the bleed valve(s), and fill the reservoir with
apply the brake by the brake
lever or pedal, close the valve with the brake held
applied, and then quickly release the lever or pedal.
until the brake line is filled
and fluid starts coming out of the plastic hose.
Replenish the fluid in the reservoir as often as nec-
essary to keep it from running completely out.
the air from the lines (See the next paragraph).
The brake fluid has a very low compression coef-
ficient so that almost all the movement of the brake
lever or pedal is transmitted directly to the caliper
for braking action. Air, however, is easily compressed.
When air enters the brake lines, brake lever or pedal
movement will be partially used in compressing the
This will make the lever or pedal feel spongy, and there
will be a loss in braking
the air from the brake whenever brake lever
or pedal action feels soft or spongy, after the brake
fluid is changed, or whenever a brake line fitting has
been loosened for any reason.
and check that there is
plenty of fluid in the
The fluid level must
be checked several times during the bleeding operation
and replenished as
If the fluid in the
voir runs completely out any time during bleeding, the
bleeding operation must be done over again from the
beginning since air will have entered the line.
Bleeding the Brake Line
Hold the brake
open and close the
Release the brake.
the reservoir cap off, slowly pump the brake lever
or pedal several times until no air bubbles can be seen
riding up through the fluid from the holes at the
bottom of the
This bleeds the air from the
master cylinder end of the line.
and connect a clear plastic
hose to the bleed valve at the caliper, running the other
end of the hose into a
Pump the brake lever
or pedal a few times until it becomes hard and then,
holding the lever squeezed or the pedal pushed
quickly open (turn counterclockwise) and close the
bleed valve. Then release the lever or pedal.
this operation until no more air can be seen coming out
into the plastic
Check the fluid level in the
ervoir every so often, replenishing it as necessary.
a dual disc
ous step one
more time for the other side
air bleeding is finished, tighten the bleed valve to
0.80 kg-m (69 in-Ibs) of torque, and install the rubber
the brake fluid level through the inspection
window in the reservoir. With the master cylinder held
level, the fluid should be filled more than level line
marked next to the window.
A. Inspection Window
B. Level Lines
Master cylinder parts
When master cylinder parts are worn or damaged
brake fluid pressure cannot be obtained in the
line, and the brake will not hold
the small relief port becomes
with a swollen or damaged
the brake pads
will drag on the disc
that there are no
rust or pitting on
and that it is not
worn past the service limit.
the pi,ston for these same
The cups are part
the piston assembl
place the piston assembl
one of the cups requires
I f a cup is
it. When inserting the cup into the
it is slightly larger than the cylinder (standard values
given in Table
If fluid leakage is noted at
brake lever, the cups should be replaced.