Brake Pad Break-In (Bedding): Meaning, Duration, Process & More
What is Brake Pad Bedding?
Brake pad bedding, also known as brake burnishing, refers to the process of transferring an even layer of brake pad material onto the surface of new brake rotors or drums through a series of heat cycles [1]. This is an important procedure when installing new brake pads and rotors, as it helps the two components mate properly for optimal braking performance.
New brake pads have a smooth surface, while new brake rotors have a shiny, freshly machined surface. Without bedding, the two surfaces can’t initially grip each other well. Bedding roughs up the rotor surface and deposits a thin transfer layer of brake pad material evenly across the rotor. This allows for better contact and friction between the pad and rotor, providing more consistent and reliable braking power [2].
Overall, bedding new brake pads and rotors ensures safe braking and reduces the chances of uneven or premature wear of the braking components. It’s a simple procedure that pays dividends through optimized brake system performance and longevity.
[1] https://tech.corvettecentral.com/2012/08/brake-pad-bedding-procedures-explained/
[2] https://www.quora.com/What-is-brake-bedding-and-what-is-its-importance
How Bedding Works
The process of bedding in brake pads transfers a thin layer of material from the pad’s friction surface to the rotor through a series of heat cycles (Autozone). As you apply the brakes, both the pad and rotor get hot through friction. When they cool down, some of the pad material gets deposited onto the rotor surface. This process repeats with successive cycles of heating and cooling to build up a uniform layer.
The end result is the creation of a smooth contact surface between the pad and rotor. This allows for more even distribution of clamping force and improved braking performance. Essentially it maximizes the contact area between the surfaces, allowing the pad and rotor to mate cleanly.
Recommended Bedding Procedure
The typical brake bedding procedure involves repeated cycles of accelerating to moderate speed and decelerating to low speed while applying firm brake pressure. This process transfers material from the brake pads onto the rotor surface and results in an even transfer layer that optimizes braking performance. According to experts at AutoZone, the basic steps are:
- Accelerate to approximately 45 mph without coming to a complete stop.
- Apply firm brake pressure to decelerate from 45 mph down to 10 mph, without locking up the wheels.
- Repeat this cycle of accelerating and firm braking around 20 times.
- Cool the brakes by cruising at 45 mph for 5-10 minutes between cycles.
It’s important to brake with moderate to firm pressure (around 50-80% brake force) rather than slamming the pedal to the floor. This allows the pad material to properly transfer to the rotor surface. Avoid dragging the brakes lightly, as this can cause uneven deposits. The key is quickly heating the brakes through firm application and then cooling them completely between cycles.
For high performance braking, PowerStop recommends more aggressive 30-0 mph cycles with full brake force. But take caution on public roads. Bedding on a closed track allows more effective speed ranges and brake pressures.
Bedding Period Duration
The typical timeframe for completing the bedding process for new brake pads and rotors is around 300-500 miles of driving in normal conditions. This allows sufficient heat cycles and pad contact with the rotors to transfer an even layer of material (https://www.tirerack.com/upgrade-garage/how-do-i-bedin-new-brake-pads-and-rotors).
Some factors that can affect the duration of the bedding period include:
- Driving conditions – More stop-and-go driving and braking creates faster heat cycles and pad transfer.
- Pad and rotor materials – More abrasive pads may require shorter bedding periods.
- Vehicle type – Heavier vehicles put more load on the brakes, accelerating the bedding process.
- Braking style – Harder, more aggressive braking helps pads mate and transfer faster.
- Experts recommend avoiding extended easy driving and taking the vehicle out for some brisk accelerations and harder braking after installations to complete the bedding process sooner (https://www.autozone.com/diy/brakes/bedding-brakes).
Signs Bedding is Complete
There are a few key signs that indicate the brake bedding process is complete:
The brakes will feel firmer and have more consistent pedal feel. As the pads transfer material to the rotors during bedding, braking performance becomes more predictable and responsive (Source 1). You should notice braking forces evening out between left and right wheels.
Visually inspect the brake pads and rotors. The pad surfaces should have an even transfer layer with no hot spots. The rotors should have an evenly distributed transfer layer with a light blue or straw color (Source 2). If you see uneven pad deposits or parts of the rotor with heavier transfer layers, additional bedding cycles may be needed.
There should be minimal brake fade after hard stops. Fade occurs when brake components overheat, so consistent pedal feel without fade indicates proper bedding.
You should not see or smell any smoke coming from the brakes. Smoke is a sign of overheating and inadequate bedding.
