Measuring The Reverse Gear Backlash; Adjusting The Reverse Gear Shim Thickness (T2) - Yamaha F150A Service Manual

Available shim thicknesses:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40,
0.50 mm
5. Install the determined forward gear shims
(T1) and taper roller bearing outer race.

Measuring the reverse gear backlash

• Spray anti-rust lubricant on the gears and
bearings before installation. Do not apply
gear oil to the parts. Otherwise, correct
measurements cannot be obtained.
• Keep the parts free of foreign material,
such as dirt and lint.
• When measuring the forward gear or
reverse gear backlash, use the original
bearings and shims.
1. Install the original reverse gear shims
(T2) and propeller shaft housing assem-
bly. See "Installing the propeller shaft
housing assembly" (8-26).
TIP:
• If the original reverse gear shims (T2) are
missing, install new shims with a combined
thickness of 0.62 mm.
• Do not reuse a shim if deformed or
scratched.
2. Measure the reverse gear backlash. See
steps 17–20 in "Measuring the forward
gear backlash and reverse gear backlash
before disassembly" (8-35).
Reverse gear backlash (F150A):
0.33–0.67 mm (0.0130–0.0264 in)
Reverse gear backlash (F150B):
0.33–0.74 mm (0.0130–0.0291 in)
Adjusting the reverse gear shim
thickness (T2)
1. Remove the propeller shaft housing
assembly and reverse gear shims (T2).
2. Measure the thickness of original reverse
gear shim (T2) in 2 places.
Shimming (regular rotation model)
TIP:
Do not reuse a shim if deformed or
scratched.
3. Determine the reverse gear shim (T2)
thickness adjustment using the "Reverse
gear shim (T2) selection chart" according
to the backlash measurement (BL2) from
"Measuring the reverse gear backlash".
See "Forward gear shim (T1) selection
chart (F150A)" (A-13) or "Reverse gear
shim (T2) selection chart (F150B)" (A-
14).
TIP:
• If the shim thickness adjustment value is
positive, increase the current shim thick-
ness by that amount and, if the value is
negative, decrease the current shim thick-
ness by that amount.
• The gray-colored area on the selection
chart indicates the range of the specified
backlash. Shimming is not required if the
measured backlash is within the gray-col-
ored area.
• The values for the shim thickness adjust-
ments specified in the selection chart are
intended to obtain the median value within
the range for the specified forward gear or
reverse gear backlash.
• The table that follows the selection chart
shows the shim thickness adjustments for
the points marked on the chart.
Example:
Backlash measurement (BL2) = 0.80 mm "a"
Reverse gear shim (T2) thickness adjustment
= –0.21 mm "b"
The current
decreased by 0.21 mm.
8-43
shim thickness must be