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ing.† If pressure exceeds 20.6 kPa (3 psi), a fault exists in governor pressure control system. (5) Release brakes, slowly increase engine speed, and observe speedometer and pressure test gauge (do not exceed 30 mph on speedometer). Governor pres- sure should increase in proportion to vehicle speed. Or approximately 6.89 kPa (1 psi) for every 1 mph. (6) Governor pressure rise should be smooth and drop back to no more than 20.6 kPa (3 psi), after engine returns to curb idle and brakes are applied to prevent wheels from rotating.
(7) Compare results of pressure test with analysis
chart.
Test Six - Transmission In Overdrive Fourth Gear
This test checks line pressure at the overdrive clutch in fourth gear range. Use 300 psi Test Gauge C-3293-SP for this test. The test should be performed on the road or on a chassis dyno.
(1) Remove tachometer; it is not needed for this
test.
(2) Move 300 psi Gauge to overdrive clutch pres- sure test port. Then remove other gauge and reinstall test port plug.
(3) Lower vehicle. (4) Turn OD switch on. (5) Secure test gauge so it can be viewed from
drivers seat.
(6) Start engine and shift into D range. (7) Increase vehicle speed gradually until 3-4 shift
occurs and note gauge pressure.
(8) Pressure should be 524-565 kPa (76-82 psi) with closed throttle and increase to 690-896 kPa (100-130 psi) at 1/2 to 3/4 throttle. Note that pres- sure can increase to around 965 kPa (140 psi) at full throttle.
(9) Return to shop or move vehicle off chassis
dyno.
PRESSURE TEST ANALYSIS CHART
TEST CONDITION
INDICATION
Line pressure OK during any one test Line pressure OK in R but low in D, 2, 1
Pressure low in D Fourth Gear Range
Pressure OK in 1, 2 but low in D3 and R Pressure OK in 2 but low in R and 1
Front servo pressure in 2Pressure low in all positions
Governor pressure too high at idle speed
Governor pressure low at all mph figures
Lubrication pressure low at all throttle positions
Line pressure high
Line pressure low
Pump and regulator valve OK Leakage in rear clutch area (seal rings, clutch seals) Overdrive clutch piston seal, or check ball problem Leakage in front clutch area Leakage in rear servo
Leakage in servo; broken servo ring or cracked servo piston Clogged filter, stuck regulator valve, worn or faulty pump, low oil level Governor pressure solenoid valve system fault. Refer to diagnostic book. Faulty governor pressure solenoid, transmission control module, or governor pressure sensor Clogged fluid cooler or lines, seal rings leaking, worn pump bushings, pump, clutch retainer, or clogged filter. Output shaft plugged, sticky regulator valve Sticky regulator valve, clogged filter, worn pump
AUTOMATIC TRANSMISSION - 48RE
21 - 324
AUTOMATIC TRANSMISSION - 48RE (Continued) DIAGNOSIS AND TESTING - AIR TESTING TRANSMISSION CLUTCH AND BAND OPERATIONAir-pressure testing can be used to check transmis- sion front/rear clutch and band operation. The test can be conducted with the transmission either in the vehicle or on the work bench, as a final check, after overhaul.
Air-pressure testing requires that the oil pan and valve body be removed from the transmission. The servo and clutch apply passages are shown (Fig. 10).
Fig.10AirPressureTestPassages
1 - LINE PRESSURE TO ACCUMULATOR 2 - REAR SERVO APPLY 3 - FRONT SERVO APPLY 4 - FRONT SERVO RELEASE 5 - PUMP SUCTION 6 - PUMP PRESSURE 7 - FRONT CLUTCH APPLY 8 - REAR CLUTCH APPLY 9 - TO TORQUE CONVERTOR 10 - TO COOLER 11 - FROM TORQUE CONVERTER
Front Clutch Air Test
Place one or two fingers on the clutch housing and apply air pressure through front clutch apply pas- sage. Piston movement can be felt and a soft thump heard as the clutch applies.
DR
Rear Clutch Air Test
Place one or two fingers on the clutch housing and apply air pressure through rear clutch apply passage. Piston movement can be felt and a soft thump heard as the clutch applies.
Front Servo Air Test
Apply air pressure to the front servo apply pas- sage. The servo rod should extend and cause the band to tighten around the drum. Spring pressure should release the servo when air pressure is removed.
Rear Servo Air Test
Apply air pressure to the rear servo apply passage. The servo rod should extend and cause the band to tighten around the drum. Spring pressure should release the servo when air pressure is removed.
DIAGNOSIS AND TESTING - CONVERTER HOUSING FLUID LEAK
When diagnosing converter housing fluid leaks,
two items must be established before repair.
(1) Verify that a leak condition actually exists. (2) Determined the true source of the leak. Some suspected converter housing fluid leaks may not be leaks at all. They may only be the result of residual fluid in the converter housing, or excess fluid spilled during factory fill or fill after repair. Converter housing leaks have several potential sources. Through careful observation, a leak source can be identified before removing the transmission for repair. Pump seal leaks tend to move along the drive hub and onto the rear of the converter. Pump body leaks follow the same path as a seal leak (Fig. 11). Pump vent or pump attaching bolt leaks are gen- erally deposited on the inside of the converter hous- ing and not on the converter itself (Fig. 11). Pump o-ring or gasket leaks usually travel down the inside of the converter housing. Front band lever pin plug leaks are generally deposited on the housing and not on the converter.
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 325
(4) Inspect pump bushing and converter hub. If bushing is scored, replace it. If converter hub is scored, either polish it with crocus cloth or replace converter.
(5) Install new pump seal, O-ring, and gasket. Replace oil pump if cracked, porous or damaged in any way. Be sure to loosen the front band before installing the oil pump, damage to the oil pump seal may occur if the band is still tightened to the front clutch retainer.
(6) Loosen kickdown lever pin access plug three turns. Apply Loctite™ 592, or Permatext No. 2 to plug threads and tighten plug to 17 N·m (150 in. lbs.) torque.
(7) Adjust front band. (8) Lubricate pump seal and converter hub with transmission fluid or petroleum jelly and install con- verter.
transmission and converter housing
(9) Install dust shield.
(10) Lower vehicle.
DIAGNOSIS AND TESTING - DIAGNOSIS CHARTS
The diagnosis charts provide additional reference when diagnosing a transmission fault. The charts provide general information on a variety of transmis- sion, overdrive unit and converter clutch fault condi- tions.
The hydraulic flow charts in the Schematics and Diagrams section of this group, outline fluid flow and hydraulic circuitry. Circuit operation is provided for PARK, NEUTRAL, FIRST, SECOND, THIRD, FOURTH, MANUAL FIRST, MANUAL SECOND, and REVERSE gear ranges. Normal working pres- sures are also supplied for each of the gear ranges.
Fig.11ConverterHousingLeakPaths
1 - PUMP SEAL 2 - PUMP VENT 3 - PUMP BOLT 4 - PUMP GASKET 5 - CONVERTER HOUSING 6 - CONVERTER 7 - REAR MAIN SEAL LEAK
TORQUE CONVERTER LEAK POINTS
Possible sources of converter leaks are: † Leaks at the weld joint around the outside diam- † Leaks at the converter hub weld.
eter weld.
CONVERTER HOUSING AREA LEAK CORRECTION
(1) Remove converter. (2) Tighten front band adjusting screw until band is tight around front clutch retainer. This prevents front/rear clutches from coming out when oil pump is removed.
(3) Remove oil pump and remove pump seal. Inspect pump housing drainback and vent holes for obstructions. Clear holes with solvent and wire.
