GM Service Manual Online
For 1990-2009 cars only

Disassembly Procedure

Tools Required

    • J 38805 Output Shaft Nut Socket (4WD only)
    • J 22912-B Split Plate Bearing Puller

Important: In order to remove the shift tower the transmission must be in neutral.


    Object Number: 178851  Size: SH
  1. Shift the transmission to neutral.
  2. Remove the bolts securing the shift tower and isolator plate to the transmission.
  3. Remove the shift tower and isolator plate.

  4. Object Number: 100518  Size: SH

    Important: Note the location of the brackets on the shift cover bolts in order to reinstall in the correct location.

  5. Remove the bolts securing the shift cover to the transmission.
  6. Using screwdrivers in the transmission case slots pry the shift cover from the transmission.

  7. Object Number: 100519  Size: SH
  8. (RWD P-models) Remove the following parts:
  9. 6.1. The mainshaft nut
    6.2. The washer
    6.3. The spline seal

    Object Number: 100520  Size: SH
  10. (RWD C-models) Remove the following parts:
  11. 7.1. The mainshaft nut
    7.2. The washer
    7.3. The yoke assembly

    Object Number: 634591  Size: SH
  12. (4WD models) Remove the transmission extension bolts.
  13. Remove the transmission extension.

  14. Object Number: 100532  Size: SH
  15. (RWD models) Remove the transmission extension bolts.
  16. Remove the transmission extension.

  17. Object Number: 634586  Size: SH
  18. (4WD models) Using the J 38805  (1), remove the mainshaft nut and washer.
  19. Discard the washer.

  20. Object Number: 100547  Size: SH
  21. Remove the overdrive gear shift fork roll pins.

  22. Object Number: 634818  Size: SH
  23. Remove the overdrive gear retainer ring.
  24. Important: For installation alignment scribe an alignment mark on the synchronizer hubs and synchronizer sleeves before removing. To prevent the synchronizer springs and struts from being lost, do not separate the synchronizer hubs from the synchronizer sleeves. Keep the synchronizer clutch gear and the blocking rings with the synchronizer hubs. Organize the components in order to install the components in their original location and position.


    Object Number: 4810  Size: SH
  25. Scribe a mark on the overdrive synchronizer hub and synchronizer hub sleeve.

  26. Object Number: 100551  Size: SH
  27. Remove the overdrive gear assembly with the shift fork from the countershaft.
  28. Remove the spacer.
  29. Remove the roller bearings.
  30. Remove the thrust washer.
  31. Remove the thrust washer pin from the countershaft.

  32. Object Number: 100553  Size: SH
  33. (RWD models) Using a suitable gear puller, remove the mainshaft overdrive gear and the vehicle speed sensor reluctor wheel from the mainshaft.

  34. Object Number: 102253  Size: SH
  35. Remove the mainshaft rear bearing retainer bolts.
  36. Remove the mainshaft rear bearing retainer.
  37. Remove the shim(s).
  38. Remove the mainshaft rear bearing cup.
  39. Move the synchronizer sleeves into the neutral position.
  40. Position the overdrive gear shift lever over to the side and hold in position with a rubber band.

  41. Object Number: 634608  Size: SH
  42. For installation alignment, mark the input shaft bearing retainer and transmission case.
  43. Remove the input shaft bearing retainer bolts.
  44. Insert a bolt in one of the threaded holes to assist in removing the retainer.
  45. Remove the input shaft retainer.

  46. Object Number: 634627  Size: SH
  47. Remove the input shaft.
  48. Remove the main drive gear bearing.

  49. Object Number: 634766  Size: SH
  50. Remove input shaft bearing cone using the J 22912-B (1) and a hydraulic press.

  51. Object Number: 100555  Size: SH
  52. Use the following procedure in order to remove the mainshaft assembly from the case:
  53. 36.1. Lift the mainshaft and move to the rear of the case.
    36.2. Tip the front of the mainshaft up and remove the mainshaft from the case.

    Object Number: 100556  Size: SH
  54. Remove the countershaft bearing retainer bolts.
  55. Remove the countershaft bearing retainer.
  56. Remove the shim(s).
  57. Remove the countershaft rear bearing cup.

  58. Object Number: 100557  Size: SH
  59. Remove the reverse idler gear and shaft:
  60. 41.1. Using a suitable punch drive the reverse idler gear shaft towards the rear of the case.
    41.2. Remove the reverse idler gear.
    41.3. Remove the thrust washers.
    41.4. Remove the bearings and spacer.

