Disassembly and Overhaul
GEAR CHANGE HOUSING1. Separate main gearbox from transfer box. drain oil and clean exterior.
2. Clamp into a large bench vice supported underneath by a wooden block.
3. Remove gear change housing cover. (Range Rover and Discovery illustrated)
4. Remove transfer gear change housing (If not already removed).
5. Remove main gear change selector housing.
EXTENSION HOUSING
1. Thread a 12 mm bolt into the end of the output shaft and using tool LRT-37-009 and LRT-37-010 withdraw oil seal collar.
2. Remove selector yoke from selector shaft and discard grub screw
3. Remove reverse/5th gear selector spool retainer.
4. Remove 10 bolts securing extension casing noting position of longer bolts.
5. Place a suitable container underneath the box to catch any oil spillage and remove the extension housing.
6. Remove oil filter.
7. Secure centre plate to casing using "slave" bolts.
5TH AND REVERSE GEAR REMOVAL.
1. Using a suitable two legged puller remove 5th gear layshaft support bearing track from the end of layshaft.
Note:
The following procedures (2) & (3) apply to this bulletin only. A new procedure for removing 5th gear layshaft nut will follow in a later bulletin.
2. Select both 5th and 1st gears to lock the gearbox.
3. Using tool LRT-51-003 and two long bolts, hold the 5th laygear and remove the 5th laygear nut.
4. Select neutral.
5. Remove thrust collar segments retaining ring and segments.
6. Drift out the roll pin.
7. Remove 5th laygear.
8. Remove mainshaft rear support bearing track using tool LRT-37-009 and LRT-37-010.
9. Remove 12 mm bolt from end of mainshaft.
10. Remove mainshaft 5th gear with synchromesh baulk ring.
11. Remove mainshaft 5th gear split needle roller bearing.
12. Remove circlip securing 5th gear synchromesh hub.
13. Rotate selector spool clear of synchro hub fork and remove 5th and reverse synchromesh hub assembly complete with fork and spool.
14. Remove mainshaft reverse gear complete with needle roller bearing and bush noting selectable spacer between reverse gear bush and centre plate bearing.
15. Remove layshaft reverse gear.
16. Remove centre plate detent plug. spring and ball.
17. Remove main case spool retainer
18. Remove "slave" bolts.
MAINCASE.
1. Align selector shaft pin with slot in centre plate and using wooden blocks and hide mallet. drive off centre plate.
2. Collect detent ball and spring. remove bearing tracks and shims.
3. Remove layshaft. mainshaft and selector shaft from casing as complete unit.
4. Remove input shaft. and 4th gear baulk ring. (If not already removed with mainshaft).
5. Remove bellhousing.
MAINSHAFT.
1. Using LRT-99-002 and support bars under 1st gear. press mainshaft support bearing from mainshaft.
2. Remove 1st gear, bush needle bearing and synchromesh baulk rings.
3. Remove 1st/2nd gear synchromesh selector hub. 2nd gear synchromesh baulk rings, second gear and needle bearing.
4. Invert mainshaft and using LRT-99-002 and support bars under 3rd gear, press off pilot bearing
5. Remove spacer, 3rd/4th gear synchromesh selector hub. synchromesh baulk rings. 3rd gear and needle bearing.
GEARBOX CASINGS AND OIL PUMP.
Degrease and clean all components. Inspect casing for damage, cracks and stripped threads.
1. Apply Hylogrip 2000 and fit level plug.
2. Fit new copper washer to drain plug.
FRONT COVER.
1. Remove front cover and remove bearing tracks. check that spring clips are intact.
2. Remove oil seal from cover. DO NOT fit new seal at this stage.
CENTRE PLATE.
1. Remove bearing tracks and shims.
2. Inspect for damage and selector rail bore for wear.
3. Remove splash shield if required.
4. Press out reverse idler gear shaft using suitable press.
5. Remove idler gear. needle bearing and spacer.
EXTENSION CASING
1. Examine for damage to threads and machined faces.
2. Remove three screws and remove oil pump.
3. Remove oil pump cover. inspect gears and housing for wear. Renew unit if necessary.
4. Remove oil pick-up pipe and check for obstruction.
5. Drift out layshaft support bearing.
6. Remove rear mainshaft oil seal.
7. Drift out mainshaft support bearing and oil pick up ring.
8. Remove shaft retaining reverse inhibition cam.
9. Remove reverse inhibition cam and spring.
10. Remove reverse light switch and sealing washer.
11. Remove gate plate.
12. Check all components for wear and renew as required.
Reassembly.
