Tools Required

Important: During assembly, lubricate the bearings and the parts that slide or mate together with J 36850 TRANSJEL Lubricant or Synchromesh Transmission Fluid GM P/N 12345349.

Important: When installing the input shaft bearing retainer oil seal, ensure the lip of the oil seal is installed toward the installing tool J 38801 .




1. Using J 38801 , install the oil seal into the main drive gear bearing retainer.



2. Using J 36190 and J 36798 , install the input shaft bearing.

Press the bearing until the snap ring is seated.




3. Using J 36511 and J 36507 , install the shift shaft front housing bushings.



4. Using J 36507 , install the two detent plunger bushings.



5. Install the first bushing to the area where the second scribe mark on the tool is aligned with the housing.
6. Install the second bushing to the area where the first scribe mark on the tool is aligned with the housing.



7. Install the transmission vent.



8. Using J 36511 install the oil drain plug.

Apply teflon pipe sealant GM P/N 12346004 to the drain plug threads.

Tighten
Tighten the drain plug to 60 N·m (44 lb ft).




9. Using J 36506 and J 36190 , install the rear housing shift shaft bearing.

9.1.	The writing on the bearing lip should face down.

9.2.	Install the bearing flush with the housing surface.




10. Install 2 dowel pins in the housing flange.

Drive the dowel pins rearward and flush with the flange surface.




11. If 4WD vehicle, install the main shaft rear bearing in the rear housing.



12. If 4WD vehicle, install the main shaft bearing retainer and the bolts.

Tighten
Tighten the main shaft bearing retainer bolts to 22 N·m (16 lb in).




13. Using the J 25070 heat the rear housing countershaft bearing bore for ten minutes.
14. Install the countershaft bearing race.

Important: Do not mix the parts for the synchronizers.

1. Install the synchronizer detent balls, springs and keys to the hub.



2. Align the scribe marks on the synchronizer hubs and sleeves.
3. Install the synchronizer rings to the synchronizer hubs.

1. Lubricate all the reverse idler gear parts with GM P/N 12345349 Synchromesh Transmission Fluid.

Assemble the reverse idler gear using the following procedure:




2. Install the snap ring on the short side of the shaft.

The short side of the shaft is on the same end of the shaft as the chamfered gear.

3. Install the thin flat washer.



4. Install the wave washer.



5. Install the locating ball.



6. Install the thrust washer.



7. Install the bearing assembly.



8. Install the reverse Idler gear.



9. Install the locating ball.



10. Install the thrust washer.



11. Install the snap ring.

Set the reverse idler gear assembly aside.

1. Using J 39924-1 , install the reverse speed gear drag seal.



2. Install the reverse speed gear needle bearing (1).
3. Install the reverse speed gear (2).



4. Install the 5th/Reverse speed gear synchronizer assembly.

4.1.	Inspect the scribe marks for the correct positions.

4.2.	Position the spiral lock ring towards the reverse speed gear.

4.3.	Manually align and engage the splines on the synchronizer hub with the splines on the main shaft.

4.4.	Using a hydraulic press, the J 36183 , and the J 36184 , press the synchronizer until seated.

4.5.	Remove all the metal shavings.




5. Install a new mainshaft snap ring.



6. Install the 5th speed gear needle bearing (1).
7. Install the synchronizer ring (2).
8. install the 5th speed gear (3).



9. UsingJ 39924-2 and J 36183 , install the 5th speed gear drag seal.



10. Install the 1st speed gear needle bearing assembly.

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.




11. Install the following components:

11.1.

The 1st speed gear (1).

11.2.

The synchronizer interim ring (2) with the teeth up

11.3.

The reactor cone (3) with the flat side towards 1st gear

11.4.

The blocker ring (4) with the teeth down

11.5.

The synchronizer cone (5) with the flat side down




12. Install the 1st/2nd speed gear synchronizer assembly with both synchronizer rings.

12.1.

Inspect the scribe marks for the correct positions.

12.2.

Manually align and engage the splines of the synchronizer hub with the main shaft splines.

12.3.

Using a hydraulic press, the J 36183 , and the J 36184 press the synchronizer hub onto the main shaft.

12.4.

Start the press operation.

12.4.1.

Stop pressing before the tangs engage.

12.4.2.

Lift and rotate the gear.

12.4.3.

Engage the synchronizer ring.

12.5.

Press the synchronizer until seated.

12.6.

