Yamaha F50 Service Manual

							62Y3A116-32
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Shimming
NOTE:
Shimming is not required when assembling
the original lower case and inner parts.
Shimming is required when assembling the
original inner parts and a new lower case.
Shimming is required when replacing the
inner parts.
Selecting the pinion shims
1. Calculate the specified value (M0) as
shown in the examples below.
NOTE:
“P” is the deviation of the lower case dimen-
sion from standard. The “P” mark a
 is
stamped on the trim tab mounting surface of
the lower case in 0.01 mm units. If the “P”
mark is unreadable, assume that “P” is zero
and check the backlash when the unit is
assembled.
Example:
If “P” is “+5”, then
M0 = 0.30 + (+5)/100 mm = 0.30 + 0.05 mm
= 0.35 mm
If “P” is “–5”, then
M0 = 0.30 + (–5)/100 mm = 0.30 – 0.05 mm
= 0.25 mm
2. Install the drive shaft and drive shaft
bearing 1
 to the shim selecting tools.
3. Attach the clamp 2
 to the gauge base
using four bolts of appropriate sizes.
NOTE:
Install the shim selecting tools to the drive
shaft so that the shaft is at the center of the
hole.
4. Install the pinion and pinion nut, and then
tighten the nut to the specified torque.
Specified value (M0) = 0.30 + P/100 mm
Pinion shim selecting tools:
YB-34432-8 3
, YB-34432-10A 4
,
YB-34432-11A 5
, YB-34432-17 2
Pinion nut: 75 N·m (7.5 kgf·m, 54 ft·lb)
Shimming (F50) (for USA and Canada) 
						

							LOWRLower unit
6-3362Y3A11
5. Measure the clearance (M) between the
shim selecting tool and the pinion as
shown.
NOTE:
Measure the pinion at three points to find the
clearance average.
6. Select the pinion shims (T3).
NOTE:
The sum of T3 and M should not be more
than M0.
Selecting the forward gear shims
1. Calculate the specified value (M0) as
shown in the examples below.
NOTE:
“F” is the deviation of the lower case dimen-
sion from standard. The “F” mark a
 is
stamped on the trim tab mounting surface of
the lower case in 0.01 mm units. If the “F”
mark is unreadable, assume that “F” is zero
and check the backlash when the unit is
assembled.
Example:
If “F” is “+5”, then
M0 = 0.95 + (+5)/100 mm = 0.95 + 0.05 mm
= 1.00 mm
If “F” is “–5”, then
M0 = 0.95 + (–5)/100 mm = 0.95 – 0.05 mm
= 0.90 mm
Pinion shim thickness (T3) = M0 – M
Available shim thicknesses:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40, and 
0.50 mm
Specified value (M0) = 0.95 + F/100 mm 
						

							62Y3A116-34
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2. Install the taper roller bearing 1
 to the
shim selecting tools.
NOTE:
Tighten the nut four turns after it contacts the
spring.
3. Measure the clearance (M) between the
gauge pin and press plate.
4. Select the forward gear shims (T1).
NOTE:
The sum of T1 and M should not be more
than M0.
Selecting the reverse gear shims
1. Measure the backlash to find the neces-
sary shim thickness (T2). Add or remove
shims if out of specification. For measur-
ing procedures, see “Measuring the for-
ward and reverse backlash” in this
chapter.
NOTE:
Measure the backlash with the original
shim(s). If the original shim(s) is unavailable,
start with a 0.50 mm shim. Forward gear shim selecting tools:
YB-34446-1 2
, YB-34446-3 3
, 
YB-34446-4 4
, YB-34446-15 5
 
Forward gear shim thickness (T1) = 
M0 – M
Available shim thicknesses:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40, and 
0.50 mm
Available shim thicknesses:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40, and 
0.50 mm
Shimming (F50) (for USA and Canada) 
						

