GM Service Manual Online
For 1990-2009 cars only

Shift Shaft Assemblies and Gear Clusters Installation

Refer to the following transmission component locator graphics as needed:

Transmission Case (1 of 2)


Object Number: 38213  Size: LF
(1)Vent
(2)Vent Pipe
(3)Transmission Case
(4)Countershaft Washer
(5)Mainshaft 6TH Gear
(6)6TH Gear Needle Bearing
(7)6TH Gear Synchronizer Blocking Ring
(8)Mainshaft Gear Bearing Spacer
(9)Synchronizer Retainer Ring
(10)Reverse Shift Fork Retainer Ring
(11)Reverse Shift Fork
(12)Reverse Shift Fork Pad
(13)Guide Plate
(14)Guide Plate Bolt
(15)9.525 mm (0.375 in) steel ball
(16)Shift Detent Ball Spring
(17)5TH Driven Gear
(18)Reverse Synchronizer Hub and Sleeve
(19)Reverse Gear Thrust Washer
(20)Reverse Synchronizer Retainer Ring
(21)Reverse Synchronizer Blocking Ring
(22)Reverse Synchronizer Spring
(23)Reverse Synchronizer Sleeve
(24)Reverse Synchronizer Hub
(25)Reverse Synchronizer Key
(26)Reverse Synchronizer Spring
(27)Reverse Synchronizer Key Retainer
(28)1ST 2ND Shift Fork Roll Pin
(29)Front Offset Shift Lever
(30)Top Shift Shaft Bushing
.

Adapter Plate and Gears


Object Number: 38214  Size: LF
(1)3RD/4TH Synchronizer Spring
(2)3RD/4TH Synchronizer Sleeve
(3)3RD 4TH Synchronizer Hub
(4)3RD/4TH Synchronizer Insert
(5)3RD/4TH Synchronizer Spring
(6)Top Shaft Rail Bushing
(7)Dowel Pin
(8)3RD Speed Drive Gear
(9)3RD Speed Drive Gear Synchronizer Blocking Ring
(10)3RD/4TH Synchronizer Assembly
(11)Synchronizer Retainer Ring
(12)4TH Speed Drive Gear Synchronizer Blocking Ring
(13)Input Shaft Bearing Race
(14)Input Shaft
(15)Input Shaft Bearing
(16)Input Shaft Bearing Race
(17)Input Shaft Bearing Shim
(18)Input Shaft Seal
(19)Front Adapter Plate
(20)Adapter Plate to Clutch Housing Pin
(21)Adapter to Transmission Case Bolt
(22)Adapter Plate Inspection Plug
(23)2ND Speed Drive Gear Friction Cone
(24)2ND Speed Drive Gear Inner Cone
(25)2ND Speed Drive Gear Thrust Washer
(26)2ND Speed Drive Gear
(27)2ND Speed Drive Gear Needle Bearing
(28)Mainshaft
(29)Mainshaft Small Tapered Bearing
(30)3RD Speed Drive Gear Needle Bearing
(31)3RD Speed Drive Gear Bearing Spacer
(32)Countershaft Rear Bearing
(33)Countershaft
(34)Countershaft Front Bearing
(35)Countershaft Bearing Race
(36)Counter Shaft Bearing Adjust Shim
.

Extension Housing (1 of 2)


Object Number: 38215  Size: LF
(1)Control Lever Boot
(2)Snap Ring
(3)Reverse Lockout
(4)Reverse Lockout Outer Spring
(5)Reverse Lockout Seat
(6)Slap Ring
(7)Reverse Lockout Inner Spring
(8)Reverse Lockout Body
(9)Reverse Lockout Solenoid Mounting Bolt
(10)Reverse Lockout Solenoid
(11)Speed sensor Bolt
(12)Transmission Extension
(13)Speed Sensor
(14)Bumper
(15)Reverse Lockout Assembly
(16)Reverse Lockout O-Ring Seal
(17)Bushing
(18)Offset Shift Lever
(19)Offset Shift Lever Pin
(20)Isolator Cup
(21)Shift Control Bolt
(22)Shift Control
(23)Shift Control Bolt
.

