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9 - CLUTCH PISTON SPRINGS 10 - OUTER PISTON SEAL 11 - FRONT CLUTCH RETAINER
DR FRONT CLUTCH (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 385
(2) Compress clutch piston retainer and piston
springs with Compressor Tool C-3863-A (Fig. 94).
(3) Remove retainer snap-ring and remove com-
pressor tool.
(4) Remove clutch piston springs (Fig. 95). Note position and number of piston springs for assembly reference.
(5) Remove clutch piston from retainer with a
(6) Remove and discard clutch piston inner and
twisting motion.
outer seals.
INSPECTION
Inspect the front clutch components. Replace the clutch discs if warped, worn, scored, burned or charred, the lugs are damaged, or if the facing is flaking off. Replace the steel plates and reaction plate if heavily scored, warped, or broken. Be sure the driving lugs on the discs and plate are also in good condition. The lugs must not be bent, cracked or damaged in any way.
Replace the piston springs and spring retainer if
either are distorted, warped or broken.
Check the lug grooves in the clutch piston retainer. The steel plates should slide freely in the slots. Replace the piston retainer if the grooves are worn or damaged. Also check action of the check ball in the piston retainer. The ball must move freely and not stick.
Fig.94RemovingFrontClutchSpringRetainer
Snap-Ring
1 - SPECIAL TOOL C-3863-A 2 - SNAP-RING
Replace the retainer bushing if worn, scored, or
there is any doubt about bushing condition.
1 - INNER PISTON SEAL 2 - CLUTCH PISTON 3 - CLUTCH PISTON SPRING RETAINER 4 - CLUTCH PLATES 5 - CLUTCH PACK SNAP-RING (WAVED) 6 - REACTION PLATE
Fig.9548REFrontClutchComponents
7 - CLUTCH DISCS 8 - RETAINER SNAP-RING 9 - CLUTCH PISTON SPRINGS 10 - OUTER PISTON SEAL 11 - FRONT CLUTCH RETAINER
21 - 386
FRONT CLUTCH (Continued)AUTOMATIC TRANSMISSION - 48RE
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 the clutch piston check ball. The ball should be securely in place. Replace the piston if the ball is missing, or seized in place.
ASSEMBLY
NOTE: The 48RE transmission uses five plates and discs for the front clutch.
(1) Soak clutch discs in transmission fluid. (2) Install new inner piston seal onto the outer
diameter of the clutch retainer inner hub.
(3) Install new outer seal onto the clutch piston. Be sure seal lips of both seals face the interior of the retainer.
(4) Lubricate new inner and outer piston seals
with petroleum jelly.
(5) Install clutch piston in retainer. Use twisting motion to seat piston in bottom of retainer. A thin strip of plastic (about 0.015 - 0.020 in. thick), 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
DR
Fig.96FrontClutchSpringPosition
1 - 9 SPRING CLUTCH
tool to help ease the piston seals into place. Metal tools will cut, shave, or score the seals.
(6) Install and position nine clutch piston springs
(Fig. 96).
(7) Install spring retainer on top of piston springs. (8) Compress spring retainer and piston springs
with Tool C-3863-A.
compressor tool.
(9) Install spring retainer snap-ring and remove
(10) Install clutch plates and discs (Fig. 97). Five clutch discs, five steel plates and one reaction plate are required.
1 - INNER PISTON SEAL 2 - CLUTCH PISTON 3 - CLUTCH PISTON SPRING RETAINER 4 - CLUTCH PLATES 5 - CLUTCH PACK SNAP-RING (WAVED) 6 - REACTION PLATE
Fig.9748REFrontClutchComponents
7 - CLUTCH DISCS 8 - RETAINER SNAP-RING 9 - CLUTCH PISTON SPRINGS 10 - OUTER PISTON SEAL 11 - FRONT CLUTCH RETAINER
DR FRONT CLUTCH (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 387
(11) Install reaction plate followed by waved snap-
ring.
(12) Check clutch pack clearance with feeler gauge (Fig. 98). Clearance between waved spring and pres- sure plate should 2.5-4.09 mm (0.098-0.161 in.). If clearance is incorrect, clutch plates, clutch discs, snap-ring, or pressure plate may have to be changed.
Fig.99FrontServo
1 - VENT 2 - INNER PISTON 3 - PISTON 4 - SPRING 5 - RELEASE PRESSURE 6 - APPLY PRESSURE 7 - PISTON ROD
OPERATION
The application of the piston is accomplished by applying pressure between the two lands of the pis- ton. The pressure acts against the larger lower land to push the piston downward, allowing the piston rod to extend though its guide against the apply lever. Release of the servo at the 2-3 upshift is accom- plished by a combination of spring and line pressure, acting on the bottom of the larger land of the piston. The small piston is used to cushion the application of the band by bleeding oil through a small orifice in the larger piston. The release timing of the kickdown servo is very important to obtain a smooth but firm shift. The release has to be very quick, just as the front clutch application is taking place. Otherwise, engine runaway or a shift hesitation will occur. To accomplish this, the band retains its holding capacity until the front clutch is applied, giving a small amount of overlap between them.
Fig.98TypicalMethodOfMeasuringFrontClutch
PackClearance
1 - FEELER GAUGE 2 - WAVED SNAP-RING 3 - FEELER GAUGE
FRONT SERVO DESCRIPTION
The kickdown servo (Fig. 99) consists of a two-land piston with an inner piston, a piston rod and guide, and a return spring. The dual-land piston uses seal rings on its outer diameters and an O-ring for the inner piston.
AUTOMATIC TRANSMISSION - 48RE
21 - 388
FRONT SERVO (Continued) DISASSEMBLYDR
(1) Remove seal ring from rod guide (Fig. 100). (2) Remove small snap-ring from servo piston rod. Then remove piston rod, spring and washer from pis- ton.
(3) Remove and discard servo component O-ring
and seal rings.
Fig.101FrontServo
1 - VENT 2 - INNER PISTON 3 - PISTON 4 - SPRING 5 - RELEASE PRESSURE 6 - APPLY PRESSURE 7 - PISTON ROD
Fig.102FrontServo
1 - PISTON RINGS 2 - SERVO PISTON 3 - O-RING 4 - SNAP-RING 5 - PISTON ROD GUIDE 6 - SEAL RING 7 - SNAP-RING 8 - SERVO SPRING 9 - WASHER 10 - SPRING 11 - PISTON ROD
Fig.100FrontServo
1 - PISTON RINGS 2 - SERVO PISTON 3 - O-RING 4 - SNAP-RING 5 - PISTON ROD GUIDE 6 - SEAL RING 7 - SNAP-RING 8 - SERVO SPRING 9 - WASHER 10 - SPRING 11 - PISTON ROD
CLEANING
Clean the servo piston components (Fig. 101) with
solvent and dry them with compressed air.
INSPECTION
Inspect the servo components (Fig. 102). Replace the springs if collapsed, distorted or broken. Replace the guide, rod and piston if cracked, bent, or worn. Discard the servo snap-ring if distorted or warped.
Check the servo piston bore for wear. If the bore is severely scored, or damaged, it will be necessary to replace the case.
Replace any servo component if doubt exists about
condition. Do not reuse suspect parts.
ASSEMBLY
Clean and inspect front servo components. (1) Lubricate new o-ring and seal rings with petro- leum jelly and install them on piston, guide and rod.
DR FRONT SERVO (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 389
(2) Install rod in piston. Install spring and washer on rod. Compress spring and install snap-ring (Fig. 103).
(3) Disengage cable eyelet at transmission shift lever and pull cable adjuster out of mounting bracket (Fig. 104) or (Fig. 105).