Consequences of Improper Bedding
Failing to properly bed in new brake pads can lead to several issues that negatively impact braking performance and pad life.
One consequence is uneven pad deposits on the rotor surface. When pads are not bedded in, the transfer layer that forms between the pad and rotor does not distribute evenly. This can cause thickness variations and hot spots on the rotor leading to vibrations and poor braking.
Braking performance is also reduced without proper bedding. The pads will not achieve optimal friction levels, so braking distances will be longer. Stopping power will never fully develop as designed by the manufacturer.
Finally, improper bedding frequently causes extra brake noise and squealing. The uneven transfer layer that forms often vibrates against the rotor, creating audible noises during braking. Bedding in the pads helps prevent this by smoothing the contact between the pad and rotor.
To avoid these issues, it is critical to follow the recommended bedding procedure when installing new brake pads and rotors. Taking the time to properly bed components ensures peak braking performance, noise-free operation, and maximum pad and rotor life.[1]
Bedding Race Brake Pads
Bedding in race brake pads requires some special considerations compared to street brake pads. Race pads are designed for repeated heavy braking at high temperatures, unlike street pads which are made for lighter braking over longer periods of time.
When bedding racing pads, it is recommended to start with very light brake applications to slowly build up heat in the pads and rotors. Aggressive braking right away can cause cracks or glazing in race pad material. Gradually increase brake pressure over multiple cycles, until reaching racing temperatures above 1000°F (538°C). This allows the pad material to transfer and properly adhere to the rotor surface [1].
The bedding cycle should be extended for race pads, up to 30-50 stops versus 10-20 for street pads. Allow pads to fully cool to under 300°F (149°C) between intervals to prevent overheating. Use an infrared thermometer to verify temperatures. Bedding should be done in a controlled environment like a track, not on public roads.
Unlike street pads, Semi-metallic and ceramic race pads require a proper heat cycle to reach maximum braking effectiveness. Take extra care to properly bed-in new race pads for safety.
Bedding Brake Pads After Change
Bedding in is crucial when installing new brake pads, as it transfers a thin layer of friction material to the brake rotor surface. This helps the pads grip and stop more efficiently. According to TireRack, bedding pads after a change is one of the most important steps to ensure optimum braking performance and pad life1.
The bedding process is the same as the initial break-in period, typically involving 20-30 stops from 60mph down to 5-10mph. Gradually increase brake pressure with each stop to transfer material. It’s normal for some smoke and smell during the bedding process. Allow brakes to fully cool between intervals. Focus on maintaining brake system temperatures and avoid overheating. The goal is an even transfer layer without glazing or cracking the rotor surface.
For high performance pads, an even more rigorous process may be required per the manufacturer instructions. Race pads can take 50-100 miles to fully bed in. Street performance pads may only need 10-15 hard stops. So check specifications and break in as directed.
Bedding vs Burnishing
Bedding and burnishing are often used interchangeably, but they refer to slightly different processes for breaking in new brake pads and rotors. According to Wagner Brake (source), bedding refers specifically to the initial break-in procedure conducted on new brake pads and rotors. This involves gradually heating up the brakes through light stops to transfer material onto the rotors.
Burnishing refers to the process of refreshing worn brake pads by lightly abrading their surface. Burnishing is done when brake pads have become glazed over time and need to restore friction. It can be performed by driving aggressively or using an on-car lathe (source).
So in summary, bedding is for brand new brake components to properly mate surfaces, while burnishing is for worn brake components to refresh their friction properties. Bedding is always required on new pads and rotors, while burnishing is only sometimes needed during the lifespan of the braking system.
Frequently Asked Questions
Here are some common queries about brake pad bedding with expert answers:
Do I really need to bed in new brake pads and rotors?
Yes, bedding in new brake pads and rotors is highly recommended according to experts. Bedding helps transfer an even layer of brake pad material onto the rotor surface, leading to optimal braking performance. Skipping this step can result in uneven pad deposits, brake noise, and reduced braking power [1].
How do I know when bedding is complete?
There is no definitive way to confirm bedding is complete, but signs include uniform pad deposits on the rotor, minimal smoke or smell from the brakes, and consistent brake pedal feel. Expect to complete the recommended bedding procedure, then inspect the rotors and brake smoothly from moderate speeds a few times to ensure proper operation [1].
Can I just drive normally to bed in the brakes?
No, normal driving is not sufficient for proper bedding. The bedding procedure involves specific cycles of moderate to hard braking to properly transfer pad material. Without following the recommended procedures, you risk uneven pad deposits and reduced stopping power [2].