For 1990-2009 cars

#### Tools Required

• | J 8092 Universal Driver

• | J 8614-01 Flange and Pulley Holding Tool

• | J 21465-13 Drive Handle Extension

• | J 25070 Heat Gun - 500-750 F

• | J 26900-12 Dial Indicator

• | J 29763 Static Timing Gage

• | J 36850 Transjel Lubricant

• | J 44725 Gear Pack Assembly Fixture

• | J 44728 Bearing Race Remover

• | J 44731 Input Shaft Seal Installer

• | J 44732 Output Shaft Seal Installer

• | J 44733 Bearing Race Remover

• | J 44735 Installation Tube

• | J 44736 Bridge and Forcing Screw

• | J 44739 Dial Indicator Bracket

• | J 44745 Countershaft Bearing Race Installer

• | J 44746 Mainshaft/Input Shaft Bearing Race Installer

Notice: Various transmission components require heating to 150°C (300°F) for 30 minutes for proper installation. Overheating may damage the components. Under-heating the components may cause hard installation, which may damage the components.

Important:

• | Certain transmission components require preheating to 150°C (300°F). In order to preheat the components, use an electric oven. It is recommended to purchase a roaster/oven style locally. The oven should have a temperature setting thermostat.

• | Lubricate all bearings, shafts, and synchronizers with transmission fluid GM P/N 12378515 (Canadian P/N 88900701) during installation.

1. Preheat the following components for 30 minutes to 150°C (300°F) in an electric oven:

• | The 6th gear bearing bushing

• | The reverse gear bearing bushing

• | The reverse gear thrust washer

• | The mainshaft rear bearing

2. Turn the mainshaft assembly over 180 degrees so that the input shaft is on the J 44725 . Hold the input shaft to the mainshaft while turning over.
3. Position the countershaft on the J 44725 .

Roll the countershaft into place to merger the countershaft and mainshaft gears.

4. Install the spacer for the 6th speed gear synchronizer hub on the countershaft.
5. Assemble the 2nd/3rd shift fork and shift shaft and the 4th/5th shift fork and shift shaft in the interlock plate.

• | The part number end of the shift shafts goes up.

• | The part number side of the interlock plate goes down.

6. Install the 2nd/3rd shift fork and the 4th/5th shift fork in the synchronizer sleeves.
7. Install the intermediate case over the countershaft, the mainshaft, 2nd/3rd shift shaft, and the 4th/5th shift shaft.

• | Align the shift shafts straight with the shift shaft bearings.

• | Wiggle the intermediate case over the shift shafts while installing.

8. Install the shift interlock plate to the intermediate case. The part number side faces away from the intermediate case.

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 interlock plate bolts. Ensure the shoulder of the bolts do not catch on the plate.

Tighten
Tighten the interlock plate bolts to 10 N·m (88 lb in).

10. Ensure the interlock plate moves freely.
11. Install the retaining ring in the 6th speed gear synchronizer hub, if removed.
12. Install the 6th speed gear synchronizer hub on the countershaft.

• | The hub side with the retaining ring goes toward the intermediate case.

• | The hub should slide on the countershaft.

13. If not already assembled, assemble the 6th gear synchronizer assembly.

The 6th gear synchronizer springs are 22.7 mm (0.893 in) long.

13.1. | Install all three springs and the pressure pieces in the synchronizer sleeve.

13.2. | Install the 6th gear synchronizer sleeve on the hub. The part numbered side goes up.

| Important: In order to prevent the springs and pressure pieces from jumping out of position, install the 6th gear synchronizer blocking ring. Move the sleeve to lock the pressure pieces in position.

13.3. | Install the 6th gear synchronizer blocking ring. Align the tabs on the blocking ring with the slots in the hub.

13.4. | Pull up on the sleeve to lock the pressure pieces in the neutral position.

Caution: Refer to Handling Preheated Parts Caution in the Preface section.

14. Wearing protective gloves, install the preheated 6th gear bushing on the countershaft. Rotate the bushing while installing in order to seat them fully and squarely.
15. Install the 6th speed gear bearing (3).
16. Install the 6th speed gear (2).
17. Install the 6th speed gear spacer washer (1).
18. Lightly lubricate the components with GM P/N 12378515 (Canadian P/N 88900701).
19. Install the 6th speed gear retaining ring.