21 - 326
AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
DIAGNOSIS CHARTS
DR
CONDITION
POSSIBLE CAUSES
CORRECTION
HARSH ENGAGEMENT (FROM NEUTRAL TO DRIVE OR REVERSE)
1. Fluid Level Low. 2. Throttle Linkage Mis-adjusted. 3. Mount and Driveline Bolts Loose.
DELAYED ENGAGEMENT (FROM NEUTRAL TO DRIVE OR REVERSE)
4. U-Joint Worn/Broken.
5. Axle Backlash Incorrect.
6. Hydraulic Pressure Incorrect.
7. Band Mis-adjusted. 8. Valve Body Check Balls Missing.
9. Axle Pinion Flange Loose.
10. Clutch, band or planetary component damaged. 11. Converter Clutch Faulty. 1. Fluid Level Low. 2. Filter Clogged. 3. Gearshift Linkage Mis-adjusted.
4. Torque Converter Drain Back (Oil drains from torque converter into transmission sump).
5. Rear Band Mis-adjusted. 6. Valve Body Filter Plugged.
7. Oil Pump Gears Worn/Damaged.
8. Governor Circuit and Solenoid Valve Electrical Fault. 9. Hydraulic Pressure Incorrect.
10. Reaction Shaft Seal Rings Worn/Broken. 11. Rear Clutch/Input Shaft, Rear Clutch Seal Rings Damaged. 12. Regulator Valve Stuck. 13. Cooler Plugged.
1. Add Fluid 2. Adjust linkage - setting may be too long. 3. Check engine mount, transmission mount, propeller shaft, rear spring to body bolts, rear control arms, crossmember and axle bolt torque. Tighten loose bolts and replace missing bolts. 4. Remove propeller shaft and replace U-Joint. 5. Check per Service Manual. Correct as needed. 6. Check pressure. Remove, overhaul or adjust valve body as needed. 7. Adjust rear band. 8. Inspect valve body for proper check ball installation. 9. Replace nut and check pinion threads before installing new nut. Replace pinion gear if threads are damaged. 10. Remove, disassemble and repair transmission as necessary. 11. Replace converter. 1. Correct level and check for leaks. 2. Change filter. 3. Adjust linkage and repair linkage if worn or damaged. 4. If vehicle moves normally after 5
seconds after shifting into gear, no repair is necessary. If longer, inspect pump bushing for wear. Replace pump house. 5. Adjust band. 6. Replace fluid and filter. If oil pan and old fluid were full of clutch disc material and/or metal particles, overhaul will be necessary. 7. Remove transmission and replace oil pump. 8. Test with DRBT scan tool and repair as required. 9. Perform pressure test, remove transmission and repair as needed. 10. Remove transmission, remove oil pump and replace seal rings. 11. Remove and disassemble transmission and repair as necessary. 12. Clean. 13. Replace cooler.DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 327
CONDITION NO DRIVE RANGE (REVERSE OK)
NO DRIVE OR REVERSE (VEHICLE WILL NOT MOVE)
POSSIBLE CAUSES
CORRECTION
1. Fluid Level Low.
2. Gearshift Linkage/Cable Loose/Misadjusted. 3. Rear Clutch Burnt.
4. Valve Body Malfunction.
5. Transmission Overrunning Clutch Broken. 6. Input Shaft Seal Rings Worn/ Damaged.
7. Front Planetary Failed Broken. 1. Fluid Level Low.
2. Gearshift Linkage/Cable Loose/Misadjusted. 3. U-Joint/Axle/Transfer Case Broken.
4. Filter Plugged.
5. Oil Pump Damaged.
6. Valve Body Malfunctioned.
7. Transmission Internal Component Damaged.
8. Park Sprag not Releasing - Check Stall Speed, Worn/Damaged/Stuck. 9. Torque Converter Damage.
1. Add fluid and check for leaks if drive is restored. 2. Repair or replace linkage components.
3. Remove and disassemble transmission and rear clutch and seals. Repair/replace worn or damaged parts as needed. 4. Remove and disassemble valve body. Replace assembly if any valves or bores are damaged. 5. Remove and disassemble transmission. Replace overrunning clutch. 6. Remove and disassemble transmission. Replace seal rings and any other worn or damaged parts. 7. Remove and repair. 1. Add fluid and check for leaks if drive is restored. 2. Inspect, adjust and reassemble linkage as needed. Replace worn/damaged parts. 3. Perform preliminary inspection procedure for vehicle that will not move. Refer to procedure in diagnosis section. 4. 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. Replace cooler as necessary. 5. Perform pressure test to confirm low pressure. Replace pump body assembly if necessary. 6. Check 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. 7. Remove and disassemble transmission. Repair or replace failed components as needed. 8. Remove, disassemble, repair.
9. Inspect and replace as required.
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AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
CONDITION
POSSIBLE CAUSES
CORRECTION
SHIFTS DELAYED OR ERRATIC (SHIFTS ALSO HARSH AT TIMES)
1. Fluid Level Low/High.
2. Fluid Filter Clogged.
3. Throttle Linkage Mis-adjusted.
4. Throttle Linkage Binding.
5. Gearshift Linkage/Cable Mis-adjusted. 6. Clutch or Servo Failure.
7. Governor Circuit Electrical Fault.
8. Front Band Mis-adjusted. 9. Pump Suction Passage Leak.
1. Gearshift Linkage/Cable Mis-adjusted/Damaged. 2. Park Sprag Sticking. 3. Rear Band Mis-adjusted/Worn. 4. Valve Body Malfunction.
5. Rear Servo Malfunction.
6. Direct Clutch in Overdrive Worn.
7. Front Clutch Burnt.
1. Governor Circuit Electrical Fault.
2. Valve Body Malfunction.
3. Front Servo/Kickdown Band Damaged/Burned. 1. Valve Body Malfunction.
NO REVERSE (D RANGES OK)
HAS FIRST/REVERSE ONLY (NO 1-2 OR 2-3
UPSHIFT)MOVES IN 2ND OR 3RD GEAR, ABRUPTLY DOWNSHIFTS TO LOW
1. Correct fluid level and check for leaks if low. 2. Replace filter. If filter and fluid contained clutch material or metal particles, an overhaul may be necessary. 3. Adjust linkage as described in service section. 4. Check cable for binding. Check for return to closed throttle at transmission. 5. Adjust linkage/cable as described in service section. 6. Remove valve body and air test clutch, and band servo operation. Disassemble and repair transmission as needed. 7. Test using DRBT scan tool and repair as required. 8. Adjust band. 9. Check for excessive foam on dipstick after normal driving. Check for loose pump bolts, defective gasket. Replace pump assembly if needed. 1. Repair or replace linkage parts as needed. 2. Replace overdrive annulus gear. 3. Adjust band; replace. 4. Remove and service valve body. Replace valve body if any valves or valve bores are worn or damaged. 5. Remove and disassemble transmission. Replace worn/damaged servo parts as necessary. 6. Disassemble overdrive. Replace worn or damaged parts. 7. Remove and disassemble transmission. Replace worn, damaged clutch parts as required. 1. Test using DRBT scan tool and repair as required. 2. Repair stuck 1-2 shift valve or governor plug. 3. Repair/replace.