Fig.103FrontServo
1 - PISTON RINGS 2 - SERVO PISTON 3 - O-RING 4 - SNAP-RING 5 - PISTON ROD GUIDE 6 - SEAL RING 7 - SNAP-RING 8 - SERVO SPRING 9 - WASHER 10 - SPRING 11 - PISTON ROD
GEARSHIFT CABLE DIAGNOSIS AND TESTING - GEARSHIFT CABLE
Fig.104GearshiftCableatTransmission-RFE
1 - GEARSHIFT CABLE 2 - RFE TRANSMISSION 3 - MANUAL LEVER
(1) Engine starts must be possible with shift lever in PARK or NEUTRAL positions only. Engine starts must not be possible in any other gear position.
(2) With the shift lever in the:
(a) PARK position - Apply upward force on the shift arm and remove pressure. Engine starts must be possible.
(b) PARK position - Apply downward force on the shift arm and remove pressure. Engine starts must be possible.
(c) NEUTRAL position - Normal position. Engine
starts must be possible.
(d) NEUTRAL position - Engine running and brakes applied, apply upward force on the shift arm. Transmission shall not be able to shift from neutral to reverse.
REMOVAL
(1) Shift transmission into PARK. (2) Raise vehicle.
Fig.105GearshiftCableatTransmission-RE
1 - GEARSHIFT CABLE 2 - RE TRANSMISSION 3 - MANUAL LEVER
21 - 390
GEARSHIFT CABLE (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(4) Lower the vehicle. (5) Remove the dash panel insulation pad as nec- essary to access the gearshift cable grommet (Fig. 106).
(6) Remove grommet from the dash panel. (7) Remove any steering column trim necessary to
access the gearshift cable and BTSI mechanism.
(8) Disconnect the BTSI wiring connector. (9) Disconnect cable at lower column bracket and shift lever pin and pull the cable through the dash panel opening into the vehicle (Fig. 107).
INSTALLATION
(1) Route the transmission end of the gearshift cable through the opening in the dash panel (Fig. 108).
(2) Seat the cable grommet into the dash panel
opening.
(3) Snap the cable into the steering column bracket so the retaining ears (Fig. 109) are engaged and snap the cable eyelet onto the shift lever ball stud.
Fig.106GearshiftCableattheDashPanel
1 - GEARSHIFT CABLE 2 - GROMMET
Fig.108GearshiftCableattheDashPanel
1 - GEARSHIFT CABLE 2 - GROMMET
Fig.107GearshiftCableatSteeringColumn
1 - STEERING COLUMN 2 - GEARSHIFT CABLE 3 - GEARSHIFT CABLE LOCK TAB 4 - BTSI SOLENOID LOCK TAB 5 - BTSI CONNECTOR
(10) Remove gearshift cable from vehicle.
Fig.109GearshiftCableatSteeringColumn
1 - STEERING COLUMN 2 - GEARSHIFT CABLE 3 - GEARSHIFT CABLE LOCK TAB 4 - BTSI SOLENOID LOCK TAB 5 - BTSI CONNECTOR
DR GEARSHIFT CABLE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 391
(4) Raise the vehicle. (5) Place the transmission manual shift lever in the “PARK” detent (rearmost) position and rotate prop shaft to ensure transmission is in PARK.
(6) Route the gearshift cable through the transmis- sion mounting bracket and secure the cable by snap- ping the cable retaining ears into the transmission bracket and snapping the cable eyelet on the manual shift lever ball stud. (7) Lower vehicle. (8) Lock the shift cable adjustment by pressing the cable adjuster lock tab downward until it snaps into place.
(9) Check for proper operation of the transmission
range sensor.
nism as necessary.
(10) Adjust the gearshift cable and BTSI mecha-
(5) Verify transmission shift
lever is in PARK detent by moving lever fully rearward. Last rearward detent is PARK position.
(6) Verify positive engagement of
transmission park lock by attempting to rotate propeller shaft. Shaft will not rotate when park lock is engaged.
(7) Snap the cable eyelet onto the transmission
manual shift lever. (8) Lower vehicle. (9) Lock shift cable by pressing cable adjuster lock
tab downward until it snaps into place.
(10) Check engine starting. Engine should start
only in PARK and NEUTRAL
ADJUSTMENTS
GEARSHIFT CABLE
is CORRECT if
Check adjustment by starting the engine in PARK and NEUTRAL. Adjustment the engine starts only in these positions. Adjustment is INCORRECT if the engine starts in one but not both positions. If the engine starts in any position other than PARK or NEUTRAL, or if the engine will not start at all, the transmission range sensor may be faulty.
Gearshift Adjustment Procedure
(1) Shift transmission into PARK. (2) Release cable adjuster lock tab (underneath the
steering column) (Fig. 110) to unlock cable.
(3) Raise vehicle. (4) Disengage the cable eyelet from the transmis-
sion manual shift lever.
Fig.110GearshiftCableatSteeringColumn
1 - STEERING COLUMN 2 - GEARSHIFT CABLE 3 - GEARSHIFT CABLE LOCK TAB 4 - BTSI SOLENOID LOCK TAB 5 - BTSI CONNECTOR
21 - 392
AUTOMATIC TRANSMISSION - 48RE
DR
OIL PUMP DESCRIPTION
The oil pump (Fig. 111) is located in the pump housing inside the bell housing of the transmission case. The oil pump consists of an inner and outer gear, a housing, and a reaction shaft support.
OPERATION
the
clearance between the
As the torque converter rotates, the converter hub rotates the inner and outer gears. As the gears rotate, teeth increases in the crescent area, and creates a suction at the inlet side of the pump. This suction draws fluid through the pump inlet from the oil pan. As the clearance between the gear teeth in the crescent area decreases, it forces pressurized fluid into the pump outlet and to the valve body.
gear
1 - OIL SEAL 2 - VENT BAFFLE 3 - OIL PUMP BODY 4 - GASKET 5 - REACTION SHAFT SUPPORT 6 - SEAL RINGS
Fig.111OilPumpAssembly
7 - BOLTS (6) 8 - #1 THRUST WASHER (SELECTIVE) 9 - INNER GEAR 10 - OUTER GEAR 11 - “O” RING 12 - TORQUE CONVERTER SEAL RING
DR OIL PUMP (Continued) DISASSEMBLY
AUTOMATIC TRANSMISSION - 48RE
21 - 393
(1) Mark position of support in oil pump body for assembly alignment reference. Use scriber or paint to make alignment marks.
(2) Place pump body on two wood blocks. (3) Remove reaction shaft support bolts and sepa-
rate support from pump body (Fig. 112).
(4) Remove pump inner and outer gears (Fig. 113). (5) Remove o-ring seal from pump body (Fig. 114).
Discard seal after removal.
(6) Remove oil pump seal with Remover Tool
C-3981. Discard seal after removal.
Fig.113PumpGears
1 - GEAR BORE 2 - PUMP BODY 3 - INNER GEAR 4 - OUTER GEAR
Fig.112ReactionShaftSupport
1 - OIL PUMP 2 - REACTION SHAFT SUPPORT
CLEANING
Clean pump and support components with solvent
and dry them with compressed air.
INSPECTION
Check condition of
the seal rings and thrust washer on the reaction shaft support. The seal rings do not need to be replaced unless cracked, broken, or severely worn.
Inspect the pump and support components. Replace the pump or support if the seal ring grooves or machined surfaces are worn, scored, pitted, or dam- aged. Replace the pump gears if pitted, worn chipped, or damaged.
Inspect the pump bushing. Then check the reaction shaft support bushing. Replace either bushing only if heavily worn, scored or damaged. It is not necessary to replace the bushings unless they are actually dam- aged.
Clearance between outer gear and reaction shaft housing should be 0.010 to 0.063 mm (0.0004 to 0.0025 in.). Clearance between inner gear and reac- tion shaft housing should be 0.010 to 0.063 mm (0.0004 to 0.0025 in.). Both clearances can be mea-
sured at the same time by installing the gears in the pump body and measure pump component clearances as follows:
(1) Position an appropriate piece of Plastigage™
across both gears.
tion shaft housing.