• | The retaining rings are different thicknesses.

• | Select a retaining ring that fills the groove.

• | Retaining ring tabs should be under the gear teeth.

• | Ensure the retaining ring is fully seated.

20. If the 1st/reverse synchronizer requires assembly, use the following procedure:

20.1. | Lightly lubricate the components with GM P/N 12378515 (Canadian P/N 88900701).

20.2. | With the oil grooves, or the part number side up, install the synchronizer hub on the 1st gear synchronizer blocking ring.

20.3. | With the synchronizer sleeve chamfer side down, install the sleeve on the hub.

20.4. | Install the synchronizer springs and pressure pieces.

20.5. | Install the reverse gear synchronizer blocking ring.

21. Install the following components on the mainshaft:

21.1. | Lightly lubricate the bearings with GM P/N 12378515 (Canadian P/N 88900701).

21.2. | The 1st gear bearings

21.3. | The 1st speed gear

21.4. | The 1st/reverse gear synchronizer assembly with the hub part numbers facing up

Caution: Refer to Handling Preheated Parts Caution in the Preface section.

22. Wearing protective gloves, install the preheated reverse speed gear bushing on the mainshaft. Rotate the bushing while installing to ensure the bushing is fully and squarely seated.
23. Install the reverse gear bearings.
24. Lightly lubricate the bearings with GM P/N 12378515 (Canadian P/N 88900701).
25. Install the reverse gear.

Caution: Refer to Handling Preheated Parts Caution in the Preface section.

26. If RWD, wearing protective gloves, install the preheated thrust washer on the mainshaft.
27. Use the J 44735 and a hammer to ensure the thrust washer is fully and squarely seated.

Caution: Refer to Handling Preheated Parts Caution in the Preface section.

Important: The mainshaft rear bearing for a 4WD vehicle is a sealed bearing.

28. Wearing protective gloves, install the preheated mainshaft rear bearing on the mainshaft. Rotate the bearing while installing to ensure the bearing is fully and squarely seated.
29. If 4WD, install the retaining ring for the mainshaft rear bearing. Ensure the retaining ring is fully seated.
30. If RWD, install the vehicle speed sensor reluctor wheel.

The reluctor wheel should slide on the mainshaft.

31. Install the 6th gear shift fork and rail.

31.1. | The part numbered end goes up on the shift rail.

31.2. | Install the shift fork to the 6th gear synchronizer assembly.

31.3. | Move the shift interlock plate toward the 1st/reverse position if necessary.

31.4. | Tap the shift rail with a soft-face hammer into the shift fork and the intermediate case.

32. Install the 1st/reverse shift fork and rail.

32.1. | The part numbered end goes up on the shift rail.

32.2. | Install the shift fork to the 1st/reverse gear synchronizer hub.

32.3. | Move the interlock plate toward 6th gear shift rail.

32.4. | Tap the shift rail with a soft-face hammer into the shift fork and the intermediate case.

33. Install the NEW roll pins in the 6th gear shift fork (2). A roll pin goes in each hole.
34. Install the NEW roll pins in the 1st/reverse gear shift fork (1). A roll pin goes in each hole.
35. If removed, install the shift block on the main shift rail.

35.1. | The part numbers on the shift block and the part number on the shift rail face the same direction.

35.2. | Install the NEW large diameter roll pin.

35.3. | Install the NEW small diameter roll pin with the roll pin split 180 degrees from the large roll pin split.

36. Install the front internal shift lever on the main shift rail.

• | Align the roll pin, or lever end, toward the part numbered end of the shift rail.

• | Do not install the roll pins.

37. With the part numbered end pointing up, install the main shift rail.
38. Align the shift block teeth on the main shift rail with the shift interlock plate.

The center tooth on the shift block installs between the two teeth on the shift interlock plate.

39. Position the front internal shift lever to align with the notch in the 2nd/3rd shift rail.
40. Install the NEW roll pins in the internal shift control front lever.

40.1. | Install the large diameter roll pin.

40.2. | Align the split on the roll pin away from the transmission.

40.3. | Install the small diameter roll pin inside of the large diameter roll pin.

40.4. | Align the split on the roll pin toward the transmission.

41. Install the internal shift control rear lever on the main shift rail.
42. Align the levers on the internal shift control rear lever with the slots in the 1st/reverse gear shift rail and the 6th gear shift rail.
43. Install the NEW roll pins in the internal shift control rear lever.