1. Remove, clean and inspect. Look for stuck 1-2 valve or governor plug.
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 329
CONDITION
POSSIBLE CAUSES
CORRECTION
NO LOW GEAR (MOVES IN 2ND OR 3RD GEAR ONLY)
1. Governor Circuit Electrical Fault.
2. Valve Body Malfunction.
NO KICKDOWN OR NORMAL DOWNSHIFT
3. Front Servo Piston Cocked in Bore. 4. Front Band Linkage Malfunction
1. Throttle Linkage Mis-adjusted. 2. Accelerator Pedal Travel Restricted. 3. Valve Body Hydraulic Pressures Too High or Too Low Due to Valve Body Malfunction or Incorrect Hydraulic Control Pressure Adjustments. 4. Governor Circuit Electrical Fault.
5. Valve Body Malfunction.
6. TPS Malfunction.
7. PCM Malfunction.
8. Valve Body Malfunction.
STUCK IN LOW GEAR (WILL NOT UPSHIFT)
1. Throttle Linkage Mis-adjusted/ Stuck.
2. Gearshift Linkage Mis-adjusted.
3. Governor Component Electrical Fault. 4. Front Band Out of Adjustment. 5. Clutch or Servo Malfunction.
1. Gearshift Linkage Mis-adjusted. 2. Rear Clutch Dragging/Warped. 3. Valve Body Malfunction.
CREEPS IN NEUTRAL
1. Test with DRBT scan tool and repair as required. 2. Remove, clean and inspect. Look for sticking 1-2 shift valve, 2-3 shift valve, governor plug or broken springs. 3. Inspect servo and repair as required.
4. Inspect linkage and look for bind in linkage. 1. Adjust linkage. 2. Verify floor mat is not under pedal, repair worn accelerator cable or bent brackets. 3. Perform hydraulic pressure tests to determine cause and repair as required. Correct valve body pressure adjustments as required.
4. Test with DRBT scan tool and repair as required. 5. Perform hydraulic pressure tests to determine cause and repair as required. Correct valve body pressure adjustments as required. 6. Replace sensor, check with DRBT scan tool. 7. Check with DRBT scan tool and replace if required. 8. Repair sticking 1-2, 2-3 shift valves, governor plugs, 3-4 solenoid, 3-4 shift valve, 3-4 timing valve. 1. Adjust linkage and repair linkage if worn or damaged. Check for binding cable or missing return spring. 2. Adjust linkage and repair linkage if worn or damaged. 3. Check operating pressures and test with DRBT scan tool, repair faulty component. 4. Adjust Band. 5. Air pressure check operation of clutches and bands. Repair faulty component. 1. Adjust linkage. 2. Disassemble and repair. 3. Perform hydraulic pressure test to determine cause and repair as required.
21 - 330
AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
CONDITION
BUZZING NOISE
SLIPS IN REVERSE ONLY
SLIPS IN FORWARD DRIVE RANGES
SLIPS IN LOW GEAR 9D9
ONLY, BUT NOT IN MANUAL 1 POSITIONPOSSIBLE CAUSES
1. Fluid Level Low 2. Shift Cable Mis-assembled.
3. Valve Body Mis-assembled.
4. Pump Passages Leaking.
5. Cooling System Cooler Plugged. 6. Overrunning Clutch Damaged. 1. Fluid Level Low. 2. Gearshift Linkage Mis-adjusted. 3. Rear Band Mis-adjusted. 4. Rear Band Worn. 5. Overdrive Direct Clutch Worn.
6. Hydraulic Pressure Too Low.
7. Rear Servo Leaking.
8. Band Linkage Binding. 1. Fluid Level Low. 2. Fluid Foaming.
3. Throttle Linkage Mis-adjusted. 4. Gearshift Linkage Mis-adjusted. 5. Rear Clutch Worn. 6. Low Hydraulic Pressure Due to Worn Pump, Incorrect Control Pressure Adjustments, Valve Body Warpage or Malfunction, Sticking, Leaking Seal Rings, Clutch Seals Leaking, Servo Leaks, Clogged Filter or Cooler Lines. 7. Rear Clutch Malfunction, Leaking Seals or Worn Plates. 8. Overrunning Clutch Worn, Not Holding (Slips in 1 Only). Overrunning Clutch Faulty.
CORRECTION
1. Add fluid and check for leaks. 2. Route cable away from engine and bell housing. 3. Remove, disassemble, inspect valve body. Reassemble correctly if necessary. Replace assembly if valves or springs are damaged. Check for loose bolts or screws. 4. Check pump for porous casting, scores on mating surfaces and excess rotor clearance. Repair as required. Loose pump bolts. 5. Replace cooler. 6. Replace clutch. 1. Add fluid and check for leaks. 2. Adjust linkage. 3. Adjust band. 4. Replace as required. 5. Disassemble overdrive. Repair as needed. 6. Perform hydraulic pressure tests to determine cause. 7. Air pressure check clutch-servo operation and repair as required. 8. Inspect and repair as required. 1. Add fluid and check for leaks. 2. Check for high oil level, bad pump gasket or seals, dirt between pump halves and loose pump bolts. Replace pump if necessary. 3. Adjust linkage. 4. Adjust linkage. 5. Inspect and replace as needed. 6. Perform hydraulic and air pressure tests to determine cause.
7. Air pressure check clutch-servo operation and repair as required. 8. Replace Clutch.
Replace overrunning clutch.
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 331
CONDITION
POSSIBLE CAUSES
CORRECTION
GROWLING, GRATING OR SCRAPING NOISES
DRAGS OR LOCKS UP
1. Drive Plate Broken. 2. Torque Converter Bolts Hitting Dust Shield. 3. Planetary Gear Set Broken/ Seized. 4. Overrunning Clutch Worn/Broken.
5. Oil Pump Components Scored/ Binding. 6. Output Shaft Bearing or Bushing Damaged. 7. Clutch Operation Faulty.
8. Front and Rear Bands Mis- adjusted. 1. Fluid Level Low. 2. Clutch Dragging/Failed
3. Front or Rear Band Mis-adjusted. 4. Case Leaks Internally.
5. Servo Band or Linkage Malfunction. 6. Overrunning Clutch Worn.
7. Planetary Gears Broken.
8. Converter Clutch Dragging.
NO 4-3 DOWNSHIFT
1. Circuit Wiring and/or Connectors Shorted.
2. PCM Malfunction.
3. TPS Malfunction 4. Lockup Solenoid Not Venting.
5. Overdrive Solenoid Not Venting.
6. Valve Body Valve Sticking.
1. Replace. 2. Dust shield bent. Replace or repair.
3. Check for debris in oil pan and repair as required. 4. Inspect and check for debris in oil pan. Repair as required. 5. Remove, inspect and repair as required.
6. Remove, inspect and repair as required.
7. Perform air pressure check and repair as required. 8. Adjust bands.
1. Check and adjust level. 2. Air pressure check clutch operation and repair as required. 3. Adjust bands. 4. Check for leakage between passages in case. 5. Air pressure check servo operation and repair as required. 6. Remove and inspect clutch. Repair as required. 7. Remove, inspect and repair as required (look for debris in oil pan). 8. Check for plugged cooler. Inspect pump for excessive side clearance. Replace pump as required. 1. Test wiring and connectors with test lamp and volt/ohmmeter. Repair wiring as necessary. Replace connectors and/or harnesses as required. 2. Check PCM operation with DRBT scan tool. Replace PCM only if faulty. 3. Check TPS with DRBT scan tool at PCM. 4. Remove valve body and replace solenoid assembly if plugged or shorted. 5. Remove valve body and replace solenoid if plugged or shorted. 6. Repair stuck 3-4 shift valve or lockup timing valve.
