How to Break In Brake Pads and Rotors
Pad and Rotor Break-In/Bed-In Instructions
Proper brake pad and rotor bed-in helps new brake components work the way they should. The goal is to bring the pads and rotors up to operating temperature in a controlled way, then allow a thin, even layer of pad material to transfer onto the rotor face. When that transfer layer forms correctly, the brakes are less likely to squeal, pulse, glaze, or feel inconsistent during normal use.
When following these instructions, avoid doing it in the presence of other vehicles. Breaking in your new pads and rotors is often best done very early in the morning or in a safe, open area where you are not surprising other drivers. Other drivers will have no idea what you are doing and may respond with fear, curiosity, or aggression. An officer of the law may not understand when you try to explain why you were driving erratically. PMB Performance does not endorse speeding on public roads and takes no responsibility for any injuries, damage, or tickets you may receive while following these instructions.
Step 1: Warm the Brakes Gradually
From a speed of about 60 mph, gently apply the brakes to slow the car down to about 45 mph, then accelerate back up to 60 mph and repeat. Do this about four or five times to bring the brakes up to operating temperature. This first step matters because it prevents you from thermally shocking the rotors and pads during the harder stops that come next.
Step 2: Perform the Main Bed-In Stops
Make a series of eight near-stops from 60 mph down to about 10 mph. Do it hard by pressing on the brakes firmly, just shy of locking the wheels or engaging ABS. At the end of each slowdown, immediately accelerate back to 60 mph. Do not come to a complete stop during this process.
With less aggressive street pads or stock brake calipers, you may need fewer than eight near-stops. Pay attention to the pedal and the way the brakes feel. If the pedal gets soft or you feel the brakes starting to go away, you have done enough and should move to the cooling step.
Why You Should Not Stop During Bed-In
During the bed-in process, you must not come to a complete stop because the pads can imprint material onto one spot on the hot rotor face. That uneven transfer can lead to vibration, pedal pulsation, uneven braking, and, in some cases, damaged rotors. Keep the car moving after each near-stop so the rotors can continue rotating while the pad material transfers more evenly.
What You May Notice
Depending on the pads you are using, the brakes may begin to fade slightly after the seventh or eighth near-stop. This fade should stabilize, but it will not completely go away until the brakes have fully cooled. A bad smell from the brakes, and even some smoke, is normal during a proper bed-in cycle. That heat is part of the process, but you still need to pay attention to brake feel and stop if the pedal becomes too soft.
Step 3: Cool the Brakes
After the eighth near-stop, accelerate back up to speed and drive around for as long as possible without using the brakes. The brakes need at least 10 minutes to cool down. It is fine to use the brakes to avoid an accident, but try to minimize brake use until the pads and rotors have cooled.
Additional Stops for Race Pads
If club race pads are being used, add four near-stops from 80 mph down to 10 mph. If full race pads are being used, add four near-stops from 100 mph down to 10 mph. These more aggressive compounds usually need more heat before they begin working properly, but the same rule still applies: do not come to a complete stop with the brakes hot.
What Proper Bed-In Looks Like
After the break-in cycle, there should be a blue tint and a light gray film on the rotor face. The blue tint tells you the rotor has reached break-in temperature. The gray film is pad material starting to transfer onto the rotor face. This is what you are looking for.
The best braking occurs when there is an even layer of pad material deposited across the face of the rotors. That transfer layer helps minimize squealing, increases braking torque, and improves pad and rotor life. If the transfer layer is uneven, the brakes may feel rough, noisy, or inconsistent even when the parts are new.
Second Bed-In Cycle
After the first break-in cycle shown above, the brakes may still not be fully bedded in. A second bed-in cycle, after the brakes have cooled down fully from the first cycle, may be necessary before the brakes really start to perform well.
If you have just installed a big brake kit, the pedal travel may not feel as firm as expected after the first cycle. After the second cycle, the pedal will usually become noticeably firmer as the pads and rotors finish seating together.