The braking component responsible for the moment that creates friction is the Pontiac disc brake calipers. This is the part that ultimately transforms hydraulic pressure into mechanical motion when the piston pushes against the brake pads. It is this friction of the brake pads against the brake rotors that actually stops your vehicle. The disc brake caliper fits over the rotor on the wheel assembly and holds pads firmly on both sides of the rotors so that friction can be equally applied to both sides at the same time. The Pontiac disc brake caliper is made entirely of metal and will not wear out except for the polymer seals around the pistons. This seal retains the pressurized hydraulic fluid, and will show signs of wear as it ages and is used. Eventually the seal in the disc brake caliper will crack or split allowing for brake fluid to exit this otherwise closed loop system on your Pontiac. Just like when there is a break in the brake line or hose, the loss of hydraulic fluid from the disc brake caliper seals can be felt in the brake pedal by it not being as stiff as before the system was breached. There will also be a puddle of brake fluid under your Pontiac near the front wheel assembly where the broken seal is located. The replacement of a failing disc brake caliper is performed similarly to a routine brake job with the addition of two extra steps. Not only does the hose on the disc brake caliper have to be removed, but since this closed loop system is now open to the atmosphere the brake system on your Pontiac will also have to be bled of air before it will function properly.