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AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
CONDITION NO 4-3 DOWNSHIFT WHEN CONTROL SWITCH IS TURNED OFF
POSSIBLE CAUSES
1. Control Switch Open/Shorted. 2. Overdrive Solenoid Connector Shorted. 3. PCM Malfunction.
4. Valve Body Stuck Valves.
CLUNK NOISE FROM DRIVELINE ON CLOSED THROTTLE 4-3
DOWNSHIFT3-4 UPSHIFT OCCURS IMMEDIATELY AFTER 2-3
SHIFT1. Transmission Fluid Low. 2. Throttle Cable Mis-adjusted. 3. Overdrive Clutch Select Spacer Wrong Spacer. 1. Overdrive Solenoid Connector or Wiring Shorted.
2. TPS Malfunction.
3. PCM Malfunction.
4. Overdrive Solenoid Malfunction. 5. Valve Body Malfunction.
WHINE/NOISE RELATED TO ENGINE SPEED
1. Fluid Level Low. 2. Shift Cable Incorrect Routing.
DR
CORRECTION
1. Test and replace switch if faulty. 2. Test solenoids and replace if seized or shorted. 3. Test with DRBT scan tool. Replace PCM if faulty. 4. Repair stuck 3-4, lockup or lockup timing valve. 1. Add Fluid. 2. Adjust cable. 3. Replace overdrive piston thrust plate spacer. 1. Test connector and wiring for loose connections, shorts or ground and repair as needed. 2. Test TPS and replace as necessary. Check with DRBT scan tool. 3. Test PCM with DRBT scan tool and replace controller if faulty. 4. Replace solenoid. 5. Remove, disassemble, clean and inspect valve body components. Make sure all valves and plugs slide freely in bores. Polish valves with crocus cloth if needed. 1. Add fluid and check for leaks. 2. Check shift cable for correct routing. Should not touch engine or bell housing.
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 333
CONDITION
NO 3-4 UPSHIFT
POSSIBLE CAUSES
1. O/D Switch In OFF Position. 2. Overdrive Circuit Fuse Blown.
3. O/D Switch Wire Shorted/Open Cut.
4. Distance or Coolant Sensor Malfunction. 5. TPS Malfunction.
6. Neutral Sense to PCM Wire Shorted/Cut.
7. PCM Malfunction.
8. Overdrive Solenoid Shorted/Open.
9. Solenoid Feed Orifice in Valve Body Blocked. 10. Overdrive Clutch Failed.
11. Hydraulic Pressure Low.
12. Valve Body Valve Stuck.
13. O/D Piston Incorrect Spacer.
14. Overdrive Piston Seal Failure. 15. O/D Check Valve/Orifice Failed.
CORRECTION
1. Turn control switch to ON position. 2. Replace fuse. Determine why fuse failed and repair as necessary (i.e., shorts or grounds in circuit). 3. Check wires/connections with 12V test lamp and voltmeter. Repair damaged or loose wire/connection as necessary. 4. Check with DRBT scan tool and repair or replace as necessary. 5. Check with DRBT scan tool and replace if necessary. 6. Test switch/sensor as described in service section and replace if necessary. Engine no start. 7. Check with DRBT scan tool and replace if necessary. 8. Replace solenoid if shorted or open and repair loose or damaged wires (DRBT scan tool). 9. Remove, disassemble, and clean valve body thoroughly. Check feed orifice. 10. Disassemble overdrive and repair as needed. 11. Pressure test transmission to determine cause. 12. Repair stuck 3-4 shift valve, 3-4 timing valve. 13. Remove unit, check end play and install correct spacer. 14. Replace both seals. 15. Check for free movement and secure assembly (in piston retainer). Check ball bleed orifice.
21 - 334
AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
CONDITION
SLIPS IN OVERDRIVE FOURTH GEAR
POSSIBLE CAUSES
1. Fluid Level Low. 2. Overdrive Clutch Pack Worn.
3. Overdrive Piston Retainer Bleed Orifice Blown Out. 4. Overdrive Piston or Seal Malfunction.
5. 3-4 Shift Valve, Timing Valve or Accumulator Malfunction.
6. Overdrive Unit Thrust Bearing Failure.
7. O/D Check Valve/Bleed Orifice Failure. 1. Fluid Level Low. 2. Throttle Valve Cable Mis-adjusted. 3. Overdrive Clutch Pack Worn/ Burnt. 4. TPS Faulty.
5. Overdrive Clutch Bleed Orifice Plugged. 6. Overdrive Solenoid or Wiring Shorted/Open.
7. Overdrive Excess Clearance.
8. O/D Check Valve Missing or Stuck. Lockup Solenoid, Relay or Wiring Shorted/Open.
Lockup Solenoid Malfunction.
DELAYED 3-4 UPSHIFT (SLOW TO ENGAGE)
TORQUE CONVERTER LOCKS UP IN SECOND AND/OR THIRD GEAR
HARSH 1-2, 2-3, 3-4 OR 3-2 SHIFTS
DR
CORRECTION
1. Add fluid and check for leaks. 2. Remove overdrive unit and rebuild clutch pack. 3. Disassemble transmission, remove retainer and replace orifice. 4. Remove overdrive unit. Replace seals if worn. Replace piston if damaged. If piston retainer is damaged, remove and disassemble the transmission. 5. Remove and overhaul valve body. Replace accumulator seals. Make sure all valves operate freely in bores and do not bind or stick. Make sure valve body screws are correctly tightened and separator plates are properly positioned. 6. Disassemble overdrive unit and replace thrust bearing (NO. 1 thrust bearing is between overdrive piston and clutch hub; NO. 2 thrust bearing is between the planetary gear and the direct clutch spring plate; NO. 3 thrust bearing is between overrunning clutch hub and output shaft). 7. Check for function/secure orifice insert in O/D piston retainer. 1. Add fluid and check for leaks. 2. Adjust throttle valve cable. 3. Remove unit and rebuild clutch pack.
4. Test with DRBT scan tool and replace as necessary 5. Disassemble transmission and replace orifice. 6. Test solenoid and check wiring for loose/corroded connections or shorts/ grounds. Replace solenoid if faulty and repair wiring if necessary. 7. Remove unit. Measure end play and select proper spacer. 8. Check for presence of check valve. Repair or replace as required. Test solenoid, relay and wiring for continuity, shorts or grounds. Replace solenoid and relay if faulty. Repair wiring and connectors as necessary. Remove valve body and replace solenoid assembly.
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 335
CONDITION
POSSIBLE CAUSES
CORRECTION
NO START IN PARK OR NEUTRAL
1. Gearshift Linkage/Cable Mis-adjusted. 2. Neutral Sense Wire Open/Cut.
NO REVERSE (OR SLIPS IN REVERSE)
3. Park/Neutral Switch, or Transmission Range Sensor Faulty. 4. Park/Neutral Switch, or Transmission Range Sensor Connection Faulty. 5. Valve Body Manual Lever Assembly Bent/Worn/Broken. 1. Direct Clutch Pack (front clutch) Worn. 2. Rear Band Mis-adjusted. 3. Front Clutch Malfunctioned/ Burned. 4. Overdrive Thrust Bearing Failure.
5. Direct Clutch Spring Collapsed/ Broken.
1. Adjust linkage/cable.
2. Check continuity with test lamp. Repair as required. 3. Refer to service section for test and replacement procedure. 4. Connectors spread open. Repair.
5. Inspect lever assembly and replace if damaged. 1. Disassemble unit and rebuild clutch pack. 2. Adjust band. 3. Air-pressure test clutch operation. Remove and rebuild if necessary. 4. Disassemble geartrain and replace bearings. 5. Remove and disassemble unit. Check clutch position and replace spring.
