NOTE: Optimum performance of the upper gear case requires “setting up” the pinion & clutch gears with
IMCO procedure as follows.
1. Take all measurements using the “SCX Setup Diagrams” (Fig 3) and the “SCX Work
Sheet” (Fig 4).
2. After all measurements are taken and proper race thickness has been determined, place
lower race [2-6] and thrust bearing [2-7] in case.
3. Place lower clutch gear [2-13] with attached tool (backlash tower 01-5579) into case.
4. Adjust rolling preload (8-10 in/lbs) on pinion gear by changing Yoke Gear End Shims [2-42].
Tighten nut [2-36] to 75 ft/lbs.
5. After proper rolling preload is determined, assemble pinion pack with pinion retainer nut “O”
ring [1-20] between pinion seal carrier [2-45] and retainer nut [2-31].
6. Torque retainer nut to 200 ft/lbs. (Tool: Pinion Retainer Nut Driver 01-5590) (torque wrench
centered on retainer nut, or, if using longer tool be sure to compensate on torque value).
Use new lock nut [2-36] and torque to 75 ft/lbs.
7. Install pinion pack using 4 screws [1-23] for testing.
8. Install dial indicator (indicator bracket 01-5588) and pinion gear locking tool (pinion gear lock
01-5587) Fig-5.
9. Check backlash, adjust backlash with pinion hub shims [2-18] (average backlash should
be .007-.010).
10. Once backlash is determined. Check upper clutch gear by placing gear in lower position with
lower thrust race and backlash tower. This will insure backlash is .007 -.010 is correct on
upper gear.
11. Assemble drive shaft gear assembly [2-(8-17)].
12. Place the lower clutch gear [2-13] onto the clutch shaft [2-17], allowing it to rest on the thrust
collar.
13. Place the lower clutch spring thrust bearing [2-14] (silver side “up), lower clutch spring [2-15],
clutch cone [2-16], upper clutch spring [2-15], upper clutch spring thrust bearing [2-14],
(Note; use a thin layer of grease between the bearing and the gear to keep bearing in place
during assembly), (silver side “down”), upper clutch gear [2-13], clutch shaft retainer [2-9]
onto the upper clutch shaft [2-17].
14. Compress the upper clutch gear and install the upper drive shaft retainer keepers [2-8].
15. Install complete clutch shaft assembly into gear case.
16. Align the clutch gear timing marks (“+” over “-“, or “-“ over “+”) with the center of the rear face
of the gear case.
17. Install pinion pack with “O” ring [1-19] and shims [2-18] (shims must be properly aligned).
18. Torque pinion pack screws [1-(22-23)] (Important: make sure copper sealing washers [1-21]
are in place, short screws in 2 top holes & 2 bottom holes [1-22] longer screws in 3 port & 3
starboard holes [1-23] to 20 ft/lbs. Use “Loctite 242” on all screws. Note: make sure that the
clutch gear timing marks align to case timing marks, roll pinion to check.
Page 6
UPPER GEAR CASE-ASSEMBLY
