21. Mainshaft Assemble

Mainshaft Assemble

^ Tools Required
- J 26900-12 Dial Indicator
- J 26900-13 Magnetic Indicator Base
- J 29763 Static Timing Gage
- J 36850 Transjel Lubricant
- J 44725 Gear Pack Assembly Fixture
- J 44734 Installation Aligner
- J 44735 Installation Tube





1. Notice: Refer to Heating Transmission Component Notice in Service Precautions.

Important: Certain transmission components require preheating to 150°C (300°F). In order to preheat the components, use an electric oven. It is recommended to purchase a roaster/oven style locally. The oven should have a temperature setting thermostat.

Preheat the following components for 30 minutes to 150°C (300°F) in an electric oven:
^ The mainshaft intermediate case bearing
^ The 2nd/3rd gear synchronizer hub
^ The 3rd speed gear bushing
^ The 4th gear thrust washer
^ The 4th speed gear bushing
^ The 4th/5th synchronizer hub
^ The mainshaft front bearing

2. Caution: Refer to Proper Handling of Preheated Components Caution in Service Precautions.

Position the mainshaft with the output end up in the J 44725 .
3. Wearing protective gloves, install the preheated mainshaft intermediate case bearing on the mainshaft. Rotate the bearing while installing, in order to seat it fully and squarely.





4. Turn the mainshaft over 180 degrees in the J 44725, with the input end facing up.
5. Install the 2nd speed gear bearing on the mainshaft.
6. Lightly lubricate the bearing with GM P/N 12378515 (Canadian P/N 88900701).
7. Install the 2nd speed gear on the mainshaft.





8. Install the 2nd speed gear synchronizer inner ring. Align the tabs on the ring with the slots in the 2nd gear.
9. Install the 2nd speed gear synchronizer middle ring. Align the tabs in the 2nd gear.
10. Install the 2nd speed gear synchronizer blocking ring.
11. Ensure the 3 tabs of the synchronizer inner ring are aligned with the synchronizer blocking ring tabs.
12. Lightly lubricate the synchronizer components with GM P/N 12378515 (Canadian P/N 88900701).





13. Position the J 44725 (2) on a hydraulic press. The J 44725 will be used to assemble the mainshaft while in a hydraulic press.
14. Position the mainshaft on the J 44725 (2) with the input facing up.
15. Position the J 44734 (1) on the end of the mainshaft. Using J 44734 will prevent the heated parts from getting caught on the mainshaft during installation.





16. Caution: Refer to Proper Handling of Preheated Components Caution in Service Precautions.

Wearing protective gloves, install the preheated 2nd/3rd gear synchronizer hub on the mainshaft. Position the hub with the part number facing up.
17. Align the tabs on the 2nd gear synchronizer rings with the slots in 2nd/3rd gear synchronizer hub while installing the hub.
18. Use the J 44735 (1) and a hydraulic press to fully seat the 2nd/3rd gear synchronizer hub.





19. Perform the following in order to ensure the 2nd gear synchronizer rings are properly installed in the 2nd/3rd gear synchronizer hub:
1. Rotate the 2nd speed gear back and forth.
2. Looking through the slot in the hub, watch for movement of the blocking ring.
3. The blocking ring should move approximately 2 mm (1/16 inch).





20. Using the J 26900-12 or the J 29763 with the J 26900-13, measure the 2nd gear axial clearance. Clearance should be 0.15 - 0.35 mm (0.0059 - 0.0138 inch).
0. Position the J 26900-12 or the J 29763 on the top of the gear teeth.
1. Zero the gage.
2. Lift up on the gear to measure the clearance.
21. If clearance is higher than the specification, inspect to ensure the 2nd/3rd synchronizer hub is installed completely.
22. If clearance is higher than the specification, inspect the 2nd speed gear, mainshaft, or 2nd/3rd synchronizer hub for wear.
23. If clearance is lower than the specification, inspect the 2nd speed gear, mainshaft, or 2nd/3rd synchronizer hub for burrs.
24. Repair or replace the damaged or worn component.





25. Install the 2nd/3rd gear synchronizer sleeve.
^ Position the sleeve part number side up.
^ Align the flat areas, square teeth, on the sleeve with the slots for the detent springs.





26. Install the 2nd/3rd gear detent springs, pressure pieces, and balls in the synchronizer hub.The 2nd/3rd synchronizer springs are 19.7 mm (0.775 inch) long.
0. Install all three springs and pressure pieces.
1. Install the balls.

Important: If the 3rd gear synchronizer blocking ring is not installed before moving the sleeve to lock the balls in position, the springs will jump out of position.

2. Install the 3rd gear synchronizer blocking ring to hold the balls and sleeve in the neutral position. The tabs on the blocking ring align with the slots in the hub without the detent pieces.
3. Pull up on the sleeve to lock the balls in position.





27. Install the 3rd gear synchronizer middle ring.
28. Install the 3rd gear synchronizer inner ring.
29. Align the 3 tabs of the inner ring with the synchronizer hub slots.
30. Lightly lubricate the synchronizer components with GM P/N 12378515 (Canadian P/N 88900701).





