the oil strikes
the stator blades and is redirected into a ªhelpingº
direction before it enters the impeller. This circula-
tion of oil from impeller to turbine, turbine to stator,
and stator to impeller, can produce a maximum
torque multiplication of about 2.4:1. As the turbine
begins to match the speed of the impeller, the fluid
that was hitting the stator in such as way as to
cause it to lock-up is no longer doing so. In this con-
dition of operation, the stator begins to free wheel
and the converter acts as a fluid coupling.
TORQUE CONVERTER CLUTCH (TCC)
In a standard torque converter, the impeller and
turbine are rotating at about the same speed and the
stator is freewheeling, providing no torque multipli-
cation. By applying the turbine's piston and friction
material to the front cover, a total converter engage-
ment can be obtained. The result of this engagement
is a direct 1:1 mechanical link between the engine
and the transmission.
The clutch can be engaged in second, third, fourth,
and fifth gear ranges depending on overdrive control
switch position. If the overdrive control switch is in
the normal ON position, the clutch will engage after
the shift to fourth gear, and above approximately 72
km/h (45 mph). If the control switch is in the OFF
Fig. 115 Torque Converter Fluid Operation - Typical
1 - APPLY PRESSURE 3 - RELEASE PRESSURE
2 - THE PISTON MOVES SLIGHTLY FORWARD 4 - THE PISTON MOVES SLIGHTLY REARWARD
21 - 268 AUTOMATIC TRANSMISSION - 545RFEWJ
TORQUE CONVERTER (Continued)

(7) Remove the screws holding the accumulator
cover onto the valve body (Fig. 128).
(8) Remove the accumulator springs and pistons
from the valve body. Note which accumulator piston
and spring belong in each location.
(9) Place the valve body on the bench with the
transfer plate upward.
NOTE: The valve body contains seven check balls.
The transfer plate must be placed upward to pre-
vent losing the check balls when the transfer plate
is removed from the valve body.
(10) Remove the screws holding the valve body to
the valve body transfer plate.
(11) Remove the transfer plate from the valve
body. Note the location of all check balls (Fig. 129).
(12) Remove the check balls from the valve body.
(13) Remove the retainers securing the solenoid
switch valve, manual valve, and the low/reverse
switch valve into the valve body and remove the
associated valve and spring. Tag each valve andspring combination with location information to aid
in assembly. (Fig. 130)
Fig. 128 Valve Body Components
1 - LOW/REVERSE ACCUMULATOR 6 - OVERDRIVE ACCUMULATOR
2 - LOW/REVERSE SWITCH VALVE 7 - UNDERDRIVE ACCUMULATOR
3 - UPPER VALVE BODY 8 - 4C ACCUMULATOR
4 - MANUAL VALVE 9 - 2C ACCUMULATOR
5 - SOLENOID SWITCH VALVE
Fig. 129 Check Ball Locations
21 - 276 AUTOMATIC TRANSMISSION - 545RFEWJ
VALVE BODY (Continued)

