There have been three known issues thus far, with the latest happening during the first test session on ahead of this weekend’s $1 Million Challenge at The Thermal Club.
The final 20 minutes of Friday’s morning two-hour run of testing, the left-front of Marcus Ericsson’s No. 28 Andretti Global Honda caught on fire as he rolled around the 17-turn, 3.067-mile road course. When he was finally able to come back around to pit lane, his crew removed the tire and fragments of brake components could be seen falling from the car to the ground.
Reason for concern?
During a mid-day media availability, Motorsport.com asked Kyle Kirkwood if he had encountered any similar issues as his Andretti team-mate, which led to him voicing the concern.
“That is actually a big topic right now with the new brakes that PFC have come out with,” Kirkwood said.
“They've cooled a lot. Everyone is trying to figure out what temperature range they want to be running.
“That wasn't a test item of theirs, but clearly got hot. I don't know if you noticed at St. Pete, a lot of the cars were catching fire and they couldn't put them out with the blowers. That's from people running them super-hot when they come into the pits. Something people are working through, I guess.”
The season-opening Grand Prix of St. Petersburg featured two brake problems on the weekend, beginning with Rahal Letterman Lanigan Racing’s Christian Lundgaard suffering an issue during practice. That was followed with Sting Ray Robb’s AJ Foyt Racing Chevrolet stranded in a run-off area with a right-front issue that needed to be extinguished after 33 laps in the race.
PFC responds
James Borner, the Technical Program Manager on design engineering for PFC Brakes, told Motorsport.com some of the changes to this year to the carbon-carbon brake system, which was introduced in 2023.
“The new PFC package has the same material and same carbon as '23, but the sizing is different, and the cooling strategy is different so that it'll run cooler,” Borner said.
“Anytime running carbon, though, it gets up to high temps above 600C. So, depending on the cooling strategies, depending on the rotor guards, the resin and the rotor guards can catch on fire. That's why you'll see a lot of times it'll be a fire after a hard brake event or something and if a car stalls out and it has no air flow that fire will just grow.
“It's also why you’ll see usually they'll have a fire, and they'll stay out.”
Borner also shed light on the issues in St. Petersburg.
“Some of the rotor guards that were on fire, the team continues to run and then it can extinguish itself with air flow to keep things cooling down,” Borner said.
“But generally, a lot of the brake temp in the surrounding areas comes from if you do a hard stop, do some hard braking and then come back in, you need to cool it down as well. So, just variety of rotor guards can catch on fire from time to time.”
Borner shared that there is nothing significant that can prevent the issues, stating that the braking system can reach peaks of up to 1200C. Due to that, incidents can arise with something as simple as bits of rubber from the tire getting caught up in the wheels or brake ducting and ignite items that are not flame resistant.
When further examining the incidents, Borner continued to stress the intense braking demands in North America’s premier open-wheel championship.
“It's just a result of really high temperature brake systems due to the high braking that IndyCar demands - 3.5-4G braking,” Borner said.
“The carbon-carbon systems are small inside a 15-inch wheel where everything's packaged very, very tight. You've got the caliper sits three millimeters off the wheel, rotor guards sit three millimeters off the rotor. It's just a result of pushing the envelope with components trying to maintain heat of systems that in a very small, constrained package. “
Colton Herta, team-mate to Ericsson and Kirkwood, was part of a media availability at the end of Friday’s running, along with Team Penske’s Will Power.
When Motorsport.com asked if they were dealing with any different feelings with the brake system this year versus 2023, the two provided a conversational thought.
“Yeah, no, pretty similar feeling, to be honest,” Power said. “It's just a bit finicky with these brakes. I wouldn't say quality control, but some have more bite, some have less bite. Hard to compare.”
Herta then chimed, “Quality control.”
Power then replied, “I don't want to say that, but yes, quality control. They're not all coming out the same basically, as Marcus found out today in two different ways.”
For his part, Herta then shared that he believes the brake system regressed in 2023.
“It feels the same as last year,” Herta said. “I felt they took a step back from 2022.”
While other drivers have found issues working within the optimal temperature for the brakes, Herta revealed that he has not.
The following moment, Power became aware of the incident that Ericsson suffered.
“That's a bad situation,” Power said. “Yeah, if that happens at the end of any of these straights...”