1. Smear a light coat of Vaseline into the pump recess.
2. Renew "O" ring and press pump unit firmly into recess.
Note:
Ensure "TOP" marking on pump is to top of casing.
3. Tap pump lightly at edges until screws take to threads and pull down pump by tightening screws.
Note:
Ensure good thread engagement before tightening.
4. Fit new mainshaft support bearing.
5. Fit new mainshaft rear oil seal using tool LRT-37-014.
6. Fit new Layshaft support bearing.
7. Fit new oil pick-up ring (Align hole with centre of drain slot).
8. Examine gate plate and renew if worn or damaged.
9. Refit reverse light switch with new copper washer. Tighten to 22-26.5 Nm.
10. Refit reverse inhibition cam and spring.
11. Apply Hylogrip 2000 and refit shaft.
12. Refit oil pipe, bend uppermost.
GEARCHANGE HOUSING
1. Remove bolts retaining bias springs.
WARNING:
To avoid personal injury, restrain each spring in turn with a pair of grips while the bolts are being removed.
2. Remove the two springs.
3. Remove remaining bolts to release lower lever assembly.
4. Check for wear in cross pin slots in housing and wear in lower gear lever.
5. Examine bias spring and renew if weak or distorted.
6. Grease lower gear lever-bail with Shell Alvina R3.
7. Fit gear lever to housing.
8. Fit adjustment plate.
Note:
Apply Hylogrip 2000 or Loctite 290 to threads of two short bolts and fit them forward of the gear lever. Tighten bolts to prevent plate moving while springs are being fitted.
9. Fit Bias springs locating long end against gear lever.
Note:
Apply above sealant to threads of spring retaining bolts. Use grips to compress springs to enable bolts to be fitted.
SYNCHROMESH ASSEMBLIES.
Note:
For assembly purposes gear identification marks are inscribed on the edges of the synchromesh selector hubs.
1. Remove spring clips from both sides of assembly.
2. Remove slippers and separate the two members.
3. Examine all parts for damage and wear including spring clips for tension.
4. No step. Go to 5.
5. Check no excessive radial movement exist between inner members and mainshaft splines.
6. Examine inner and outer splines for wear.
7. Examine the dog teeth on all gears for wear and damage.
Note:
Example "A" shows a tooth in good condition. Example "B" shows the rounded corners of a worn tooth.
8. Replace unit If excessively worn.
Reassembly.
9. Befit inner member to outer.
Note:
Inner and outer members have a master spline and can only be assembled in one way.
10. Fit slippers and secure with a spring each side of the synchromesh.
CHECKING BAULK RING CLEARANCES.
Check clearance of all baulk rings and gears by pressing the baulk rings against the gear and measuring the gap. The minimum clearance should be 0.5 mm (0.020 in).
INPUT SHAFT.
1. Examine the gear and dog teeth for wear and damage.
2. Using tool LRT-99-004 and LRT-37-04 remove pilot bearing track
Note:
Ensure that the bearing is supported by the lip inside LRT-37-001.
3. Using LRT-37-001 and LRT-90-002 remove taper roller bearing.
4. Support the shaft under LRT-99-002 and press in a new pilot bearing track.
5. Using LRT-99-002, Collets LRT-37-001 and adaptor LRT-37-002 fit a new taper bearing.
MAINSHAFT.
1. Examine bearing journals for wear and scores
2. Examine splines for wear and damage.
3. Use an air line to check that the main oil feed from pump and feed to spigot bearing are clear.
4. Check oil feed holes to roller bearing are clear.
LAYSHAFT.
1. Using extractor tool LRT-99-002 and collets LRT-37-022 withdraw layshaft bearings.
2. Examine layshaft for wear and damage.
3. Using press LRT-99-002 and support bars fit new taper roller bearings.