Why Bench Bleeding
Many of us are guilty of installing a new master cylinder right out of the box. Did you know doing that runs the risk of having unwanted trapped air in the braking system? Air must be removed from the master cylinder prior to installation. All you have to do is locate the master cylinder in a bench vice, fill it with fluid, and slowly press the piston, as shown here. Watch the bubbles pass from the cylinder back into the reservoir. Once all air traffic is gone, the cylinder is bled and ready for installation, but install and secure the cap first.