GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 22912-O1 Split Plate
    • J 34846 Countershaft Bearing Installer
    • J 35664 Press Tube and Bearing Installer
    • J 39497 Friction Ring Remover and Installer
    • J 36850 Transjel® Transmission Assembly Lubricant

Removal Procedure


    Object Number: 422442  Size: SH

    Notice: Observe the hydraulic pressure gage during countershaft disassembly. Pressure on the countershaft or its components should not exceed 4990 kg (11,000 lb). If pressure higher than specified is needed for countershaft disassembly, the countershaft may be misaligned in the press support. Reset the press and press support before resuming countershaft disassembly or damage to the countershaft and its components may occur.

  1. Use the J 22912-O1 and a press arbor in order to remove the left countershaft bearing (1) .

  2. Object Number: 422451  Size: SH
  3. Use the press arbor in order to remove the countershaft fourth gear (1) from the countershaft.

  4. Object Number: 155656  Size: SH
  5. Use the J 22912-O1 and a press arbor in order to remove the third and fourth gear spacer with the countershaft third gear and countershaft second gear from the countershaft.
  6. Remove the second gear synchronizer ring from the countershaft.

  7. Object Number: 155657  Size: SH
  8. Remove the low speed synchronizer snap ring from the countershaft.

  9. Object Number: 155658  Size: SH
  10. Use the J 22912-O1 and a press arbor in order to remove the low speed sleeve and hub together with the first gear synchronizer ring and countershaft first gear from the countershaft.
  11. Remove the low speed sleeve from the low speed hub.
  12. Remove the low speed synchronizer spring from the low speed hub.

  13. Object Number: 422456  Size: SH
  14. Remove the first and second gear bearing (2) from the countershaft (1) .

  15. Object Number: 155659  Size: SH
  16. Use the J 22912-O1 , a press arbor extension and a press arbor in order to remove the right countershaft bearing from the countershaft.
  17. Important: Do not spin dry the bearings. Damage to the bearings may result.

  18. Clean all of the components thoroughly with clean solvent. Dry the components.
  19. Inspect the countershaft for the following conditions. Replace as necessary:
  20. • Flat spots
    • Excessive wear
    • Damage

    Object Number: 155660  Size: SH
  21. Inspect the countershaft oil passages for obstructions:
  22. 13.1. Apply compressed air into the end of the countershaft.
    13.2. If the air does not flow freely out of the countershaft oil passages, replace the countershaft.
  23. Inspect all of the bearings for the following conditions. Replace as necessary:
  24. • Roughness
    • Locking
    • Damage
  25. Inspect all of the gears for the following conditions. Replace as necessary:
  26. • Cracks
    • Chipped teeth
    • Broken teeth
    • Other damage
  27. Inspect all of the synchronizer components for the following conditions. Replace as necessary:
  28. • Chipped teeth
    • Broken teeth
    • Excessive wear
    • Damage

    Object Number: 155661  Size: SH
  29. Use a feeler gage in order to measure the clearance between the first gear synchronizer ring and the countershaft first gear.
  30. Standard clearance is 1.0 to 1.4 mm (0.039 to 0.055 in).

    If the clearance is below 0.5 mm (0.019 in), replace the first gear synchronizer ring and the countershaft first gear.

  31. Use a feeler gage in order to measure the clearance between the second gear synchronizer ring and countershaft second gear.
  32. Standard clearance is 1.0 to 1.4 mm (0.039 to 0.055 in).

    If the clearance is below 0.5 mm (0.019 in), replace the second gear synchronizer ring and the countershaft second gear.

Installation Procedure

  1. Apply a thin coat of J 36850 to all of the parts before assembly.

  2. Object Number: 155721  Size: SH
  3. Use the J 34846 and a hammer in order to install the right countershaft bearing onto the countershaft.
  4. Install the first and second gear bearing onto the countershaft.

  5. Object Number: 155725  Size: SH
  6. Install the low speed synchronizer spring onto the low speed hub.

  7. Object Number: 155729  Size: SH
  8. Install the low speed sleeve onto the low speed hub.

  9. Object Number: 155732  Size: SH

    Important: The key slot width of the first gear synchronizer ring is smaller than that of the second gear synchronizer ring. The difference in the key slot width must be distinguished for correct countershaft assembly. If these synchronizer rings are transposed during countershaft assembly, shift failure may occur.

  10. Identify the first gear synchronizer ring.

  11. Object Number: 155734  Size: SH
  12. Support the countershaft with the J 34846 .
  13. Use the J 35664 and a press arbor in order to install the following components onto the countershaft:
  14. • The countershaft first gear
    • The first gear synchronizer ring
    • The low speed sleeve and hub
  15. Inspect the countershaft first gear for smooth rotation.
  16. If the countershaft first gear does not rotate smoothly, remove the gear and reinstall it until smooth rotation occurs.


    Object Number: 155773  Size: SH
  17. Install the low speed synchronizer snap ring onto the countershaft.
  18. Important: Install the countershaft second gear and countershaft third gear first, then install the third and fourth gear spacer separately.

    This will prevent undue stress on the countershaft.

  19. Install the second gear synchronizer ring onto the countershaft.

  20. Object Number: 155790  Size: SH
  21. Support the countershaft with the J 34846 .
  22. Use the J 39497 with a press arbor in order to install the following components onto the countershaft:

    • The countershaft second gear and the countershaft third gear
    • The third and fourth gear spacer

    Object Number: 155806  Size: SH
  23. Support the countershaft with the J 34846 .
  24. Use the J 39497 and a press arbor in order to install the following components onto the countershaft:

    • The countershaft fourth gear
    • The left countershaft bearing