Some manufacturers call for brake inspections as often as every six months. The norm, however, seems to be every 12/24 months.

As you apply the brake pedal, check for excessive travel and sponginess. Listen for noises - not just the obvious grinding of the pads or shoes, but also mechanical clanks, clunks and rattles. A pulsating pedal normally indicates that a rotor is warped or a drum is out-of-round. You can check power booster operation by pressing the pedal several times with the engine off and then starting the engine with the brakes applied. When the engine is started with the pedal depressed, the pedal should drop slightly as vacuum hits the booster.

For a complete inspection, you'll have to remove the wheels, to get a clear view of the brake pads and caliper mounting hardware. Now is the time to verify smooth caliper operation and lubricate, if necessary.

Normally, you can check disc brake pad lining thickness through the openings in the calipers, but you'll have to pull the drums to check the linings on drum brakes. In either case, most carmakers specify a minimum thickness of 1/32”. However, you may want to change disc pads when the lining is 1/8” thick or less. 1/32” may be the minimum to prevent rotor or drum scoring, but braking efficiency is dramatically reduced with worn linings because they're unable to dissipate the heat.

A careful visual inspection of rotors often reveals problems. Use a caliper (or micrometer if you have one) to measure thickness at six or more points around the rotor, and check flatness across the face using a straightedge. When checking brake drums measure the diameter at several points to check for "out-of-roundness". In some cases, it may be possible to re-machine it. Nowadays though, the cost of replacement is generally a better value compared with the cost of re-machining.