(2) Align the plastigage to a flat area on the reac-
(3) Install the reaction shaft to the pump housing. (4) Separate the reaction shaft housing from the pump housing and measure the Plastigage™ follow- ing the instructions supplied with it.
Clearance between inner gear tooth and outer gear should be 0.051 to 0.19 mm (0.002 to 0.0075 in.). Measure clearance with an appropriate feeler gauge (Fig. 115).
Clearance between outer gear and pump housing should be 0.10 to 0.229 mm (0.004 to 0.009 in.). Mea- sure clearance with an appropriate feeler gauge.
ASSEMBLY
(1) Lubricate pump gears with transmission fluid
and install them in pump body.
(2) Install thrust washer on reaction shaft support hub. Lubricate washer with petroleum jelly or trans- mission fluid before installation.
(3) If reaction shaft seal rings are being replaced, install new seal rings on support hub. Lubricate seal rings with transmission fluid or petroleum jelly after installation. Squeeze each ring until ring ends are securely hooked together.
21 - 394
OIL PUMP (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
1 - OIL SEAL 2 - VENT BAFFLE 3 - OIL PUMP BODY 4 - GASKET 5 - REACTION SHAFT SUPPORT 6 - SEAL RINGS
Fig.114OilPumpAssembly
7 - BOLTS (6) 8 - #1 THRUST WASHER (SELECTIVE) 9 - INNER GEAR 10 - OUTER GEAR 11 - “O” RING 12 - TORQUE CONVERTER SEAL RING
CAUTION: The reaction shaft support seal rings will break if overspread, or twisted. If new rings are being installed, spread them only enough for instal- lation. Also be very sure the ring ends are securely hooked together after installation. Otherwise, the rings will either prevent pump installation, or break during installation.
(4) Align and install reaction shaft support on
pump body.
(5) Install bolts attaching reaction shaft support to pump. Tighten bolts to 20 N·m (175 in. lbs.) torque.
Fig.115CheckingPumpGearTipClearance
1 - FEELER GAUGE 2 - INNER GEAR 3 - OUTER GEAR
DR OIL PUMP (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 395
(6) Install new pump seal with Installer Tool C-3860-A (Fig. 116). Use hammer or mallet to tap seal into place.
(7) Install new o-ring on pump body. Lubricate oil
seal and o-ring with petroleum jelly.
(8) Cover pump assembly to prevent dust entry
and set aside for assembly installation.
Fig.116OilPumpSeal
1 - SPECIAL TOOL C-3860-A 2 - PUMP BODY 3 - PUMP SEAL
OUTPUT SHAFT FRONT BEARING REMOVAL
(1) Remove overdrive unit from the vehicle. (2) Remove overdrive geartrain from housing. (3) Remove snap-ring holding output shaft front
bearing to overdrive geartrain. (Fig. 117).
(4) Pull bearing from output shaft.
INSTALLATION
(1) Place replacement bearing in position on geartrain with locating retainer groove toward the rear.
(2) Push bearing onto shaft until the snap-ring
(3) Install snap-ring to hold bearing onto output
groove is visible.
shaft.
(4) Install overdrive geartrain into housing. (5) Install overdrive unit in vehicle.
Fig.117OutputShaftFrontBearing
1 - OUTPUT SHAFT FRONT BEARING 2 - SNAP-RING 3 - OUTPUT SHAFT 4 - GROOVE TO REAR 5 - OVERDRIVE GEARTRAIN
OUTPUT SHAFT REAR BEARING REMOVAL
(1) Remove overdrive unit from the vehicle. (Refer to 21 - TRANSMISSION/AUTOMATIC/OVERDRIVE - REMOVAL)
(2) Remove overdrive geartrain from housing. (3) Remove snap-ring holding output shaft rear
bearing into overdrive housing (Fig. 118).
(4) Using a suitable driver inserted through the
rear end of housing, drive bearing from housing.
Fig.118OutputShaftRearBearing
1 - OUTPUT SHAFT REAR BEARING 2 - OVERDRIVE HOUSING 3 - SNAP-RING
AUTOMATIC TRANSMISSION - 48RE
21 - 396
OUTPUT SHAFT REAR BEARING (Continued) INSTALLATIONOPERATION
DR
(1) Place replacement bearing in position in hous-
(2) Using a suitable driver, drive bearing into
housing until the snap-ring groove is visible.
(3) Install snap-ring to hold bearing into housing
ing.
(Fig. 118).
(4) Install overdrive geartrain into housing. (5) Install overdrive unit in vehicle.
OVERDRIVE CLUTCH DESCRIPTION
The overdrive clutch (Fig. 119) is composed of the pressure plate, clutch plates, holding discs, overdrive piston retainer, piston, piston spacer, and snap-rings. The overdrive clutch is the forwardmost component in the transmission overdrive unit and is considered a holding component. The overdrive piston retainer, piston, and piston spacer are located on the rear of the main transmission case.
NOTE: The number of discs and plates may vary with each engine and vehicle combination.
To apply the clutch, pressure is applied between the piston retainer and piston. The fluid pressure is provided by the oil pump, transferred through the control valves and passageways, and enters the clutch through passages at the lower rear portion of the valve body area. With pressure applied between the piston retainer and piston, the piston moves away from the piston retainer and compresses the clutch pack. This action applies the clutch pack, allowing torque to flow through the intermediate shaft into the overdrive planetary gear set. The over- drive clutch discs are attached to the overdrive clutch hub while the overdrive clutch plates, reaction plate, and pressure plate are lugged to the overdrive hous- ing. This allows the intermediate shaft to transfer the engine torque to the planetary gear and overrun- ning clutch. This drives the planetary gear inside the annulus, which is attached to the overdrive clutch drum and output shaft, creating the desired gear ratio. The waved snap-ring is used to cushion the application of the clutch pack for the 5 disc version of the overdrive clutch. The 6 disc overdrive clutch does not use a waved snap-ring.
1 - REACTION PLATE
Fig.119OverdriveClutch
2 - PRESSURE PLATE
DR
AUTOMATIC TRANSMISSION - 48RE
21 - 397
OVERDRIVE SWITCH DESCRIPTION
The overdrive OFF (control) switch is located in the shift lever arm (Fig. 120). The switch is a momentary contact device that signals the PCM to toggle current status of the overdrive function.
Fig.121OverdriveOffSwitchRetainer
1 - GEAR SHIFT LEVER 2 - OVERDRIVE OFF SWITCH RETAINER 3 - PLASTIC TRIM TOOL
(2) Pull the switch outwards to release it from the
connector in the lever (Fig. 122)
Fig.122RemovetheOverdriveOffSwitch
1 - GEAR SHIFT LEVER 2 - OVERDRIVE OFF SWITCH
INSTALLATION
NOTE: There is enough slack in the wire to pull out the connector from the lever.
(1) Pull the connector out of the lever just enough
to grasp it.
CAUTION: Be careful not to bend the pins on the overdrive off switch. Use care when installing the switch, as it is not indexed, and can be accidentally installed incorrectly.
Fig.120OverdriveOffSwitch
OPERATION
At key-on, overdrive operation is allowed. Pressing the switch once causes the overdrive OFF mode to be entered and the overdrive OFF switch lamp to be illuminated. Pressing the switch a second time causes normal overdrive operation to be restored and the overdrive lamp to be turned off. The overdrive OFF mode defaults to ON after the ignition switch is cycled OFF and ON. The normal position for the con- trol switch is the ON position. The switch must be in this position to energize the solenoid and allow a 3-4
upshift. The control switch indicator light illuminates only when the overdrive switch is turned to the OFF position, or when illuminated by the transmission control module.DIAGNOSIS AND TESTING - OVERDRIVE ELECTRICAL CONTROLS
The overdrive off switch, valve body solenoid, case connectors and related wiring can all be tested with a 12 volt test lamp or a volt/ohmmeter. Check conti- nuity of each component when diagnosis indicates this is necessary.
