Dismantling a four-speed manual transmission

Transmission input shaft

Transmission output shaft

Synchronizer

Differential

1. Place the gearbox on a suitable assembly table or place it on a workbench on the clutch housing.




2. Unscrew the locking bolt, remove the clutch release shaft and release bearing.

3. Unscrew the bolts and remove the rear cover from the crankcase.



4. Using a screwdriver, remove the circlips of the input and output shaft bearings in the directions indicated by the arrows.

5. Unscrew the bolts securing the gearbox housing to the clutch housing and with light blows of a mallet on the upper part of the gearbox housing, separate it from the clutch housing and remove.



6. Remove the magnet from the socket in the direction indicated by the arrow.




7. Remove the shift fork shaft and spring.



8. Remove the gear selector forks and the selector lock.



9. At the same time, remove the input and output shafts and the reverse idle gear from the crankcase.



10. Remove differential box.


11. Remove the output shaft bearing from the clutch housing, for which, sequentially, using a screwdriver or tweezers, remove the bearing rollers, the outer bearing ring and the oil deflector.



12. From both crankcases, remove the O-rings and the outer races of the tapered roller bearings of the differential. outer ring (1) gearbox housing bearing is supported by two special spring washers (2), directed by convex parts to each other, and the washer of smaller diameter is at the bottom of the socket.

Disassembly of the input shaft

13. input shaft (see fig. Transmission input shaft) It is made as a single block of gears, only bearings can be removed from it for replacement. To remove the bearings, you must use a universal puller, preferably with two jaws. When removing the front bearing, the grips of the puller cling to the end of the outer ring, and when removing the rear bearing, to the annular groove for the circlip or to the re-installed circlip of the bearing.

Dismantling the output shaft

14. Fasten the output shaft (see fig. Transmission output shaft) vertically in a vise, on the jaws of which there are soft metal linings. The location of the shaft is with the drive gear of the differential down.

15. Remove from shaft:

• bearing retaining ring;
• install the outer retaining ring of the bearing into the outer ring of the bearing and, having hooked the universal puller grips on the retaining ring, remove the bearing.;
• 4th gear gear;
• synchronizer retaining ring;
• 3rd and 4th gear synchronizer assembly;
• 3rd gear gear;
• retaining ring and thrust half rings of the 2nd gear gear;
• 2nd gear gear;
• retaining ring and synchronizer of 1st and 2nd gears assy;
• snap ring and 1st gear.

Synchronizers

16. Remove the spring synchronizer from both sides.

17. Remove the sliding ring of the synchronizer clutch and blocking crackers (see rice. Synchronizer).

18. Clean and check the condition of the synchronizer parts.

19. When assembling the synchronizer, ensure that the grooves on the hub and the sliding sleeve for crackers match.

20. Install the springs in such a way that the bent ends of the springs enter the same cracker, but the direction of the bending of the springs must be opposite.

21. In case of jamming of the blocking rings of the synchronizer on the gears, they must be replaced.

Disassembly of the differential box

22. Remove the plugs holding the side gears and remove them from the differential box (see rice. Differential).

23. Remove the fixing lock of the axis of the satellites, remove the axis and satellites.

24. Using a universal puller, remove the bearings from the differential case.

25. Remove the speedometer drive gear.

26. Unscrew the bolts of the final drive driven gear and remove the gear from the differential box with light taps.

Checking Gearbox Parts

1. Thoroughly clean and visually inspect all parts of the gearbox.

2. Check gears for wear and chipped teeth.

3. In case of wear of the teeth of one of the gears of the input shaft, the shaft must be replaced.

4. Check reusable rolling bearings for wear and cages.

5. Check the synchronizers and the ends of the shift forks for wear, as the forks constantly rub in the grooves of the synchronizer sliding ring.

6. In the case of disassembly of synchronizers, it is necessary to note the relative position of the hub and the sliding ring of the synchronizer.

7. Keep the synchronizer rings on the corresponding gears.

8. To clean the mating surfaces of the clutch and gearbox housings, do not use hard metal tools that could damage the mating surface, but use a rag soaked in solvent.