(18) Squeeze front band together slightly and slide
band over front clutch retainer and out of case (Fig.
28).
(19) Remove front and rear clutch assemblies as a
unit (Fig. 29).(20) Remove front band reaction pin and lever.
Start pin through lever and out of case bore with
drift or punch. Then use pencil magnet to withdraw
pin completely (Fig. 30).
(21) Remove intermediate shaft thrust washer. Tri-
angular shaped washer will either be on shaft pilot
hub or in rear clutch retainer (Fig. 31).
Fig. 29 Removing Front/Rear Clutch Assemblies
1 - FRONT AND REAR CLUTCH ASSEMBLIES
Fig. 30 Front Band Lever And Pin
1 - BAND LEVER
2 - USE PENCIL MAGNET TO REMOVE REACTION PIN
Fig. 31 Intermediate Shaft Thrust Washer
1 - THRUST WASHER
2 - INTERMEDIATE SHAFT PILOT HUB
Fig. 28 Front Band Removal
1 - FRONT BAND
2 - FRONT CLUTCH RETAINER
DRAUTOMATIC TRANSMISSION - 48RE 21 - 163
AUTOMATIC TRANSMISSION - 48RE (Continued)
assembled. Verify that thrust washers, thrust plates
and seal rings are correctly positioned.
The planetary geartrain, front/rear clutch assem-
blies and oil pump are all much easier to install
when the transmission case is upright. Either tilt the
case upward with wood blocks, or cut a hole in the
bench large enough for the intermediate shaft and
rear support. Then lower the shaft and support into
the hole and support the rear of the case directly on
the bench.
FRONT/REAR SERVO
(1) Lubricate rear servo piston seal with ATF +4.
Lubricate servo bore in case with ATF +4.
(2) Install rear servo piston in case. Position piston
at slight angle to bore and insert piston with twisting
motion (Fig. 40).
(3) Install rear servo spring and retainer in case
bore (Fig. 41). Be sure spring is seated on piston.
(4) Compress rear servo piston with C-clamp or
Valve Spring Compressor C-3422-B and install servo
piston snap-ring (Fig. 42).
(5) Lubricate front servo piston components and
servo bore in case with transmission fluid.
(6) Install front servo piston in bore. Carefully
ªrunº small, suitable tool around piston ring to press
it back into groove and ease installation (Fig. 43).
Rotate piston into bore at same time. Rock piston
slightly to ease piston ring past snap-ring groove and
into bore.
Fig. 40 Rear Servo Piston
1 - REAR SERVO PISTON
Fig. 41 Rear Servo Piston Spring And Retainer
1 - PISTON SPRING
2 - REAR SERVO PISTON
3 - SPRING RETAINER
Fig. 42 Rear Servo Snap Ring
1 - TOOL C-4470
2 - C-CLAMP
3 - REAR SERVO SPRING RETAINER
4 - RETAINER SNAP-RING
DRAUTOMATIC TRANSMISSION - 48RE 21 - 167
AUTOMATIC TRANSMISSION - 48RE (Continued)
(9) Install the two screws to hold the TRS to the
mounting bracket. Tighten the screws to 5 N´m (45
in.lbs.).
(10) Verify proper sensor operation (Fig. 62).
(11) Move the transmission manual shaft lever to
the PARK position.
(12) Install torque converter. Use C-clamp or metal
strap to hold converter in place for installation.
BAND ADJUSTMENT AND FINAL
(1) Adjust front and rear bands as follows:
(a) Loosen locknut on each band adjusting screw
4-5 turns.
(b) Tighten both adjusting screws to 8 N´m (72
in. lbs.).
(c) Back off front band adjusting screw 1-3/4
turns.
(d) Back off rear band adjusting screw 3 turns.
(e) Hold each adjusting screw in position and
tighten locknut to 34 N´m (25 ft. lbs.) torque.
(2) Install magnet in oil pan. Magnet seats on
small protrusion at corner of pan.
(3) Position new oil pan gasket on case and install
oil pan. Tighten pan bolts to 13.6 N´m (125 in. lbs.).
(4) Install throttle valve and shift selector levers
on valve body manual lever shaft.
(5) Apply small quantity of dielectric grease to ter-
minal pins of solenoid case connector and neutral
switch.
(6) Fill transmission with recommended fluid.
INSTALLATION
(1) Check torque converter hub inner and outer
diameters and hub drive notches for sharp edgesburrs, scratches, or nicks. Polish the hub and notches
with 320/400 grit paper and crocus cloth if necessary.
