Overdrive Unit
UNIT-OVERDRIVEREMOVAL
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 necessary.
5. Disconnect and remove the rear propeller shaft, if necessary.
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 diagnosis indicated overdrive problems only, remove just the overdrive unit.
8. Support transmission with transmission jack.
9. Remove bolts (2) attaching overdrive unit (1) to transmission.
CAUTION: Support the overdrive unit with a jack before moving it rearward. This is necessary to prevent damaging the intermediate shaft. Do not allow the shaft to support the entire weight of the overdrive unit.
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 62272 in splines of planetary gear and overrunning clutch to prevent splines from rotating out of alignment. If misalignment occurs, overdrive unit will have to be disassembled 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 overrunning clutch splines.
DISASSEMBLY
1. Remove transmission speed sensor (2) and o-ring seal (3) from overdrive case.
2. Remove overdrive piston thrust bearing (1).
OVERDRIVE PISTON
1. Remove overdrive piston thrust plate (2). Retain thrust plate. It is a select fit part and may possibly be reused.
2. Remove intermediate shaft spacer (2). Retain spacer. It is a select fit part and may possibly be reused.
3. Remove overdrive piston (2) from retainer (1).
OVERDRIVE CLUTCH PACK
1. Remove overdrive clutch pack wire retaining ring
2. Remove overdrive clutch pack (1).
3. Note position of clutch pack components for assembly reference (1-4).
OVERDRIVE GEARTRAIN
1. Remove overdrive clutch wave spring (1), 5 disc clutch only
2. Remove overdrive clutch reaction snap-ring (1). Note that snap-ring is located in same groove as wave spring.
3. Remove Torx head screws (1) attach access cover and gasket to overdrive case.
4. Remove access cover and gasket (1).
5. Expand output shaft bearing snap-ring (1) with expanding-type snap-ring pliers. Then push output shaft forward to release shaft bearing from locating ring.
6. Lift gear case (2) up and off geartrain assembly (1).
7. Remove snap-ring (3) that retains rear bearing (2) on output shaft (1).
8. Remove rear bearing from output shaft.
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 approximately 830 pounds. Use spring compressor tool 62271 and a hydraulic shop press with a minimum ram travel of 56 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.
1. Mount geartrain assembly in shop press (1, 5).
2. Position Compressor Tool 62271 (6) on clutch hub (3). Support output shaft flange with steel press plates (4) as shown and center assembly under press ram (1).
3. Apply press pressure slowly. Compress hub and spring far enough to expose clutch hub retaining ring (3) and relieve spring pressure on clutch pack snap-ring.
4. Remove direct clutch pack retaining ring (3).
5. Remove direct clutch hub retaining ring (2).
6. Release press load slowly and completely.
7. Remove Special Tool 62271 (1). Then remove clutch pack (3) from hub (2). Note the orientation of the clutch discs. The clutch pack consists of 10 double-sided friction discs and they must be installed in the same orientation as they were removed.
GEARTRAIN
1. Remove direct clutch hub (2) and spring (1).
2. Remove sun gear (5) and spring plate (3). Then remove planetary thrust bearing (2) and planetary gear (1).
3. Remove overrunning clutch assembly (1) with expanding type snap-ring pliers. Insert pliers 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.
6. Mark position of annulus gear and direct clutch drum (1) for assembly alignment reference. Use small center punch (3) or scriber to make alignment marks.
7. Remove direct clutch drum (2) rear retaining ring (1).
8. Remove direct clutch drum outer retaining ring (1).
9. Mark annulus gear and output shaft (1) for assembly alignment reference. Use punch (3) or scriber to mark gear and shaft.
10. Remove snap-ring (3) that secures annulus gear (2) on output shaft (1). Use two screwdrivers to unseat and work snap-ring out of groove as shown.
11. Remove annulus gear (2) from output shaft (1). 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 solvent. Dry all parts except the bearings with compressed 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 sufficient quantity of lint (from shop towels, cloths, rags, etc.) could plug the transmission filter and fluid passages.
Discard the old case gasket and seals. Do not attempt to salvage these parts. They are not reusable. 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 components; 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 bearings 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 bushings 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 bushing is the intermediate shaft pilot bushing. The large bushing is the overrunning clutch hub bushing. Replace either bushing if scored, pitted, cracked, or worn.
ASSEMBLY
GEARTRAIN AND DIRECT CLUTCH
1. Soak direct clutch and overdrive clutch discs in Mopar ATF +4, Automatic Transmission fluid. Allow discs to soak for 10 - 20 minutes.
2. Install annulus gear (3) on output shaft, if removed. Then install annulus gear retaining snap-ring (1).
3. Align and install clutch drum (3) on annulus gear (1). Be sure drum is engaged in annulus gear lugs.
4. Install clutch drum outer retaining ring (2).
5. Slide clutch drum (3) forward and install inner retaining ring (2).
6. Install rear bearing (1) and snap-ring (2) on output shaft. Be sure locating ring groove in bearing is toward rear.
7. Install overrunning clutch (2) on hub (1). 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 (2) in output shaft (6). Insert snap-ring pliers in hub splines. Expand pliers to grip hub. Then install assembly with counterclockwise, twisting motion.
10. Install planetary gear (1) in annulus gear (2). Be sure planetary pinions are fully seated in annulus gear before proceeding.
11. Coat planetary thrust bearing (2) 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 (2) on sun gear (3). 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 (1). Be sure sun gear and thrust bearing are fully seated before proceeding.
