YAMAHA YZ450F 2015 Owners Manual

REAR SHOCK ABSORBER ASSEMBLY
4-55
Disassembling the relay arm
Order Part name Q’ty Remarks
1 Relay arm 1
2 Connecting arm 1
3Collars 3
4Oil seals 6
5Washers 8
6 Bearing 6
For assembly, reverse the disassemble pro-
cedure.
5
3
5
6
165
4
5
5
4
5
6
6
5
4
3
2
4
6
6
3
4
4
T.R.80 Nm (8.0 mlbf) kgf, 58 ft
M
M
M
M
M MM

REAR SHOCK ABSORBER ASSEMBLY
4-56
EAS1SL5177HANDLING THE REAR SHOCK ABSORBEREWA13740
WARNING
This rear shock absorber contains highly
compressed nitrogen gas. Before handling
the rear shock absorber, read and make
sure that you understand the following in-
formation. The manufacturer cannot be held
responsible for property damage or person-
al injury that may result from improper han-
dling of the rear shock absorber.
• Do not tamper or attempt to open the rear
shock absorber.
• Do not subject the rear shock absorber to
an open flame or any other source of high
heat. High heat can cause an explosion
due to excessive gas pressure.
• Do not deform or damage the rear shock
absorber in any way. Rear shock absorber
damage will result in poor damping perfor-
mance.
TIP
A break-in is required up to about 50 km of run-
ning.
EAS1SL5178DISPOSING OF A REAR SHOCK ABSORB-
ER
Before disposing the rear shock absorber, be
sure to extract the nitrogen gas from valve “1”.
EWA33DD052
WARNING
• Wear protective glasses to prevent your
eyes from damage due to possible gas or
metal chips scattered.
• To dispose of a damaged or a worn-out
rear shock absorber, take the unit to your
Yamaha dealer for this disposal proce-
dure.
EAS1SL5179REMOVING THE REAR SHOCK ABSORBER
ASSEMBLY
1. Use a suitable stand to raise the rear wheel
off the ground.
EWA13120
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Remove:
• Rear shock absorber assembly lower bolt
“1”
TIP
While removing the rear shock absorber as-
sembly lower bolt, hold the swingarm so that it
does not drop down.
3. Remove:
• Rear shock absorber assembly upper bolt
• Rear shock absorber assembly
EAS1SL5180REMOVING THE BEARING
1. Remove:
• Stopper ring (upper bearing) “1”
TIP
Press in the bearing while pressing its outer
race and remove the stopper ring.
1
1

REAR SHOCK ABSORBER ASSEMBLY
4-57
2. Remove:
• Upper bearing “1”
TIP
Remove the bearing by pressing its outer race.
3. Remove:
• Lower bearing “1”
TIP
Remove the bearing by pressing its outer race.
EAS1SL5181CHECKING THE REAR SHOCK ABSORBER
ASSEMBLY
1. Check:
• Rear shock absorber rod
Bends/damage  Replace the rear shock
absorber assembly.
• Rear shock absorber
Gas leaks/oil leaks  Replace the rear
shock absorber assembly.
•Spring
Damage/wear  Replace.
• Spring guide
Damage/wear  Replace.
• Bearing
Damage/wear  Replace.
•Bolts
Bends/damage/wear  Replace.
EAS1SL5182
CHECKING THE CONNECTING ARM AND
RELAY ARM
1. Check:
• Connecting arm
• Relay arm
Damage/wear  Replace.
2. Check:
• Bearing
• Spacers
Damage/pitting/scratches  Replace the
bearings and spacers as a set.
3. Check:
• Oil seals
Damage/pitting  Replace.
EAS1SL5183INSTALLING THE RELAY ARM
1. Lubricate:
• Oil seals
• Bearing
• Spacers
• Washers
•Collars
2. Install:
• Bearing “1”
• Washer “2”
• Oil seals “3”
(to relay arm “4”)
3. Install:
• Bearing “1”
• Oil seals “2”
(to connecting arm “3”)
1
Recommended lubricant
Molybdenum disulfide grease
Installed depth “a”
0 mm (0 in)
Installed depth “a”
0 mm (0 in)
New
3 3
43
2 2
22
a
1
11
New