Switch and solenoid continuity should be checked whenever the transmission fails to shift into fourth gear range.
REMOVAL
(1) Using a plastic trim tool, remove the overdrive
off switch retainer from the shift lever (Fig. 121).
21 - 398
OVERDRIVE SWITCH (Continued)AUTOMATIC TRANSMISSION - 48RE
(2) Install the overdrive off switch into the connec-
tor (Fig. 123)
DR
CAUTION: Support the overdrive unit with a jack before moving it rearward. This is necessary to pre- vent damaging the intermediate shaft. Do not allow the shaft to support the entire weight of the over- drive unit.
Fig.123InstalltheOverdriveOffSwitch
1 - GEAR SHIFT LEVER 2 - OVERDRIVE OFF SWITCH WIRING CONNECTOR 3 - OVERDRIVE OFF SWITCH
(3) Push the overdrive off switch and wiring into
(4) Install the overdrive off switch retainer onto
the shift lever.
the shift lever.
OVERDRIVE UNIT REMOVAL
(1) Shift transmission into PARK. (2) Raise vehicle. (3) Remove transfer case, if equipped. (4) Mark propeller shaft universal joint(s) and axle pinion yoke, or the companion flange and flange yoke, for alignment reference at installation, if neces- sary.
(5) Disconnect and remove the rear propeller shaft, if necessary. (Refer to 3 - DIFFERENTIAL & DRIV- ELINE/PROPELLER SHAFT/PROPELLER SHAFT - REMOVAL)
(6) Remove transmission oil pan, remove gasket,
drain oil and reinstall pan.
(7) If overdrive unit had malfunctioned, or if fluid is contaminated, remove entire transmission. If diag- nosis indicated overdrive problems only, remove just the overdrive unit.
(8) Support transmission with transmission jack. (9) Remove bolts attaching overdrive unit to trans-
mission (Fig. 124).
Fig.124OverdriveUnitBolts
1 - OVERDRIVE UNIT 2 - ATTACHING BOLTS (7)
(10) Carefully work overdrive unit off intermediate shaft. Do not tilt unit during removal. Keep it as level as possible.
(11) If overdrive unit does not require service, immediately insert Alignment Tool 6227-2 in splines of planetary gear and overrunning clutch to prevent splines from rotating out of alignment. If misalign- ment occurs, overdrive unit will have to be disassem- bled in order to realign splines.
(12) Remove and retain overdrive piston thrust bearing. Bearing may remain on piston or in clutch hub during removal.
(13) Position drain pan on workbench. (14) Place overdrive unit over drain pan. Tilt unit
to drain residual fluid from case.
(15) Examine fluid for clutch material or metal fragments. If fluid contains these items, overhaul will be necessary.
(16) If overdrive unit does not require any service, leave alignment tool in position. Tool will prevent accidental misalignment of planetary gear and over- running clutch splines.
DR OVERDRIVE UNIT (Continued) DISASSEMBLY
(1) Remove transmission speed sensor and o-ring
seal from overdrive case (Fig. 125).
(2) Remove overdrive piston thrust bearing (Fig.
126).
AUTOMATIC TRANSMISSION - 48RE
21 - 399
OVERDRIVE PISTON
(1) Remove overdrive piston thrust plate (Fig. 127). Retain thrust plate. It is a select fit part and may possibly be reused.
Fig.127OverdrivePistonThrustPlateRemoval/
Installation
1 - OVERDRIVE PISTON 2 - OVERDRIVE PISTON SPACER (SELECT FIT)
(2) Remove intermediate shaft spacer (Fig. 128). Retain spacer. It is a select fit part and may possibly be reused.
Fig.125TransmissionSpeedSensor
1 - SOCKET AND WRENCH 2 - SPEED SENSOR 3 - O-RING
Fig.128IntermediateShaftSpacerLocation
1 - INTERMEDIATE SHAFT 2 - INTERMEDIATE SHAFT SPACER (SELECT FIT)
Fig.126OverdrivePistonThrustBearingRemoval/
Installation
1 - THRUST BEARING 2 - OVERDRIVE PISTON 3 - THRUST PLATE
21 - 400
OVERDRIVE UNIT (Continued)AUTOMATIC TRANSMISSION - 48RE
(3) Remove overdrive piston from retainer (Fig.
129).
DR
Fig.129OverdrivePistonRemoval
1 - PISTON RETAINER 2 - OVERDRIVE PISTON
OVERDRIVE CLUTCH PACK
(1) Remove overdrive clutch pack wire retaining
ring (Fig. 130).
(2) Remove overdrive clutch pack (Fig. 131). (3) Note position of clutch pack components for
assembly reference (Fig. 132).
Fig.131OverdriveClutchPackRemoval
1 - OVERDRIVE CLUTCH PACK
Fig.132OverdriveClutchComponentPosition-
Typical
1 - REACTION PLATE 2 - CLUTCH PLATES
3 - PRESSURE PLATE 4 - CLUTCH DISCS
OVERDRIVE GEARTRAIN
(1) Remove overdrive clutch wave spring (Fig.
133), 5 disc clutch only.
Fig.130RemovingOverdriveClutchPackRetaining
Ring
1 - OVERDRIVE CLUTCH PACK RETAINING RING
Fig.133OverdriveClutchWaveSpringRemoval-5
DiscClutchOnly
1 - WAVE SPRING
DR OVERDRIVE UNIT (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 401
(2) Remove overdrive clutch reaction snap-ring (Fig. 134). Note that snap-ring is located in same groove as wave spring.
(5) Expand output shaft bearing snap-ring with expanding-type snap-ring pliers. Then push output shaft forward to release shaft bearing from locating ring (Fig. 137).
Fig.134OverdriveClutchReactionSnap-Ring
Removal
1 - REACTION RING 2 - CLUTCH HUB
(3) Remove Torx™ head screws that attach access
cover and gasket to overdrive case (Fig. 135).
(4) Remove access cover and gasket (Fig. 136).
Fig.137ReleasingBearingFromLocatingRing
1 - EXPAND BEARING LOCATING RING WITH SNAP-RING PLIERS 2 - ACCESS HOLE
(6) Lift gear case up and off geartrain assembly
(Fig. 138).
Fig.135AccessCoverScrewRemoval
1 - TORX SCREWDRIVER (T25) 2 - ACCESS COVER SCREWS
Fig.138RemovingGeartrain
1 - GEARTRAIN ASSEMBLY 2 - GEAR CASE
Fig.136AccessCoverAndGasketRemoval
1 - ACCESS COVER AND GASKET
21 - 402
OVERDRIVE UNIT (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(7) Remove snap-ring that retains rear bearing on
(8) Remove rear bearing from output shaft (Fig.
output shaft.
139).
Fig.139RearBearingRemoval
1 - OUTPUT SHAFT 2 - REAR BEARING 3 - SNAP-RING
DIRECT CLUTCH, HUB AND SPRING
WARNING: THE NEXT STEP IN DISASSEMBLY INVOLVES COMPRESSING THE DIRECT CLUTCH SPRING. IT IS EXTREMELY IMPORTANT THAT PROPER EQUIPMENT BE USED TO COMPRESS THE SPRING AS SPRING FORCE IS APPROXI- MATELY 830 POUNDS. USE SPRING COMPRESSOR TOOL 6227-1 AND A HYDRAULIC SHOP PRESS WITH A MINIMUM RAM TRAVEL OF 5-6 INCHES. THE PRESS MUST ALSO HAVE A BED THAT CAN BE ADJUSTED UP OR DOWN AS REQUIRED. RELEASE CLUTCH SPRING TENSION SLOWLY AND COMPLETELY TO AVOID PERSONAL INJURY.