14. Mount assembled output shaft, annulus gear, and clutch drum in shop press (3). Direct clutch spring, hub and clutch pack are easier to install with assembly mounted in press.
15. Align splines in hubs of planetary gear and overrunning clutch with Alignment tool 62272 (1). Insert tool through sun gear and into splines of both hubs. Be sure alignment tool is fully seated before proceeding.
16. Install direct clutch spring (2). Be sure spring is properly seated on spring plate (4).
NOTE: The direct clutch in a 48RE transmission uses 10 double-sided clutch discs.
17. Assemble and install direct clutch pack on hub as follows:
a. Install direct clutch reaction plate (2) on clutch hub first. Note that one side of reaction plate is counterbored (1). Be sure this side faces rearward. Splines at rear of hub (3) are raised slightly. Counterbore in plate fits over raised splines. Plate should be flush with this end of hub (3).
b. Install first friction disc with internal splines, followed by a steel separator disc with external lugs. Continue alternating internal and external discs until all discs have been installed.
18. Install pressure plate (1). This is last clutch pack (2) item to be installed. Be sure plate is installed with shoulder side facing upward (3).
19. Install clutch hub (1) and clutch pack (2) on direct clutch spring. Be sure hub is started on sun gear splines before proceeding.
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 compressor tool C-62271 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.
20. Position Compressor Tool 62271 (1) on clutch hub.
21. Compress clutch hub and spring just enough to place tension on hub and hold it in place.
22. Slowly compress clutch hub and spring. Compress spring and hub only enough to expose ring grooves for clutch pack snap-ring and clutch hub retaining ring.
23. Realign clutch pack on hub and seat clutch discs and plates in clutch drum.
24. Install direct clutch pack snap-ring (2). Be very sure snap-ring is fully seated in clutch drum ring groove.
25. Install clutch hub retaining ring (2). Be very sure retaining ring is fully seated in sun gear ring groove.
26. Slowly release press ram, remove compressor tools and remove geartrain assembly.
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 Nm (20 ft. lbs.) torque.
3. Install park lock reaction plug (3). Note that plug has locating pin (2) at rear. Be sure pin is seated in hole in case before installing snap-ring (1).
4. Install reaction plug snap-ring (1). Compress snap-ring only enough for installation; do not distort it.
5. Verify that tab ends of rear bearing locating ring (2) extend into access hole (1) in gear case.
6. Support geartrain on Tool 6227-1. Be sure tool is securely seated in clutch hub.
7. Install overdrive gear case (2) on geartrain (1).
8. Expand front bearing locating ring with snap-ring pliers (1). Then slide case downward until locating ring locks in bearing groove and release snap-ring.
9. Install locating ring access cover, gasket and screws (2) in overdrive unit case.
OVERDRIVE CLUTCH
NOTE: The overdrive clutch in a 48RE transmission uses 5 or 6 clutch discs depending on the application.
1. Install overdrive clutch reaction ring (1) first. Reaction ring is flat with notched ends.
2. For 5 disc overdrive clutch versions, install wave spring (1) on top of reaction ring. Reaction 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.
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 (1).
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 Gauge 6312 (1) through sun gear, planetary gear and into pilot bushing in output shaft. Be sure tool bottoms against planetary shoulder.
b. Position Gauge Bar 6311 (2) across face of overdrive case. Then position Dial Caliper over gauge tool.
c. Extend sliding scale of dial caliper downward through gauge tool slot until scale contacts end of Gauge 6312 (1). Lock scale in place. Remove dial caliper tool and note distance measured.
3. Select proper thickness end play spacer from spacer chart based on distance measured.
4. Remove Gauge Alignment Tool 6312.
OD 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 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 (1) across face of overdrive case. Then position Dial Caliper over gauge tool.
b. Measure distance to clutch hub thrust bearing seat (2) at four points 90° apart. Then average measurements by adding them and dividing by 4.
3. Select and install required thrust plate from information in thrust plate chart.
4. Leave Alignment Tool 62272 in place. Tool will keep planetary and clutch hub splines in alignment until overdrive unit is ready for installation on transmission.
5. 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.
OVERDRIVE PISTON
1. Install new seals on overdrive piston.
2. Stand transmission case upright on bellhousing.
3. Position Guide Ring 8114-1 on outer edge of overdrive piston retainer.
4. Position Seal Guide 8114-3 on inner edge of overdrive piston retainer.
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 Mopar ATF+4.
c. Install piston over Seal Guide 8114-3 and inside Guide Ring 8114-1.
d. Push overdrive piston into position in retainer.
e. Verify that the locating lugs entered the lug bores in the retainer.
6. Install intermediate shaft spacer on intermediate shaft.
7. Install overdrive piston thrust plate on overdrive piston.
8. Install overdrive piston thrust bearing on overdrive piston.
9. Install transmission speed sensor and o-ring seal in overdrive case.
INSTALLATION
1. Be sure overdrive unit Alignment Tool 62272 is fully seated before moving unit. If tool is not seated and gear splines rotate out of alignment, overdrive 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.
3. Cut out old case gasket (1) around piston retainer with razor knife (2).
4. Use old gasket as template and trim new gasket 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.
6. Install selective spacer (1) on intermediate shaft (3), if removed. Spacer goes in groove just rearward of shaft rear splines.
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 diameter of the bearing is facing forward.
8. Verify that splines in overdrive planetary gear and overrunning clutch hub are aligned with Alignment 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 overdrive 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 necessary 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 transmission unit. Tighten bolts in diagonal pattern to 34 Nm (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 necessary.