Remove all the metal shavings.




13. Install a new mainshaft snap ring.



14. Install the following 2nd gear synchronizer components:

14.1.

The synchronizer cone with the flat up

14.2.

The blocker ring with the tangs up

14.3.

The reaction cone with the wide flat portion up

14.4.

The interim ring




15. Install the 2nd speed gear needle bearing (2).
16. Install the 2nd speed gear (1).

Ensure that the synchronizer ring gear teeth are positioned toward the 1st gear.




17. Install the 2nd speed gear 2-piece thrust washer. Ensure that the dots on the thrust washer are facing up.
18. Install the retainer ring. Ensure that the retainer ring is installed around the washer.



19. Install the following components:

19.1.

The 3rd speed gear needle bearing (1).

19.2.

The 3rd speed gear (2).

19.3.

The synchronizer ring (3).




20. Install the 3rd/4th speed gear synchronizer assembly with both synchronizer rings. Ensure that the groove in the synchronizer ring faces upward.

20.1.

Inspect the scribe marks for the correct positions.

20.2.

Manually align and engage the splines of the synchronizer hub with the main shaft splines.

20.3.

Using a hydraulic press, the J 36183 , and the J 36184 press the synchronizer hub onto the main shaft.

20.4.

Start the press operation.

20.4.1.

Stop pressing before the tangs engage.

20.4.2.

Lift and rotate the gear.

20.4.3.

Engage the synchronizer ring.

20.5.

Press the synchronizer until seated.

20.6.

Remove all the metal shavings.




21. Install a new mainshaft snap ring.



22. Install the input shaft (1) on the assembly fixture J 36515-15 and J 36515 :
23. Install the pilot bearing (2) in the input shaft (1).

23.1.

Ensure the small diameter of the bearing is positioned toward the input shaft.

23.2.

Lubricate the pilot bearing with J 36850 .

24. Install the synchronizer ring (3) on the input shaft (1).
25. Install the mainshaft assembly (4) onto the input shaft (1).



26. Install the following parts on the mainshaft and on the assembly fixture J 36515-16 :

26.1.

The countershaft assembly (1)

26.2.

The reverse idler assembly (2)

26.3.

The 1st/2nd speed gear shift fork (3)

26.4.

The 5th/reverse speed gear shift fork (4)

27. Install the countershaft bearing on the countershaft.

Use the J 36850 in order to retain the bearing.

The smaller diameter of the bearing cage is positioned toward the housing.




28. If RWD vehicle, install the output shaft bearing (2) on the mainshaft.
29. Install a new mainshaft snap ring (1).



30. If RWD vehicle, using J 6133-A , install the reluctor wheel onto the main shaft.



31. If 4WD vehicle install the rear housing assembly.

31.1.

Make sure the reverse idler shaft is lined up with the hole in the case.

31.2.

Rotate the housing back and forth while pulling down.




32. If 4WD vehicle install a new output shaft bearing snap ring.



33. If RWD vehicle, install the following components:

33.1.

Install the J 36515-10 through the bolt holes in the rear housing.

33.2.

Screw the threaded cable ends into the output shaft bearing retainer (1).

33.3.

Position the notch in the bearing retainer towards the oil delivery tube assembly.

34. If RWD vehicle, install the rear housing assembly.

34.1.

Make sure the reverse idler shaft is lined up with the hole in the case.

34.2.

Rotate the housing back and forth while pulling down.

34.3.

Pull up on the J 36515-10 while installing the rear housing.

34.4.

Loosely install a rear bearing retainer bolt in the open hole. This is to hold the bearing retainer in place when the J 36515-10 is removed.




35. Remove the J 36515-10 .



36. Install the three rear bearing retainer bolts.

Apply threadlocker GM P/N 12345382 to the bolt threads.

Tighten
Tighten the rear bearing retainer bolts to 22 N·m (16 lb ft).




37. Lay the housing assembly down on a workbench.
38. Remove the rear housing assembly from the J 36515 , the J 36515-15 , and the J 36515-16 .



39. Install the following components:

39.1.

The idler shaft support

39.2.

The idler shaft bolts

Apply threadlocker GM P/N  12345382 or equivalent to the bolt threads.

39.3.

Line up the bolt threads in the idler shaft support with the bolt hole.

39.4.

Hold the reverse idler shaft against the idler support while tightening the bolts.

Tighten
Tighten the bolt to 22 N·m (16 lb ft).




