Road course racing is a delicate dance which often includes high speeds and hard braking as race cars are pushed to the limits on the track. The braking system is one of the most important components on the vehicle as it’s essential on each corner of each lap, whether it’s during a 100-minute street course race or the Rolex 24 At Daytona.
With excessive braking on challenging road course circuits and four grueling endurance events during the season, race teams need to be able to have a quick visual check of the temperatures of their brake packages. This is done through three different colored paints located on the edge of the front brake rotor, which can be seen when the wheels are off the Lexus RC F GT3.
These three simple paint colors located on the brake disc are actually thermal paints to check the brake temperatures of the RC F GT3. The three thermal paints, which typically include green, orange and red, change colors as the brake rotors get to different temperatures. Each of the colors will turn white within a specific temperature band to give the team an idea of how hot the brake package is running, with green being the lowest temperature and red being the hottest. For example, if the colors are completely unchanged, that signifies the brakes are not hot enough. However, if the three colors all turn to white, the brakes are too hot, and generally, the key is to find a balance somewhere in the middle where the red remains untouched.
The paint near the friction face of the disk always turns white before the center of the disc because cool air comes up through the cooling veins of the disc. The tire changers keep an eye on all of this while changing tires during a normal pit stop, which includes a four-tire change, occasionally a driver change and fuel in under a minute. If the tire changer notices the edges of the green color go white with just a band of green in the middle, as well as the orange color just starting to go white, that’s a good sign to the team that the brakes are in a good place. If the team pulls the wheel off during a pit stop and the red color is starting to go white, they have to keep a close eye on the brakes because there is a concern that the temperatures might be too high and that will exacerbate the brake wear and potentially the brake durability during the race.
While brakes are always important, the team will likely not have to undergo a complete change in a sprint race. However, in endurance races, it’s not unusual for the brakes to be changed out on pit road to ensure the Lexus RC F GT3 can get back on-track and contend for the win.