							LOWRLower unit
6-3562Y3A11
Shimming (F50A) (for worldwide)6 
						

							62Y3A116-36
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Shimming
NOTE:
Shimming is not required when assembling
the original lower case and inner parts.
Shimming is required when assembling the
original inner parts and a new lower case.
Shimming is required when replacing the
inner parts.
Selecting the pinion shims
1. Install the drive shaft and drive shaft
bearing 1
 to the shimming tools.
NOTE:
Select the shim thickness (T3) by using the
specified measurement(s) and the calcula-
tion formula.
Install the shimming tool to the drive shaft
so that the shaft is at the center of the hole.
Tighten the wing nuts another 1/4 turn after
they contact the fixing plate 2
.
2. Install the pinion and pinion nut, and then
tighten the nut to the specified torque.3. Measure the distance (M) between the
shimming tool and the pinion as shown.
NOTE:
Measure the pinion at three points to find the
clearance average.
4. Calculate the pinion shim thickness (T3)
as shown in the examples below.
NOTE:
“P” is the deviation of the lower case dimen-
sion from standard. The “P” mark a
 is
stamped on the trim tab mounting surface of
the lower case in 0.01 mm units. If the “P”
mark is unreadable, assume that “P” is zero
and check the backlash when the unit is
assembled.
Pinion height gauge 3
: 90890-06702
Pinion nut: 75 N·m (7.5 kgf·m, 54 ft·lb)
Digital caliper 4
: 90890-06704
Pinion shim thickness (T3) =
M – 11.30 mm – P/100
Shimming (F50A) (for worldwide) 
						

							LOWRLower unit
6-3762Y3A11
Example:
If “M” is “11.70 mm” and “P” is “+5”, then
T3 = 11.70 – 11.30 – (+5)/100 mm
= 0.40 – 0.05 mm = 0.35 mm
If “M” is “11.70 mm” and “P” is “–5”, then
T3 = 11.70 – 11.30 – (–5)/100 mm
= 0.40 + 0.05 mm = 0.45 mm
5. Select the pinion shim(s) (T3) as follows.
Example:
If “T3” is “0.44 mm”, then the pinion shim is
0.45 mm.
If “T3” is “0.39 mm”, then the pinion shim is
0.40 mm.
Selecting the forward gear shims
1. Turn the taper roller bearing outer race
1
 two or three times to seat the rollers,
and then measure the bearing height (M)
as shown.
NOTE:
Select the shim thickness (T1) by using the
specified measurement(s) and the calcula-
tion formula.
Measure the bearing outer race at three
points to find the height average.
2. Calculate the forward gear shim thick-
ness (T1) as follows.
NOTE:
“F” is the deviation of the lower case dimen-
sion from standard. The “F” mark a
 is
stamped on the trim tab mounting surface of
the lower case in 0.01 mm units. If the “F”
mark is unreadable, assume that “F” is zero
and check the backlash when the unit is
assembled. Calculated numeral 
at 1/100 placeRounded numeral
1, 2 2
3, 4, 5 5
6, 7, 8 8
9, 10 10
Available shim thicknesses:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40, and 
0.50 mm
Shimming plate 2
: 90890-06701
Digital caliper 3
: 90890-06704
Forward gear shim thickness (T1) =
22.75 + F/100 – M 
						

