(3) Using suitable suction gun, draw fluid from
PTU. Make sure hose contacts bottom of case to
ensure all fluid is removed.
(4) Add 1.15 liters (1.22 quarts) of Moparž Gear
and Axle Lubricant 80W-90 with suction gun (Fig. 9).
(5) Install inspection plug and torque to 20 N´m
(180 in. lbs.) torque.(6) Lower vehicle.
REMOVAL
(1) Raise vehicle and remove front wheels.
CAUTION: A certain amount of oil will drain out of
the transaxle when the drive shaft is removed.
Fig. 6 Inspection Plug
1 - INSPECTION PLUG
Fig. 7 Removing/Adding PTU Fluid
1 - SUCTION GUN
2 - INSPECTION HOLE
Fig. 8 Inspection Plug
1 - INSPECTION PLUG
Fig. 9 Adding Fluid to PTU
1 - SUCTION GUN
2 - INSPECTION HOLE
RSPOWER TRANSFER UNIT21-5
POWER TRANSFER UNIT (Continued)
(2) Remove right front drive shaft. Install a plug
into the right driveshaft seal hole. (Refer to 3 - DIF-
FERENTIAL & DRIVELINE/HALF SHAFT -
REMOVAL)
(3) Mark propeller shaft front flange.
CAUTION: Do not let propeller shaft to hang freely.
Damage to the shaft will occur.
(4) Remove propeller shaft assembly (Fig. 10).
(Refer to 3 - DIFFERENTIAL & DRIVELINE/PRO-
PELLER SHAFT - REMOVAL)
(5) Remove cradle plate (Fig. 11).(6) Remove the Power Transfer Unit mounting
bracket bolts at the rear of the unit (Fig. 12).
(7) Remove the right outboard support bracket and
bolts near the right axle shaft.
(8) Remove the four mounting bolts for the P.T.U.
(Fig. 13)and (Fig. 14).
(9) Remove P.T.U. assembly from vehicle.
INSTALLATION
(1) To install, reverse removal procedure. Check
transaxle fluid and P.T.U. fluid and fill to level.
(2) Refer to the Specifications section for the
proper torque specifications.
Fig. 10 Driveshaft Flange
1 - DRIVESHAFT FLANGE
Fig. 11 Cradle Plate
1 - CRADLE PLATE
Fig. 12 Remove Rear P.T.U Bracket Bolts
1 - P.T.U. MOUNT BRACKET
2 - P.T.U.
Fig. 13 P.T.U. Lower Mounting Bolts
1 - P.T.U.
2 - P.T.U. MOUNTING BOLTS
21 - 6 POWER TRANSFER UNITRS
POWER TRANSFER UNIT (Continued)
ADJUSTMENT - OUTPUT FLANGE SHIM
SELECTION
This procedure is used when the output flange is
replaced. Replacement of the output flange requires
installation of the correct size shim to maintain bear-
ing preload.The shim must protrude from the
new output flange the same distance that the
original shim protruded from the original
flange.
(1) Stand the original output flange on end with
shim side pointing up.
(2) Place original shim into groove in top of flange.
(3) Place a straight edge across the shim.
(4) Using feeler gauge, measure the distance
between the straight edge and the top of the flange
(Fig. 15). Record this measurement.
(5) Repeat steps Step 1 through Step 4using the
new flange and the original shim.Record this
measurement.
(6) If measurements are not equal, use a new shim
that protrudes from new output flange. Make sure it
protrudes the same amount.
(7) For Example: The original shim protrudes
0.075 inch from the original output flange. Place the
original shiminto the new output flange. The pro-
trusion of the shim in the new flange is 0.085 inch.
This indicates that a 0.010 inch thinner shim is
required to maintain the original protrusion.
(8) Install output flange and torque flange nut to
244 N´m (180 ft. lbs.).
(9) Check the turning torque of the pinion before
installing the rear cover into the P.T.U. The turning
torque should be between 2.0 N´m and 2.5 N´m (17
in. lbs. and 22 in. lbs.).
SPECIFICATIONS
TORQUE
DESCRIPTION...................TORQUE
End Cover................ 28N´m(250 in. lbs.)
Fill Plug.................. 27N´m(240 in. lbs.)
Flange Nut............... 162N´m(120 ft. lbs.)
Inspection Plug............ 20N´m(180 in. lbs.)
Rear Cover................ 28N´m(250 in. lbs.)
