brake YAMAHA YZ125LC 2003 Owner's Guide

5-1
CHASFRONT WHEEL AND REAR WHEEL
Extent of removal Order Part name Q’ty Remarks
FRONT WHEEL REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
1 Hose cover 1
2 Bolt (brake hose holder) 2 Only loosening.
3 Bolt (axle holder) 4 Only loosening.
4 Nut (front wheel axle) 1
5 Front wheel axle 1
6 Front wheel 1
7 Collar 2
8 Oil seal 2
9 Bearing 2 Refer to “REMOVAL POINTS”.
10 Brake disc 1
EC500000
CHASSISEC590000
FRONT WHEEL AND REAR WHEELEC598000
FRONT WHEEL
2
13
3
Extent of removal:1Front wheel removal2Wheel bearing removal3Brake disc removal
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Support the machine securely so there is no dan-
ger of it falling over.
23 Nm (2.3 m•kg, 17 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
105 Nm (10.5 m•kg, 75 ft•lb)
16 Nm (1.6 m•kg, 11 ft•lb)
7 Nm (0.7 m•kg, 5.1 ft•lb)12 Nm (1.2 m•kg, 8.7 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)

5-2
CHASFRONT WHEEL AND REAR WHEEL
EC598100
REAR WHEEL
Extent of removal:1Rear wheel removal2Wheel bearing removal3Brake disc removal
Extent of removal Order Part name Q’ty Remarks
REAR WHEEL REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
1 Nut (rear wheel axle) 1
2 Rear wheel axle 1
3 Chain puller 2
4 Rear wheel 1 Refer to “REMOVAL POINTS”.
5 Collar 2
6 Driven sprocket 1
7 Oil seal 2
8 Circlip 1
9 Bearing 2 Refer to “REMOVAL POINTS”.
10 Brake disc 1
2
13
3
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Support the machine securely so there is no dan-
ger of it falling over.
125 Nm (12.5 m•kg, 90 ft•lb)
14 Nm (1.4 m•kg, 10 ft•lb)
16 Nm (1.6 m•kg, 11 ft•lb)
16 Nm (1.6 m•kg, 11 ft•lb)
42 Nm (4.2 m•kg, 30 ft•lb)

5-4
CHASFRONT WHEEL AND REAR WHEEL
EC514200
Wheel axle
1. Measure:
9Wheel axle bends
Out of specificationReplace.
Use the dial gauge 1.
NOTE:
The bending value is shown by one half of the
dial gauge reading.
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Do not attempt to straighten a bent axle.
EC594200
Brake disc
1. Measure:
9Brake disc deflection (only rear brake disc)
Use the dial gauge 1.
Out of specificationInspect wheel runout.
If wheel runout is in good condition, re-
place the brake disc.
2. Measure:
9Brake disc thickness a
Out of limitReplace.
Wheel axle bending limit:
0.5 mm (0.020 in)
Disc wear limit:
Standard
Front 3.0 mm (0.12 in) 2.5 mm (0.10 in)
Rear 4.0 mm (0.16 in) 3.5 mm (0.14 in)
Disc deflection limit:
Standard
Rear —
0.15 mm (0.006 in)

5-5
CHASFRONT WHEEL AND REAR WHEEL
EC595000
ASSEMBLY AND INSTALLATION
EC595101
Front wheel
1. Install:
9Bearing (left) 1
9Spacer 2
9Bearing (right) 3
9Oil seal 4
NOTE:
9Apply the lithium soap base grease on the
bearing and oil seal lip when installing.
9Use a socket that matches the outside diam-
eter of the race of the bearing.
9Left side of bearing shall be installed first.
9Install the oil seal with its manufacture’s
marks or numbers facing outward.
cC
Do not strike the inner race of the bearing.
Contact should be made only with the out-
er race.
2. Install:
9Brake disc 1
9Bolt (brake disc) 2
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
3. Install:
9Collar 1
NOTE:
9Apply the lithium soap base grease on the oil
seal lip.
9Install the collars with their projections afacing
the wheel.
4. Install:
9Wheel
NOTE:
Install the brake disc 1between the brake pads
2correctly.
12 Nm (1.2 m•kg, 8.7 ft•lb)

5-6
CHASFRONT WHEEL AND REAR WHEEL
5. Install:
9Wheel axle 1
NOTE:
Apply the lithium soap base grease on the wheel
axle.
6. Install:
9Nut (wheel axle) 1
7. Tighten:
9Bolt (axle holder) 1
NOTE:
Before tightening the bolt, fit the wheel axle to
the axle holder by stroking the front fork several
times with the front brake applied.
8. Install:
9Brake hose 1
To brake hose holder 2.
NOTE:
Before tightening the bolt (brake hose holder),
align the top aof the brake hose neck with the
brake hose holder bottom b. Then pass the
brake hose in front of the axle boss cand fit it
into the hose groove dso that the brake hose
does not contact the nut (wheel axle).
105 Nm (10.5 m•kg, 75 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)

