Bleeding the Brake Line
The brake fluid has a very low compression coefficient 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 air. This will make the lever or pedal feel
spongy, and there will be a loss in braking power.
Be sure to bleed the air from the brake whenever
brake lever or pedal action feels soft or spongy, af-
ter the brake fluid is changed, or whenever a brake
line fitting has been loosened for any reason.
The procedure to bleed the front brake line is as follows.
Bleeding the rear brake line is the same as for the front
Remove the reservoir cap and diaphragm, and then fill
the reservoir with brake fluid to the upper level line [A] in
The fluid level must be checked often during the bleed-
ing operation and replenished with fresh brake fluid as
necessary. If the fluid in the reservoir runs almost out
any time during bleeding operation, the bleeding opera-
tion must be done over again from the beginning since
air will have entered the line.
With the reservoir cap off, slowly pump the brake lever
several times until no air bubbles can be seen rising up
through the fluid from the holes at the bottom of the reser-
voir. Bleed the air completely from the master cylinder by
Tap the brake hose lightly from the caliper to the reser-
voir for easier bleeding.
Install the reservoir cap.
Attach a clear plastic hose [A] to the bleed valve on the
caliper, and run the other end of the hose into a container.