Shift Shaft and Clutch Housing


Object Number: 38216  Size: LF
(1)Clutch Actuator Cylinder Bracket
(2)Clutch Actuator Stud
(3)Clutch Release Fork
(4)Clutch Lever Nut
(5)Clutch Lever Bolt
(6)Clutch Housing
(7)Bolt
(8)Offset Shift Lever
(9)Reverse Shift Lever Pin
(10)5TH 6TH Shift Lever Pad
(11)5TH 6TH Shift Shaft Lever Bushing
(12)5TH 6TH Shift Lever
(13)5TH 6TH Reverse Shift Shaft
(14)Collar
(15)Reverse Shift Collar Pin
(16)5TH 6TH Shift Lever Assembly
(17)1ST 2ND Shift Shaft Assembly
(18)3RD 4TH Shift Fork Pad
(19)3RD 4TH Shift Fork
(20)Gear Select Interlock Plate
(21)Control Select Arm Pin
(22)1ST 2ND Shift Fork Pin
(23)Skip Shift Lever
(24)Roll Pin
(25)Shift Interlock Plate
(26)Interlock Shift Plate
(27)1ST 2ND Shift Fork Pad
(28)1ST 2ND Shift Fork
(29)Shift Shaft
.

Tools Required

J 36850 Transjel® Transmission Assembly Lube

  1. Lubricate all components as assembly progresses. Use J 36850 or the equivalent.

  2. Object Number: 38399  Size: SH
  3. Install the selective shims. Refer to the Input Shaft, Mainshaft, and Countershaft in Shimming Procedures .

  4. Object Number: 38402  Size: SH
  5. Install the following parts:
  6. • The input shaft bearing race
    • The countershaft bearing race

    Object Number: 38318  Size: SH
  7. Install the following parts:
  8. 4.1. The input shaft
    4.2. The 4TH speed gear blocking ring

    Object Number: 38612  Size: SH
  9. Assemble the shift shaft to the mainshaft.
  10. Install the mainshaft and the shift shaft assembly.


    Object Number: 38611  Size: SH
  11. Install the countershaft assembly using the following sequence:
  12. 6.1. Lift up the mainshaft assembly enough in order to install the countershaft assembly.
    6.2. Install the countershaft assembly.
    6.3. Lift the mainshaft assembly enough in order to rotate the input shaft to engage the synchronizer keys with 4TH gear blocking ring.

    Object Number: 38610  Size: SH
  13. Install the 5TH/6TH and the reverse shift shaft.
  14. Align the slots of the shift shaft levers with the interlock plate.

Transmission Case Installation

Tools Required

J 36850 Transjel® Transmission Assembly Lube

  1. Lubricate all components as the assembly progresses. Use J 36850 or the equivalent.

  2. Object Number: 38403  Size: SH
  3. Apply sealant at the transmission case to adapter plate mating surface. Use GM P/N 12345739 or the equivalent.

  4. Object Number: 38404  Size: SH
  5. Install the ball detent and the spring in the front offset lever.

  6. Object Number: 38607  Size: SH
  7. Do the following in order to install the transmission case and the front offset lever:
  8. 4.1. Shift the transmission into NEUTRAL in order to keep the 3RD/4TH shift shaft from engaging.
    4.2. Compress the front offset lever together while sliding it onto the shift shaft. This will prevent the spring release of the inner components.
    4.3. Slide the transmission case onto the gear clusters and the shift rail components.

    Object Number: 38712  Size: SH
  9. Apply anaerobic threadlocker to the threads of the shift lever guide bolts. Use GM P/N 12345382 or the equivalent.