Ring Gear.................. 94N´m(70ft.lbs.)
Fig. 14 P.T.U. Upper Mounting Bolts
1 - P.T.U. UPPER MOUNTING BOLTS
2 - P.T.U.
Fig. 15 Output Flange Shim Measurement
1 - MEASURE THIS DIMENSION
2 - SHIM
3 - O-RING
4 - OUTPUT FLANGE
RSPOWER TRANSFER UNIT21-7
POWER TRANSFER UNIT (Continued)
AUTOMATIC - 31TH
TABLE OF CONTENTS
page page
AUTOMATIC - 31TH
DESCRIPTION...........................22
OPERATION.............................24
DIAGNOSIS AND TESTING.................24
PRELIMINARY DIAGNOSIS...............24
ROAD TEST...........................31
HYDRAULIC PRESSURE TESTS...........32
TORQUE CONVERTER HOUSING FLUID
LEAKAGE.............................34
CLUTCH AND SERVO AIR PRESSURE
TESTS...............................35
STANDARD PROCEDURE..................36
ALUMINUM THREAD REPAIR.............36
REMOVAL..............................36
DISASSEMBLY...........................39
ASSEMBLY.............................50
INSTALLATION...........................59
SCHEMATICS AND DIAGRAMS..............63
SPECIFICATIONS........................71
SPECIAL TOOLS.........................74
ACCUMULATOR
DESCRIPTION...........................78
OPERATION.............................78
BANDS
DESCRIPTION...........................79
OPERATION.............................79
ADJUSTMENTS..........................79
CLUTCH - FRONT
DESCRIPTION...........................80
OPERATION.............................81
DISASSEMBLY...........................81
ASSEMBLY.............................84
CLUTCH - REAR
DESCRIPTION...........................85
OPERATION.............................85
DISASSEMBLY...........................86
ASSEMBLY.............................89
FINAL DRIVE
DISASSEMBLY...........................90
ASSEMBLY.............................94
ADJUSTMENTS..........................96
FLUID
STANDARD PROCEDURE..................98
FLUID LEVEL AND CONDITION CHECK......98
FLUID AND FILTER CHANGE..............98
GEAR SHIFT CABLE
REMOVAL.............................100
INSTALLATION..........................101
ADJUSTMENTS.........................103GOVERNOR
DESCRIPTION..........................103
OPERATION............................103
CLEANING.............................104
INSPECTION...........................104
OIL PUMP
DESCRIPTION..........................104
OPERATION............................104
STANDARD PROCEDURE.................105
OIL PUMP VOLUME CHECK..............105
DISASSEMBLY..........................105
CLEANING.............................105
INSPECTION...........................105
ASSEMBLY............................105
PARK/NEUTRAL POSITION SWITCH
DIAGNOSIS AND TESTING................106
PARK/NEUTRAL POSITION SWITCH.......106
REMOVAL.............................106
INSTALLATION..........................107
PLANETARY GEARTRAIN
DISASSEMBLY..........................107
ASSEMBLY............................107
SEAL - OIL PUMP
REMOVAL.............................109
INSTALLATION..........................109
SERVO - KICKDOWN
DESCRIPTION..........................109
OPERATION............................109
DISASSEMBLY..........................110
CLEANING.............................111
INSPECTION...........................111
ASSEMBLY.............................112
SERVO - LOW/REVERSE
DESCRIPTION..........................112
OPERATION............................112
DISASSEMBLY..........................112
CLEANING.............................113
ASSEMBLY.............................113
SHIFT INTERLOCK SOLENOID
DESCRIPTION..........................113
OPERATION............................114
DIAGNOSIS AND TESTING................115
BRAKE/TRANSMISSION SHIFT INTERLOCK
SOLENOID...........................115
REMOVAL.............................115
INSTALLATION..........................116
SOLENOID - TCC
DESCRIPTION..........................117
OPERATION............................117
RSAUTOMATIC - 31TH21-21
REMOVAL.............................118
INSTALLATION..........................118
THROTTLE VALVE CABLE
REMOVAL.............................118
INSTALLATION..........................118
ADJUSTMENTS.........................120
TORQUE CONVERTER
DESCRIPTION..........................120
OPERATION............................123
REMOVAL.............................125
INSTALLATION..........................125
TRANSFER SYSTEM - OUTPUT SHAFT/GEAR/
BEARING
REMOVAL.............................126
INSTALLATION..........................129
ADJUSTMENTS.........................132TRANSFER SYSTEM - TRANSFER SHAFT/
GEAR/BEARING
REMOVAL.............................134
INSTALLATION..........................137
ADJUSTMENTS.........................142
VALVE BODY
REMOVAL.............................142
DISASSEMBLY..........................145
CLEANING.............................151
INSPECTION...........................152
ASSEMBLY............................152
INSTALLATION..........................155
ADJUSTMENTS.........................157
VEHICLE SPEED SENSOR/PINION GEAR
REMOVAL.............................157
INSTALLATION..........................157
AUTOMATIC - 31TH
DESCRIPTION
This transaxle combines torque converter, three
speed transmission, final drive gearing, and differen-
tial into a front wheel drive system.
