The difference between adherent and abrasive brake pads

The difference between adherent and abrasive brake pads and how each type stops your car

Brake pads use either adherent or abrasive friction material, But no brake pad is 100% abrasive or adherent. Abrasive brake pads contain some lubricant additives and have some adherent qualities. Adherent brake pads contain some abrasive components. There are advantages and disadvantages to each type. Learn the differences between adherent and abrasive brake pads.

Abrasive friction material explained

In simple terms, abrasive brake pads create stopping power by pressing hard abrasive brake pads against a softer metal brake rotor. In this application, the brake pad acts like sandpaper and the rotor is like wood.

It’s this mechanical rubbing of an abrasive material against the metal rotor that converts kinetic energy into heat that stops the vehicle. Abrasive pads wear away the rotor surface much faster than it wears out the brake pads.

The most common “abrasive” brake pads are semi-metallic. Due to their construction, hardness and abrasiveness, they provide the best stopping power of all brake pad types. That’s why they’re used on heavy SUV, light trucks and larger trucks.

Adherent friction material uses a transfer layer

Adherent brake pads operate differently. During the break-in or ‘bedding” operation,  the technician or owner drives the vehicle and makes multiple smooth brake applications to heat up the brake pad’s friction surface in order to deposit a thin film of brake pad friction material into the pores of the rotor face. The thin film of brake pad material that adheres to the rotor face is called the transfer layer.

During all future braking the brake pad friction material presses against the transfer layer, creating friction. This film-n-film braking creates heat by rubbing a hot sticky friction material against a hot sticky transfer layer.

The heat breaks the transfer layer bond to the rotor, changing the transfer layer on a molecular basis. The brake pad then replaces the damaged transfer layer with a new layer of material from the brake pad. The process of damaging and replacing the transfer layer happens multiple times during braking.

Because the brake pads are always depositing a new transfer layer onto the rotor, the pads wear faster in this system than the brake rotor.

The most common adherent brake pads are non-asbestos organic (NAO) and ceramic.

Adherent friction has less stopping power than abrasive friction. But it is easier on the rotors, makes less noise than abrasive friction, and gives off far less brake dust.

©, 2022 Rick Muscoplat