40. Install the transmission holding fixture on the transmission.



41. Install the 3rd/4th speed gear shift fork onto the 3rd/4th speed gear synchronizer sleeve.

Align all three insert notches.




42. Slide the shift shaft through the following parts:

42.1.

The 3rd/4th speed gear shift fork (1). Ensure that the detent reliefs in the shift shaft point out.

42.2.

The shift lever (2).

42.3.

The block-out bushing (3).

42.4.

The 1st/2nd speed gear shift fork (4).

42.5.

The shift socket (5).




43. Slide the shift shaft all the way into the housing.



44. Install a new short roll pin into the shift lever. The end of the spiral must face toward the direction of the thrust.

44.1.

Rotate the shift shaft and the shift lever/block-out bushing assembly. Ensure the roll pin holes are aligned and horizontal.

44.2.

Support the shift shaft while installing the roll pin.

44.3.

Install the roll pin flush with the shift lever.




45. Install the detent spring and the ball plunger into the hole in the shift lever.

45.1.

Rotate the shift shaft counterclockwise. The shift lever should be almost into the 5th/Reverse speed gear insert notch.

45.2.

Install the spring (1) and the ball plunger (2) into the shift lever.

45.3.

Rotate the shift shaft until the shift lever aligns with the 3rd/4th speed gear insert.

Important: Excessive force peens the shift shaft and damages the shift shaft bearing causing increased shift effort.

Important: Use the rear roll pin hole (2) on transmissions to be installed on S/T (small) trucks.

Use the front roll pin hole (1) on transmissions to be installed on C/K (large) trucks.



46. Install the shift shaft and shift shaft socket and roll pin.

46.1.

Align the holes in the shift shaft socket and the shift shaft.

46.2.

Drive the roll pin flush with the bottom of the shift shaft socket.

Important: The smaller diameter of the bearing cage goes into the bearing race.




47. Install the countershaft bearing onto the counter shaft.

Ensure the smaller diameter side of the bearing is positioned toward the front case half.




48. Apply gasket maker GM P/N 1052943 or equivalent to the front housing sealing surface.
49. Install the front housing to the rear housing.



50. Install a new snap ring on the input shaft. It may be necessary to pull out on the input shaft in order to install the snap ring.



51. Install the housing bolts except for the bottom two.

Do not tighten the bolts.

Important: Do not allow sealant into the oil return hole in the housing or bearing retainer.




52. Apply RTV sealer GM P/N 12345739 or equivalent to the inside edge of the bearing retainer mating surface.



53. Install the input shaft bearing retainer to the housing with six bolts.

Align the retainer oil drain hole with the drain hole in the housing.

Tighten
Tighten the retainer bolts to 14 N·m (10 lb ft).

54. Rotate the input shaft a few turns to align the transmission bearings and to test for any excessive binding.
55. Tighten the front to rear housing bolts.

Tighten
Tighten the housing bolts to 35 N·m (26 lb ft).




56. Install the following components:

56.1.

The shift shaft detent plunger

56.2.

The shift shaft detent spring

56.3.

The shift shaft detent plug

Apply teflon pipe sealant GM P/N 12346004 or equivalent to the detent plug.




57. If RWD vehicle, coat the speed sensor O-ring with Synchromesh Transmission Fluid GM P/N  12345349 or equivalent.
58. Install the speed sensor, O-ring, and bolt.

Tighten
Tighten the bolt to 9 N·m (80 lb in).




59. Install the backup lamp switch.

Apply teflon pipe sealant GM P/N 12345349 or equivalent to the threads of the backup lamp switch.

Tighten
Tighten the switch to 14 N·m (10 lb ft).




60. Install the shift shaft block-out bushing pin.

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




61. If RWD vehicle, using the J 36503 , install the slip yoke oil seal.



62. If 4WD vehicle, install the J 36502-2A on the output shaft.
63. Install the output shaft seal using the J 36502 .
64. Remove the J 36502-2A from the output shaft.



65. Fill the space between the seal lips with chassis grease.



66. Remove the J 8763-B and the J 36824 from the transmission.



67. Install the two remaining rear to front housing bolts.

Tighten
Tighten the housing bolts to 35 N·m(26 lb ft).

68. To prevent the transmission fluid from spilling while installing the transmission in the vehicle, fill the transmission after installing with Synchromesh Transmission Fluid GM P/N  12345349.