31. Caution: Refer to Proper Handling of Preheated Components Caution in Service Precautions.

Wearing protective gloves, install the preheated 3rd speed gear bushing.
32. Use the J 44735 and a hydraulic press to fully seat the bushing.





33. Allow the 3rd speed gear bushing to cool.
34. Install the 3rd speed gear bearing on the mainshaft.
35. Lightly lubricate the bearing with GM P/N 12378515 (Canadian P/N 88900701).
36. Install the 3rd speed gear.
37. Align the 3rd gear synchronizer middle ring tabs with the holes in the 3rd speed gear.





38. Caution: Refer to Proper Handling of Preheated Components Caution in Service Precautions.

Wearing protective gloves, install the preheated 4th gear thrust washer on the mainshaft.
39. Using the J 44735 and a hydraulic press, fully seat the thrust washer.
40. Allow the 4th gear thrust washer to cool.





41. Using the J 26900-12 or the J 29763 with the J 26900-13, measure the 3rd gear axial clearance. Clearance should be 0.15 - 0.35 mm (0.0059 - 0.0138 inch).
0. Position the J 26900-12 or the J 29763 on the top of the gear teeth.
1. Zero the gage.
2. Lift up on the gear to measure the clearance.
42. If clearance is higher than the specification, inspect to ensure the 4th gear thrust washer is installed completely.
43. If clearance is higher than the specification, inspect the 3rd speed gear, the 4th gear thrust washer, or 2nd/3rd synchronizer hub for wear.
44. If clearance is lower than the specification, inspect the 3rd speed gear, the 4th gear thrust washer, or 2nd/3rd synchronizer hub for burrs.
45. Repair or replace the damaged or worn component.





46. Caution: Refer to Proper Handling of Preheated Components Caution in Service Precautions.

Wearing protective gloves, install the preheated 4th speed gear bushing on the mainshaft.
47. Use the J 44735 and a hydraulic press to fully seat the bushing.





48. Allow the 4th speed gear bushing to cool.
49. Install the 4th speed gear bearing.
50. Lightly lubricate the bearing with GM P/N 12378515 (Canadian P/N 88900701).





51. Install the 4th speed gear on the mainshaft.
52. Install the 4th speed gear synchronizer ring.
53. Lightly lubricate the synchronizer components with GM P/N 12378515 (Canadian P/N 88900701).





54. Caution: Refer to Proper Handling of Preheated Components Caution in Service Precautions.

Wearing protective gloves, install the preheated 4th/5th synchronizer hub on the mainshaft.
^ Install the hub with the part number facing up.
^ Align the tabs on the synchronizer ring with the slots in the hub.





55. Use the J 44735 and a hydraulic press to fully seat the synchronizer hub.





56. Install the retaining ring for the 4th/5th gear synchronizer hub.
^ The retaining rings are different thicknesses.
^ Select a retaining ring that fills the groove.
^ Ensure the retaining ring is fully seated.





57. Using the J 26900-12 or the J 29763 with the J 26900-13, measure the 4th gear axial clearance. Clearance should be 0.15 - 0.35 mm (0.0059 - 0.0138 inch).
0. Position the J 26900-12 or the J 29763 on the top of the gear teeth.
1. Zero the gage.
2. Lift up on the gear to measure the clearance.
58. If clearance is higher than the specification, inspect to ensure the 4th/5th gear synchronizer hub is installed completely.
59. If clearance is higher than the specification, inspect the 4th speed gear, the 4th gear thrust washer, or 4th/5th synchronizer hub for wear.
60. If clearance is lower than the specification, inspect the 4th speed gear, the 4th gear thrust washer, or 4th/5th synchronizer hub for burrs.
61. Repair or replace the damaged or worn component.





62. Caution: Refer to Proper Handling of Preheated Components Caution in Service Precautions.

Wearing protective gloves, install the preheated mainshaft front bearing on the mainshaft using the J 44734 and hydraulic press.
^ Turn the J 44734 over to use it to press on the bearing.
^ Do not use a hammer on the J 44734. Damaging the J 44734 may prevent further use of the tool for transmission assembly.





63. Install the 4th/5th speed gear synchronizer sleeve. Align the sleeve with the part number facing up.





64. Install the 4th/5th speed gear detent springs, and pressure pieces in the synchronizer hub.The 4th/5th synchronizer springs are 22.7 mm (0.893 inch) long.
0. Install all 3 springs and pressure pieces.

Important: In order to prevent the springs and balls from jumping out of position, install the 5th gear synchronizer blocking ring. Move the sleeve to lock the sleeve in position.

1. Install the 5th gear synchronizer ring to hold the pressure pieces and the sleeve in position.
2. Pull up on the sleeve to lock the pressure pieces in the neutral position.





65. Fill the input shaft front mainshaft bearing race with J 36850 or equivalent.
66. Install the input shaft.
67. Move the 4th/5th synchronizer sleeve to the 5th gear position. Locking the mainshaft to the input shaft prevents the synchronizer from falling apart.