5-7
CHASFRONT WHEEL AND REAR WHEEL
EC5251A1
Rear wheel
1. Install:
9Bearing (right) 1
9Circlip 2
9Spacer 3
9Bearing (left) 4
9Oil seal 5
NOTE:
9Apply the lithium soap base grease on the
bearing and oil seal lip when installing.
9Install the bearing with seal facing outward.
9Use a socket that matches the outside diam-
eter of the race of the bearing.
9Right side of bearing shall be installed first.
9Install the oil seal with its manufacture’s
marks or numbers facing outward.
cC
Do not strike the inner race of the bearing.
Contact should be made only with the out-
er race.
2. Install:
9Brake disc 1
9Bolt (brake disc) 2
NOTE:
Tighten the bolts in stage, using a crisscross
pattern.
9. Install:
9Hose cover 1
9Plain washer 2
9Bolt [hose cover (M8)] 3
9Bolt [hose cover (M6)] 4
16 Nm (1.6 m•kg, 11 ft•lb)
7 Nm (0.7 m•kg, 5.1 ft•lb)
14 Nm (1.4 m•kg, 1.0 ft•lb)

5-8
CHASFRONT WHEEL AND REAR WHEEL
3. Install:
9Driven sprocket 1
9Bolt (driven sprocket) 2
9Plain washer (driven sprocket) 3
9Nut (driven sprocket) 4
NOTE:
Tighten the nuts in stage, using a crisscross pat-
tern.
4. Install:
9Collar 1
NOTE:
Apply the lithium soap base grease on the oil
seal lip.
5. Install:
9Wheel
NOTE:
Install the brake disc 1between the brake pads
2correctly.
6. Install:
9Drive chain 1
NOTE:
Push the wheel 2forward and install the drive
chain.
7. Install:
9Chain puller (left) 1
9Wheel axle 2
NOTE:
9Install the chain puller (left), and insert the
wheel axle from left side.
9Apply the lithium soap base grease on the
wheel axle.
42 Nm (4.2 m•kg, 30 ft•lb)

5-10
CHASFRONT BRAKE AND REAR BRAKE
Extent of removal Order Part name Q’ty Remarks
FRONT BRAKE REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Drain the brake fluid. Refer to “REMOVAL POINTS”.
1 Hose cover 1
2 Brake hose holder 1
3 Bolt (brake hose holder) 2 Only loosening.
4 Union bolt 2
5 Brake hose 1
6 Pad pin plug 1
Remove when loosening the pad pin.
7 Pad pin 1Loosen when disassembling the caliper.
8 Caliper 1
9 Brake lever 1
10 Master cylinder bracket 1
11 Master cylinder 1
EC5A0000
FRONT BRAKE AND REAR BRAKEEC5A8000
FRONT BRAKE
Extent of removal:1Brake hose removal2Caliper removal3Master cyilinder removal
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Support the machine securely so there is no dan-
ger of it falling over.
2
1
3
3
2
9 Nm (0.9 m•kg, 6.5 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
3 Nm (0.3 m•kg, 2.2 ft•lb)
18 Nm (1.8 m•kg, 13 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
7 Nm (0.7 m•kg, 5.1 ft•lb)16 Nm (1.6 m•kg, 11 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
30 Nm (3.0 m•kg, 22 ft•lb)
30 Nm (3.0 m•kg, 22 ft•lb)

5-11
CHASFRONT BRAKE AND REAR BRAKE
EC5A8100
REAR BRAKE
Extent of removal Order Part name Q’ty Remarks
REAR BRAKE REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
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 1Loosen when disassembling the caliper.
8 Caliper 1
Extent of removal:1Master cylinder removal2Brake hose removal3Caliper removal
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Support the machine securely so there is no dan-
ger of it falling over.
2
3
31
1
1 Nm (0.1 m•kg, 0.7 ft•lb)
30 Nm (3.0 m•kg, 22 ft•lb)
30 Nm (3.0 m•kg, 22 ft•lb)
3 Nm (0.3 m•kg, 2.2 ft•lb)
18 Nm (1.8 m•kg, 13 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
26 Nm (2.6 m•kg, 19 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
7 Nm (0.7 m•kg, 5.1 ft•lb)

5-12
CHASFRONT BRAKE AND REAR BRAKE
Extent of removal Order Part name Q’ty Remarks
CALIPER DISASSEMBLYAB
1Pad pin 1 1
2Brake pad 2 2
3Pad support 1 1
4Caliper piston 2 1 Refer to “REMOVAL POINTS”.
5Dust seal 2 1
Refer to “REMOVAL POINTS”.
6Piston seal 2 1
EC5A8200
CALIPER DISASSEMBLY
A Front
B Rear
Extent of removal:1Front caliper disassembly2Rear caliper disassembly
21



6 Nm (0.6 m•kg, 4.3 ft•lb)
3 Nm (0.3 m•kg, 2.2 ft•lb)18 Nm (1.8 m•kg, 13 ft•lb)
6 Nm (0.6 m•kg, 4.3 ft•lb)
18 Nm (1.8 m•kg, 13 ft•lb)
3 Nm (0.3 m•kg, 2.2 ft•lb)