Within this transaxle, there are three primary
areas:
(1) Main center line plus valve body.
(2) Transfer shaft center line (includes governor
and parking sprag).
(3) Differential center line.
Center distances between the main rotating parts
in these three areas are held precise to maintain a
low noise level.
The torque converter, transaxle area, and differen-
tial are housed in an integral aluminum die casting.
The differential oil sump is common with the
transaxle sump. Separate filling of the differen-
tial is NOT necessary.
The torque converter is attached to the crankshaft
through a flexible driving plate. Cooling of the con-
verter is accomplished by circulating the transaxle
fluid through a remote cooler. There are two types of
coolers used. An oil-to-water type cooler located in
the radiator side tank and/or an oil-to-air heat
exchanger. The torque converter assembly is a sealed
unit that cannot be disassembled.
The transaxle fluid is filtered by an internal filter
attached to the lower side of the valve body assembly.Engine torque is transmitted to the torque con-
verter and then through the input shaft to multiple-
disc clutches in the transaxle. The power flow
depends on the application of the clutches and bands.
Refer to Elements in Use Chart in Diagnosis and
Tests section.
The transaxle consists of:
²Two multiple-disc clutches
²An overrunning clutch
²Two servos
²A hydraulic accumulator
²Two bands
²Two planetary gear sets
This provides three forward ratios and a reverse
ratio. The common sun gear of the planetary gear
sets is connected to the front clutch by a driving
shell. The driving shell is splined to the sun gear and
front clutch retainer. The hydraulic system consists
of an oil pump and a single valve body which con-
tains all of the valves except the governor valves.
The transaxle sump and differential sump are both
vented through the dipstick. Output torque from the
main center line is delivered through helical gears to
the transfer shaft. This gear set is a factor in the
transaxle final drive (axle) ratio. The shaft also car-
ries the governor and parking sprag. An integral heli-
cal gear on the transfer shaft drives the differential
ring gear.
21 - 22 AUTOMATIC - 31THRS
31TH Automatic Transaxle
1 - TORQUE CONVERTER CLUTCH
2 - TORQUE CONVERTER
3 - OIL PUMP
4 - FRONT CLUTCH
5 - REAR CLUTCH
6 - OVER-RUNNING CLUTCH7 - PLANETARY GEARS
8 - TRANSFER GEARS
9 - TRANSFER SHAFT
10 - GOVERNOR
11 - DIFFERENTIAL
RSAUTOMATIC - 31TH21-23
AUTOMATIC - 31TH (Continued)
CONDITION POSSIBLE CAUSES CORRECTION
NO DRIVE OR
REVERSE (VEHICLE
WILL NOT MOVE)1. Fluid Level Low. 1. Add fluid and check for leaks if drive is
restored.
2. Gearshift Linkage/Cable Loose/
Misadjusted.2. Inspect, adjust and reassemble linkage
as needed. Replace worn/damaged parts.
3. Filter Plugged. 3. Remove and disassemble transmission.
Repair or replace failed components as
needed. Replace filter. If filter and fluid
contained clutch material or metal
particles, an overhaul may be necessary.
Perform lube flow test. Flush oil. Replace
cooler as necessary.
4. Oil Pump Damaged. 4. Perform pressure test to confirm low
pressure. Replace pump body assembly if
necessary.
5. Valve Body Malfunctioned. 5. Check press and inspect valve body.
Replace valve body (as assembly) if any
valve or bore is damaged. Clean and
reassemble correctly if all parts are in
good condition.
6. Transmission Internal Component
Damaged.6. Remove and disassemble transmission.
