Ideally, brake linings should be composed of relatively soft but tough and heat resistant material (e.g.CHRYSOTILE) with a high coefficient of dynamic friction (and ideally an identical coefficient of static friction). Typically, it is mounted on solid metal backing using high-temperature adhesives or metal rivets. The complete assembly of the brake lining and metal backing is often called the brake pad or brake shoe.
Using a typical bicycle brake as an example, the backing would be the metal shell which provides mechanical support, and the lining would be the rubbery portion which contact the rims when the brakes are applied.
The lining is the portion of the braking system which converts the vehicle's kinetic energy into heat during breaking, therefore, the brake lining must be capable of surviving high temperatures without excessive wear.
In this view of an automobile brake assembly, the brake lining is the light material held by the metal component (brake shoe). The brake lining is that part which actually contacts the brake drum when the brake is engaged.
The brake shoe carries the brake lining which is riveted or bonded to the shoe. When the brake is applied, the shoe moves and presses the lining against the inside of the drum. The friction between the lining and drum provides the braking.
The best kind of maintenance is preventive maintenance--checking your machines before anything happens. For automotive brakes, the best time for brake lining preventive maintenance is when you rotate your tires. Check if the linings are worn or nearly worn out. REMEMBER - Replacing brake linings are cheaper than replacing your brake drums.
When the brake lining is worn out, the backing or rivets will get in contact with the rotor/ brake drum during breaking generating an annoying squeal. If left unattended, the rotor/brake drum will eventually be damaged requiring re-facing/machining or even costly replacement.
The lining may also become contaminated by leaking oil or leaked brake fluid. The typical sign is brake chatter (the pads vibrate as contact slips from the drum/rotor). The solution is to repair the source of the leak and replace the damaged linings for safety reasons.
The brake linings on the brake shoe/pad installed on each end of the same axle must always be replaced at the same time. Failure to do so will cause difficulty in steering the vehicle due to uneven braking. Upon applying the brakes, a vehicle may lurch in the direction of the side of the new lining and lag on the side with the old lining. For most vehicles, replacing the linings is very easy, requiring a minimum of tools and time--the linings are designed to be consumable and should therefore be easy to service. <<MORE>>
Since the brake systems of almost all cars differ, THE FOLLOWING INFORMATION SHOULD BE CONSIDERED ONLY AS A VERY GENERAL GUIDE ON HOW TO CHANGE YOUR BRAKE PADS. Some specialized procedures will not be covered.
GET THE CORRECT BRAKE LININGS- Linings are available at any auto parts store or your local car dealership. Just let them know the year, make and model of your vehicle.
MAKE SURE THE VEHICLE IS COOLED DOWN - If you have recently driven, you may be working with extremely hot linings, shoes and drums.
REMOVE THE WHEELS - Loosen the lug nuts, before jacking the car up. Take off the lug nuts and then pull the wheel towards you.
REMOVE THE WHOLE BRAKE DRUM - to lessen confusion later on when you have to reinstall the drum brakes, take a picture of the original placings so that you will have a reference.
BRAKE SHOES should be of the same width and should have the same hole placements so that they fit.
TAKE OUT THE RETURN SPRINGS
REMOVE the BRAKE LEVER.
TAKE OUT THE RETAINING SPRINGS.
SPREAD BRAKE SHOE PARTS on your workstation and unfasten them from the cylinder pins.
TAKE OUT the SELF ADJUSTER from the new brake shoes and attach them right after you remove the spring.
REPLACE the SELF ADJUSTER and align the holes to properly secure the retainer pins.
REATTACH the BRAKE SHOES to the cylinder pins and replace the parking brake lever.
REINSTALL the BRAKE SPRINGS and refer to the photograph which you took if there are any inconsistencies with your work.
ADJUST BRAKE SHOES - After brake shoes have been installed, they need to be adjusted. Normally, they are self-adjusting but the first time after installation, a primary adjustment must be made. After installing the brake drum and spinning it on the bearing hub, adjust the brake shoes to lightly contact the brake drum and recheck regularly.
BLEED THE BRAKE SYSTEM - until free from air and leaks
PUT the DRUM on the STUDS
PUT the TIRE BACK.
REMOVE the JACK stands once you've finished your work on one side. Continue with the other wheels.
!!! IMPORTANT: ALWAYS TEST BRAKE SYSTEM BEFORE DRIVING !!!.