    Object Number: 100558  Size: SH
  61. Remove the countershaft rear bearing using a suitable gear puller.
  62. Removing the countershaft rear bearing will allow the countershaft to be angled for removal.


    Object Number: 100559  Size: SH
  63. Remove the countershaft from the transmission case. Slide the countershaft rearward and lift the front of the countershaft and out of the case.

  64. Object Number: 634648  Size: SH
  65. Using a punch or chisel remove the countershaft front bearing cap.
  66. Discard the removed bearing cap.
  67. Remove the countershaft front bearing cup.

  68. Object Number: 100569  Size: SH
  69. Remove the roll pin from the overdrive gear shift lever.
  70. Remove the shift lever shaft.
  71. Remove the overdrive gear shift lever.

  72. Object Number: 634666  Size: SH
  73. Remove the seal from the input shaft bearing retainer.

  74. Object Number: 100843  Size: SH
  75. (RWD only) Remove the mainshaft seal from the extension housing.

  76. Object Number: 100846  Size: SH
  77. (RWD only) Remove the mainshaft rear bearing retainer ring.
  78. Remove the rear output shaft rear bearing.
  79. Remove the speedometer drive spacer, if equipped.

  80. Object Number: 102279  Size: SH

    Important: For installation alignment scribe an alignment mark on the synchronizer hubs and synchronizer sleeves before removing. To prevent the synchronizer springs and struts from being lost, do not separate the synchronizer hubs from the synchronizer sleeves. Keep the synchronizer clutch gear and the blocking rings with the synchronizer hubs. Organize the components in order to install the components in their original location and position.

  81. Remove the 4th speed gear clutch gear.
  82. Remove the 4th speed gear synchronizer ring.
  83. Remove the main drive gear thrust bearing.

  84. Object Number: 38500  Size: SH
  85. Using a hydraulic press and the J 22912-B remove the 3rd speed gear and the synchronizer assembly. Use the J 22912-B under the gear to prevent the synchronizer hub from separating from the synchronizer sleeve.

  86. Object Number: 100573  Size: SH
  87. Remove the 3rd speed gear bearing spacer and bearing.

  88. Object Number: 100575  Size: SH
  89. Remove the 2nd speed gear thrust washer retainer ring.
  90. Remove the 2nd speed gear thrust washer.
  91. Remove the 2nd speed gear thrust washer retaining pin.

  92. Object Number: 102272  Size: SH
  93. Remove the 2nd speed gear.

  94. Object Number: 100577  Size: SH
  95. Remove the 2nd speed gear bearing.

  96. Object Number: 100579  Size: SH
  97. Remove the 2nd speed gear synchronizer retainer ring.

  98. Object Number: 100583  Size: SH
  99. Remove the 2nd speed gear synchronizer rings.

  100. Object Number: 100586  Size: SH
  101. Remove the 1st/2nd synchronizer retainer ring.
  102. Important: For installation alignment scribe an alignment mark on the synchronizer hubs and synchronizer sleeves before removing. To prevent the synchronizer springs and struts from being lost, do not separate the synchronizer hubs from the synchronizer sleeves. Keep the synchronizer clutch gear and the blocking rings with the synchronizer hubs. Organize the components in order to install the components in their original location and position.


    Object Number: 100588  Size: SH
  103. Remove the 1st/2nd synchronizer.

  104. Object Number: 100590  Size: SH
  105. Remove the 1st gear synchronizer retainer ring.

  106. Object Number: 100748  Size: SH
  107. Remove the synchronizer rings.
  108. Remove the clutch gear snap ring.
  109. Remove the 1st gear clutch gear.

  110. Object Number: 100829  Size: SH
  111. Using a hydraulic press, remove the rear mainshaft bearing.
  112. Remove the reverse gear thrust washer.

  113. Object Number: 100835  Size: SH
  114. Remove the synchronizer.
  115. Remove the reverse gear.

  116. Object Number: 100838  Size: SH
  117. Remove the reverse bearing spacer.
  118. Remove the bearing.

  119. Object Number: 100840  Size: SH
  120. Remove the reverse gear clutch gear retainer ring.
  121. Remove the reverse gear clutch gear and the synchronizer ring.
  122. Remove the 1st gear bearing and the 1st speed gear.