Repair or replace failed components as
needed. Remove and disassemble
transmission. Repair or replace failed
components as needed.
7. Park Sprag not Releasing - Check Stall
Speed, Worn/Damaged/Stuck.7. Remove, disassemble, repair.
8. Torque Converter Damage. 8. Inspect and replace as required.
SHIFTS DELAYED OR
ERRATIC (ALSO
SHIFTS HARSH AT
TIMES)1. Fluid Level Low/High. 1. Correct fluid level and check for leaks if
low.
2. Fluid Filter Clogged. 2. Replace filter. If filter and fluid
contained clutch material or metal
particles, an overhaul may be necessary.
Perform lube flow test.
3. Throttle Linkage Misadjusted. 3. Adjust linkage as described in service
section.
4. Throttle Linkage Binding. 4. Check cable for binding. Check for
return to closed throttle at transmission.
5. Gearshift Linkage/Cable Misadjusted. 5. Adjust linkage/cable as described in
service section.
6. Governor Valve Sticking. 6. Inspect, clean or repair.
7. Governor Seal Rings Worn/Damaged. 7. Inspect/replace.
8. Clutch or Servo Failure. 8. Remove valve body and air test clutch,
and band servo operation. Disassemble
and repair transmission as needed.
9. Front Band Misadjusted. 9. Adjust band.
10. Pump Suction Passage Leak. 10. Check for excessive foam on dipstick
after normal driving. Check for loose
pump bolts, defective gasket. Replace
pump assembly if needed.
21 - 26 AUTOMATIC - 31THRS
AUTOMATIC - 31TH (Continued)
CONDITION POSSIBLE CAUSES CORRECTION
SLIPS IN FORWARD
DRIVE RANGES1. Fluid Level Low. 1. Add fluid and check for leaks.
2. Fluid Foaming. 2. Check for high oil level, bad pump
gasket or seals, dirt between pump halves
and loose pump bolts. Replace pump if
necessary.
3. Throttle Linkage Misadjusted. 3. Adjust linkage.
4. Gearshift Linkage Misadjusted. 4. Adjust linkage.
5. Rear Clutch Worn. 5. Inspect and replace as needed.
6. Low Hydraulic Pressure Due to Worn
Pump, Incorrect Control Pressure
Adjustments, Valve Body Warpage or
Malfunction, Sticking Governor, Leaking
Seal Rings, Clutch Seals Leaking, Servo
Leaks, Clogged Filter or Cooler Lines6. Perform hydraulic and air pressure
tests to determine cause.
7. Rear Clutch Malfunction, Leaking Seals
or Worn Plates.7. Air pressure check clutch-servo
operation and repair as required.
8. Overrunning Clutch Worn, Not Holding
(Slips in 1 Only).8. Replace Clutch.
SLIPS IN LOW GEAR
9D9ONLY, BUT NOT IN
1 POSITIONOverrunning Clutch Faulty. Replace overrunning clutch.
GROWLING, GRATING
OR SCRAPING
NOISES1. Drive Plate Broken. 1. Replace.
2. Torque Converter Bolts Hitting Dust
Shield.2. Dust shield bent. Replace or repair.
3. Planetary Gear Set Broken/Seized. 3. Check for debris in oil pan and repair
as required.
4. Overrunning Clutch Worn/Broken. 4. Inspect and check for debris in oil pan.
Repair as required.
5. Oil Pump Components Scored/Binding. 5. Remove, inspect and repair as
required.
6. Output Shaft Bearing or Bushing
Damaged.6. Remove, inspect and repair as
required.
7. Clutch Operation Faulty. 7. Perform air pressure check and repair
as required.
8. Front and Rear Bands Misadjusted. 8. Adjust bands.
DRAGS OR LOCKS UP 1. Fluid Level Low. 1. Check and adjust level.
2. Clutch Dragging/Failed 2. Air pressure check clutch operation and
repair as required.
3. Front or Rear Band Misadjusted. 3. Adjust bands.
4. Case Leaks Internally. 4. Check for leakage between passages
in case.
5. Servo Band or Linkage Malfunction. 5. Air pressure check servo operation and
repair as required.
6. Overrunning Clutch Worn. 6. Remove and inspect clutch. Repair as
required.
7. Planetary Gears Broken. 7. Remove, inspect and repair as required
(look for debris in oil pan).
RSAUTOMATIC - 31TH21-29
AUTOMATIC - 31TH (Continued)