Part 1
TRANSFER CASE OVERHAUL - Part 1NOTE: Before commencing the overhaul procedure thoroughly clean the exterior of the transfer case. If the gearbox oil has not previously been drained, drain the oil into a suitable container.
DISMANTLING
NOTE: Before commencing the dismantling procedure remove the brake drum assembly.
Rear Output Housing
1. Remove the six bolts and withdraw the rear output housing complete with output shaft.
Front Output Housing
NOTE: Invert the gearbox. Level up the assembly by placing wooden blocks under the transfer case rear output housing face.
2. Remove the eight bolts and withdraw the front output housing complete with viscous unit.
Front Cover, Main Casing
3. Remove the eleven bolts and one stud bolt securing the front and rear cover (main case) together. Note position of the stud bolt for reassembly.
4. Clean any previous sealant from the threads of the bolts.
5. Using two levers between the cast lugs on the outer edges of the casing, to assist in separating the gearbox, carefully lever the front cover from the rear cover.
CAUTION: Do not lever between the mating faces.
Transfer Sprocket, Center Differential, Assembly And Chain
NOTE: Before dismantling, mark one chain link and corresponding tooth on the transfer sprocket with an identification line. This is to ensure that the balance of the unit is maintained when reassembled with original components and that the chain is fitted the correct way up.
6. Remove the circlip retaining the transfer sprocket to the transfer shaft.
7. Place two thin pieces of wood on the joint face to prevent damage and using two levers behind the differential assembly carefully lever the differential bearing from its bore while simultaneously easing the transfer sprocket off the transfer shaft to maintain alignment during removal.
8. Remove the transfer sprocket from the chain.
9. Remove the differential assembly from the chain.
Bearing Carrier And Transfer Shaft
10. Insert a screw driver between the anti rotation dowel and snap ring, gently pry the snap ring out of the groove.
11. Withdraw the carrier complete with transfer shaft.
12. Withdraw the anti rotation dowel.
Selector Fork Assembly
13. Using Torx 25 bit remove the screw securing the selector arm to the selector lever shaft.
14. Remove the retaining clip securing the selector fork arm to the selector lever shaft.
15. Using Torx 25 bit remove the screw retaining the selector lever.
16. Remove the selector lever shaft from the case and fork assembly.
17. Withdraw the selector fork assembly and selector sleeve.
18. Remove the selector plunger and spring from the rear cover.
Planetary Set (Epicyclic unit)
19. Turn the case over and pry the end cap off the planetary set housing.
20. Remove the circlip retaining the sun gear shaft.
21. Turn the casing over and remove the large snap ring retaining the planetary set.
22. Withdraw the ring gear and planetary assembly from the planetary set housing, complete with oil pump, feed pipe and filter.
Rear Cover Main Case, Dismantle and Inspection
1. Remove the circlip retaining the bearing in the rear cover.
2. Drive or press the bearing from the cover and discard the bearing.
3. Remove any previous sealant evident on the rear cover joint faces.
4. Using a suitable solvent thoroughly clean the cover.
5. Examine the cover for damage, cracks and porosity, renew if necessary.
6. Check the selector lever shaft bore, for out of round and wear. If worn renew the cover.
Rear Cover Main Case, Assemble
7. Drive or press a new bearing into the cover and secure in position with the circlip.
NOTE: If the neutral warning switch was removed from the case, Teflon tape must be applied to the threads of the switch on re-assembly.
8. Place the cover aside until the gearbox is ready to be assembled.
Front Cover Main Case, Dismantle And Inspection
9. Pry the input shaft oil seal from the front cover and discard the oil seal.
10. Remove the snap ring retaining the needle roller bearing, withdraw the bearing and discard.
11. Remove any previous sealant from the joint faces of the front cover.
12. Thoroughly clean the cover using a suitable solvent.
13. Examine the cover for damage, cracks and porosity. renew if necessary.
14. Check the inside edges of the case for witness marks which may indicate a chain that has stretched.
Front Cover Main Case, Assemble
15. Lubricate a new oil seal. Using service tool LST 550- 6 in conjunction with bearing and oil seal replacer 18G134 fit the seal, open side of the seal forward until the face of the seal is 1 mm (0.039 in) below the surface of the boss.
16. Lubricate a new needle roller bearing and drive or press the bearing into its recess until contact is made with the shoulder at the bottom of the bore.
