Engineers James Borner and Paul Rankin guided us through how Performance Friction optimized the brake package for one of the most grueling categories in motorsport. Performance Friction started bu supplying pads and rotors to IndyCar teams in 2017 stepped in 2017 then for 2018 engineered a unique new caliper specifically for the class.
The unique continuous single-weave carbon matrix setup was developed to address the reduction in downforce due to the simplified aerokits first run this year. In other words, the drivers would spend more time braking, top speeds would be higher, and PFC had to maximize the existing brakes within the parameters already established. Simply put, dissipating heat in an IndyCar is a tall order, but their shrewdness and comprehensive understanding of the sport and all its demands enabled them to conquer the challenge.
Heat is the Enemy
They established their priorities early in the process. “Heat is the biggest issue on the hardest tracks; you have to design to be able to handle what St. Petersburg is going to throw at you,” says Borner. “We also had to come up with a rotor which wouldn’t lose its float throughout the race.” To do this, they they utilized PFC’s V3 attachment system to fasten the disk to the hat which can accommodate growth in both axises.
The titanium bobbin-based V3 attachment system not only allows the rotor to float freely but as the titanium resists heat transfer to the aluminum hat
The innovative design does away with the usual nuts and bolts. Fifteen titanium bobbins isolate the heat from going into the aluminum hat and allow for axial and radial growth, because the bobbins are not constraining the disc from growing when they heat. This allows for full float, and yet the vital components are separated—the hat and the disc may only be separated by one millimeter, but there can be a difference of as much as 800°C between the two.
The new discs weight 4 pounds a piece-compare that to a 20 pound steel disc of a comparable size.
Carbon is thermally stable and doesn’t expand much under heat. “The disc and pad are the same material, essentially” Rankin adds. The biggest issue, brake-wise, in IndyCar is longevity. The teams want to avoid replacing the friction material and discs every race, and this heat dissipation means these brakes can last several races.
All-Purpose Pads and Rotors
This also makes them versatile. Regardless of the style of course—street track or speedway—the teams want to run the same brakes, basically. The teams will install full-depth rotors and pads at a course that’s tough on brakes, like St. Petersburg, and then reuse the now thinner and lighter rotor and pads on a superspeedway where braking force isn’t as much of an issue as reducing weight.
In addition, the PFC engineers improved cold air ducting ducting around the confines of the basic package; they still needed to remain within the wheel clearance. Glove ducting, which directs air beyond the pack of the pad and into the throat of the caliper (by the pistons, where most of the heat is generated) which helps drop 100°C from the former as a result of this configuration.
These were just some of the examples of their detail-oriented approach to maximizing braking power. With this insistence on maximizing every aspect of the braking system, it’s no wonder these brakes have become so prevalent in Porsche GT racing and full-bodied racers, and have become massively popular among track day regulars who need a seek the highest levels of performance and confidence in their binders.