Disk Brakes

Calipers

The caliper is an assembly mounted to the vehicle with a bracket so it wraps around two sides of the rotor.
It looks and functions likea c-clamp. It contains:

Brakepads: metal plates bonded with material that provides stopping friction.
One or two pistons to push the brake pads against the rotor when you brake.
A bleeder screw to allow for servicing the brakes and replacing the fluid.
A rubber piston seal that prevents brake fluid leakage and retracts the piston when the brakes release.
A dust boot to keep contaminants out of the cylinder.
Anti-rattle clips that keep the brake pads stable.

Rotor

The rotor is made of cast iron or a steel/cast iron composite. It’s attached to the wheel hub and turns with the wheel. It’s the surface the brake pads contact. When you step on the brakes, pressurized brake fluid pushes against the pistons inside the caliper, forcing the brake pads against the rotor. As the brake pads press against both sides of the disc, the friction stops the wheel’s rotation.

Rotors can either be solid or vented. Vented ones have more surface area which allows for more contact with atmosphere (air) to dump heat to ... This is heat dissapation.

Brake Pads

There are three main types of brake pads:

semi-metallic,
non-asbestos organic (NAO), and
ceramic

The diagram to the right lists the pros and cons of each type!

For more information visit Wagner.

Thickness Guages are a quick way of measuring Pad thickness

Green is Good to go, basically new pads and are around 12mm thick

Yellow is Worn and should be replaced soon and are around 4.5mm thick

Red is Worn and should be replaced IMMEDIATELY! They are around 3mm thick

Lubrication

Two lubricants are used. For metal on metal rubbing where there is minimal movement over time, an anit-sieze compound like copper cote is used (for example on pad backs and mounting tabs)

For bushings and slide pins, a silicone lubricant is generally used

Fixed Calipers

Fixed calipers have pistons on both sides of the rotor which will squeeze in on the rotor in unison.

Floating Calipers

Floating calipers generally have pistons on one side only which allows the caliper to slide on the slide pins to press the pads against both sides of the roter

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