43.1. | Install the large diameter roll pin.

43.2. | Align the split on the roll pin away from the transmission.

43.3. | Install the small diameter roll pin inside of the large diameter roll pin.

43.4. | Align the split on the roll pin toward the transmission.

44. Install the shift shaft detent plungers and springs.
45. Apply a thin layer of gasket maker GM P/N 12378517 (Canadian P/N 88900757) to the shift shaft detent caps.
46. Using an 11 mm (27/64 in) punch, install the shift shaft detent caps.
47. Shift the transmission into 5th gear in order to lock the input shaft to the mainshaft.
48. Install S-hooks and a chain to the intermediate case.
49. Position the front of the front case on boards in order to allow the protrusion of the input shaft.
50. Using a suitable lifting device, install the gear assembly to the front case.

• | Lower the gear assembly slowly in order to align the intermediate case dowel pins with the front case.

• | Do not use a sealer at this time.

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.

51. Install the two intermediate to front case bolts.

Tighten
Tighten the intermediate case bolts to 23 N·m (17 lb ft).

52. Assemble the J 44739 to the intermediate case, to measure the countershaft preload.

52.1. | Install the crosspiece so that the 2 holes are closer to the single bolt hole upright in the lowest notch. Do not tighten the thumbscrew.

52.2. | Install the crosspiece to the 2 bolt hole upright in the lowest notch. Do not tighten the thumbscrew.

52.3. | Using a case bolt, install the single bolt hole upright to the 7th case bolt hole from the top, on the right side of the case.

52.4. | Using a case bolt in the hole away from the upright, install the 2 bolt hole upright to the 5th case bolt hole from the top, on the left side of the case.

52.5. | Tighten the crosspiece thumbscrews.

53. Use the following procedure in order to measure the countershaft bearing clearance:

53.1. | Install the J 26900-12 or the J 29763 in the J 44739 .

53.2. | Adjust the J 26900-12 or the J 29763 to zero.

53.3. | Using a suitable prying tool, lift up the countershaft.

53.4. | Record the dial indicator reading. This is the countershaft bearing clearance.

54. Using the following formula, establish the shim thickness required for the countershaft bearing preload:

54.1. | Add the mainshaft preload specification 0.02-0.09 mm (0.0008-0.0035 in) to the countershaft bearing clearance measurement.

54.2. | The total is the shim thickness required under the countershaft bearing race in order to set the bearing preload.

#### Example

• | 1.8 mm (0.070 in) mainshaft bearing clearance measurement

• | Plus 0.02-0.09 mm (0.0008-0.0035 in) countershaft preload specification

• | Equals 1.82-1.89 mm (0.070-0.074 in) shim thickness required

55. Assemble the J 44739 to the intermediate case, to measure the mainshaft preload.

55.1. | Install the crosspiece so that the 2 holes are closer to the single bolt hole upright in the upper notch, for RWD, or center notch for 4WD. Do not tighten the thumbscrew.

55.2. | Install the crosspiece to the 2 bolt hole upright in the upper notch, for RWD, or center notch for 4WD. Do not tighten the thumbscrew.

55.3. | Using a case bolt, install the single bolt hole upright to the 3rd case bolt hole from the top, on the right side of the case.

55.4. | Using a case bolt in the hole closest to the upright, install the upright with the 2 bolt holes to the 6th case bolt hole from the top, on the left side of the case.

55.5. | Tighten the thumbscrews.

56. Use the following procedure in order to measure the mainshaft bearing clearance.

56.1. | Install the J 26900-12 or the J 29763 in the J 44739 .

56.2. | Adjust the J 26900-12 or the J 29763 to zero.

56.3. | Using a suitable prying tool, lift the mainshaft up.

56.4. | Record the dial indicator reading. This is the mainshaft bearing clearance measurement.

57. Using the following formula, establish the shim thickness required for the mainshaft bearing preload:

57.1. | Measure the input shaft bearing oil deflector thickness. Record this measurement.

57.2. | Subtract the oil deflector measurement from the mainshaft bearing clearance measurement.

57.3. | Add the mainshaft preload specification 0.02-0.09 mm (0.0008-0.0035 in).

57.4. | The total is the shim thickness required under the input bearing race in order to set the bearing preload.

