Disassembly
DISASSEMBLY / NV3550 Manual TransmissionFRONT HOUSING
1. Shift transmission into Neutral.
2. Remove drain plug and drain lubricant
3. Inspect drain plug magnet for debris.
4. Remove backup light switch located on passenger side of rear housing (Fig. 4).
5. Remove shift tower bolts and remove tower and lever assembly (Fig. 5).
6. Remove shift shaft lock bolt (Fig. 6) located just forward of shift tower.
7. Remove shift shaft detent plug with Remover 8117A. Attach the fingers of the remover to the detent plug (Fig. 7). Then push the cup down till it contacts the trans. Tighten the nut (Fig. 8) till it pulls the plug from the bans case.
8. Remove shift shaft detent spring and plunger with a pencil magnet.
9. Remove input shaft bearing retainer bolts.
10. Loosen input shaft bearing retainer by carefully lifting the retainer with a pry tool to break sealer bead (Fig. 9).
11. Remove bearing retainer from input shaft (Fig. 10).
12. Remove snap ring that secures input shaft in front bearing (Fig. 11).
13. Remove front housing bolts that attach it to the rear housing (Fig. 12). Three bolts at rear of housing are for the output shaft bearing retainer. Leave one of these bolts in place until the geartrain is ready to be removed from case.
14. Separate the housings (Fig. 13) by taping the front housing off the alignment dowels with a plastic mallet.
15. Remove and inspect input shaft bearing and countershaft front bearing race (Fig. 14).
16. Remove screw from reverse blocker and remove blocker (Fig. 15) from case.
17. Note position of input shaft, shift shaft, forks and geartrain components in housing (Fig. 16).
SHIFT/FORK SHAFTS AND REVERSE IDLER SEGMENT
1. To remove the roll pin that secures the shift socket to the shift shaft, position Remover 6858 on the shift shaft. Center the tool over the roll pin and verify tool legs are firmly seated on the shift socket (Fig. 17).
2. Tilt the socket toward the side of the case, to positions the roll pin at a slight angle. This will prevent the pin from being trapped between the gear teeth.
3. Tighten the tool to press the roll pin downward and out of the shift socket (Fig. 17).
NOTE: Press roll pin just enough to clear the shift shaft. Be careful not to push the pin into the geartrain.
4. Rotate lever and bushing upward and out of the shift forks and catch detent ball and spring (Fig. 18) as they exit the shaft lever.
NOTE: Place shop towel over shaft to contain detent ball and spring.
5. Drive out roll pin that secures shift bushing and lever to shift shaft (Fig. 19) with a hammer and punch.
CAUTION: Use proper size punch to avoid bending the shift shaft.
6. Pull shift shaft straight (Fig. 20) out of rear housing.
7. Remove shift socket from rear housing (Fig. 21).
8. Remove lever and bushing (Fig. 22).
9. Rotate 3-4 fork around synchro sleeve until fork clears shift arms on 1-2 and fifth-reverse forks, then remove 3-4 fork (Fig. 23).
10. Remove the reverse idler shaft support bolt and loosen rear reverse idler shaft bolt (Fig. 24).
11. Slide reverse idler shaft support (Fig. 25) straight out of housing.
12. Support geartrain and rear housing on Fixture 6747 as follows:
a. Adjust height of reverse idler pedestal rod until the reverse idle shaft bottoms in Cup 8115.
b. Position Adapters 6747-1A and 6747-2B on Fixture 6747.
c. Slide fixture tool onto input shaft, countershaft and idler gear (Fig. 26).
d. Stand geartrain and rear housing upright on fixture (Fig. 27). Have helper hold fixture tool in place while housing and geartrain is being rotated into upright position.
13. Remove rear bolt holding reverse idler shaft in housing.
REAR ADAPTER HOUSING - 4WD
1. Locate rear seal dimples (Fig. 32). Insert slide hammer mounted screw into one of the seal dimples and remove seal (Fig. 33).
2. Remove rear bearing snap ring from output shaft with snap ring pliers (Fig. 34).
3. Lift rear adapter housing upward and off geartrain (Fig. 35).
4. Remove bearing retainer bolts, rear bearing retainer and rear bearing (Fig. 36).
NOTE: If needed push or tap bearing out of the housing with a hammer.
5. Inspect condition of bearing bore, countershaft rear bearing race and idler shaft notch in rear housing. Replace housing if race, bore or notch are worn or damaged.
GEARTRAIN FROM FIXTURE
1. Remove reverse idler gear assembly from assembly fixture cup.
2. Remove 1-2 and fifth-reverse forks from synchro sleeves.
3. Slide countershaft out of fixture tool.
4. Remove output shaft bearing retainer from rear surface of fifth gear (retainer will drop onto gear after bolts are removed).
5. Lift and remove output shaft and gears off input shaft.
6. Lift and remove input shaft, pilot bearing and fourth gear synchro ring from assembly fixture tool.
OUTPUT SHAFT
NOTE: The synchronizer hubs and sleeves are different and must not be intermixed. Remove each synchronizer unit as an assembly to avoid intermixing parts. Reference mark or tag each synchro hub and sleeve for correct assembly.
1. Remove snap ring that secures 3-4 synchro hub on output shaft.
2. Remove 3-4 synchro assembly, third gear synchro ring and third gear with shop press and Bearing Splitter 1130. Position splitter between second and third gears.
3. Remove third gear needle bearing (Fig. 37).
4. Remove retaining ring that secures two-piece thrust washer on shaft (Fig. 38) with a small pry tool.
5. Remove two-piece thrust washer (Fig. 39).
NOTE: Record location of washer locating lugs in shaft notches for installation reference.
6. Remove second gear and needle bearing (Fig. 40).
7. Remove second gear synchro ring, synchro friction cone and synchro cone (Fig. 41).
8. Remove interim ring and 1-2 synchro hub snap ring.
9. Remove 1-2 synchro hub, sleeve and first gear from output shaft with a press and Bearing Splitter 1130 (Fig. 42). Position splitter between first and reverse gears.
10. Remove first gear needle bearing (Fig. 43).
11. Remove output shaft bearing snap ring (Fig. 44).
12. Remove output shaft bearing on 2-wheel drive models.
13. Remove fifth gear (Fig. 45).
14. Remove fifth gear needle bearing by spreading it apart just enough to clear shoulder on output shaft (Fig. 46).
15. Remove fifth-reverse synchro hub snap ring (Fig. 47).
16. Remove fifth-reverse synchro hub and sleeve with a press (Fig. 48).
17. Remove reverse gear and needle bearing (Fig. 49).
REVERSE IDLER
1. Remove idler gear snap rings (Fig. 50).
2. Remove thrust washer, wave washer, thrust plate and idler gear from shaft.
3. Remove idler gear needle bearing from shaft.