  10. Object Number: 38406  Size: SH
  11. Pull up on 5th/6th and reverse shift rail assembly. This will help align the slot of the shift interlock plate with the guide bolt hole.
  12. Install the shift lever guide bolts.
  13. Tighten
    Tighten the bolts to 27 N·m (20 Ib ft).

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


    Object Number: 38426  Size: SH
  14. Install the adapter plate to transmission case bolts.
  15. Tighten
    Tighten the bolts to 35 N·m (26 Ib ft).


    Object Number: 38251  Size: SH
  16. Install the front offset lever roll pin.
  17. Install the roll pin (182). Refer to

    Shift Shaft and Clutch Housing


    Object Number: 38216  Size: LF
    (1)Clutch Actuator Cylinder Bracket
    (2)Clutch Actuator Stud
    (3)Clutch Release Fork
    (4)Clutch Lever Nut
    (5)Clutch Lever Bolt
    (6)Clutch Housing
    (7)Bolt
    (8)Offset Shift Lever
    (9)Reverse Shift Lever Pin
    (10)5TH 6TH Shift Lever Pad
    (11)5TH 6TH Shift Shaft Lever Bushing
    (12)5TH 6TH Shift Lever
    (13)5TH 6TH Reverse Shift Shaft
    (14)Collar
    (15)Reverse Shift Collar Pin
    (16)5TH 6TH Shift Lever Assembly
    (17)1ST 2ND Shift Shaft Assembly
    (18)3RD 4TH Shift Fork Pad
    (19)3RD 4TH Shift Fork
    (20)Gear Select Interlock Plate
    (21)Control Select Arm Pin
    (22)1ST 2ND Shift Fork Pin
    (23)Skip Shift Lever
    (24)Roll Pin
    (25)Shift Interlock Plate
    (26)Interlock Shift Plate
    (27)1ST 2ND Shift Fork Pad
    (28)1ST 2ND Shift Fork
    (29)Shift Shaft
    .

  18. Object Number: 38409  Size: SH
  19. Apply anaerobic threadlocker to the threads of the shift detent assembly. Use GM P/N 12345382 or the equivalent.

  20. Object Number: 38249  Size: SH
  21. Install the shift detent assembly.
  22. Tighten
    Tighten the detent assembly to 40 N·m (30 Ib ft).


    Object Number: 38411  Size: SH
  23. Apply sealant to the mating surface of the cover plate. Use GM P/N 12345739 or the equivalent.

  24. Object Number: 38248  Size: SH
  25. Install the cover plate and the cover plate bolts.
  26. Tighten
    Tighten the bolts to 20 N·m (15 Ib ft).


    Object Number: 33363  Size: SH
  27. Install the computer aided gear select solenoid.
  28. Tighten
    Tighten the solenoid to 40 N·m (30 Ib ft).

Countershaft Extension Installation


    Object Number: 38247  Size: SH
  1. Position the transmission in the horizontal position.
  2. Install the countershaft extension assembly and the 5th/6th shift fork. The splines of the countershaft extension must engage the splines of the countershaft.

  3. Object Number: 38246  Size: SH
  4. Install the 5th/6th shift fork retainer ring.

5th/6th Speed Driven Gear Installation

Tools Required

J 39441 Gear Installer


Object Number: 38433  Size: SH

Install the 5TH/6TH speed driven gear using the J 39441 . The smaller OD of the gear faces down.

Reverse Shift Fork Installation


    Object Number: 38242  Size: SH
  1. Install the reverse shift fork, the synchronizer and the thrust washer.

