Even if you have no experience repairing cars, you can check your brake pads and the condition of the rotors with these simple how to instructions.
Measure the pad thickness by placing the compass points between the backing plate and the rotor. Measure the thickness at both the top and the bottom of the pad.
Run your fingernail across the rotor surface. If your nail catches in deep grooves, the rotors should be machined or replaced as a pair.
Here’s how to check your brakes yourself in two steps. First find a safe area to test your brakes and check for brake pedal pulsation. Brake to a stop from about 30 mph. The pedal should feel smooth with no pulsation at all. Then try braking at highway speeds. If you get pulsation, the rotors are “warped” and must be machined or replaced.
With the engine cold, remove a front wheel. Then use a compass and a tape measure to check the brake pad thickness (Photo 1). A new brake pad is about 1/2 in. thick. Replace the pads when they get down to 1/8 in. Compare the readings top to bottom; they shouldn’t vary by more than 1/16 in. If they do, the caliper isn’t releasing properly and must be serviced. Finally, check the rotor disc for grooves (Photo 2).