Rotor Tempering/Brake Bedding

Final Steps of Brake Installation

OK, you finally have your new brakes installed. What's the first thing you want to do? Well, first you want to make sure they actually work before you go flying out of your driveway. What next? Hit 60 mph and stand on them to see how much abuse your neck will take. No, before you do that there is still some last minute work do be done.

Rotor Seasoning

All rotors from the manufacture come with a light coating of oil to prevent rust from forming during shipping and storage. This layer of oil needs to be burned off. At the same time your new rotors also need to be heat cycled to help further their tempering. What is tempering? Tempering as defined by the Merriam Webster Dictionary is:

2 a : the state of a substance with respect to certain desired qualities (as hardness, elasticity, or workability); especially : the degree of hardness or resiliency given steel by tempering

b : to anneal or toughen (glass) by a process of gradually heating and cooling

Irratic tempering is what causes rotors to warp. By gradually heat cycling rotors you allow them a chance to adjust to the hub as well as become further tempered. Rotor seasoning is best accomplished on the highway with little or light traffic. The goal of seasoning is to burn off any extra oil, as well as heat cycle the rotors. From any given speed, slowly apply the the brakes until you have lost approximately 30 mph of speed. Do not come to a stop. Instead accelerate back up to speed and maintain this speed for at least two minutes before applying the brakes again. This allows your rotors a chance to slowly cool off. Now repeat this cycle a minimum of 10 times. If possible repeat the process again after the rotors have completely cooled, about 3 hours, except this time brake faster. If you must come to a complete stop, try not to hold the brakes in any harder than necessary. Also while breaking in your rotors, avoid using the emergency brake. Your rotors will continue to temper over time as you drive your car, but you can obtain almost a complete temper in under 5 hours. Depending on your driving habits, and area, you will want to wait anywhere from 500-1000 miles before really you push the limits of your new rotors.

Pad Burnishing

Pad burnishing is very similar to rotor seasoning. The goal here is to get the pads to make full flush contact with the rotors, as well as burn off any excess binders and oil. Pads typically can be burnished in less than 100 miles. Care must be taken though not to glaze the pads in that time. Excess heat before the pads are ready can cause the un-tempered resin to form into a glossy layer on the pads surface called glazing and greatly compromise the efficiency.

Brake Terminology

Pad Burnishing
Preparation process for brake pads.

Continuum Fade
Condition of brake fade caused by the pads leaving their optimum temperature range. Excess of both heat and cold can cause this scenario.

Glazing
Most severe condition of brake fade. Extremely high temperatures cause the resin to break down and reset. The newly formed polymer is much denser. The hard slick layer has a poor drag coefficient, thus inducing fade.

Green Fade
Condition of brake fade caused by the overheated resin producing a gas layer between the pad and rotor.

Rotor Seasoning
The process of preparing new rotors for service.

Warping
Warping is the condition when the rotor is no longer within spec. Most notably run-out is out of tolerance. This is usually felt by a strong vibration during any braking.