GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1997 🢒 Firebird 🢒 Transmission/Transaxle 🢒 Manual Transmission - M49 🢒 Main Shaft Assemble

Tools Required

    • J 25234 Front and Rear Bearing Installer
    • J 37360 Spiral Snap Ring Installer
    • J 37372 Synchronizer and Gear Installer
  1. Soak the new 1ST/2ND or 3RD/4TH speed blocking ring assemblies in transmission fluid for 10 minutes. Use Dexron® III.
  2. Coat the mainshaft and the gear bores with transmission lubricant. Use Dexron® III.

    3. Object Number: 4810 Size: SH
  3. Check the 1ST/2ND speed gear synchronizer assembly scribe marks for correct positions.

    4. Object Number: 38519 Size: SH
  4. Install the reverse sliding gear on the mainshaft hub.

    5. Important: Hard shifting will result if the synchronizer is assembled with improper spring replacement.


    Object Number: 38671 Size: SH
  5. Assemble the synchronizer as follows:
    6. 5.1. Install the synchronizer keys and the springs.
    5.2. Engage the tang end of each spring in the same synchronizer key.
    5.3. Position the open end of the springs opposite of each other.

    Object Number: 38753 Size: SH
  6. Install the following parts:
    7. 6.1. The 1ST/2ND speed synchronizer blocking ring
    6.2. The 1ST/2ND speed synchronizer outer cone
    6.3. The 1ST/2ND speed synchronizer inner cone

    Object Number: 38755 Size: SH
  7. Install the following parts:
    8. 7.1. The locating pin
    7.2. The 1ST speed gear sleeve ( Align the notch in the sleeve with the locating pin.)
    7.3. The 1ST speed gear sleeve bearing

    Object Number: 38757 Size: SH
  8. Install the 1ST speed gear. Align the slots in the 1ST speed gear with the tabs on the blocker ring assembly.

    9. Object Number: 38673 Size: SH
  9. Install the rear mainshaft bearing.

    10. Object Number: 38758 Size: SH
  10. Lubricate 5TH speed gear splines with petroleum jelly.

    11. Notice: Align the mainshaft and the gear splines before pressing the gear onto the mainshaft. Damage could occur if the splines are improperly aligned.


    Object Number: 38761 Size: SH
  11. Install the 5TH speed driven gear. Use the J 25234 and a hydraulic press.

    12. Object Number: 38763 Size: SH
  12. Install a new retainer ring.

    13. Object Number: 38518 Size: SH
  13. Install the following parts:
    14. 13.1. The 1ST-2ND speed synchronizer blocking ring
    13.2. The 1ST-2ND speed synchronizer outer cone
    13.3. The 1ST-2ND speed synchronizer inner cone
    13.4. The thrust washer

    Object Number: 38676 Size: SH
  14. Install the synchronizer spiral retainer ring. Use the J 37360 .

    15. Object Number: 38514 Size: SH
  15. Install the spacer and the needle bearing assembly.

    16. Object Number: 38747 Size: SH
  16. Install the 2ND speed gear and the thrust washer. Align the slots in the 2ND speed gear with the tabs on the blocker ring assembly.

    17. Object Number: 38504 Size: SH
  17. Install a new retainer ring.

    18. Object Number: 38503 Size: SH
  18. Install the 3RD speed gear spacer and the needle bearing assembly. Make sure the bearing spacer is not trapped between the gear face and the retainer ring. The spacer runs inside the gear bore.

    19. Object Number: 4810 Size: SH
  19. Check the 3RD/4TH speed gear synchronizer assembly scribe marks for correct positions.

    20. Object Number: 38586 Size: SH
  20. Assemble the 3RD/4TH speed synchronizer parts.

    21. Important: Hold the 3RD speed gear against the synchronizer in order to maintain the blocking ring alignment with the keys.


    Object Number: 38736 Size: SH
  21. Install the following parts as an assembly:
    22. 21.1. The 3RD speed gear
    21.2. The 3RD/4TH speed synchronizer blocking rings
    21.3. The 3RD/4TH speed synchronizer hub and sleeve assembly. Use the J 37372 and a hydraulic press.

    Object Number: 38764 Size: SH
  22. Install the main drive gear thrust bearing and the thrust bearing race.