2003 YAMAHA WR 450F brake

5 - 12
CHAS
EC5A8100
REAR BRAKE
Extent of removal:1 Master cylinder removal2 Brake hose removal
3 Caliper removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalREAR BRAKE REMOVAL
Hold the machine by placing the
suitable stand under the engine.
WARNING
Support the machine securely so there is nodanger of it falling over.
Rear wheel Refer to “FRONT WHEEL AND REAR
WHEEL” section.
Drain the brake fluid. Refer to “REMOVAL POINTS”.
1 Brake pedal 1
2 Master cylinder 1
3 Brake hose holder 2
4 Union bolt 2
5 Brake hose 1
6 Pad pin plug 1 Remove when loosening the pad pin.
7 Pad pin 1 Loosen when disassembling the caliper.
8Caliper
1
3
1
321
FRONT BRAKE AND REAR BRAKE

5 - 13
CHAS
EC5A8200
CALIPER DISASSEMBLY
ÅFront
ıRear
Extent of removal:1 Front caliper disassembly2 Rear caliper disassembly
Extent of removal Order Part name Q’ty Remarks
CALIPER DISASSEMBLYAB
1 Pad pin 1 1
2 Brake pad 2 2
3 Pad support 1 1
4 Caliper piston 2 1
Refer to “REMOVAL POINTS”. 5 Dust seal 2 1
6 Piston seal 2 1
12
FRONT BRAKE AND REAR BRAKE

5 - 14
CHASFRONT BRAKE AND REAR BRAKE
EC5A8300
MASTER CYLINDER DISASSEMBLY
ÅFront
ıRear
Extent of removal:1 Front master cylinder disassembly2 Rear master cylinder disassembly
Extent of removal Order Part name Q’ty Remarks
MASTER CYLINDER DISAS-
SEMBLY
1 Master cylinder cap 1
2 Diaphragm 1
3 Master cylinder boot 1
4 Circlip 1 Use a long nose circlip pliers.
5 Plain washer 1
6 Push rod 1
7 Master cylinder kit
1
12
12

5 - 15
CHASFRONT BRAKE AND REAR BRAKE
EC5A3000
REMOVAL POINTS
Brake fluid
1. Remove:
[Front]
Master cylinder cap 1
[Rear]
Master cylinder cap 1
Protector
NOTE:
Do not remove the diaphragm.
ÅFront
ıRear
2. Connect the transparent hose 2 to the
bleed screw 1 and place a suitable con-
tainer under its end.
ÅFront
ıRear
Å
ı
3. Loosen the bleed screw and drain the
brake fluid while pulling the lever in or
pushing down on the pedal.
ACHTUNG:CAUTION:
Do not reuse the drained brake fluid.
Brake fluid may erode painted surfaces or
plastic parts. Always clean up spilled
fluid immediately.
EC533301
Caliper piston
1. Remove:
Caliper piston
Use compressed air and proceed care-
fully.
WARNING
Cover piston with rag and use extreme
caution when expelling piston from cylin-
der.
Never attempt to pry out piston.
ÅFront
ıRear
Caliper piston removal steps:
Insert a piece of rag into the caliper to lock
one caliper.
Carefully force the piston out of the caliper
cylinder with compressed air.
ı
Å
Å
ı

5 - 16
CHASFRONT BRAKE AND REAR BRAKE
EC533402
Piston seal kit
1. Remove:
Dust seal 1
Piston seal 2
NOTE:
Remove the piston seals and dust seals by
pushing them with a finger.
ACHTUNG:CAUTION:
Never attempt to pry out piston seals and
dust seals.
WARNING
Replace the piston seals and dust seals
whenever a caliper is disassembled.
ÅFront
ıRear
Å
ı
EC5A4000
INSPECTION
EC534112
Master cylinder
1. Inspect:
Master cylinder inner surface a
Wear/scratches → Replace master cyl-
inder assembly.
Stains → Clean.
WARNING
Use only new brake fluid.
ÅFront
ıRear
2. Inspect:
Diaphragm 1
Crack/damage → Replace.
ÅFront
ıRear
ı
Å
ı
Å
3. Inspect:
Master cylinder piston 1
Master cylinder cup 2
Wear/damage/score marks → Replace
master cylinder kit.
ÅFront
ıRear
Åı

5 - 17
CHAS
EC534214
Caliper
1. Inspect:
Caliper cylinder inner surface a
Wear/score marks → Replace caliper
assembly.
ÅFront
ıRear
ı Å
2. Inspect:
Caliper piston 1
Wear/score marks → Replace caliper
piston assembly.
WARNING
Replace the piston seals and dust seals 2
whenever a caliper is disassembled.
EC534301
Brake hose
1. Inspect:
Brake hose 1
Crack/damage → Replace.
EC5A5000
ASSEMBLY AND INSTALLATION
WARNING
All internal parts should be cleaned in
new brake fluid only.
Internal parts should be lubricated with
brake fluid when installed.
Replace the piston seals and dust seals
whenever a caliper is disassembled.
EC5A5800
Caliper piston
1. Clean:
Caliper
Piston seal
Dust seal
Caliper piston
Clean them with brake fluid.
FRONT BRAKE AND REAR BRAKE

5 - 18
CHAS
2. Install:
Piston seal 1
Dust seal 2
WARNING
Always use new piston seals and dust
seals.
NOTE:
Fit the piston seals and dust seals onto the slot
on caliper correctly.
ÅFront
ıRear
Å
New
New
ı
3. Install:
Caliper piston 1
NOTE:
Apply the brake fluid on the piston wall.
ACHTUNG:CAUTION:
Install the piston with its shallow
depressed side a facing the caliper.
Never force to insert.
ÅFront
ıRear
EC5A5700
Front caliper
1. Install:
Pad support 1
Brake pad 2
Pad pin 3
NOTE:
Install the brake pads with their projections
a into the caliper recesses b.
Temporarily tighten the pad pin at this point.
Å
ı
FRONT BRAKE AND REAR BRAKE

5 - 19
CHASFRONT BRAKE AND REAR BRAKE
2. Install:
Copper washer 1
Union bolt 2
WARNING
Always use new copper washers.
ACHTUNG:CAUTION:
Install the brake hose so that its pipe por-
tion a directs as shown and lightly
touches the projection b on the caliper.
New
T R..30 Nm (3.0 m · kg, 22 ft · lb)
3. Install:
Brake hose holder 1
Caliper 2
Bolt (caliper) 3
NOTE:
Fit the brake hose holder cut a over the pro-
jection b on the front fork and clamp the brake
hose.
4. Tighten:
Pad pin 4
5. Install:
Pad pin plug 5
EC5A5100
Rear caliper
1. Install:
Pad support 1
Brake pad 2
Pad pin 3
NOTE:
Install the brake pads with their projections
a into the caliper recesses b.
Temporarily tighten the pad pin at this point.
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..3 Nm (0.3 m · kg, 2.2 ft · lb)