21 - 336
AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
CONDITION
POSSIBLE CAUSES
CORRECTION
OIL LEAKS.
NOISY OPERATION IN FOURTH GEAR ONLY
1. Fluid Lines and Fittings Loose/ Leaks/Damaged. 2. Fill Tube (where tube enters case) Leaks/Damaged. 3. Pressure Port Plug Loose Loose/Damaged. 4. Pan Gasket Leaks.
5. Valve Body Manual Lever Shaft Seal Leaks/Worn. 6. Rear Bearing Access Plate Leaks. 7. Gasket Damaged or Bolts are Loose. 8. Adapter/Extension Gasket Damaged Leaks/Damaged. 9. Park/Neutral Switch, or Transmission Range Sensor Leaks/Damaged. 10. Converter Housing Area Leaks.
11. Pump Seal Leaks/Worn/ Damaged. 12. Torque Converter Weld Leak/Cracked Hub. 13. Case Porosity Leaks. 1. Overdrive Clutch Discs, Plates or Snap Rings Damaged. 2. Overdrive Piston or Planetary Thrust Bearing Damaged. 3. Output Shaft Bearings Scored/ Damaged. 4. Planetary Gears Worn/Chipped. 5. Overdrive Unit Overrunning Clutch Rollers Worn/Scored.
1. Tighten fittings. If leaks persist, replace fittings and lines if necessary. 2. Replace tube seal. Inspect tube for cracks in fill tube. 3. Tighten to correct torque. Replace plug or reseal if leak persists. 4. Tighten pan screws (150 in. lbs.). If leaks persist, replace gasket. 5. Replace shaft seal.
6. Replace gasket. Tighten screws. 7. Replace bolts or gasket or tighten both.
8. Replace gasket.
9. Replace switch and gasket.
10. Check for leaks at seal caused by worn seal or burr on converter hub (cutting seal), worn bushing, missing oil return, oil in front pump housing or hole plugged. Check for leaks past O-ring seal on pump or past pump-to-case bolts; pump housing porous, oil coming out vent due to overfill or leak past front band shaft access plug. 11. Replace seal.
12. Replace converter.
13. Replace case. 1. Remove unit and rebuild clutch pack.
2. Remove and disassemble unit. Replace either thrust bearing if damaged. 3. Remove and disassemble unit. Replace either bearing if damaged. 4. Remove and overhaul overdrive unit. 5. Remove and overhaul overdrive unit.
DR AUTOMATIC TRANSMISSION - 48RE (Continued) STANDARD PROCEDURE - ALUMINUM THREAD REPAIR
AUTOMATIC TRANSMISSION - 48RE
21 - 337
(4) Disconnect and lower or remove necessary
exhaust components.
and (Fig. 14).
(5) Remove engine-to-transmission struts (Fig. 13)
Damaged or worn threads in the aluminum trans- mission case and valve body can be repaired by the use of Heli-Coils™, or equivalent. This repair con- sists of drilling out the worn-out damaged threads. Then tap the hole with a special Heli-Coil™ tap, or equivalent, and installing a Heli-Coil™ insert, or equivalent, into the hole. This brings the hole back to its original thread size.
Heli-Coil™, or equivalent, tools and inserts are readily available from most automotive parts suppli- ers.
REMOVAL
NOTE: The overdrive unit can be removed and ser- viced separately. It is not necessary to remove the entire transmission assembly to perform overdrive unit repairs.
(1) Disconnect battery negative cable. (2) Raise vehicle. (3) Remove the transfer case skid plate (Fig. 12), if
equipped.
Fig.12TransferCaseSkidPlate
1 - FRAME RAIL 2 - SKID PLATE 3 - BOLTS (6)
Fig.13RightSideEngine-to-TransmissionStrut
1 - TRANSMISSION 2 - ENGINE 3 - STRUT
Fig.14LeftSideEngine-to-TransmissionStrut
1 - TRANSMISSION 2 - ENGINE 3 - STRUT
(6) Remove starter motor. (Refer to 8 - ELECTRI-
CAL/STARTING/STARTER MOTOR - REMOVAL)
(7) Disconnect and remove the crankshaft position sensor. (Refer to 14 - FUEL SYSTEM/FUEL INJEC- TION/CRANKSHAFT REMOVAL) Retain the sensor attaching bolts.
POSITION
SENSOR
(8) If transmission is being removed for overhaul, remove transmission oil pan, drain fluid and reinstall pan.
(9) Remove torque converter access cover.
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AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(10) Rotate crankshaft in clockwise direction until converter bolts are accessible. Then remove bolts one at a time. Rotate crankshaft with socket wrench on dampener bolt.
(11) Mark propeller shaft and axle yokes for assembly alignment. Then disconnect and remove propeller shaft. On 4 x 4 models, remove both propel- ler shafts. (Refer to 3 - DIFFERENTIAL & DRIV- ELINE/PROPELLER SHAFT/PROPELLER SHAFT - REMOVAL)
(12) Disconnect wires from the transmission range
sensor and transmission solenoid connector.
(13) Disconnect gearshift cable (Fig. 15) from the
transmission.
Fig.16EngineRearMount-4X2Automatic
Transmission
1 - ENGINE REAR MOUNT 2 - BOLT 3 - NUT 4 - THROUGH BOLT NUT 5 - TRANSMISSION
Fig.17EngineRearMount-4X4Automatic
Transmission
1 - TRANSMISSION 2 - ENGINE REAR MOUNT 3 - BOLT
Fig.15GearshiftCableAtTransmission
1 - GEARSHIFT CABLE 2 - TRANSMISSION MANUAL LEVER 3 - CABLE SUPPORT BRACKET
(14) Disconnect throttle valve cable from transmis-
sion bracket and throttle valve lever.
(15) On 4X4 models, disconnect shift rod from
transfer case shift lever.
(16) Support rear of engine with safety stand or
jack.
(17) Raise transmission slightly with service jack
to relieve load on crossmember and supports.
(18) Remove bolts securing rear support and cush- ion (Fig. 16) and (Fig. 17) to transmission and cross- member and remove rear support.
(19) Remove bolts attaching crossmember to frame
and remove crossmember.
(20) On 4X4 models, remove transfer case with
transmission jack or aid of helper.
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 339
(21) Disconnect fluid cooler lines at transmission
(Fig. 18).
(26) To remove torque converter, remove C-clamp from edge of bell housing and carefully slide torque converter out of the transmission.
DISASSEMBLY
(1) Clean exterior of transmission with suitable
solvent or pressure washer.
(2) Place transmission in vertical position. (3) Measure the input shaft end play as follows
(Fig. 20).
8266-8.
(a) Attach Adapter 8266-5 to Handle 8266-8. (b) Attach dial
indicator C-3339 to Handle
(c) Install the assembled tool onto the input shaft of the transmission and tighten the retaining screw on Adapter 8266-5 to secure it to the input shaft.
(d) Position the dial indicator plunger against a flat spot on the oil pump and zero the dial indica- tor.
(e) Move input shaft in and out and record read- ing. Record the maximum travel for assembly ref- erence
Fig.18TransmissionCoolerLines
1 - TRANSMISSION 2 - RADIATOR 3 - COOLER LINES
(22) Remove fill tube bracket bolts and pull tube out of transmission. Retain fill tube seal. On 4X4
models, it will also be necessary to remove bolt attaching transfer case vent tube to converter hous- ing (Fig. 19).Fig.19FillTubeAttachment
Fig.20CheckingInputShaftEndPlay
1 - TRANSFER CASE VENT TUBE 2 - FILL TUBE (V8) 3 - TUBE SEAL 4 - FILL TUBE (V6)
1 - TOOL 8266-8
2 - TOOL 8266-5
3 - TOOL C-3339(23) Remove all converter housing bolts. (24) Carefully work transmission and torque con-
verter assembly rearward off engine block dowels.