The hub must be smooth to avoid damaging pump
seal at installation.
(2) Lubricate pocket in the rear oil pump seal lip
with transmission fluid.
(3) Lubricate converter pilot hub of the crankshaft
with a light coating of MopartHigh Temp Grease.
(4) Align and install converter in oil pump.
(5) Carefully insert converter in oil pump. Then
rotate converter back and forth until fully seated in
pump gears.
(6) Check converter seating with steel scale and
straightedge (Fig. 63). Surface of converter lugs
should be 19mm (0.75 in.) to rear of straightedge
when converter is fully seated.
(7) Temporarily secure converter with C-clamp.
(8) Position transmission on jack and secure it
with chains.
(9) Check condition of converter driveplate.
Replace the plate if cracked, distorted or damaged.
Also be sure transmission dowel pins are seated
in engine block and protrude far enough to
hold transmission in alignment.
(10) Raise transmission and align converter with
drive plate and converter housing with engine block.
(11) Move transmission forward. Then raise, lower
or tilt transmission to align converter housing with
engine block dowels.
(12) Carefully work transmission forward and over
engine block dowels until converter hub is seated in
crankshaft.
Fig. 62 Transmission Range Sensor Operation
1 - NEUTRAL CONTACT
2 - MANUAL LEVER AND SENSOR PLUNGER IN REVERSE
POSITION
3 - PARK CONTACT
4 - TRANSMISSION RANGE SENSOR
Fig. 63 Checking Converter Seating - Typical
1 - SCALE
2 - STRAIGHTEDGE
21 - 174 AUTOMATIC TRANSMISSION - 48REDR
AUTOMATIC TRANSMISSION - 48RE (Continued)
INSPECTION
Inspect the accumulator piston and seal rings.
Replace the seal rings if worn or cut. Replace the pis-
ton if chipped or cracked.
Check condition of the accumulator inner and
outer springs. Replace the springs if the coils are
cracked, distorted or collapsed.
BANDS
DESCRIPTION
KICKDOWN (FRONT) BAND
The kickdown, or ªfrontº, band (Fig. 70) holds the
common sun gear of the planetary gear sets. The
front (kickdown) band is made of steel, and faced on
its inner circumference with a friction-type lining.
One end of the band is anchored to the transmission
case, and the other is acted on with a pushing force
by a servo piston. The front band is a single-wrap
design (the band does not completely encompass/
wrap the drum that it holds).
LOW/REVERSE (REAR) BAND
The low/reverse band, or ªrearº, band (Fig. 71) is
similar in appearance and operation to the front
band. The rear band is slightly different in that it
does not use a link bar, but is acted directly on by
the apply lever. This is referred to as a double-wrapband design (the drum is completely encompassed/
wrapped by the band). The double-wrap band pro-
vides a greater holding power in comparison to the
single-wrap design.
OPERATION
KICKDOWN (FRONT) BAND
The kickdown band holds the common sun gear of
the planetary gear sets by applying and holding the
front clutch retainer, which is splined to the sun gear
driving shell, and in turn splined directly to the sun
gear. The application of the band by the servo is typ-
ically done by an apply lever and link bar.
Fig. 69 Accumulator in SECOND Gear Position
1 - BOTTOM OF BORE
2 - LINE PRESSURE
3 - SHUTTLE VALVE
Fig. 70 Front Band
1 - FRONT BAND
2 - TRANSMISSION HOUSING
Fig. 71 Rear Band
1 - ADJUSTING SCREW
2 - LOCKNUT
3 - LEVER
4 - REAR BAND
5 - REACTION PIN
6 - O-RINGS
7 - PIVOT PIN
21 - 194 AUTOMATIC TRANSMISSION - 48REDR
ACCUMULATOR (Continued)
(16) Install direct clutch spring (Fig. 157). Be sure
spring is properly seated on spring plate.
NOTE: The direct clutch in a 48RE transmission
uses 23 single-sided clutch discs.
(17) Assemble and install direct clutch pack on
hub as follows:
(a) Install direct clutch reaction plate on clutch
hub first. Note that one side of reaction plate is
counterbored. Be sure this side faces rearward.
Splines at rear of hub are raised slightly. Counter-
bore in plate fits over raised splines. Plate should
be flush with this end of hub (Fig. 158).(b) Install first clutch disc with internal splines
friction side up, followed by a disc with external
lugs friction side up. Continue alternating internal
and external discs until all discs have been
installed.