REAR SHOCK ABSORBER ASSEMBLY
4-58
EAS1SL5184INSTALLING THE REAR SHOCK ABSORB-
ER ASSEMBLY
1. Lubricate:
• Bearing (lower side)
•Dust seal
•Collars
• Bushing
ECA1DX1012
NOTICE
Do not apply the grease to the bearing outer
race because it will wear the rear shock ab-
sorber surface on which the bearing is
press fitted.
2. Lubricate:
• O-ring
3. Install:
• Bearing
• Stopper ring
(to rear shock absorber assembly (upper
side))
TIP
• Install the bearing parallel until the stopper
ring groove appears by pressing its outer
race.
• After installing the stopper ring, push back the
bearing unit it contacts the stopper ring.
4. Install:
• Bearing “1”
• Bushing “2”
• Collar “3”
• Dust seal “4”
(to rear shock absorber assembly (lower
side))
TIP
Install the dust seals with their lips facing in-
ward.
5. Lubricate:
• Connecting arm and frame bolt
• Relay arm and connecting arm bolt
• Relay arm and swingarm bolt
(circumference and threaded portion)
• Rear shock absorber assembly upper bolt
• Rear shock absorber assembly lower bolt
6. Install:
• Rear shock absorber assembly
TIP
• When installing the rear shock absorber as-
sembly, lift up the swingarm.
• Install the rear shock absorber assembly up-
per bolt, and connecting arm bolt (frame side)
from the right.
• Install the rear shock absorber assembly low-
er bolts, connecting arm bolt (relay arm side),
and relay arm bolt (swingarm side) from the
left.
7. Tighten:
• Rear shock absorber assembly upper bolt
• Connecting arm bolt (frame side) Recommended lubricant
Molybdenum disulfide grease
Recommended lubricant
Molybdenum disulfide grease
3
a 1
12
a
2
New
Installed depth “a”
4.25 mm (0.17 in)
Recommended lubricant
Molybdenum disulfide grease
Rear shock absorber assembly
upper bolt
56 Nm (5.6 m·kgf, 41 ft·lbf)
Connecting arm bolt (frame side)
80 Nm (8.0 m·kgf, 58 ft·lbf)
T R..
T R..

REAR SHOCK ABSORBER ASSEMBLY
4-59
• Connecting arm bolt (relay arm side)
• Relay arm bolt (swingarm side)
• Rear shock absorber assembly lower boltConnecting arm bolt (relay arm
side)
80 Nm (8.0 m·kgf, 58 ft·lbf)
Relay arm bolt (swingarm side)
70 Nm (7.0 m·kgf, 51 ft·lbf)
Rear shock absorber assembly
lower bolt
53 Nm (5.3 m·kgf, 38 ft·lbf)
T R..
T R..
T R..

SWINGARM
4-60
EAS1SL5185
SWINGARM
Removing the swingarm
Order Part name Q’ty Remarks
Use a suitable stand to raise the front wheel
off the ground.
Brake hose holder Refer to “REAR BRAKE” on page 4-21.
Rear brake caliper Refer to “REAR BRAKE” on page 4-21.
Bolt (brake pedal)
Drive chain
1Collars 2
2Oil seals 2
3Thrust bearing 2
4Bushing 2
5Oil seals 2
6 Bearing 4
For installation, reverse the removal proce-
dure.
1
2
3
6
4
6
4
1
3
6
2
5
T.R.70 Nm (7.0 mlbf) kgf, 51 ft
T.R.4.0 Nm (0.40 mlbf) kgf, 2.9 ft