(25) Lower
transmission and remove assembly
from under the vehicle.
(4) Remove throttle and shift levers from valve
body manual shaft and throttle lever shaft.
(5) Remove transmission oil pan and gasket.
21 - 340
AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
(6) Remove filter from valve body (Fig. 21). Keep fil- ter screws separate from other valve body screws. Filter screws are longer and should be kept with filter.
DR
Fig.21OilFilterRemoval
1 - OIL FILTER 2 - VALVE BODY 3 - FILTER SCREWS (2)
(7) Remove the transmission range sensor.. (8) Remove hex head bolts attaching valve body to transmission case (Fig. 22). A total of 10 bolts are used. Note different bolt lengths for assembly refer- ence.
(9) Remove valve body assembly. Push valve body harness connector out of case. Then work park rod and valve body out of case (Fig. 23).
Fig.23ValveBodyRemoval
1 - GOVERNOR PRESSURE SENSOR 2 - VALVE BODY 3 - PARK ROD 4 - ACCUMULATOR PISTON 5 - GOVERNOR PRESSURE SOLENOID
(10) Remove accumulator outer spring, piston and inner spring (Fig. 24). Note position of piston and springs for assembly reference. Remove and discard piston seals if worn or cut.
Fig.24AccumulatorComponentRemoval
1 - ACCUMULATOR PISTON 2 - OUTER SPRING 3 - INNER SPRING
Fig.22ValveBodyBoltLocations
1 - VALVE BODY BOLTS 2 - VALVE BODY BOLTS
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 341
(11) Remove pump oil seal with suitable pry tool or
slide-hammer mounted screw.
(12) Remove front band lever pin access plug (Fig. 25). Use square end of 1/4 in. drive extension to remove plug as shown.
Fig.25FrontBandLeverPinAccessPlug
1 - FRONT BAND REACTION PIN ACCESS PLUG 2 - 1/4 DRIVE EXTENSION AND RATCHET
(13) Remove oil pump and reaction shaft support
assembly as follows:
(a) Tighten front band adjusting screw until band is tight around front clutch retainer (Fig. 26). This will prevent retainer from coming out with pump and possibly damaging clutch or pump com- ponents.
(b) Remove oil pump bolts.
(c) Thread Slide Hammer Tools C-3752 into threaded holes in flange of oil pump housing (Fig. 27).
(d) Remove oil pump and reaction shaft support by bumping slide hammers outward alternately to pull pump from case (Fig. 28).
Fig.27OilPumpRemovalTools
1 - PUMP HOUSING 2 - SLIDE HAMMER TOOLS (THREAD INTO PUMP HOUSING)
Fig.26TighteningFrontBandToHoldFrontClutch
InPlace
1 - LOCK-NUT 2 - FRONT BAND ADJUSTER
Fig.28OilPumpRemoval 1 - OIL PUMP AND REACTION SHAFT SUPPORT
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AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
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(14) Remove oil pump gasket (Fig. 29). Note gas-
ket position in case for assembly reference.
(15) Loosen front band adjusting screw until band
is completely loose.
(16) Remove front band strut and anchor (Fig. 30). (17) Squeeze front band together slightly and slide band over front clutch retainer and out of case (Fig. 31).
Fig.31FrontBandRemoval
1 - FRONT BAND 2 - FRONT CLUTCH RETAINER
(18) Remove front and rear clutch assemblies as a
unit (Fig. 32).
Fig.29OilPumpGasket
1 - OIL PUMP GASKET
Fig.32RemovingFront/RearClutchAssemblies
1 - FRONT AND REAR CLUTCH ASSEMBLIES
Fig.30FrontBandLinkage
1 - LEVER 2 - STRUT 3 - ANCHOR 4 - FRONT BAND
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
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21 - 343
(19) 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. 33).
(20) Remove intermediate shaft thrust washer. Tri- angular shaped washer will either be on shaft pilot hub or in rear clutch retainer (Fig. 34).
(21) Remove thrust plate from intermediate shaft
hub (Fig. 35). (22) Remove
intermediate
shaft-planetary
geartrain assembly (Fig. 36).
(23) If overdrive unit is not to be serviced, install Alignment Shaft 6227-2 into the overdrive unit to prevent misalignment of the overdrive clutches dur- ing service of main transmission components.
Fig.35IntermediateShaftThrustPlate
1 - SHAFT THRUST PLATE 2 - INTERMEDIATE SHAFT PILOT HUB
Fig.33FrontBandLeverAndPin
1 - BAND LEVER 2 - USE PENCIL MAGNET TO REMOVE REACTION PIN
Fig.36IntermediateShaftAndPlanetaryGeartrain 1 - INTERMEDIATE SHAFT AND PLANETARY GEAR TRAIN ASSEMBLY
Fig.34IntermediateShaftThrustWasher
1 - THRUST WASHER 2 - INTERMEDIATE SHAFT PILOT HUB
21 - 344
AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(24) Loosen rear band locknut and loosen adjust-
(29) Remove rear band adjusting lever and reac-
ing screw 3-4 turns.
(25) Remove snap-ring that retains low-reverse
drum on overdrive piston retainer hub (Fig. 37).
tion pin.
(30) Remove rear band.
Fig.37Low-ReverseDrumSnap-Ring
1 - LOW-REVERSE DRUM 2 - TABBED WASHER 3 - SNAP-RING
(26) Slide low-reverse drum and thrust washer off
piston retainer hub and out of rear band (Fig. 38).
(27) Note that overrunning clutch race will remain on splines of low-reverse drum after removal (Fig. 39). The race is a permanent press fit on the hub splines. Do not attempt to remove the race. (28) Remove overrunning clutch assembly (Fig. 40). Assembly can be removed without displacing rollers and springs if care is exercised. Note position of rollers and springs for assembly reference.
Fig.39OverrunningClutchRacePositionOn
Low-ReverseDrum
1 - OVERRUNNING CLUTCH RACE 2 - LOW-REVERSE DRUM
Fig.40OverrunningClutch
1 - CLUTCH CAM 2 - OVERRUNNING CLUTCH ASSEMBLY
Fig.38Low-ReverseDrumAndThrustWasher
1 - LOW-REVERSE DRUM 2 - SPOTFACE FOR WASHER 3 - THRUST WASHER
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 345
(31) Compress front servo rod guide with large C-clamp and Tool C-4470, or Compressor Tool C-3422-B (Fig. 41). Compress guide only enough to permit snap-ring removal (about 1/8 in.).
(32) Remove servo piston snap-ring (Fig. 41). Unseat one end of ring. Then carefully work removal tool around back of ring until free of ring groove. Exercise caution when removing snap-ring. Servo bore can be scratched or nicked if care is not exercised.
(33) Remove tools and remove servo piston and
spring.
(34) Compress rear servo piston with C-clamp and Tool C-4470, or Valve Spring Compressor C-3422-B (Fig. 42). Compress servo spring retainer only enough to permit snap-ring removal.
(35) Remove servo piston snap-ring (Fig. 42). Start one end of ring out of bore. Then carefully work removal tool around back of snap-ring until free of ring groove. Exercise caution when removing snap-ring. Servo bore can be scratched or nicked if care is not exercised.
