Mercury 100 FourStroke, Service Manual

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6A-36 - LOWER UNIT 90-830234R3 DECEMBER 1997
10. Apply Loctite Grade 271 on threads of gear hous-
ing retaining bolts.
NOTE: If, while performing Step 11, the drive shaft
splines will not align with the crankshaft splines,
place a propeller onto propeller shaft and turn it coun-
terclockwise as the gear housing is being pushed to-
ward drive shaft housing.
NOTE: During installation of gear housing, it may be
necessary to move the shift block (located under
cowl) slightly to align upper shift shaft splines with
shift shaft coupler splines.
11. Position gear housing so that the drive shaft is
protruding into drive shaft housing.
12. Move gear housing up toward drive shaft hous-
ing, while aligning upper shift shaft splines with
shift shaft coupler splines, water tube with water
tube seal, and crank shaft splines with drive shaft
splines.
13. Install 4 bolts and washers (two each side).
14. Install locknut and washer.
15. Torque bolts and locknut (or nuts only if applica-
ble) to 40 lbs. ft. (54.0 N·m).
a
b
53922
a - Bolts and Washers (4)
b - Locknut and Washer
16. Check shift operation as follows:
a. Place shift lever in forward gear. Gear hous-
ing should ratchet when propeller shaft is
turned clockwise and resistance should be
felt when propeller shaft is turned counter-
clockwise.
b. Place shift lever in neutral. Propeller shaft
should rotate freely in either direction.
c. While rotating propeller shaft, place shift
lever in reverse gear. Resistance should be
felt when propeller shaft is rotated in either
direction.
IMPORTANT: If shift operation is not as de-
scribed, preceding, the gear housing must be re-
moved and the cause corrected.
Trim Tab Adjustment
1. Check trim tab position as follows:
a. Operate boat at the speed at which it normally
would be operated.
b. If the boat pulls to the right (STARBOARD),
the trailing edge of trim tab must be moved to
the right. If the boat pulls to the left (PORT),
the trailing edge of trim tab must be moved to
the left.
2. If necessary, adjust trim tab as follows:
a. Shift engine control into NEUTRAL and turn
ignition key to “OFF” position.
NOTE: Loosen trim tab bolt sufficiently to allow trim
tab to disengage from locking ridges in gear case be-
fore attempting to move tab. DO NOT strike trim tab
with a hard object to make adjustments.
b. If boat pulls to the left, adjust trailing edge of
trim tab to the left. If boat pulls to the right, ad-
just trailing edge of trim tab to the right.
3. Tighten trim tab retaining bolt and washer to
22 lb. ft. (30.0 N·m).