							62Y3A116-38
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Example:
If “M” is “22.45 mm” and “F” is “+5”, then
T1 = 22.75 + (+5)/100 – 22.45mm
= 0.30 + 0.05 mm = 0.35 mm
If “M” is “22.45 mm” and “F” is “–5”, then
T1 = 22.75 + (–5)/100 – 22.45mm
= 0.30 – 0.05 mm = 0.25 mm
3. Select the forward gear shim(s) (T1) as
follows.
Example:
If “T1” is “0.45 mm”, then forward gear shim
is 0.42 mm.
If “T1” is “0.50 mm”, then forward gear shim
is 0.48 mm.
Selecting the reverse gear shims
1. Measure the backlash to find the shim
thickness (T2). Add or remove shims if
out of specification. For measuring pro-
cedures, see “Measuring the forward and
reverse backlash” in this chapter.
NOTE:
Measure the backlash with the original
shim(s). If the original shim(s) is unavailable,
start with a 0.50 mm shim.
Calculated numeral 
at 1/100 placeRounded numeral
1, 2 0
3, 4, 5 2
6, 7, 8 5
9, 10 8
Available shim thicknesses:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40, and 
0.50 mm
Available shim thicknesses:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40, and 
0.50 mm
Shimming (F50A) (for worldwide) 
						

							LOWRLower unit
6-3962Y3A11
Backlash (F50/F50A)6
Measuring the forward and reverse 
gear backlash
1. Remove the water pump assembly.
2. Set the gearshift to the neutral position.
ÈFor USA and Canada
ÉFor worldwide
3. Install the special service tool so that it
pushes against the propeller shaft.
ÈFor USA and Canada
ÉFor worldwide
NOTE:
Tighten the universal puller or center bolt
while turning the drive shaft until the drive
shaft can no longer be turned.
4. Install the backlash indicator onto the
drive shaft (18 mm [0.71 in] in diameter),
then the dial gauge onto the lower unit.
NOTE:
Install the dial gauge so that the plunger 
a
contacts the mark 
b on the backlash indica-
tor. Shift rod push arm: YB-06052
Shift rod push arm: 90890-06052
Bearing housing puller 1
: YB-06234
Universal puller 2
: YB-06117
Bearing housing puller claw 3
:
90890-06564
Stopper guide plate 4
: 90890-06501
Center bolt 5
: 90890-06504
Backlash indicator gauge 6
: YB-06265
Backlash indicator 6
: 90890-06706
Magnetic plate 7
: YB-07003
Magnet base plate 7
: 90890-07003
Dial gauge 8
: YU-03097
Dial gauge set 8
: 90890-01252
Magnet flexible stand 9
: YU-34481
Magnet base 9
: 90890-06705 
						

							62Y3A116-40
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5. Slowly turn the drive shaft clockwise and
counterclockwise and measure the back-
lash when the drive shaft stops in each
direction.
6. Add or remove shims if out of specifica-
tion.
M: Measurement
7. Remove the special service tools from
the propeller shaft.
8. Apply a load to the reverse gear by
installing the propeller 0
 without the
spacer A
, the washer B
 backwards,
then the washer C
 as shown.
NOTE:
Tighten the propeller nut D
 while turning the
drive shaft until the drive shaft can no longer
be turned.9. Slowly turn the drive shaft clockwise and
counterclockwise and measuring the
backlash when the drive shaft stops in
each direction.
10. Add or remove shims if out of specifica-
tion.
M: Measurement
11. Remove the special service tools, and
then install the water pump assembly. Forward gear backlash:
0.18–0.54 mm (0.007–0.021 in)
Forward gear 
backlashShim thickness
Less than
0.18 mm (0.007 in)To be decreased by 
(0.36 – M) ×
 0.56
More than
0.54 mm (0.021 in)To be increased by 
(M – 0.36) ×
 0.56
Available shim thicknesses:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40, and 
0.50 mm
Reverse gear backlash:
0.71–1.07 mm (0.028–0.042 in)
Reverse gear 
backlashShim thickness
Less than
0.71 mm (0.028 in)To be decreased by 
(0.89 – M) ×
 0.56
More than
1.07 mm (0.042 in)To be increased by 
(M – 0.89) ×
 0.56
Available shim thicknesses:
0.10, 0.12, 0.15, 0.18, 0.30, 0.40, and 
0.50 mm
Backlash (F50/F50A) 
						

							LOWRLower unit
6-4162Y3A11
Lower unit (T50/FT50B, FT50C)6