  2. Object Number: 38241  Size: SH
  3. Install a new shift fork retainer ring.

  4. Object Number: 38239  Size: SH
  5. Install the reverse synchronizer retainer ring.

Reverse Speed Gear Installation


    Object Number: 38238  Size: SH
  1. Install the following parts in order:
  2. 1.1. The blocking ring
    1.2. The wave washer
    1.3. The wave washer so the concave side faces the blocking ring
    1.4. The caged needle bearing
    1.5. The reverse speed gear
    1.6. The thrust washer
    1.7. The retainer ring

    Object Number: 38233  Size: SH
  3. Install the following parts in order:
  4. 2.1. The spacer
    2.2. The roller bearing
    2.3. The spacer
    2.4. The roller bearing retainer ring

Speedometer Sensor Gear Installation

Tools Required

J 39441 Gear Installer


    Object Number: 38231  Size: SH
  1. Install the speedometer gear retainer ring.

  2. Object Number: 38414  Size: SH
  3. Install the speedometer gear. Use the J 39441 .

  4. Object Number: 38235  Size: SH
  5. Install the speedometer retaining ring.

  6. Object Number: 38227  Size: SH
  7. Install the sealing ring.

Extension Housing Installation


    Object Number: 38379  Size: SH
  1. Install the following parts:
  2. 1.1. The funnel
    1.2. The selective shims. Refer to the Countershaft Extension in Shimming Procedures .
    1.3. The countershaft extension bearing race

    Object Number: 38378  Size: SH
  3. Install the following parts:
  4. 2.1. The reverse idler shaft
    2.2. The thrust washer
    2.3. The roller bearing
    2.4. The reverse idler gear
    2.5. The reverse idler gear thrust washer

    Object Number: 38712  Size: SH
  5. Apply thread sealer to the reverse idler shaft brackets bolt threads. Use GM P/N 12345382 or the equivalent.

  6. Object Number: 38375  Size: SH
  7. Install the following parts:
  8. 4.1. The reverse idler shaft bracket
    4.2. The reverse idler shaft bracket bolts

    Tighten
    Tighten the bolts to 25 N·m (18 Ib ft).

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


    Object Number: 38416  Size: SH
  9. Apply sealant at extension housing to the transmission case mating surface. Use GM P/N 12345739 or the equivalent.

  10. Object Number: 38712  Size: SH
  11. Apply thread sealer to the extension housing bolt threads. Use GM P/N 12346004 or the equivalent.

  12. Object Number: 38225  Size: SH
  13. Install the extension housing. Align the 5TH/6TH and reverse shift shaft with the extension housing bore.
  14. Install the extension housing bolts and the transmission bumper.
  15. Tighten
    Tighten the bolts to 35 N·m (26 lb ft).


    Object Number: 38224  Size: SH
  16. Install the rear offset shift lever and the isolator cup.

  17. Object Number: 38223  Size: SH
  18. Install the rear offset shift lever roll pin.

Shifter Installation


    Object Number: 38417  Size: SH
  1. Apply sealant at extension housing to the shifter mating surface. Use GM P/N 12345739 or the equivalent.

  2. Object Number: 38222  Size: SH
  3. Install the shifter and the shifter bolts.
  4. Tighten
    Tighten the shifter bolts to 20 N·m (15 Ib ft).

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  5. Remove the transmission from the support fixture.

  6. Object Number: 38712  Size: SH
  7. Apply sealant to the threads of the clutch fork pivot lever bolt. Use GM P/N 12345382 or the equivalent.

  8. Object Number: 38221  Size: SH
  9. Install the following parts:
  10. 5.1. The clutch fork pivot lever
    5.2. The clutch fork pivot lever nut
    5.3. The clutch fork bolt. Apply thread sealer to the clutch fork bolt. Use GM P/N 12345382.

    Tighten
    Tighten the bolt to 25 N·m (18 Ib ft).


    Object Number: 38218  Size: SH
  11. Install the clutch housing and the clutch housing bolts.
  12. Tighten
    Tighten the bolts to 35 N·m (26 Ib ft).


    Object Number: 38219  Size: SH
  13. Install the vent tube.