Fig.140GeartrainMountedInShopPress
1 - PRESS RAM 2 - SPECIAL TOOL C-3995-A (OR SIMILAR TOOL) 3 - CLUTCH HUB 4 - PLATES 5 - PRESS BED 6 - SPECIAL TOOL 6227-1
(1) Mount geartrain assembly in shop press (Fig.
140).
(2) Position Compressor Tool 6227-1 on clutch hub (Fig. 140). Support output shaft flange with steel press plates as shown and center assembly under press ram.
(3) Apply press pressure slowly. Compress hub and spring far enough to expose clutch hub retaining ring and relieve spring pressure on clutch pack snap-ring (Fig. 140).
DR OVERDRIVE UNIT (Continued)
(4) Remove direct clutch pack snap-ring (Fig. 141). (5) Remove direct clutch hub retaining ring (Fig.
142).
AUTOMATIC TRANSMISSION - 48RE
21 - 403
(6) Release press load slowly and completely (Fig.
143).
(7) Remove Special Tool 6227-1. Then remove clutch pack from hub (Fig. 143). Note the orientation of the clutch discs. The clutch pack consists of 23 sin- gle-sided discs and they must be installed in the same orientation as they were removed.
Fig.141DirectClutchPackSnap-RingRemoval
1 - CLUTCH HUB 2 - SPECIAL TOOL 6227-1
3 - DIRECT CLUTCH PACK SNAP-RING 4 - PRESS PLATES 5 - CLUTCH DRUMFig.143DirectClutchPackRemoval
1 - SPECIAL TOOL 6227-1
2 - DIRECT CLUTCH HUB 3 - DIRECT CLUTCH PACKGEARTRAIN
(1) Remove direct clutch hub and spring (Fig. 144).
Fig.142DirectClutchHubRetainingRingRemoval 1 - SPECIAL TOOL 6227-1
2 - CLUTCH HUB RETAINING RING 3 - PRESS BED 4 - PRESS PLATESFig.144DirectClutchHubAndSpringRemoval
1 - DIRECT CLUTCH SPRING 2 - DIRECT CLUTCH HUB
21 - 404
OVERDRIVE UNIT (Continued)AUTOMATIC TRANSMISSION - 48RE
(2) Remove sun gear and spring plate. Then remove planetary thrust bearing and planetary gear (Fig. 145).
DR
(6) Mark position of annulus gear and direct clutch drum for assembly alignment reference (Fig. 147). Use small center punch or scriber to make alignment marks.
Fig.145RemovingSunGear,ThrustBearingAnd
PlanetaryGear
1 - PLANETARY GEAR 2 - PLANETARY THRUST BEARING 3 - CLUTCH SPRING PLATE 4 - SPRING PLATE SNAP-RING 5 - SUN GEAR
(3) Remove overrunning clutch assembly with expanding type snap-ring pliers (Fig. 146). Insert pli- ers into clutch hub. Expand pliers to grip hub splines and remove clutch with counterclockwise, twisting motion.
(4) Remove
thrust
bearing
from overrunning
clutch hub.
(5) Remove overrunning clutch from hub.
Fig.147MarkingDirectClutchDrumAndAnnulus
GearForAssemblyAlignment
1 - DIRECT CLUTCH DRUM 2 - HAMMER 3 - PUNCH
(7) Remove direct clutch drum rear retaining ring
(Fig. 148).
Fig.148ClutchDrumInnerRetainingRingRemoval 1 - INNER RETAINING RING 2 - DIRECT CLUTCH DRUM 3 - ANNULUS GEAR
Fig.146OverrunningClutchAssemblyRemoval/
Installation
1 - OVERRUNNING CLUTCH 2 - NEEDLE BEARING
DR OVERDRIVE UNIT (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 405
(8) Remove direct clutch drum outer retaining ring
(Fig. 149).
(9) Mark annulus gear and output shaft for assem- bly alignment reference (Fig. 150). Use punch or scriber to mark gear and shaft.
Fig.151AnnulusGearSnap-RingRemoval
1 - OUTPUT SHAFT 2 - ANNULUS GEAR 3 - SNAP-RING
Fig.149ClutchDrumOuterRetainingRingRemoval 1 - OUTER RETAINING RING
Fig.152AnnulusGearRemoval
1 - OUTPUT SHAFT 2 - ANNULUS GEAR
Fig.150MarkingAnnulusGearAndOutputShaft
ForAssemblyAlignment
1 - OUTPUT SHAFT 2 - HAMMER 3 - PUNCH
(10) Remove snap-ring that secures annulus gear on output shaft (Fig. 151). Use two screwdrivers to unseat and work snap-ring out of groove as shown.
(11) Remove annulus gear from output shaft (Fig. 152). Use rawhide or plastic mallet to tap gear off shaft.
GEAR CASE AND PARK LOCK
(1) Remove locating ring from gear case.
(2) Remove park pawl shaft retaining bolt and
remove shaft, pawl and spring.
(3) Remove reaction plug snap-ring and remove
reaction plug.
(4) Remove output shaft seal.
CLEANING
Clean the geartrain and case components with sol- vent. Dry all parts except the bearings with com- pressed air. Allow bearings to air dry.
Do not use shop towels for wiping parts dry unless the towels are made from a lint-free material. A suffi- cient quantity of lint (from shop towels, cloths, rags, etc.) could plug the transmission filter and fluid pas- sages.
Discard the old case gasket and seals. Do not attempt to salvage these parts. They are not reus-
21 - 406
OVERDRIVE UNIT (Continued)AUTOMATIC TRANSMISSION - 48RE
able. Replace any of the overdrive unit snap-rings if distorted or damaged.
Minor nicks or scratches on components can be smoothed with crocus cloth. However, do not attempt to reduce severe scoring on any components with abrasive materials. Replace severely scored compo- nents; do not try to salvage them.
INSPECTION
Check condition of the park lock components and
the overdrive case.
Check the bushings in the overdrive case. Replace the bushings if severely scored or worn. Also replace the case seal if loose, distorted, or damaged.
Examine the overdrive and direct clutch discs and plates. Replace the discs if the facing is worn, severely scored, or burned and flaking off. Replace the clutch plates if worn, heavily scored, or cracked. Check the lugs on the clutch plates for wear. The plates should slide freely in the drum. Replace the plates or drum if binding occurs.
Check condition of the annulus gear, direct clutch hub, clutch drum and clutch spring. Replace the gear, hub and drum if worn or damaged. Replace the spring if collapsed, distorted, or cracked.
Be sure the splines and lugs on the gear, drum and hub are in good condition. The clutch plates and discs should slide freely in these components.
Inspect
the thrust bearings and spring plate. Replace the plate if worn or scored. Replace the bear- ings if rough, noisy, brinnelled, or worn.
Inspect the planetary gear assembly and the sun gear and bushings. If either the sun gear or the bushings are damaged, replace the gear and bush- ings as an assembly. The gear and bushings are not serviced separately.
The planetary carrier and pinions must be in good condition. Also be sure the pinion pins are secure and in good condition. Replace the carrier if worn or damaged. Inspect the overrunning clutch and race. The race surface should be smooth and free of scores. Replace the overrunning clutch assembly or the race if either assembly is worn or damaged in any way.
Replace the shaft pilot bushing and inner bushing if damaged. Replace either shaft bearing if rough or noisy. Replace the bearing snap-rings if distorted or cracked.
Check the machined surfaces on the output shaft. These surfaces should clean and smooth. Very minor nicks or scratches can be smoothed with crocus cloth. Replace the shaft if worn, scored or damaged in any way. Inspect the output shaft bushings. The small bush- ing is the intermediate shaft pilot bushing. The large bushing is the overrunning clutch hub bushing. Replace either bushing if scored, pitted, cracked, or worn.
DR
ASSEMBLY
GEARTRAIN AND DIRECT CLUTCH
(1) Soak direct clutch and overdrive clutch discs in Mopart ATF +4, Automatic Transmission fluid. Allow discs to soak for 10-20 minutes.