Inspect all the valve and plug bores in the valve
body. Use a penlight to view the bore interiors.
Replace the valve body if any bores are distorted or
scored. Inspect all of the valve body springs. The
springs must be free of distortion, warpage or broken
coils.
Trial fit each valve and plug in its bore to check
freedom of operation. When clean and dry, the valves
and plugs should drop freely into the bores.
Valve body bores do not change dimensionally with
use. If the valve body functioned correctly when new,
it will continue to operate properly after cleaning and
inspection. It should not be necessary to replace a
valve body assembly unless it is damaged in han-
dling.
Inspect all the accumulator bores in the valve body.
Use a penlight to view the bore interiors. Replace the
valve body if any bores are distorted or scored.Inspect all of the accumulator springs. The springs
must be free of distortion, warpage or broken coils.
Inspect all the fluid seals on the valve body (Fig.
133). Replace any seals that are cracked, distorted, or
damaged in any way. These seals pass fluid pressure
directly to the clutches. Any pressure leak at these
points, may cause transmission performance prob-
lems.
ASSEMBLY
(1) Lubricate valves, springs, and the housing
valve bores with clean transmission fluid.
(2) Install solenoid switch valve, manual valve,
and the low/reverse switch valve into the valve body.
(3) Install the retainers to hold each valve into the
valve body.
(4) Install the valve body check balls into their
proper locations.
(5) Position the transfer plate onto the valve body.
(6) Install the screws to hold the transfer plate to
the valve body. Tighten the screws to 5.6 N´m (50 in.
lbs.).
(7) Install the accumulator pistons and springs
into the valve body in the location from which they
were removed. Note that all accumulators except the
overdrive have two springs. The overdrive accumula-
tor piston has only one spring.
Fig. 132 Valve Body Components
1 - SOLENOID SWITCH VALVE
2 - MANUAL VALVE
3 - LOW REVERSE SWITCH VALVE
4 - LOW REVERSE ACCUMULATOR
5 - 2ND CLUTCH ACCUMULATOR
6 - UNDERDRIVE ACCUMULATOR
7 - OVERDRIVE ACCUMULATOR
8 - 4TH CLUTCH ACCUMULATOR
9 - CHECK BALLS (7)
Fig. 133 Valve Body Seals
1 - UNDERDRIVE ACCUMULATOR (2 SPRINGS)
2 - 4TH CLUTCH ACCUMULATOR (2 SPRINGS)
3 - 2ND CLUTCH ACCUMULATOR (2 SPRINGS)
4 - LOW REVERSE ACCUMULATOR (2 SPRINGS)
5 - LOW/REVERSE PASSAGE SEAL
6 - 2ND CLUTCH PASSAGE SEAL
7 - 4TH CLUTCH PASSAGE SEAL
8 - OVERDRIVE ACCUMULATOR (1 SPRING)
21 - 278 AUTOMATIC TRANSMISSION - 545RFEWJ
VALVE BODY (Continued)

LIFTGATE
REMOVAL
CAUTION: DO NOT DISCONNECT THE SUPPORT ROD
CYLINDERS WITH THE LIFTGATE CLOSED. THE SUP-
PORT ROD PISTONS ARE OPERATED BY HIGH PRES-
SURE GAS. THIS PRESSURE COULD CAUSE DAMAGE
AND /OR PERSONAL INJURY IF THEY ARE REMOVED
WHILE THE PISTONS ARE COMPRESSED.
(1) Open the liftgate. Support the liftgate for ease
of repair.
(2) Remove the liftgate trim panel.
(3) Remove the prop rods from the liftgate.
(4) Unplug the wire harnesses and disconnect the
washer hose.
(5) Mark the hinge location with a wax pencil or
other suitable device (Fig. 5).
(6) Remove the hinge screws and remove liftgate
from vehicle.
INSTALLATION
(1) Position the liftgate on the vehicle and align
the witness marks.
(2) Install the hinge screws at liftgate. Tighten
hinge screws to 28N´m (21ft. lbs.).
(3) Connect the wire harnesses and the washer
hose.
(4) Install the trim panel.
(5) Install the prop rods.
(6) Close the liftgate and check for proper latching
and alignment.
ADJUSTMENTS
LIFTGATE ADJUSTMENT
The position of the liftgate can be adjusted upward
or downward by the use of slots in the hinge. An
inward or outward adjustment is achieved by use of
slots in the body. If an inward or outward adjustment
is needed, use 3MŸ Fast and Firm or equivalent on
the hinge to body mating surface as a sealant.
TRIM PANEL
REMOVAL
REMOVAL - LIFTGATE TRIM PANEL
NOTE: The liftgate trim panel is attached with
screws and spring clips.
(1) Raise the liftgate.
(2) Remove the screws securing the liftgate trim
panel to the liftgate (Fig. 6).
(3) Disconnect the rear window defroster wires.
(4) Using a trim stick, or other suitable tool, pry
the liftgate trim panel off the liftgate.
Fig. 5 Liftgate
1 - HINGE
2 - LIFTGATE
Fig. 6 Liftgate Trim Panel
1 - LIFTGATE
2 - LIFTGATE TRIM PANEL
WJDECKLID/HATCH/LIFTGATE/TAILGATE 23 - 9