Replace semi-metallic brake linings with semi-metallics, nonasbestos organic (NAO) linings with nonasbestos, and asbestos linings with either asbestos or NAO.
Asbestos linings should never be substituted for semi-metallics. Asbestos in such an application will wear too quickly and may not provide the stopping power necessary for safe braking.
Semi-metallic linings are usually required on the front brakes of front-wheel drive cars because of higher operating temperatures. Front brakes typically handle up to 85% of the brake load. Semi metallic linings help conduct heat away from brake rotors. Asbestos does not because it is an insulator.
If asbestos linings are used in a FWD application, brakes may run too hot. Since heat is directly proportional to lining life, asbestos pads won’t last.
Most friction suppliers offer a choice between economy and premium replacement linings. Some also offer a midrange lining. Most people either want the best replacement linings or the cheapest. Recommend a quality brand of premium lining because they will last longer and they generally provide better braking performance.
To assure maximum performance, quiet operation and long life, rotors and/or drums should be resurfaced when linings are replaced. You might also recommend shims or an antisqueal compound for application to the backs of disc brake pads. These help dampen vibrations to quiet brake squeal.