Mainshaft: Service and Repair

MAINSHAFT AND GEARS

DISASSEMBLY
1. Before disassembly, measure gear end plays. If end play is not within the specified limit, disassemble and check the parts.
Gear end play:
1st main gear 0.18 - 0.31 mm (0.0071 - 0.0122 inch)
2nd, 3rd, 4th main gear 0.20 - 0.30 mm (0.0079 - 0.0118 inch)





2. Press out mainshaft front and rear bearing with Tool.





3. Remove C-ring holder, mainshaft C-rings and thrust washer.





4. Press out 5th main gear with Tool.





5. Remove 4th main gear, 4th bushing and steel ball. Be careful not to lose steel ball.





6. Remove 3rd & 4th synchronizer, 3rd main gear, 2nd & 3rd bushing, steel ball and 2nd main gear with Tool. Be careful not to lose steel ball.





7. Remove 1st & 2nd synchronizer and 1st main gear, then remove 1st gear needle bearing.

INSPECTION





Gear And Shaft
- Check shaft for cracks, wear or bending.
- Check gears for excessive wear, chips or cracks.





Synchronizer
- Check spline portion of coupling sleeves, hubs and gears for wear or cracks.
- Check baulk rings for cracks or deformation.
- Check shifting inserts for wear or deformation.





- Measure clearance between baulk ring and gear.
Clearance between baulk rings and 1st through 5th main gears:
Standard: 1.0 - 1.35 mm (0.0394 - 0.0531 inch)
Wear limit: 0.7 mm (0.028 inch)





Bearing
- Make sure bearings roll freely and are free from noise. cracks, pitting or wear.
- When replacing tapered roller bearing' replace outer and inner race as a set.








ASSEMBLY
1. Assemble 1st & 2nd and 3rd & 4th synchronizers. Be careful not to hook front and rear ends of spread spring to the same insert.





2. Install 1st gear needle bearing and 1st main gear.
3. Press on 1st & 2nd synchronizer.





4. Install steel ball, 2nd main gear, 2nd & 3rd bushing, 3rd main gear and 3rd & 4th synchronizer with Tool.
- Apply multi-purpose grease to steel ball before installing it.
- 2nd & 3rd bushing has a groove in which steel ball fits.





5. Install steel ball, 4th bushing and 4th main gear.
- Apply multi-purpose grease to steel ball before installing it.
- 4th bushing has a groove in which steel ball fits.





6. Press on 5th main gear.





7. Install thrust washer.





8. Select and install mainshaft C-ring that gives proper clearance of groove in mainshaft.
Allowable clearance of groove: 0 - 0.1 mm (0 - 0.004 inch)
Refer to the illustration for mainshaft C-ring information.
9. Install C-ring holder.





10. Press on mainshaft rear bearing with Tool.





11. Press on mainshaft front bearing.
12. Measure gear end play as the final check.