When you replace your brake pads, which is the simplest part of repairing the brakes on your car, you release the pressure on the calipers that hold the brake pads against the brake rotors or disks. The friction of the pads against the rotors or discs is what stops the vehicle. Here is how to seat the new brake pads properly.
Reattach the brake caliper to the wheel. Make sure you have compressed the caliper enough to fit it over the disc with the new pads. Because the new pads are thicker than the older ones, you may have to remove the new pads and spread the calipers a bit more to fit it around the wheel. Snug down the bolts to the caliper until it is in place, and then give the bolts one last good, tight turn on the wrench.
Check the master cylinder reservoir under the hood to make sure you have enough fluid. If you don't, refill the reservoir to the fill line. If the level of brake fluid falls too low, air may get into the brake lines. Braking when air is in the lines makes the pedal feel soft due to the compressibility of the air.
Get behind the driver's wheel and press the brake pedal. This act forces hydraulic brake fluid into the brake system and applies pressure to the calipers on the wheels. As pressure is applied, the gap between the brake pads and the brake disc will close until the brake pads are seated on the surface of the disc. Pump the brake a few more times and make sure the pedal feels solid, with no softness. Hold your foot on the pedal and make sure itl doesn't start strong and then soften after a minute or so.
