Yamaha 20C Service Manual page 202

LOWR
ASSEMBLY AND ADJUSTMENT
Example:
If M is "16.35 mm", then
T1 = 16.8 + 0/100 – 16.35
= 0.45 mm
Available shim thickness:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40
and 0.50 mm
NOTE:
9 Use a minimum number of shims to obtain the
thickness equal or nearly equal to the calculation.
9 Install the shims with the thicker one on the outer
side.
Reverse gear shim
1) Find reverse gear shim thickness (T2) by
selecting shims until the specified measure-
ment (M) with the special tool is obtained
NOTE:
Be sure to remove the O-ring from under the thrust
washer.
2) Using digital caliper at the specified measure-
ment (M) established above, measure the dis-
tance between the washer top and special tool
top as shown.
Shim thickness (T2) =
M – 24 mm + R/100 mm
R = +5
3) R is the deviation of the lower case dimension
from standard. It is stamped on the trim tab
mounting surface of the lower case in 0.01 mm
units. If the R mark is missing or unreadable,
assume an R mark of "+5", and check the back-
lash when the unit is assembled.
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E