Shift Shaft Assemblies and Gear Clusters Installation

Tools Required

J 36850 Transjel® Lubricant Assembly Lube

  1. Lubricate all components as assembly progresses, using J 36850 .

  2. Object Number: 388448  Size: SH
  3. Install the input shaft in the adapter plate.

  4. Object Number: 388446  Size: SH
  5. Assemble the shift shaft to the mainshaft.
  6. Install the neutral return roll pin to the shift shaft.
  7. Install the mainshaft and the shift shaft assembly into the adapter plate.

  8. Object Number: 388442  Size: SH
  9. Install the countershaft assembly using the following sequence:
  10. 6.1. Lift up the mainshaft assembly enough in order to install the countershaft assembly.
    6.2. Install the countershaft assembly.
    6.3. Lift the mainshaft assembly enough in order to rotate the input shaft to engage the synchronizer keys with 4th gear blocking ring.

    Object Number: 388439  Size: SH
  11. Install the 5th/6th and the reverse shift shaft.
  12. Align the slots of the shift shaft levers with the interlock plate.

Reverse Lockout Assembly Assemble


    Object Number: 350562  Size: SH

    Caution: The reverse lockout assembly is under spring pressure. Exercise caution when removing the retainer ring, as bodily injury may result.

  1. Install the reverse lockout plunger (6).
  2. Install the reverse lockout outer spring (5).
  3. Install the reverse lockout collar (4).
  4. Compress the reverse lockout plunger and the collar (4) in a vise and Install the retainer ring (3).
  5. Install the reverse lockout inner spring (2).
  6. Install the reverse lockout components in the body (1).
  7. Install the retainer ring (7).
  8. Install the O-ring to body (8).

Transmission Case Installation

Tools Required

    • J 41099 Skip Shift Sensor Remover/Installer
    • J 36850 Transjel® Lubricant

    Object Number: 38403  Size: SH

    Important: Lubricate all components as the assembly progresses. Use J 36850 or the equivalent.

  1. Apply sealant GM P/N United States 12345739, GM P/N Canada 10953472 or equivalent to the transmission case to adapter plate mating surface.

  2. Object Number: 350591  Size: SH
  3. Install the ball detent and the spring in the front offset lever.

  4. Object Number: 388438  Size: SH
  5. Do the following in order to install the transmission case and the offset lever:
  6. 3.1. Shift the transmission into NEUTRAL in order to keep the 3rd/4th shift shaft from engaging.
    3.2. Install the offset lever.
    3.3. Compress the front offset lever together while sliding it onto the shift shaft. This will prevent the spring release of the inner components.
    3.4. Slide the transmission case onto the gear clusters and the shift rail components.

    Object Number: 350592  Size: SH
  7. Apply threadlock GM P/N United States 12346004, GM P/N Canada 10953480 or equivalent to the threads of the shift lever guide bolts.

  8. Object Number: 105691  Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  9. Install the shift lever guide bolts and pull up on 5th/6th and reverse shift rail assembly. This will help align the slot of the shift interlock plate with the guide bolt hole.
  10. Tighten
    Tighten the bolts to 27 N·m (20 Ib ft).


    Object Number: 105692  Size: SH
  11. Install the adapter plate to transmission case bolts.
  12. Tighten
    Tighten the bolts to 48 N·m (36 Ib ft).


    Object Number: 350556  Size: SH
  13. Install the magnets into the transmission case.

  14. Object Number: 350558  Size: SH
  15. Install the offset lever roll pin.

  16. Object Number: 388460  Size: SH
  17. Install the shift detent assembly.
  18. Tighten
    Tighten the detent assembly to 40 N·m (30 Ib ft).


    Object Number: 38411  Size: SH
  19. Apply sealant GM P/N United States 12345739, GM P/N Canada 10953472 or the equivalent to the mating surface of the cover plate.

  20. Object Number: 105689  Size: SH
  21. Install the transmission case cover and the case cover bolts.
  22. Tighten
    Tighten the bolts to 20 N·m (15 Ib ft).


    Object Number: 388457  Size: SH
  23. Install the reverse lockout body and bolt in the cover plate.
  24. Tighten
    Tighten the bolts to 18 N·m (13 Ib ft).


