Mercury 90 Service Manual

90-830234R3 DECEMBER 1997 LOWER UNIT - 6A-29
5. Install components as shown.
e
f
d
c
a
c
b
51117
a - Threaded Rod (Obtain Locally)
b - Washers
c - Nuts
d - Dial Indicator Adaptor Kit (91-83155)
e - Dial Indicator (91-58222A1)
f - Backlash Indicator Tool
6. Position Dial Indicator on appropriate line (from
chart) marked on Backlash Indicator Tool.
MODEL
ALIGN POINTER OF
DIAL INDICATOR WITH MARK
50 Bigfoot (4-stroke)
Backlash
Indicator
Tool (91-78473)
4
60 Seapro/60 Mara-
thon/60 Bigfoot
Backlash
Indicator
Tool (91-78473)
4
75-thru-90
(3 Cylinder)
Backlash
Indicator
Tool (91-78473)
4
100/115/125
(4 Cylinder)
Backlash
Indicator
Tool (91-19660--1)
1
7. Lightly turn drive shaft back and forth (no move-
ment should be noticed at propeller shaft).
8. Dial Indicator registers amount of backlash,
which must be between specification shown in
chart.
MODEL
DIAL
INDICATOR
MINIMUM
READING
MAXIMUM
50 Bigfoot
(4-Stroke)
0.012 in.
(0.30mm)
0.019 in.
(.48mm)
60 Bigfoot
0.012 in.
(0.30mm)
0.019 in.
(.48mm)
75-thru-90
(3 Cylinder)
0.012 in.
(0.30mm)
0.019 in.
(.48mm)
100/115/125
(4 Cylinder)
0.015 in.
(0.38mm)
0.022 in.
(0.55mm)
9. If backlash is less than the minimum specifica-
tion, remove shim(s) from in front of forward gear
bearing race to obtain correct backlash. When re-
installing pinion nut, apply Loctite 271 on threads
of nut.
10. If backlash is more than the maximum specifica-
tion, add shim(s)* in front of forward gear bearing
race to obtain correct backlash. When reinstal-
ling pinion nut, apply Loctite 271 on threads of
nut.
NOTE: By adding or subtracting 0.001 in. (0.03mm)
shim, the backlash will change approximately 0.001
in. (.03mm).

Mercury 90 Specifications

General

Brand	Mercury
Model	90
Category	Outboard Motor
Language	English