(2) Install annulus gear
if removed. Then install annulus gear retaining snap- ring (Fig. 153).
on output
shaft,
(3) Align and install clutch drum on annulus gear (Fig. 154). Be sure drum is engaged in annulus gear lugs.
(4) Install clutch drum outer retaining ring (Fig.
154).
Fig.153AnnulusGearInstallation
1 - SNAP-RING 2 - OUTPUT SHAFT FRONT BEARING 3 - ANNULUS GEAR
Fig.154ClutchDrumAndOuterRetainingRing
Installation
1 - ANNULUS GEAR 2 - OUTER SNAP-RING 3 - CLUTCH DRUM
DR OVERDRIVE UNIT (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 407
(5) Slide clutch drum forward and install
inner
retaining ring (Fig. 155).
(6) Install rear bearing and snap-ring on output shaft (Fig. 156). Be sure locating ring groove in bear- ing is toward rear.
Fig.155ClutchDrumInnerRetainingRing
Installation
1 - ANNULUS GEAR 2 - INNER SNAP-RING 3 - CLUTCH DRUM
Fig.156RearBearingAndSnap-RingInstallation 1 - REAR BEARING 2 - SNAP-RING
(7) Install overrunning clutch on hub (Fig. 157). Note that clutch only fits one way. Shoulder on clutch should seat in small recess at edge of hub.
(8) Install thrust bearing on overrunning clutch hub. Use generous amount of petroleum jelly to hold bearing in place for installation. Bearing fits one way only. Be sure bearing is seated squarely against hub. Reinstall bearing if it does not seat squarely.
(9) Install overrunning clutch in output shaft (Fig. 158). Insert snap-ring pliers in hub splines. Expand pliers to grip hub. Then install assembly with coun- terclockwise, twisting motion.
Fig.157AssemblingOverrunningClutchAndHub 1 - CLUTCH HUB 2 - OVERRUNNING CLUTCH
Fig.158OverrunningClutchInstallation
1 - CLUTCH DRUM 2 - OVERRUNNING CLUTCH ASSEMBLY 3 - EXPANDING-TYPE SNAP-RING PLIERS 4 - CLUTCH DRUM 5 - ANNULUS GEAR 6 - OVERRUNNING CLUTCH ASSEMBLY SEATED IN OUTPUT SHAFT
21 - 408
OVERDRIVE UNIT (Continued)AUTOMATIC TRANSMISSION - 48RE
(10) Install planetary gear in annulus gear (Fig. 159). Be sure planetary pinions are fully seated in annulus gear before proceeding.
DR
Fig.161SunGearInstallation
1 - SUN GEAR AND SPRING PLATE ASSEMBLY
(14) Mount assembled output shaft, annulus gear, and clutch drum in shop press. Direct clutch spring, hub and clutch pack are easier to install with assem- bly mounted in press.
(15) Align splines in hubs of planetary gear and overrunning clutch with Alignment tool 6227-2 (Fig. 162). Insert tool through sun gear and into splines of both hubs. Be sure alignment tool is fully seated before proceeding.
Fig.159PlanetaryGearInstallation
1 - PLANETARY GEAR 2 - ANNULUS GEAR
(11) Coat planetary thrust bearing and bearing contact surface of spring plate with generous amount of petroleum jelly. This will help hold bearing in place during installation.
(12) Install planetary thrust bearing on sun gear (Fig. 160). Slide bearing onto gear and seat it against spring plate as shown. Bearing fits one way only. If it does not seat squarely against spring plate, remove and reposition bearing.
(13) Install assembled sun gear, spring plate and thrust bearing (Fig. 161). Be sure sun gear and thrust bearing are fully seated before proceeding.
Fig.160PlanetaryThrustBearingInstallation
1 - SPRING PLATE 2 - PLANETARY THRUST BEARING 3 - SUN GEAR
Fig.162AlignmentToolInstallation
1 - SPECIAL TOOL 6227-2
2 - PRESS PLATES 3 - ASSEMBLED DRUM AND ANNULUS GEAR 4 - SUN GEARDR OVERDRIVE UNIT (Continued)
(16) Install direct clutch spring (Fig. 163). Be sure
spring is properly seated on spring plate.
AUTOMATIC TRANSMISSION - 48RE
21 - 409
Fig.163DirectClutchSpringInstallation
1 - SPECIAL TOOL 6227-2
2 - DIRECT CLUTCH SPRING 3 - CLUTCH HUB 4 - PRESS PLATESNOTE: The direct clutch in a 48RE transmission uses 23 single-sided clutch discs.
Fig.164CorrectPositionOfDirect
ClutchReactionPlate
1 - REACTION PLATE COUNTERBORE 2 - DIRECT CLUTCH REACTION PLATE (FLUSH WITH END OF HUB) 3 - CLUTCH HUB
(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. 164).
(b) Install first clutch disc with external lugs fol- lowed by a disc with internal spline teeth. Con- tinue alternating internal and external discs until all discs have been installed.
(c) Install pressure plate. This is last clutch pack item to be installed. Be sure plate is installed with shoulder side facing upward (Fig. 165).
Fig.165CorrectPositionOfDirectClutch
1 - DIRECT CLUTCH PRESSURE PLATE 2 - CLUTCH PACK 3 - BE SURE SHOULDER SIDE OF PLATE FACES UPWARD
21 - 410
OVERDRIVE UNIT (Continued)AUTOMATIC TRANSMISSION - 48RE
(18) Install clutch hub and clutch pack on direct clutch spring (Fig. 166). Be sure hub is started on sun gear splines before proceeding.
Fig.166DirectClutchPackAndClutchHub
Installation
1 - CLUTCH HUB 2 - DIRECT CLUTCH PACK 3 - CLUTCH DRUM
WARNING: THE NEXT STEP IN GEARTRAIN ASSEMBLY INVOLVES COMPRESSING THE DIRECT CLUTCH HUB AND SPRING. IT IS EXTREMELY IMPORTANT THAT PROPER EQUIPMENT BE USED TO COMPRESS THE SPRING AS SPRING FORCE IS APPROXIMATELY 830 POUNDS. USE COMPRES- SOR TOOL C-6227-1 AND A HYDRAULIC-TYPE SHOP PRESS WITH A MINIMUM RAM TRAVEL OF 6
INCHES. THE PRESS MUST ALSO HAVE A BED THAT CAN BE ADJUSTED UP OR DOWN AS REQUIRED. RELEASE CLUTCH SPRING TENSION SLOWLY AND COMPLETELY TO AVOID PERSONAL INJURY.(19) Position Compressor Tool 6227-1 on clutch
hub.
(20) Compress clutch hub and spring just enough
to place tension on hub and hold it in place.
(21) Slowly compress clutch hub and spring. Com- press spring and hub only enough to expose ring grooves for clutch pack snap-ring and clutch hub retaining ring.
(22) Realign clutch pack on hub and seat clutch
discs and plates in clutch drum.
DR
(23) Install direct clutch pack snap-ring (Fig. 167). Be very sure snap-ring is fully seated in clutch drum ring groove.
(24) Install clutch hub retaining ring (Fig. 168). Be very sure retaining ring is fully seated in sun gear ring groove.
(25) Slowly release press ram, remove compressor
tools and remove geartrain assembly.
Fig.167DirectClutchPackSnap-RingInstallation 1 - SPECIAL TOOL 6227-1
2 - DIRECT CLUTCH PACK SNAP-RINGFig.168ClutchHubRetainingRingInstallation
1 - SPECIAL TOOL 6227-1
2 - CLUTCH HUB RETAINING RINGDR OVERDRIVE UNIT (Continued) GEAR CASE
(1) Position park pawl and spring in case and install park pawl shaft. Verify that end of spring with 90° bend is hooked to pawl and straight end of spring is seated against case.
(2) Install pawl shaft retaining bolt. Tighten bolt
to 27 N·m (20 ft. lbs.) torque.
