GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 22873 Main Shaft Bushing Installer


    Object Number: 648789  Size: SH

    Important: Lightly oil all bearing and synchronizer surfaces with the recommended lubricant before assembly.

  1. Lightly oil the mainshaft bearing surfaces and the bearings for the mainshaft gears with SAE 90 Multipurpose Oil.
  2. Install the 3rd gear bearing on the mainshaft.
  3. Install the 3rd gear.

  4. Object Number: 648790  Size: SH
  5. Position the 3rd/4th gear synchronizer assembly on the mainshaft.
  6. Turn the mainshaft 180 degrees and using a hydraulic press start pressing on the 3rd/4th synchronizer assembly.

  7. Object Number: 648791  Size: SH
  8. Align the following components while pressing on the synchronizer hub:
  9. • The center synchronizer ring tabs with the holes in the third gear
    • The cam on the blocker ring with the slot in the synchronizer hub
    • The inside tab on the blocker ring with the slots in the inner ring

    Object Number: 648793  Size: SH
  10. Install the 4th gear. Ensure the synchronizer center ring tabs are aligned in the gear.
  11. Install the 4th gear bearings.

  12. Object Number: 648814  Size: SH
  13. Install the 4th gear roller bearing spacer using the J 22873  (1) and a hydraulic press. Do not damage the 4th gear bearings while pressing the roller bearing spacer.

  14. Object Number: 647381  Size: SH
  15. Install the retaining ring for the 4th gear bearing roller spacer.

  16. Object Number: 647377  Size: SH
  17. Install the 5th gear bearing.
  18. Install the 5th gear.

  19. Object Number: 648794  Size: SH
  20. Install the 5th/6th synchronizer assemble on the mainshaft. The double ridge on the synchronizer sleeve faces the 6th gear.
  21. Using a hydraulic press and the J 22873  (1) install the 5th/6th synchronizer assembly.

  22. Object Number: 647374  Size: SH
  23. Install a NEW retaining ring for the 5th/6th synchronizer hub.

  24. Object Number: 648795  Size: SH
  25. Install the 2nd gear bearing.
  26. Install the 2nd gear.

  27. Object Number: 649155  Size: SH
  28. Install the following 2nd gear synchronizer rings:
  29. 18.1. The inner ring
    18.2. The center ring aligning the tabs with the holes in the gear
    18.3. The blocker ring aligning the inside tabs with the inner ring

    Object Number: 648796  Size: SH
  30. Position the 1st/2nd synchronizer hub on the mainshaft. The retaining ring groove faces toward 1st gear.

  31. Object Number: 648800  Size: SH
  32. Using a hydraulic press install the 1st/2nd synchronizer hub.
  33. Align the following components while pressing on the synchronizer hub:
  34. • The center synchronizer ring tabs with the holes in the third gear
    • The cam on the blocker ring with the slot in the synchronizer hub
    • The inside tab on the blocker ring with the slots in the inner ring

    Object Number: 647372  Size: SH
  35. Install the retaining ring for the 1st/2nd gear synchronizer hub.

  36. Object Number: 648804  Size: SH
  37. Install the 1st/2nd synchronizer sleeve on the synchronizer hub.
  38. • Align the thick shoulder of the sleeve facing the first gear.
    • Align the sleeve stops with the flat area of the hub.

    Object Number: 648808  Size: SH
  39. Install the synchronizer blocks, the springs, and the shift block plungers.
  40. Install the retaining ring in the 1st/2nd synchronizer hub.
  41. Move the synchronizer sleeve in the neutral position in order to hold the shift block plungers in place.

  42. Object Number: 647369  Size: SH
  43. Install the 1st gear bearing.
  44. Install the 1st gear.

  45. Object Number: 647361  Size: SH
  46. Install the reverse gear hub.
  47. • The oil grooves on the hub go towards reverse gear.
    • Use a brass drift and a hammer to install the hub.
  48. Install the reverse gear shift sleeve. The oil holes in the sleeve go towards reverse gear.

  49. Object Number: 647358  Size: SH
  50. Install the reverse gear bearing race.
  51. Install the reverse gear bearing.
  52. Install the reverse gear.
  53. Install the 6th gear synchronizer ring on the front end of the mainshaft.