(36) Remove tools and remove rear servo retainer,
spring and piston assembly.
Fig.41FrontServoRetainingSnap-Ring
1 - C-CLAMP 2 - FRONT SERVO ROD GUIDE 3 - SNAP-RING 4 - TOOL C-4470
CLEANING
Clean the case in a solvent tank. Flush the case bores and fluid passages thoroughly with solvent. Dry the case and all fluid passages with compressed air. Be sure all solvent is removed from the case and that all fluid passages are clear.
NOTE: Do not use shop towels or rags to dry the case (or any other transmission component) unless they are made from lint-free materials. Lint will stick to case surfaces and transmission components and
Fig.42RearServoRetainingSnap-Ring
1 - TOOL C-4470
2 - C-CLAMP 3 - REAR SERVO SPRING RETAINER 4 - RETAINER SNAP-RINGcirculate throughout the transmission after assem- bly. A sufficient quantity of lint can block fluid pas- sages and interfere with valve body operation.
Lubricate transmission parts with Mopart ATF +4, Automatic Transmission fluid during overhaul and assembly. Use petroleum jelly to prelubricate seals, O-rings, and thrust washers. Petroleum jelly can also be used to hold parts in place during reassembly.
INSPECTION
Inspect the case for cracks, porous spots, worn bores, or damaged threads. Damaged threads can be repaired with Helicoil thread inserts. However, the case will have to be replaced if it exhibits any type of damage or wear.
Lubricate the front band adjusting screw threads with petroleum jelly and thread the screw part-way into the case. Be sure the screw turns freely.
Inspect the transmission bushings during overhaul. Bushing condition is important as worn, scored bush- ings contribute to low pressures, clutch slip and accelerated wear of other components. However, do not replace bushings as a matter of course. Replace bushings only when they are actually worn, or scored.
Use recommended tools to replace bushings. The tools are sized and designed to remove, install, and seat bushings correctly. The bushing replacement tools are included in Bushing Tool Set C-3887-B. available
for replacement purposes. Only the sun gear bushings are not serviced.
Pre-sized service
bushings
are
The use of crocus cloth is permissible where neces- sary, providing it is used carefully. When used on
21 - 346
AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
shafts, or valves, use extreme care to avoid rounding off sharp edges. Sharp edges are vital as they pre- vent foreign matter from getting between the valve and valve bore.
Do not reuse oil seals, gaskets, seal rings, or O-rings during overhaul. Replace these parts as a matter of course. Also do not reuse snap rings or E-clips that are bent or distorted. Replace these parts as well.
ASSEMBLY
If
the condition of
CAUTION: the transmission before the overhaul procedure caused excessive metallic or fiber contamination in the fluid, replace the torque converter. Fluid contamination and trans- mission failure can result if not done.
Do not allow dirt, grease, or foreign material to enter the case or transmission components during assembly. Keep the transmission case and compo- nents clean. Also make sure the tools and workbench area used for reassembly operations are equally clean.
Shop towels used for wiping off tools and your hands must be made from lint free materials. Lint will stick to transmission parts and could interfere with valve operation or even restrict fluid passages. Lubricate transmission clutch and gear compo- nents with Mopart ATF +4 during reassembly. Soak clutch discs in transmission fluid before installation. Petroleum jelly can be used to lubricate and hold thrust washers and plates in position during assem- bly.
Do not use chassis grease, bearing grease, white grease, or similar lubricants on any part. These types of lubricants can eventually block or restrict fluid passages and valve operation. Use petroleum jelly only.
Do not force parts into place. The transmission components and sub-assemblies are easily installed by hand when properly aligned. If a part seems dif- ficult to install, it is either misaligned or incorrectly 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. 43).
(3) Install rear servo spring and retainer in case
bore (Fig. 44). Be sure spring is seated on piston.
Fig.43RearServoPiston
1 - REAR SERVO PISTON
Fig.44RearServoPistonSpringAndRetainer
1 - PISTON SPRING 2 - REAR SERVO PISTON 3 - SPRING RETAINER
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
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21 - 347
(4) Compress rear servo piston with C-clamp or Valve Spring Compressor C-3422-B and install servo piston snap-ring (Fig. 45).
(5) Lubricate front servo piston components and
servo bore in case with transmission fluid.
(6) Install
front servo piston in bore. Carefully “run” small, suitable tool around piston ring to press it back into groove and ease installation (Fig. 46). Rotate piston into bore at same time. Rock piston slightly to ease piston ring past snap-ring groove and into bore.
Fig.46FrontServoPiston
1 - USE SUITABLE TOOL TO HELP SEAT PISTON RING 2 - FRONT SERVO PISTON
Fig.45RearServoSnap-Ring
1 - TOOL C-4470
2 - C-CLAMP 3 - REAR SERVO SPRING RETAINER 4 - RETAINER SNAP-RING(7) Bottom front servo piston in bore and install
servo spring.
(8) Install front servo piston rod guide as follows: (a) Place Tool SP-5560 (or similar size tool) on guide and position C-clamp on tool and case (Fig. 47).
(b) Slowly compress rod guide while simulta- neously easing seal ring into bore with suitable tool. (9) Install rod guide snap-ring (Fig. 47).
OVERRUNNING CLUTCH, REAR BAND, AND LOW-REVERSE DRUM
(1) Install overrunning clutch components if not
yet installed.
(2) Position rear band reaction pin and band in case. Be sure that the twin lugs on the band are seated against the reaction pin.
Fig.47FrontServoRodGuideAndSnap-Ring
1 - C-CLAMP 2 - ROD GUIDE 3 - SMALL SCREWDRIVER 4 - ROD GUIDE SNAP-RING 5 - TOOL SP-5560
(3) Install low-reverse drum. Slide drum through rear band, onto piston retainer hub and into engage- ment with overrunning clutch and race.
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AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(4) Install thrust washer in low-reverse drum spot- face (Fig. 48). Use petroleum jelly to hold washer in place.
(5) Install snap-ring that secures low-reverse drum
to piston retainer hub (Fig. 48).
(6) Insert the rear band pivot pin part way into
the case.
(7) Install rear band adjusting lever and pivot pin. Be sure lever and the single lug on the band are aligned and engaged before seating band pivot pin in case.
Fig.49IntermediateShaftAndPlanetaryGeartrain 1 - INTERMEDIATE SHAFT AND PLANETARY GEAR TRAIN ASSEMBLY
Fig.50IntermediateShaftThrustPlate
1 - SHAFT THRUST PLATE 2 - INTERMEDIATE SHAFT PILOT HUB
Fig.48Low-ReverseDrumSnap-Ring
1 - LOW-REVERSE DRUM 2 - TABBED WASHER 3 - SNAP-RING
PLANETARY GEARTRAIN, FRONT/REAR CLUTCH, AND FRONT BAND
(1) Remove Alignment Shaft 6227-2,
if
installed
previously.
(2) Install assembled intermediate shaft and plan- etary geartrain (Fig. 49). Support shaft carefully during installation. Do not allow shaft bearing/ bushing or scratched.
surfaces
become
nicked
to
(3) Lubricate intermediate shaft thrust plate with petroleum jelly and install plate on shaft pilot hub (Fig. 50).
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
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21 - 349
(4) Check input shaft front seal rings, fiber thrust washer and rear seal ring (Fig. 51). Be sure the ends of the rear seal ring are hooked together and diago- nal cut ends of front seal rings are firmly seated against each other as shown. Lubricate seal rings with petroleum jelly after checking them.