    Object Number: 71530  Size: SH
  25. Install the reverse lockout solenoid to reverse lockout body assembly, using the J 41099 .
  26. Tighten
    Tighten the solenoid to 40 N·m (30 Ib ft).


    Object Number: 350553  Size: SH
  27. Install the computer aided gear select solenoid.
  28. Tighten
    Tighten the solenoid to 40 N·m (30 Ib ft).

Countershaft Extension Installation


    Object Number: 388437  Size: SH
  1. Position the transmission in the horizontal position.
  2. Install the countershaft extension assembly and the 5th/6th shift fork. The splines of the countershaft extension must engage the splines of the countershaft.

  3. Object Number: 388434  Size: SH
  4. Install the 5th/6th shift fork retainer ring.

5th/6th Speed Driven Gear Installation

Tools Required

    • J 39441 5th/6th Driven Gear Installer
    • J 39441-10 5th Gear Installer Adapter

Object Number: 389848  Size: SH

Install the 5th/6th speed driven gear using the J 39441 and J 39441-10 . The smaller outside diameter (OD) of the gear faces down.

Reverse Shift Fork Installation


    Object Number: 388432  Size: SH
  1. Install the reverse shift fork, the synchronizer and the thrust washer.

  2. Object Number: 388431  Size: SH
  3. Install a new shift fork retainer ring.

  4. Object Number: 388430  Size: SH
  5. Install the reverse synchronizer retainer ring.

Reverse Speed Gear Installation


    Object Number: 38238  Size: SH
  1. Install the following parts in order:
  2. 1.1. The blocking ring
    1.2. The wave washer
    1.3. The wave washer so the concave side faces the blocking ring
    1.4. The caged needle bearing
    1.5. The reverse speed gear
    1.6. The thrust washer
    1.7. The retainer ring

    Object Number: 38233  Size: SH
  3. Install the following parts in order:
  4. 2.1. The spacer
    2.2. The roller bearing
    2.3. The spacer
    2.4. The roller bearing retainer ring

Extension Housing Assemble

Tools Required

J 44395 Transmission Support Fixture


    Object Number: 38379  Size: SH
  1. Install the following parts in order:
  2. 1.1. The funnel
    1.2. The selective shims. Refer to the Countershaft Extension in Shimming Procedures.
    1.3. The countershaft extension bearing race

    Object Number: 105688  Size: SH
  3. Install the following parts in order:
  4. 2.1. The reverse idler shaft
    2.2. The roller bearing
    2.3. The reverse idler gear

    Object Number: 38712  Size: SH
  5. Apply Loctite® 272 GM P/N 12345382 or the equivalent to the reverse idler shaft brackets bolt threads.

  6. Object Number: 38375  Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  7. Install the following parts in order:
  8. 4.1. The reverse idler shaft bracket.
    4.2. The reverse idler shaft bracket bolts.

    Tighten
    Tighten the bolts to 25 N·m (18 Ib ft).


    Object Number: 38416  Size: SH
  9. Apply sealant GM P/N 12345739 or equivalent to the extension housing to the transmission case mating surface.

  10. Object Number: 38712  Size: SH
  11. Apply thread sealer GM P/N 12346004 or equivalent to the top two extension housing bolts.

  12. Object Number: 74203  Size: SH

    Important: Align the 5th/6th shift shaft to the extension housing bore in order to install the extension housing.

  13. Install the extension housing.
  14. Install the extension housing bolts.
  15. Tighten
    Tighten the bolts to 48 N·m (36 lb ft).

  16. Install the vent tube.

  17. Object Number: 74206  Size: SH
  18. Remove the J 44395 .

  19. Object Number: 639703  Size: SH
  20. Install the remaining two adapter plate bolts (1) and (2).
  21. Tighten
    Tighten the adapter plate bolts to 48 N·m (36 lb ft).