When it comes to race cars, most people like to talk about how much power they can make. Everybody is possessed by power. The reality is, in road racing most competitive passes are done during braking. It isn’t always horsepower that wins races, often it is good brakes. The folks over at PFC Brakes understand this concept and they put all of their hard work and engineering into it to ensure their brake products are the best they can be, especially for their motorsports customers. Their efforts paid off and PFC Brakes are now spec on all open-wheel racing in the U.S. such as the Verizon IndyCar Series, Indy Lights, Pro Mazda, USF 2000, and F4 — a testament to the footprint it has amassed.
At TURNology we have covered PFC Brakes’ history and which pads to choose for your specific needs, but we haven’t discussed one of PFC Brakes’ crowning achievements — its floating rotors. Its floating carbon rotor was so innovative, it earned the 51st Annual Louis Schwitzer Award in 2017 from BorgWarner. PFC Brakes was the first brake company to ever earn the award presented annually to an engineer, or a team of engineers, for excellence in the design, development and implementation of new, innovative motorsports technology concepts for use in the Indianapolis 500.
Speaking to PFC’s Motorsports Sales Manager Justin Cockerham, what makes the V3 innovative is it has the lightest two-piece attachment. “The disc has flange tabs on the inside diameter and a snap ring holds the hat in place. Our V1 and V2 rotors used fixtures that held the rotor and hat together. Because the V3 uses a ring instead of nuts and bolts, it is lighter and has less inertia. The disc is fully floating and it can swell as it gets hot, often seeing well in excess of 1,000 degrees Fahrenheit — active duty stops can see temps above 1,300 degrees. It is important that the disc can swell during expansion from heat or it will warp. The V3 is a serviceable system with replaceable outer discs.”
Cockerham mentioned that its floating rotor design isn’t just for race cars but high-performing street cars as well, “These rotors are available for a street BMW E46, Porsche lines, Ford Mustangs, and of course, on up to IndyCar and NASCAR. It was on Porsches where we really tested the design.”
To find out more about the testing between Porsche and PFC Brakes, I spoke to Craig Watkins, chief engineer for Flying Lizard Motorsports. Flying Lizard used the PFC rotors on its American LeMans Series (ALMS) Porsche 911 RSRs. According to Watkins, in engineering speak, nothing is infinitely rigid, “As cars go through turns the suspension loads and unloads. During loading all of the components distort a bit.
“On 99.9 percent of cars this isn’t a problem, but on a race car, the distortion can be enough that the rotor isn’t running perfectly perpendicular to the spindle and parallel to the caliper. When this happens, the rotor rubs against one brake pad or the other and pushes them (and the caliper pistons) back slightly into the caliper. This is known as rotor slap or knock-back.” Because race cars use such a large brake rotor, the radius from the center of a spindle to the outer edge of a rotor is larger, highlighting any flex in the system and exaggerating this knock-back.
“As the driver goes back to the brakes, the master cylinder must push the caliper pistons and pads back into their previous position enough to contact the rotor,’ Watkins continues. “Since there is greater (just slightly more) fluid flow in the system, the brake pedal will not get hard in the same position as before, and, human cognition is expecting the pedal to get hard in a consistent position. When it doesn’t it’s distracting or frightening for the driver and they lose confidence in the brakes.” In short, knock-back is a bad thing.
PFC’s V3 Disc Technology was so innovative they patented it, specifically the retention ring that holds the hat and disc together. The ring means no need for torque wrenches or hardware. The ability to change the disc quickly saves time and effort.
Great care is taken with all rotors produced by PFC, not just the IndyCar V3 rotors. Cockerham discussed the manufacturing process for the rotors so they won’t warp or cause issues with brake pads. “What we do to our rotors . . . that is unique due to cost: Our rotor castings go through intense heat cycles. We actually warp our castings on purpose. We heat up one state, then cool down one state. We pre-warp the disc, and then we finish the machining process.
“This makes our discs virtually un-warpable. We machine it down to get it to plane flatness. When we cut the rotors we don’t use cutting solvents or bit oils. We don’t want those rotors absorbing these oils. You will see this stuff come out on the track, called greening rotors. Sure, it is more expensive for us to use this method, but it keeps away the greening process. Even our shipping is without oil on the rotors, inside moisture free bags, to ensure they don’t rust along the way to their destination.”
The rotor game has been changed by PFC. If you want to go deeper than the rest, look into some V3 rotors for your go-fast ride.