SWINGARM
4-61
EAS1SL5186REMOVING THE SWINGARM
1. Use a suitable stand to raise the rear wheel
off the ground.
EWA13120
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Measure:
• Swingarm side play
• Swingarm vertical movement
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Measure the tightening torque of the pivot
shaft nut.
b. Measure the swingarm side play “a” by mov-
ing the swingarm from side to side.
c. If the swingarm side play is out of specifica-
tion, check the spacers, the bearings, and
the collars.
d. Check the swingarm vertical movement “b”
by moving the swingarm up and down.
If swingarm vertical movement is not smooth
or if there is binding, check the spacers, the
bearings, and the collars.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS1SL5187REMOVING THE BEARING
1. Remove:
• Bearing “1”
TIP
Remove the bearing by pressing its outer race.
EAS1SL5188CHECKING THE SWINGARM
1. Check:
• Swingarm
Bends/cracks/damage  Replace.
2. Check:
• Pivot shaft
Roll the pivot shaft on a flat surface.
Bends  Replace.
EWA13770
WARNING
Do not attempt to straighten a bent pivot
shaft.
3. Wash with kerosene:
• Pivot shaft
• Spacers
•Collars
• Bearing
4. Check:
• Oil seals
Damage  Replace.
• Bearing
• Spacers
Free play exists/unsmooth revolution/rust 
Replace bearing and bushing as a set. Pivot shaft nut
85 Nm (8.5 m·kgf, 61 ft·lbf)
Swingarm end free play limit (ra-
dial)
1.0 mm (0.04 in)
T R..

SWINGARM
4-62
EAS1SL5189INSTALLING THE SWINGARM
1. Lubricate:
• Bearing
•Collars
• Spacers
• Oil seal
• Pivot shaft
2. Install:
• Bearing “1”
• Oil seals “2”
(to the swingarm)
TIP
First install the outer and then the inner bear-
ings to a specified depth from inside.
3. Install:
• Swingarm
TIP
Install the pivot shaft from the right.
4. Install:
• Rear wheel
Refer to “REAR WHEEL” on page 4-7.
5. Adjust:
• Drive chain slack
Refer to “ADJUSTING THE DRIVE CHAIN
SLACK” on page 3-27.Recommended lubricant
Molybdenum disulfide grease
Installed depth “a”
0–0.5 mm (0–0.02 in)
Installed depth “b”
6.5 mm (0.26 in)
Pivot shaft nut
85 Nm (8.5 m·kgf, 61 ft·lbf)
Drive chain slack
50–60 mm (1.97–2.36 in)
New
New
2 22
1 1
aaa
b ba
NewNewNew
T R..

CHAIN DRIVE
4-63
EAS1SL5190
CHAIN DRIVE
Removing the drive chain
Job Order Part name Q’ty Servicing Information
Drive sprocket Refer to “ENGINE REMOVAL” on page 5-1.
1 Drive chain 1
For installation, reverse the removal proce-
dure.
1
T.R.75 Nm (7.5 mlbf) kgf, 54 ft
T.R.7 Nm (0.7 mlbf) kgf, 5.1 ft

CHAIN DRIVE
4-64
EAS1SL5191REMOVING THE DRIVE CHAIN
1. Use a suitable stand to raise the rear wheel
off the ground.
EWA13120
WARNING
Securely support the vehicle so that there is
no danger of it falling over.
2. Remove:
• Joint clip
• Drive chain joint “1”
• Drive chain “2”
EAS1SL5192CHECKING THE DRIVE CHAIN
1. Measure:
• 15-link section of the drive chain
Out of specification  Replace the drive
chain.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Measure the length “a” between the inner
sides of the pins and the length “b” between
the outer sides of the pins on a 15-link sec-
tion of the drive chain as shown in the illus-
tration.
b. Calculate the length “c” of the 15-link section
of the drive chain using the following formu-
la.
Drive chain 15-link section length “c” =
(length “a” between pin inner sides + length
“b” between pin outer sides)/2
TIP
• When measuring a 15-link section of the drive
chain, make sure that the drive chain is taut.
• Perform this procedure 2–3 times, at a differ-
ent location each time.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
2. Check:
•Drive chain
Stiffness  Clean, lubricate, or replace.
3. Clean:
•Drive chain
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Wipe the drive chain with a clean cloth.
b. Put the drive chain in kerosene and remove
any remaining dirt.
c. Remove the drive chain from the kerosene
and completely dry it.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
15-link length limit
242.9 mm (9.56 in)