Fig. 158 Correct Position Of Direct Clutch Reaction
Plate
1-REACTION PLATE COUNTERBORE
2 - DIRECT CLUTCH REACTION PLATE (FLUSH WITH END OF HUB)
3 - CLUTCH HUB
Fig. 157 Direct Clutch Spring Installation
1 - SPECIAL TOOL 6227-2
2 - DIRECT CLUTCH SPRING
3 - CLUTCH HUB
4 - PRESS PLATES
DRAUTOMATIC TRANSMISSION - 48RE 21 - 229
OVERDRIVE UNIT (Continued)
OPERATION
To apply the clutch, pressure is applied between
the clutch retainer and piston. The fluid pressure is
provided by the oil pump, transferred through the
control valves and passageways, and enters the
clutch through the hub of the reaction shaft support.
With pressure applied between the clutch retainer
and piston, the piston moves away from the clutch
retainer and compresses the clutch pack. This action
applies the clutch pack, allowing torque to flow
through the input shaft into the driving discs, and
into the clutch plates and pressure plate that are
lugged to the clutch retainer. The waved spring is
used to cushion the application of the clutch pack.
The snap-ring is selective and used to adjust clutch
pack clearance.
When pressure is released from the piston, the
spring returns the piston to its fully released position
and disengages the clutch. The release spring also
helps to cushion the application of the clutch assem-
bly. When the clutch is in the process of being
released by the release spring, fluid flows through a
vent and one-way ball-check-valve located in the pis-
ton. The check-valve is needed to eliminate the pos-
sibility of plate drag caused by centrifugal force
acting on the residual fluid trapped in the clutch pis-
ton retainer.
DISASSEMBLY
(1) Remove fiber thrust washer from forward side
of clutch retainer.
(2) Remove input shaft front and rear seal rings.
(3) Remove selective clutch pack snap-ring (Fig.
214).
(4) Remove the reaction plate, clutch discs, steel
plates, pressure plate, wave spring, spacer ring, and
piston spring (Fig. 214).
(5) Remove clutch piston with rotating motion.
(6) Remove and discard piston seals.
(7) Remove input shaft retaining ring. It may be
necessary to press the input shaft in slightly to
relieve tension on the retaining ring
(8) Press input shaft out of retainer with shop
press and suitable size press tool. Use a suitably
sized press tool to support the retainer as close to the
input shaft as possible.
CLEANING
Clean the clutch components with solvent and dry
them with compressed air. Do not use rags or shop
towels to dry any of the clutch parts. Lint from such
materials will adhere to component surfaces and
could restrict or block fluid passages after assembly.
INSPECTION
Replace the clutch discs if warped, worn, scored,
burned/charred, the lugs are damaged, or if the fac-
ing is flaking off. Replace the top and bottom pres-
sure plates if scored, warped, or cracked. Be sure the
driving lugs on the pressure and clutch plates are
also in good condition. The lugs must not be bent,
cracked or damaged in any way.
Replace the piston spring and wave spring if either
part is distorted, warped or broken.
Check the lug grooves in the clutch retainer. The
clutch and pressure plates should slide freely in the
slots. Replace the retainer if the grooves are worn or
damaged. Also check action of the check balls in the
retainer and piston. Each check ball must move
freely and not stick.
Replace the retainer bushing if worn, scored, or
doubt exists about bushing condition.
Inspect the piston and retainer seal surfaces for
nicks or scratches. Minor scratches can be removed
with crocus cloth. However, replace the piston and/or
retainer if the seal surfaces are seriously scored.
Check condition of the fiber thrust washer and
metal output shaft thrust washer. Replace either
washer if worn or damaged.
Check condition of the seal rings on the input shaft
and clutch retainer hub. Replace the seal rings only
if worn, distorted, or damaged. The input shaft front
seal ring is teflon with chamfered ends. The rear ring
is metal with interlocking ends.
Check the input shaft for wear, or damage. Replace
the shaft if worn, scored or damaged in any way.
21 - 248 AUTOMATIC TRANSMISSION - 48REDR
REAR CLUTCH (Continued)
ASSEMBLY
(1) Soak clutch discs in transmission fluid while
assembling other clutch parts.
(2) Install new seal rings on clutch retainer hub
and input shaft if necessary.
(a) Be sure clutch hub seal ring is fully seated in
groove and is not twisted.
