GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Jimmy - 2WD 🢒 Transmission/Transaxle 🢒 Manual Transmission - NV 3500 🢒 Main Shaft Assemble

Mainshaft Assembly

Tools Required

    • Hydraulic Press
    • J 36183 Input Shaft Press Tube with Cap
    • J 36184 Adapter Press Tube Reducer
    • J 39924-1 Reverse Drag Seal Installer
    • J 39924-2 5th Speed Gear Drag Seal Installer

    Important: Some components require an assembly lubricant. Use TRANSJEL or equivalent.


    Object Number: 4736 Size: SH
  1. Install the 5th speed gear drag seal. Use J 39924-2 and J 36183 .

    2. Object Number: 4737 Size: SH
  2. Install the reverse speed gear drag seal. Use J 39924-1 .

    3. Object Number: 4735 Size: SH
  3. Install the following components:
    4. 3.1. The reverse speed gear needle bearing assembly
    3.2. The reverse speed gear

    Object Number: 4738 Size: SH
  4. Install the 5th/Reverse speed gear synchronizer.
    5. 4.1. Check the scribe marks for correct positions.
    4.2. Position the spiral lock ring towards the reverse speed gear.
    4.3. Manually align and engage the splines.
    4.4. Use J 36183 and J 36184 .
    4.5. Press the synchronizer until seated.
    4.6. Remove all the metal shavings.

    Object Number: 7906 Size: SH
  5. Install a new mainshaft snap ring.

    6. Object Number: 4739 Size: SH
  6. Install the following components:
    7. 6.1. The 5th speed gear needle bearing assembly
    6.2. The synchronizer ring
    6.3. The 5th speed gear

    Object Number: 4811 Size: SH
  7. Install the 1st speed gear needle bearing assembly

    8. Important: The groove on the outside of the synchronizer sleeve must go towards the 2nd speed gear. This prevents gear clash during 1st and 2nd speed gear shifts. The teeth of the sleeve have different angles.


    Object Number: 4740 Size: SH
  8. Install the following components:
    9. 8.1. The 1st speed gear
    8.2. The synchronizer interim ring with the teeth up
    8.3. The reactor cone with the flat side towards 1st gear
    8.4. The blocker ring with the teeth down
    8.5. The synchronizer cone with the flat side down

    Object Number: 4810 Size: SH
  9. Check the 1st/2nd speed gear synchronizer assembly scribe marks for correct positions.

    10. Object Number: 4741 Size: SH
  10. Install the 1st/2nd speed gear synchronizer assembly with both synchronizer rings.
    11. 10.1. Manually align and engage the splines.
    10.2. Use J 36183 , J 36184 and a hydraulic press.
    10.3. Start the press operation.
             10.3.1. Stop pressing before the tangs engage.
             10.3.2. Lift and rotate the gear.
             10.3.3. Engage the synchronizer ring.
    10.4. Press the synchronizer until seated.
    10.5. Remove all the metal shavings.

    Object Number: 4815 Size: SH
  11. Install the following components:
    12. 11.1. The synchronizer cone with the flat up
    11.2. The blocker ring with the tangs up
    11.3. The reaction cone with the wide flat portion up
    11.4. The interim ring

    Object Number: 7907 Size: SH
  12. Install a new mainshaft snap ring.

    13. Object Number: 4743 Size: SH
  13. Install the following components:
    14. 13.1. The 2nd speed gear needle bearing assembly
    13.2. The 2nd speed gear

    Ensure that the bearing cage is together. Ensure that the synchronizer ring gear teeth are toward 1st gear.


    Object Number: 4812 Size: SH
  14. Install the following components:
    15. 14.1. The 2nd speed gear 2-piece thrust washer

    Ensure that the dots are facing up.

    14.2. The retainer ring

    Ensure that the retainer ring is installed around the washer.


    Object Number: 4745 Size: SH
  15. Install the following components:
    16. 15.1. The 3rd speed gear needle bearing assembly
    15.2. The 3rd speed gear
    15.3. The synchronizer ring

    Object Number: 4810 Size: SH
  16. Check the 3rd/4th speed gear synchronizer assembly scribe marks for correct positions.

    17. Object Number: 4746 Size: SH
  17. Install the 3rd/4th speed gear synchronizer assembly with both synchronizer rings. Ensure that the groove in the synchronizer ring faces upward.
    18. 17.1. Manually align and engage the splines.
    17.2. Use J 36183 , J 36184 , and a hydraulic press.
    17.3. Start the press operation
             17.3.1. Stop pressing before the tangs engage.
             17.3.2. Lift and rotate the gear.
             17.3.3. Engage the synchronizer ring.
    17.4. Press the synchronizer until seated.
    17.5. Remove all the metal shavings.

    Object Number: 4808 Size: SH
  18. Install a new mainshaft snap ring.