(3) Install park lock reaction plug. Note that plug has locating pin at rear (Fig. 169). Be sure pin is seated in hole in case before installing snap-ring.
(4) Install reaction plug snap-ring (Fig. 170). Com- press snap-ring only enough for installation; do not distort it.
AUTOMATIC TRANSMISSION - 48RE
21 - 411
(5) Verify that tab ends of rear bearing locating ring extend into access hole in gear case (Fig. 171). (6) Support geartrain on Tool 6227-1 (Fig. 172). Be
sure tool is securely seated in clutch hub.
(7) Install overdrive gear case on geartrain (Fig.
172).
Fig.169ReactionPlugLocatingPinAndSnap-Ring 1 - REACTION PLUG SNAP-RING (DO NOT OVERCOMPRESS TO INSTALL) 2 - LOCATING PIN 3 - PARK LOCK REACTION PLUG
Fig.171CorrectRearBearingLocatingRing
Position
1 - CASE ACCESS HOLE 2 - TAB ENDS OF LOCATING RING
Fig.170ReactionPlugAndSnap-RingInstallation 1 - REACTION PLUG SNAP-RING 2 - SNAP-RING PLIERS
1 - GEARTRAIN ASSEMBLY 2 - GEAR CASE
Fig.172OverdriveGearCaseInstallation
21 - 412
OVERDRIVE UNIT (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(8) Expand front bearing locating ring with snap- ring pliers (Fig. 173). Then slide case downward until locating ring locks in bearing groove and release snap-ring.
(9) Install locating ring access cover and gasket in
overdrive unit case (Fig. 174).
Fig.173SeatingLocatingRingInRearBearing
1 - EXPAND BEARING LOCATING RING WITH SNAP-RING PLIERS 2 - ACCESS HOLE
Fig.174LocatingRingAccessCoverAndGasket
Installation
1 - TORX SCREWDRIVER (T25) 2 - ACCESS COVER SCREWS
OVERDRIVE CLUTCH
NOTE: The overdrive clutch in a 48RE transmission uses 5 or 6 clutch discs depending on the applica- tion.
(1) Install overdrive clutch reaction ring first.
Reaction ring is flat with notched ends (Fig. 175).
(2) For 5 disc overdrive clutch versions,
install wave spring on top of reaction ring (Fig. 176). Reac- tion ring and wave ring both fit in same ring groove. Use screwdriver to seat each ring securely in groove.
Also ensure that the ends of the two rings are offset from each other.
(3) Assemble overdrive clutch pack.
Fig.175OverdriveClutchReactionRingInstallation 1 - REACTION RING 2 - CLUTCH HUB
Fig.176OverdriveClutchWaveSpringInstallation-
5DiscClutchOnly
1 - WAVE SPRING
(4) Install overdrive clutch reaction plate first. (5) Install first clutch disc followed by first clutch plate. Then install remaining clutch discs and plates in same order.
(6) Install clutch pack pressure plate. (7) Install clutch pack wire-type retaining ring
(Fig. 177).
INTERMEDIATE SHAFT SPACER SELECTION
(1) Place overdrive unit in vertical position. Mount it on blocks, or in workbench with appropriate size mounting hole cut into it. Be sure unit is facing upward for access to direct clutch hub. Also be sure output shaft is not loaded and internal components are moved rearward for accurate measurement.
(2) Determine correct thickness intermediate shaft
spacer as follows:
(a) Insert Special Tool 6312 through sun gear, planetary gear and into pilot bushing in output shaft. Be sure tool bottoms against planetary shoulder.
DR OVERDRIVE UNIT (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 413
Fig.179IntermediateShaftEndPlaySpacer
Selection
Fig.177OverdriveClutchPackRetainingRing
Installation
1 - OVERDRIVE CLUTCH PACK RETAINING RING
(b) Position Gauge Tool 6311 across face of over- drive case (Fig. 178). Then position Dial Caliper C-4962 over gauge tool.
(c) Extend sliding scale of dial caliper downward through gauge tool slot until scale contacts end of Gauge Alignment Tool 6312. Lock scale in place. Remove dial caliper tool and note distance mea- sured (Fig. 178).
(d) Select proper thickness end play spacer from spacer chart based on distance measured (Fig. 179).
(e) Remove Gauge Alignment Tool 6312.
upward for access to direct clutch hub. Also be sure output shaft is not loaded and internal components are moved rearward for accurate measurement.
(2) Determine correct thickness overdrive piston
thrust plate as follows:
(a) Position Gauge Tool 6311 across face of over- drive case. Then position Dial Caliper C-4962 over gauge tool (Fig. 180).
(b) Measure distance to clutch hub thrust bear- ing seat at four points 90° apart. Then average measurements by adding them and dividing by 4. (c) Select and install required thrust plate from
information in thrust plate chart (Fig. 181). (3) Leave Alignment Tool 6227-2 in place. Tool will keep planetary and clutch hub splines in alignment until overdrive unit is ready for installation on trans- mission.
(4) Transmission speed sensor can be installed at this time if desired. However, it is recommended that sensor not be installed until after overdrive unit is secured to transmission.
Fig.178ShaftEndPlayMeasurement
1 - SPECIAL TOOL 6312
2 - SPECIAL TOOL 6311
3 - SPECIAL TOOL C-4962OD THRUST PLATE SELECTION
(1) Place overdrive unit in vertical position. Mount it on blocks, or in workbench with appropriate size mounting hole cut into it. Be sure unit is facing
Fig.180OverdrivePistonThrustPlateMeasurement 1 - SPECIAL TOOL 6311
2 - DIRECT CLUTCH HUB THRUST BEARING SEAT 3 - SPECIAL TOOL C-496221 - 414
OVERDRIVE UNIT (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(3) Cut out old case gasket around piston retainer
with razor knife (Fig. 182).
(4) Use old gasket as template and trim new gas-
ket to fit.
(5) Position new gasket over piston retainer and on transmission case. Use petroleum jelly to hold gasket in place if necessary. Do not use any type of sealer to secure gasket. Use petroleum jelly only.
Fig.181OverdrivePistonThrustPlateSelection
OVERDRIVE PISTON
(1) Install new seals on overdrive piston. (2) Stand transmission case upright on bellhous-
ing.
(3) Position Guide Ring 8114-1 on outer edge of
overdrive piston retainer.
overdrive piston retainer.
(4) Position Seal Guide 8114-3 on inner edge of
(5) Install overdrive piston in overdrive piston
retainer by:
(a) Aligning locating lugs on overdrive piston to
the two mating holes in retainer.
(b) Lubricate overdrive piston seals with Mopart
ATF+4.
retainer.
(c) Install piston over Seal Guide 8114-3 and
inside Guide Ring 8114-1.
(d) Push overdrive piston into position in
(e) Verify that the locating lugs entered the lug
bores in the retainer. (6) Install intermediate shaft spacer on intermedi-
ate shaft.
drive piston.
drive piston.
(7) Install overdrive piston thrust plate on over-
(8) Install overdrive piston thrust bearing on over-
(9) Install transmission speed sensor and o-ring
seal in overdrive case.
INSTALLATION
(1) Be sure overdrive unit Alignment Tool 6227-2
is fully seated before moving unit. If tool is not seated and gear splines rotate out of alignment, over- drive unit will have to be disassembled in order to realign splines.(2) If overdrive piston retainer was not removed during service and original case gasket is no longer reusable, prepare new gasket by trimming it.
Fig.182TrimmingOverdriveCaseGasket
1 - GASKET 2 - SHARP KNIFE
(6) Install selective spacer on intermediate shaft, if removed. Spacer goes in groove just rearward of shaft rear splines (Fig. 183).
Fig.183IntermediateShaftSelectiveSpacer
Location
1 - SELECTIVE SPACER 2 - SPACER GROOVE 3 - INTERMEDIATE SHAFT
(7) Install thrust bearing in overdrive unit sliding hub. Use petroleum jelly to hold bearing in position.