17. Fit the snap ring to retain the bearing.
18. Place the cover aside until the gearbox is ready to be assembled.
Planetary Set (Epicyclic Unit) And Oil Pump, Dismantle And Inspection
NOTE: The Epicyclic unit and oil pump are serviced as a complete assembly, if after inspection either of the units is found to be worn a complete new assembly must be fitted.
1. Remove the ring gear from the planetary set.
2. Thoroughly clean all components using a suitable solvent.
3. Examine the helical teeth of the ring gear for wear or damage. If damage is evident it will be necessary to renew both the ring gear and planetary set.
4. Examine the planetary gears and high/low gear teeth for wear or damage. If damaged renew both the ring gear and planetary set.
5. Check the end play of the four planet gears, between the end of the gear and planetary set carrier. End play of each planet gear should not exceed 0.83 mm (0.033 in). If any one of the planet gears is out of limits renew the planetary set assembly.
6. Check the end play of the sun gear to the planetary set carrier by supporting the body of the assembly on the top of a vice. Using a dial test indicator attached to a magnetic base, position the base on top of the assembly and zero the indicator on the end of the sun gear shaft, lift the shaft and check the end play. End play should not exceed 1.02 mm (0.04 in). Fit a new planetary set assembly if out of limits.
NOTE: If the previous inspection instructions prove the assembly to be in an acceptable condition carry out the following examination of the oil pump.
Oil Pump And Filter, Dismantle And Inspection
7. To aid re assembly mark an identification line on the edges of the oil pump plates. Remove the four bolts securing the pump front and rear plates, separate the pump by removing the plungers, spring and bearing plate.
NOTE: The front plate of the oil pump is stamped TOP, the center bearing plate is stamped REAR and the rear plate is stamped TOP REAR. The bolt holes of the plates and body are also offset to ensure correct re-assembly of the pump.
8. Depress the retaining clips, remove the oil pick-up pipe and rubber connection tubes. Examine the tubes and pipe for damage or fractures, renew as necessary.
9. Clean the pump components and check for damage and wear, i.e.: blueing of the pump plungers, scoring of the center bearing plate. If any wear is evident a new planetary set must be fitted, as the pump is part of the complete assembly.
10. Thoroughly clean the oil pick-up filter. examine the filter screen for damage and blockage, renew or clean the filter as necessary.
Oil Pump And Filter, Assemble
11. Clean the sealant from the oil pump securing screws.
12. Prior to assembly lubricate the pump components with clean oil.
13. Fit the plate stamped TOP to the sun gear shaft with the word TOP facing the planetary assembly.
14. Fit the plungers and spring noting that the flats on the plungers must be uppermost to enable the TOP REAR plate to be fitted.
15. Compress the plungers and fit the middle bearing plate with the word REAR uppermost. Align the offset fixing holes and also noting the previously marked identification line.
16. Fit the top rear plate with the words TOP REAR uppermost.
17. Apply Loctite(r) 242 to the threads of the four screws and fit the screws, tighten to 4-8.5 Nm (35-75 in lb).
18. Fit the rubber connection tube and oil pick-up pipe to the oil pump, fit the retaining clip. Note that the clip securing the tube to the pick-up pipe is positioned in front of the flare on the pipe.
19. Fit the rubber connection tube to the filter end of the pipe, fit the clip ensuring that the tube is clamped by the clip in front of the flare on the pipe.
20. Push the filter into the tube. The radial position of the filter to pipe at this stage is unimportant.
Planetary Set (Epicyclic Unit) And Ring Gear, Assemble
21. Lubricate the planetary set and ring gear with clean oil.
22. Position the ring gear around the planetary set, fit the assembly to the rear cover locating the oil pump inlet port in the groove at the bottom of the planetary set housing, the sun gear shaft in the bearing and the lugs on the outer edge of the ring gear in the anti-rotation lugs. It may be necessary to tap the sun gear shaft into the bearing to enable the large ring gear snap ring to be fitted.
23. Fit the snap ring with the stepped ends adjacent to the selector shaft bore.
24. Turn the rear cover over and fit the circlip to retain the sun gear shaft.
25. Remove any previous sealant from the end cap and rear cover. Apply Dow Corning 732 silicon sealant or a suitable equivalent to the outside diameter of the rear cover evenly tap the cap into position.
26. If necessary re-position the filter on the oil pick-up pipe until the lug on the filter can be pushed into the slot in the rear cover.