(3) Lubricate splined end of input shaft and clutch
retainer with transmission fluid. Then partially press
input shaft into retainer (Fig. 215). Use a suitably
sized press tool to support retainer as close to input
shaft as possible.
(4) Install input shaft retaining ring.
(5) Press the input shaft the remainder of the way
into the clutch retainer.
(6) Install new seals on clutch piston. Be sure lip
of each seal faces interior of clutch retainer.
(7) Lubricate lip of piston seals with generous
quantity of MopartDoor Ease. Then lubricateretainer hub and bore with light coat of transmission
fluid.
(8) Install clutch piston in retainer. Use twisting
motion to seat piston in bottom of retainer. A thin
strip of plastic (about 0.0209thick), can be used to
guide seals into place if necessary.
CAUTION: Never push the clutch piston straight in.
This will fold the seals over causing leakage and
clutch slip. In addition, never use any type of metal
tool to help ease the piston seals into place. Metal
tools will cut, shave, or score the seals.
(9) Install piston spring in retainer and on top of
piston. Concave side of spring faces downward
(toward piston).
Fig. 214 Rear Clutch Components
1 - REAR CLUTCH RETAINER 11 - REACTION PLATE
2 - TORLONŸ SEAL RINGS 12 - CLUTCH PLATES
3 - INPUT SHAFT 13 - WAVE SPRING
4 - PISTON RETAINER 14 - SPACER RING
5 - OUTPUT SHAFT THRUST WASHER 15 - PISTON
6 - INNER PISTON SEAL 16 - OUTER PISTON SEAL
7 - PISTON SPRING 17 - REAR SEAL RING
8 - PRESSURE PLATE 18 - FIBER THRUST WASHER
9 - CLUTCH DISCS 19 - RETAINING RING
10 - SNAP-RING (SELECTIVE)
DRAUTOMATIC TRANSMISSION - 48RE 21 - 249
REAR CLUTCH (Continued)
(6) Reconnect cable end to attachment stud. Then
with aid of a helper, observe movement of transmis-
sion throttle lever and lever on throttle body.
²If both levers move simultaneously from idle to
half-throttle and back to idle position, adjustment is
correct.
²If transmission throttle lever moves ahead of, or
lags behind throttle body lever, cable adjustment will
be necessary. Or, if throttle body lever prevents
transmission lever from returning to closed position,
cable adjustment will be necessary.
ADJUSTMENT PROCEDURE
(1) Turn ignition switch to OFF position.
(2) Remove air cleaner if necessary.
(3) Disconnect cable end from attachment stud.
Carefully slide cable off stud. Do not pry or pull
cable off.
(4) Verify that transmission throttle lever is in
fully closed position. Then be sure lever on throttle
body is at curb idle position.
(5) Pry the T.V. cable lock (A) into the UP position
(Fig. 226). This will unlock the cable and allow for
readjustment.
(6) Apply just enough tension on the T.V. cable (B)
to remove any slack in the cable.Pulling too tight
will cause the T.V. lever on the transmission to
move out of its idle position, which will result
in an incorrect T.V. cable adjustment.Slide the
sheath of the T.V. cable (D) back and forth until the
centerlines of the T.V. cable end (B) and the throttle
bell crank lever (C) are aligned within one millimeter
(1mm) (Fig. 226).
(7) While holding the T.V. cable in the set position
push the T.V. cable lock (A) into the down position
(Fig. 226). This will lock the present T.V. cable
adjustment.
NOTE: Be sure that as the cable is pulled forward
and centered on the throttle lever stud, the cable
housing moves smoothly with the cable. Due to the
angle at which the cable housing enters the spring
housing, the cable housing may bind slightly and
create an incorrect adjustment.
(8) Reconnect the T.V. cable (B) to the throttle
bellcrank lever (C).
(9) Check cable adjustment. Verify transmission
throttle lever and lever on throttle body move simul-
taneously.
TORQUE CONVERTER
DESCRIPTION
The torque converter (Fig. 227) 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 torque
converter hub drives the transmission oil (fluid)
pump.
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 all transmission fluid
cooler(s) and lines.
Fig. 227 Torque Converter Assembly
1 - TURBINE
2 - IMPELLER
3 - HUB
4-STATOR
5 - FRONT COVER
6 - CONVERTER CLUTCH DISC
7 - DRIVE PLATE
DRAUTOMATIC TRANSMISSION - 48RE 21 - 255
THROTTLE VALVE CABLE (Continued)