#### Example

• | 0.50 mm (0.020 in) oil deflector thickness

• | minus 2.2 mm (0.087 in) mainshaft bearing clearance measurement

• | equals 1.7 mm (0.067 in)

• | plus 0.02-0.09 mm (0.008-0.0035 in) mainshaft preload specification

• | equals 1.75 mm (0.069 in) shim thickness required

58. Remove the 2 bolts retaining the intermediate case to the front case.
59. Using S-hooks, a chain and a suitable lifting device, remove the gear assembly.
60. Remove the mainshaft front bearing race using the J 44736 (1) and the J 44733 (2).

60.1. | Expand the J 44733 (2) to fit securely under the bearing race.

60.2. | Align the legs of the J 44733 to rest on the webbing of the case.

60.3. | Remove the mainshaft front bearing race.

61. Remove the countershaft front bearing race using the J 44736 (1) and the J 44728 (2).

61.1. | Install the J 44728 (2) in order for the fingers to fit in the notches in the case.

61.2. | Expand the J 44728 (2) to fit securely in the bearing race.

61.3. | Align the legs of the J 44736 to rest on the webbing of the case.

61.4. | Remove the countershaft front bearing race.

62. Using the J 25070 , heat the front case for 10-15 minutes.
63. Install the required shims for the countershaft bearing preload.

Important: Install the bearing races with the front case still hot. Do not allow the front case to cool.

64. Install the countershaft front bearing race using the J 8092 (1), J 21465-13 (2) and the J 44745 (3).
65. Install the oil trough.
66. Install the required shims for the mainshaft bearing preload.
67. Install the input shaft gear oil deflector.
68. Install the mainshaft front bearing race using the J 8092 (1),J 21465-13 (2) and theJ 44746 (3).
69. Allow the front case to cool.
70. Apply a thin layer of gasket maker GM P/N 12378517 (Canadian P/N 88900757) to the sealing surface of the front case.
71. Using a suitable lifting device, install the gear assembly to the front case.
72. Install the 2 intermediate case to front case bolts.

Tighten
Tighten the intermediate case bolts to 23 N·m (17 lb ft).

73. Apply a thin layer of gasket maker GM P/N 12378517 (Canadian P/N 88900757) to the sealing surface of the rear case.
74. Install the rear case on the intermediate case.
75. Using a soft-face hammer, tap down on the rear case to seat it on the dowel pins. Do not use the bolts to draw the case together.
76. Install the required brackets and the rear case bolts.

Tighten
Tighten the rear case bolts in a crossover sequence to 23 N·m (17 lb ft).

77. Apply a thin layer of threadlocker GM P/N 12345382 (Canadian P/N 10953489) to the threads of the shift shaft detent sleeve.
78. Install the shift shaft detent plunger and sleeve.

Tighten
Tighten the detent sleeve to 65 N·m (48 lb ft).

79. If RWD, install the vehicle speed sensor (VSS), with an O-ring seal, in the rear case.
80. Install the VSS bolt.

Tighten
Tighten the VSS bolt to 20 N·m (15 lb ft).

81. If RWD, install the rear oil seal using the J 44732 . The seal installer will install the seal at the correct depth.
82. Lightly lubricate the seal surface with J 36850 or equivalent.
83. If RWD, install the propeller shaft yoke.
84. Install a NEW propeller shaft yoke nut.
85. Install the J 8614-01 in order to hold the transmission shaft from rotating.

Tighten
Tighten the NEW propeller shaft yoke nut to 330 N·m (244 lb ft).

86. Install the transmission drain plug and O-ring seal. Ensure the O-ring seal is not damaged.

Tighten
Tighten the drain plug to 35 N·m (26 lb ft).

87. If the lower shift lever requires installation before installing in the vehicle, apply a thin layer of gasket maker GM P/N 12378517 (Canadian P/N 88900757) to the sealing surface of the lower shift control lever.
88. Install the lower shift control lever.
89. Install the lower shift control lever bolts.

Tighten
Tighten the lower shift control lever bolts to 23 N·m (17 lb ft).

90. Position the transmission on the transmission bottom.
91. Install the input shaft seal using the J 44731 .
92. Shift the transmission through all of the gears to ensure proper shifting.
93. Rotate the transmission by the input shaft.

There should be resistance to turn.