(5) Assemble front and rear clutches (Fig. 52). Align lugs on front clutch discs. Mount front clutch on rear clutch. Turn front clutch retainer back and forth until front clutch discs are fully seated on rear clutch splined hub.
Fig.52AssemblingFrontAndRearClutches
1 - FRONT CLUTCH ASSEMBLY 2 - REAR CLUTCH ASSEMBLY 3 - REAR CLUTCH SPLINED HUB
Fig.51InputShaftSealRingsAndThrustWasher 1 - TORLONT FRONT SEAL RINGS 2 - INPUT SHAFT 3 - REAR SEAL RING 4 - THRUST WASHER
(6) Install intermediate shaft thrust washer in hub of rear clutch retainer (Fig. 53). Use petroleum jelly to hold washer in place. Position washer so grooves are facing outward. Washer only fits one way in clutch retainer hub.
(7) Place transmission case in upright position, or place blocks under front end of transmission repair stand to tilt case rearward. This makes it easier to install front/rear clutch assembly.
Fig.53IntermediateShaftThrustWasher 1 - BE SURE WASHER GROOVES FACE OUT AS SHOWN 2 - REAR CLUTCH RETAINER HUB 3 - SHAFT THRUST WASHER
21 - 350
AUTOMATIC TRANSMISSION - 48RE (Continued)AUTOMATIC TRANSMISSION - 48RE
DR
(8) Align discs in rear clutch. Then install and engage assembly in front planetary and driving shell (Fig. 54). Turn clutch retainers back and forth until both clutches are seated.
(9) Position front band lever in case and over servo rod guide. Then install front band lever pin in case and slide it through lever.
(10) Coat threads of front band pin access plug with sealer and install it in case. Tighten plug to 17
N·m (13 ft. lbs.) torque.(11) Slide front band over front clutch retainer and
install front band strut and anchor (Fig. 55).
(12) Tighten front band adjusting screw until band is tight on clutch retainer. This will hold clutches in place while oil pump is being installed. Verify that front/rear clutch assembly is still properly seated before tightening band.
Fig.55FrontBandAndLinkage
1 - LEVER 2 - STRUT 3 - ANCHOR 4 - FRONT BAND
Fig.56OilPumpGasketAndPilotStuds
1 - OIL PUMP GASKET 2 - PILOT STUDS C-3288-B
CAUTION: The thrust washer bore (I.D.), is cham- fered on one side. Make sure the chamfered side is installed so it faces the pump.
Fig.54Front/RearClutchAssemblies
1 - FRONT AND REAR CLUTCH ASSEMBLIES
OIL PUMP
(1) Install oil pump Pilot Studs C-3288-B in case
(Fig. 56).
(2) Install new oil pump gasket on pilot studs and seat it in case. Be sure gasket is properly aligned with fluid passages in case (Fig. 56).
(3) Coat the reaction shaft thrust washer with petroleum jelly to hold it in place. Then install washer over reaction shaft hub and seat it on pump (Fig. 57).
DR AUTOMATIC TRANSMISSION - 48RE (Continued)
AUTOMATIC TRANSMISSION - 48RE
21 - 351
(4) Check seal rings on reaction shaft support. Be sure rings are hooked together correctly. Also be sure fiber thrust washer is in position (Fig. 58). Use extra petroleum jelly to hold washer in place if necessary. (5) Check the torque converter hub seal ring on the reaction shaft for damage. Also check that the seal ring rotates freely in the reaction shaft groove. Replace if necessary.
oil pump seals with petroleum
(6) Lubricate Mopart ATF +4.
(7) Mount oil pump on pilot studs and slide pump into case opening (Fig. 59). Work pump into case by hand. Do not use a mallet or similar tools to seat pump.
(8) Remove pilot studs and install oil pump bolts. Tighten pump bolts alternately and evenly to fully seat pump in case. Then final-tighten pump bolts to 20 N·m (15 ft. lbs.) torque.
(9) Verify correct installation. Rotate input and intermediate shafts and check for bind. If bind exists, components are either mis-assembled, or not seated. Disassemble and correct as necessary before proceed- ing.
Fig.58ReactionShaftSealRingAndThrustWasher 1 - SEAL RINGS 2 - REACTION SHAFT SUPPORT 3 - THRUST WASHER (FIBER)
Fig.57ReactionShaftThrustWasher
1 - THRUST WASHER 2 - CHAMFERED SIDE OF WASHER BORE GOES TOWARD PUMP
Fig.59OilPump
1 - SEAT OIL PUMP IN CASE BY HAND 2 - REMOVE PILOT STUDS WHEN PUMP IS SEATED
AUTOMATIC TRANSMISSION - 48RE
21 - 352
AUTOMATIC TRANSMISSION - 48RE (Continued) INPUT SHAFT END PLAY CHECKNOTE: Overdrive unit must be installed in order to correctly measure the input shaft end-play.
(1) Measure input shaft end play (Fig. 60).
If end play is incorrect,
NOTE: incorrectly assembled, or washer washer is selective.
reaction shaft is incorrect. The reaction shaft
transmission is thrust thrust
(a) Attach Adapter 8266-5 to Handle 8266-8. (b) Attach dial indicator C-3339 to Handle 8266-8. (c) Install the assembled tool onto the input shaft of the transmission and tighten the retaining screw on Adapter 8266-5 to secure it to the input shaft.
(d) Position the dial
indicator plunger against a flat spot on the oil pump and zero the dial indicator. (e) Move input shaft in and out and record read- ing. End play should be 0.86 - 2.13 mm (0.034 - 0.084 in.). Adjust as necessary.
Fig.60CheckingInputShaftEndPlay
1 - TOOL 8266-8
2 - TOOL 8266-5
3 - TOOL C-3339ACCUMULATOR, VALVE BODY, OIL PAN, AND TORQUE CONVERTER
(1) Install accumulator inner spring, piston and
outer spring (Fig. 63).
(2) Verify that the transmission range sensor has not been installed in case. Valve body can not be installed if sensor is installed.
(3) Install new valve body manual shaft seal in case (Fig. 64). Lubricate seal lip and manual shaft
DR
with petroleum jelly. Start seal over shaft and into case. Seat seal with 15/16 inch, deep well socket.
(4) Install valve body as follows:
(a) Start park rod into park pawl. If rod will not slide past park pawl, pawl is engaged in park gear. Rotate overdrive output shaft with suitable size 12
point socket; this will free pawl and allow rod to engage.(b) Align and seat valve body on case. Be sure lever shaft and overdrive connector are
manual fully seated in case.
(c) Install and start all valve body attaching bolts by hand. Then tighten bolts evenly, in a diag- onal pattern to 12 N·m (105 in. lbs.) torque. Do not overtighten valve body bolts. This could result in distortion and cross leakage after installation.. (5) Install new filter on valve body. Tighten filter
screws to 4 N·m (35 in. lbs.).
(6) Move the transmission manual shaft lever to
the manual LOW position.
(7) Install the TRS mounting bracket into the trans- mission case. Using Adapter 8581 (Fig. 61), tighten the mounting bracket to 34 N·m (300 in.lbs.).
Fig.61TightentheTRSMountingBracket
1 - SOLENOID CASE CONNECTOR 2 - TRS MOUNTING BRACKET 3 - ADAPTER 8581
(8) Install the TRS (Fig. 62) into the mounting bracket with the wiring connector facing the front of the transmission.
(9) Install the two screws to hold the TRS to the mounting bracket. Tighten the screws to 3.4 N·m (30
in.lbs.).If
the condition of
CAUTION: the transmission before the overhaul procedure caused excessive
