How to break in brake pads
Brake pad break-in, brake pad burnishing, or brake pad bedding procedure
Just about every brake pad manufacturer now recommends a brake pad break in procedure when installing new pads. Some manufacturers call it a brake pad break in procedure, while others call it a bedding in or brake pad burnishing procedure.
The process does at least three things to the pads and the rotor:
1. The cycle physically converts the composition of the pad and rotor surfaces.
2. It also smooths the roughness, unevenness of the mating surfaces.
3. Finally, it heat cycles the entire pad structure
What does brake pad bedding do?
The brake pad bedding procedure process works two ways depending on the type of brake pad. If the pads are made of “adherent” material (think ceramic and NAO type brake pads), the bedding process transfers a thin film of brake friction material to the pores of the rotor. Adherent brakes work by literally rubbing a brake pad against a thin film of the same brake material. The friction material contains special lubricants and raw materials that create sticky friction, but also lubricate to prevent chatter and vibration. You’ll find this composition on many ceramic style break pads. Adherent pads are much gentler on rotors.
If the pads are made of abrasive material (think semi-metallic), the bedding process acts like a polishing procedure to mate the pad to the rotor. Semi-metallic brake pads have a high metal content, so you’re literally rubbing metal against metal to wear the surfaces into one another. Abrasive pad material works by creating friction that wears away the surface of the rotor.
What is the brake pad break in procedure?
There is no single brake pad brake in procedure. Anyone who tells you to perform a certain procedure without knowing what brake pads you installed is someone who doesn’t know what they’re talking about. In fact, there’s a lot of really bad break in advice on the Internet including advice to slam on the brakes. All that does is overheat the brake pads and cause them to glaze over. From that point on, you’ll have noisy brakes.
There are several brake pad break in procedures. One common method is called 30-30-30. You make a gradual stop from 30-mpg, let the brakes cools for 30-secs, and repeat 30 times.
But each brake pad manufacturer may have their own preferred method. Here’s the instructions from Raybestos:
Raybestos burnishing procedure
• Perform 8 moderate brake applications from 40 to 10 mph at approximately ¼-mile intervals.
• Then perform 8 somewhat harder brake applications from 60 to 10 mph at approximately ½-mile intervals.
• Next, drive 1.5 miles
• Perform 5 hard (but less than ABS) applications from 80 to 20 mph at 3/4-mile intervals. Drive at least two miles after last application.
• Finally, allow brakes to cool at least 15 minutes either by parking the vehicle or continuing to drive at moderate speeds with minimal brake applications.
*If practical. If not, repeat the 60 to 10 mph section.
The WORST suggestion I see on the Internet is slam on the brakes from 50MPH as a way to break in the pads. That’ll overheat the pads and rotors resulting in glazed pads. They’ll never work properly after that.
Consult the brake pad manufacturer’s website to find their recommended brake pad break in procedure.
Here’s an example of a break in procedure from a major car maker
From GM service bulletin PIC5268C
“If the brake pads and rotors are replaced it is important to burnish the new brake linings. This is done by driving the vehicle 25-35 MPH and doing 10 separate brake applies from this MPH to a stop. Allow the brakes to cool down (15 minutes – 1/2 hour) and repeat the 10 brake applies at the MPH stated. Allow the brakes to cool down and do this procedure one final time.”
©, 2015 Rick Muscoplat
Posted on by Rick Muscoplat