CAUTION: Be sure the shoulder on the inside diam- eter of the bearing is facing forward.
(8) Verify that splines in overdrive planetary gear and overrunning clutch hub are aligned with Align-
DR OVERDRIVE UNIT (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 415
ment Tool 6227-2. Overdrive unit cannot be installed if splines are not aligned. If splines have rotated out of alignment, unit will have to be disassembled to realign splines.
(9) Carefully slide Alignment Tool 6227-2 out of over-
drive planetary gear and overrunning clutch splines.
(10) Raise overdrive unit and carefully slide it straight onto intermediate shaft. Insert park rod into park lock reaction plug at same time. Avoid tilting overdrive during installation as this could cause planetary gear and overrunning clutch splines to rotate out of alignment. If this occurs, it will be nec- essary to remove and disassemble overdrive unit to realign splines.
(11) Work overdrive unit forward on intermediate
shaft until seated against transmission case.
(12) Install bolts attaching overdrive unit to trans- mission unit. Tighten bolts in diagonal pattern to 34
N·m (25 ft-lbs).(13) Connect the transmission speed sensor and
overdrive wiring connectors.
(14) Install the transfer case, if equipped. (15) Align and install rear propeller shaft, if nec- essary. (Refer to 3 - DIFFERENTIAL & DRIVELINE/ PROPELLER INSTALLATION)
SHAFT/PROPELLER
SHAFT
OVERRUNNING CLUTCH CAM/OVERDRIVE PISTON RETAINER DESCRIPTION
The overrunning clutch (Fig. 184) consists of an inner race, an outer race (or cam), rollers and springs, and the spring retainer. The number of roll- ers and springs depends on what transmission and which overrunning clutch is being dealt with.
OPERATION
As the inner race is rotated in a clockwise direction (as viewed from the front of the transmission), the race causes the rollers to roll toward the springs, causing them to compress against their retainer. The compression of the springs increases the clearance between the rollers and cam. This increased clear- ance between the rollers and cam results in a free- wheeling condition. When the inner race attempts to rotate counterclockwise, the action causes the rollers to roll in the same direction as the race, aided by the pushing of the springs. As the rollers try to move in the same direction as the inner race, they are wedged between the inner and outer races due to the design of the cam. In this condition, the clutch is locked and acts as one unit.
Fig.184OverrunningClutch
1 - OUTER RACE (CAM) 2 - ROLLER 3 - SPRING 4 - SPRING RETAINER 5 - INNER RACE (HUB)
DISASSEMBLY
(1) Remove the overdrive piston (Fig. 185). (2) Remove the overdrive piston retainer bolts. (3) Remove overdrive piston retainer. (4) Remove case gasket.
Fig.185OverdrivePistonRemoval
1 - OVERDRIVE CLUTCH PISTON 2 - INTERMEDIATE SHAFT 3 - SELECTIVE SPACER 4 - PISTON RETAINER
21 - 416
OVERRUNNING CLUTCH CAM/OVERDRIVE PISTON RETAINER (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(5) Tap old cam out of case with pin punch. Insert punch through bolt holes at rear of case (Fig. 186). Alternate position of punch to avoid cocking cam dur- ing removal.
(6) Clean clutch cam bore and case. Be sure to remove all chips/shavings generated during cam removal.
are aligned (Fig. 187). Then tap cam into case just enough to hold it in place.
(3) Verify that cam is correctly positioned before proceeding any further. Narrow ends of cam ramps should be to left when cam is viewed from front end of case (Fig. 187).
(4) Insert Adapter Tool SP-5124 into piston
retainer (Fig. 188).
Fig.186OverrunningClutchCam
1 - PIN PUNCH 2 - REAR SUPPORT BOLT HOLES
CLEANING
Clean the overrunning clutch assembly, clutch cam, low-reverse drum, and overdrive piston retainer in solvent. Dry them with compressed air after clean- ing.
INSPECTION
Fig.187PositioningReplacementClutchCamIn
Case
1 - ALIGN SERRATIONS ON CAM AND IN CASE 2 - CLUTCH CAM
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 drum if the clutch race, roller surface or inside diameter is scored, worn or damaged. Do not remove the clutch race from the low-reverse drum under any circumstances. Replace the drum and race as an assembly if either component is damaged.
Examine the overdrive piston retainer carefully for wear, cracks, scoring or other damage. Be sure the retainer hub is a snug fit in the case and drum. Replace the retainer if worn or damaged.
ASSEMBLY
Fig.188PositioningAdapterToolInOverdrive
PistonRetainer
1 - PISTON RETAINER 2 - SPECIAL TOOL SP-5124
(1) Temporarily install overdrive piston retainer in
case. Use 3-4 bolts to secure retainer.
(2) Align and start new clutch cam in the trans- mission case. Be sure serrations on cam and in case
DR OVERRUNNING CLUTCH CAM/OVERDRIVE PISTON RETAINER (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 417
(5) Assemble Puller Bolt SP-3701 and Press Plate
SP-3583-A (Fig. 189).
Fig.190PositioningPullerPlateOnClutchCam
1 - SPECIAL TOOL SP-3701
2 - BE SURE PLATE SP-3583-A IS SEATED SQUARELY ON CAMFig.189AssemblingClutchCamPullerBoltAnd
PressPlate
1 - PULLER BOLT SP-3701
2 - PRESS PLATE SP-3583-A(6) Install assembled puller plate and bolt (Fig. 190). Insert bolt through cam, case and adapter tool. Be sure plate is seated squarely on cam.
(7) Hold puller plate and bolt in place and install
puller nut SP-3701 on puller bolt (Fig. 191).
(8) Tighten puller nut to press clutch cam into case (Fig. 191). Be sure cam is pressed into case evenly and does not become cocked.
(9) Remove clutch cam installer tools. (10) Stake case in 14 places around clutch cam to help secure cam in case. Use blunt punch or chisel to stake case.
(11) Remove piston retainer
from case. Cover retainer with plastic sheeting, or paper to keep it dust free.
(12) Clean case and cam thoroughly. Be sure any chips/shavings generated during cam installation are removed from case.
Fig.191PressingOverrunningClutchCamInto
Case
1 - SPECIAL TOOL SP-3583-A 2 - TIGHTEN NUT TO DRAW CAM INTO CASE (NUT IS PART OF BOLT SP-3701) 3 - SPECIAL TOOL SP-5124
4 - SPECIAL TOOL SP-370121 - 418
OVERRUNNING CLUTCH CAM/OVERDRIVE PISTON RETAINER (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(13) Install new gasket at rear of transmission case. Use petroleum jelly to hold gasket in place. Be sure to align governor feed holes in gasket with feed passages in case (Fig. 192). Also install gasket before overdrive piston retainer. Center hole in gasket is smaller than retainer and cannot be installed over retainer.
(14) Position overdrive piston retainer on trans- mission case and align bolt holes in retainer, gasket and case (Fig. 193). Then install and tighten retainer bolts to 17 N·m (13 ft. lbs.) torque.
Fig.193AligningOverdrivePistonRetainer
1 - PISTON RETAINER 2 - GASKET 3 - RETAINER BOLTS
(e) Verify that the locating lugs entered the lug
bores in the retainer.
PISTONS DESCRIPTION
There are several sizes and types of pistons used in an automatic transmission. Some pistons are used to apply clutches, while others are used to apply bands. 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 con- verts 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: “Pressure on a confined fluid is transmitted equally in all directions and acts with equal force on equal areas.”
Fig.192Installing/AligningCaseGasket
1 - CASE GASKET 2 - BE SURE GOVERNOR TUBE FEED HOLES IN CASE AND GASKET ARE ALIGNED
(15) Install new seals on overdrive piston. (16) Stand transmission case upright on bellhous-
