Introduction; Checking The Front Brake Disc; Removing The Front Brake Caliper; Disassembling The Front Brake Caliper - Yamaha YZ 2019 Series Owner's Service Manual

EAM30028

INTRODUCTION

EWA19210
WARNING
If you need to disassemble the disc brake
components, observe the following precau-
tions.
• Never disassemble the brake components
unless absolutely necessary.
• If there is any problem with connections on
the hydraulic brake system, perform the
following jobs. Disassemble the brake sys-
tem, drain the brake fluid, and clean it. After
that, add a suitable amount of brake fluid.
Then, bleed it after reassembly.
• Use only brake fluid for washing brake
components.
• Use new brake fluid for cleaning the brake
components.
• Immediately wipe off the spilled brake fluid
to avoid damage to painted surfaces or
plastic parts.
• Handle brake fluid with special care not to
let it enter your eyes so that you may not
lost your eyesight.
• FIRST AID FOR BRAKE FLUID ENTERING
THE EYES:
• Flush with water for 15 minutes and get im-
mediate medical attention.
EAM30029

CHECKING THE FRONT BRAKE DISC

1. Remove:
• Front wheel
Refer to "FRONT WHEEL" on page 4-3.
2. Check:
• Front brake disc
Damage/galling  Replace.
3. Measure:
• Brake disc thickness
Measure the brake disc thickness at a few dif-
ferent locations.
Out of specification  Replace.
Brake disc thickness limit
2.5 mm (0.10 in)
4. Install:
• Front wheel
Refer to "FRONT WHEEL" on page 4-3.
EAM30030

REMOVING THE FRONT BRAKE CALIPER

TIP
Before disassembling the brake caliper, drain
the brake fluid from the entire brake system.
1. Remove:
• Union bolt
• Copper washer
• Brake hose
TIP
Put the end of the brake hose into a container
and pump out the brake fluid.
EAM30031
DISASSEMBLING THE FRONT BRAKE
CALIPER
1. Remove:
• Brake caliper piston "1"
• Brake caliper piston dust seal "2"
• Brake caliper piston seal "3"
1
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Blow compressed air into the brake hose joint
opening to force out the piston from the brake
caliper.
EWA13550
WARNING
• Cover the brake caliper piston with a rag.
Be careful not to get injured when the pis-
ton is expelled from the brake caliper.
• Never try to pry out the brake caliper pis-
ton.
4-15
FRONT BRAKE
3
2