Brake Pad Bedding
Published: December 8, 2016
This is the procedure I use for bedding PFC and Raybestos brake pads. I have been unsuccessful trying to bed Carbotech pads properly, and I have had various issues with Hawk pads. Your mileage may vary - use my approach as a guideline and pay attention to what your car is telling you.
I bed brake pads on the track, because street driving simply does not input enough energy into the braking system to generate the required amount of heat and get the temperatures high enough. Five 70 mph to 30 mph stops are really not doing much compared to running even 10 minutes at a track with corners every 15 seconds (10 turns with a hypothetical 1:30 lap time).
The procedure is the same for new pads, new rotors or new pads and rotors together. I also use a virtually identical process for scrubbing in new tires.
Usually I try to bed the pads in the first session of the event because it is the slowest session for me as well as everyone else, reducing the likelihood of me getting in the way of other drivers. However, decent pace is required, hence warm-up sessions that are done entirely under full course yellow (thus, with no passing is allowed anywhere) are typically unsuitable.
I start by running 1-2 laps at warm-up pace, primarily warming up the tires and acclimating to any changes in the track as well as performing reconnaissance of the track conditions. This is done with light braking, approximately with as much braking intensity as would be found in normal street driving.
After these initial laps I start slowly increasing my pace across the board. The increase is roughly linear in aggression rather than lap time. The goal is to be at 9/10ths about 15 minutes into the session. I try to reach this pace well before the session is over, hence a 15 minute time frame which will work for 20-25 minute sessions typical at DE events.
At this point I would have run about 7-10 laps total depending on course length. The brakes should be running at operating temperature at this point, getting normal but not excessive use. At around this time the various chemicals that are supposed to burn off the friction surfaces should be burning off, and the pedal should go a bit soft. I am likely to start smelling burning brakes at this point too. Depending on how many laps I have run and how hard the last lap was, I would either keep pushing to get to 9/10ths if I have not gotten there or back off.
I would then run a lap or two for shorter courses with minimal brake usage to cool the brakes down with airflow. Tracks that involve unavoidable heavy braking zones are less suitable to such cooldown. Following the one or two easy laps I will come in the pits.
Once in the paddock I will park the car and let the brakes cool down the rest of the way. Especially now I will try to move the car a couple of feet every few minutes to alternate where on the rotors the pads are resting, to promote even cooling of the braking system. After about 30 minutes the brakes are bedded and the car is ready for track duty.
I find that the above procedure works great for PFC and Raybestos pads. Both require minimal bedding prior to use; I believe Raybestos pads are even less sensitive to bedding than PFC ones are.
In my experience Carbotech/G-Loc brake pads require a very specific bedding process that I have not been able to achieve. In particular, I had a very hard time bedding Carbotech pads in wet conditions.
I think Hawk pads can be overheated even performing the described bedding process, and this does not end well. I would try a shorter bedding process for Hawk pads, perhaps one lap of warmup followed by 3-4 laps at speed followed by one cooldown lap.
The bedding process is useless for street brake pads .
Changing Brake Pads On Rotors
While some will recommend changing rotors whenever brake pads are changed, this is not always necessary depending on the pad compound. I would absolutely only use fresh rotors with Carbotech pads, however I have reused rotors with PFC, Raybestos and Hawk pads without issues. That said, if I am able to keep matching pad and rotor sets I try to do that.
I avoid continuously alternating brake pad compounds, especially of different manufacturers, on the same rotors. In particular I would not want to swap brake pads from track pads to street pads on the same rotor. This means either swapping rotors any time pads are swapped or running track pads on the street.