Checking brake pads

Part 1. Preparation and safety

Objective

• Check brake pads and calipers. Check and measure rotors.

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection - such as rubber gloves and barrier cream
• Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

• Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.

Points to note

• Most vehicles have four-wheel disc brakes.
• You should check the disc brakes and disc brake linings every 15,000 kilometers (10,000 miles).
• After checking the brake pads, replace the road wheel but don't put lug nuts into the socket of the impact wrench and power the lug nuts on; this practice can lead to the wheel nuts going on cross-threaded.
• When inspecting the caliper be very careful because the caliper may be hot if the car has been driven recently.

Part 2: Step-by-step instruction

1. Check brake caliper
   Make sure the caliper is cool to the touch, then grasp it and try to move it to make sure it’s mounted securely.
2. Check brake pads
   Look through the dust shield on the caliper and look at the brake pads. Check the linings on the brake pads. If they are too worn, they may have to be replaced. The easiest way to estimate the wear is to look at the thickness of the backing plate of the pad, and, if the thickness of the remaining brake lining surface of the pad is the same or less than that of the thickness of the backing plate, the pads should be replaced. If the linings have worn so much that they are running on the pads backing plates, have your supervisor inspect the system, as the disc may have to be reground.
3. Check and measure the rotor
   Check the visible part of the rotor for rust, scoring, and uneven wear. Check the shop manual for the specifications of this rotor and measure its thickness with an outside micrometer. If the reading is outside the manufacturers specification, report it to your supervisor. Repeat these procedures for the other three wheels.