Denny Hamlin, NASCAR spar over brake safety rules at Iowa Speedway

NEWTON, Iowa — Denny Hamlin's brake problems at Iowa Speedway nearly turned into a showdown with NASCAR before the race even started. The Cup Series championship leader says he pleaded with officials to allow a safety-related brake change, only to be told the rulebook offered no room for common sense.

Hamlin, along with Toyota teammates Chase Briscoe, Riley Herbst and Bubba Wallace, spent extended time in the garage making pre-race adjustments at the Iowa track. He detailed the ordeal on his Actions Detrimental podcast, explaining that his brake pressure became dangerously erratic during green flag runs.

What went wrong with Hamlin's brakes at Iowa

Hamlin said his brake pressure dropped to roughly 10 percent during long green flag runs, creating a serious safety risk. NASCAR rules prohibit teams from changing brake pads until after the race starts, a lengthy behind-the-wall process. Teams can change calipers but must start from the rear.

“I told them I'd start on pit lane,” Hamlin said. “We have a major problem. And they were like, 'That's not the way it's written right now.' And I said, 'I know that. However, this is where common sense has to come into play.'”

Crew chief Chris Gayle tried a 50/50 solution by changing the air cooling ducts on the No. 11 car before the race. It didn't work. Hamlin had to race with compromised brakes, finishing fifth.

Did Hamlin and crew try an experimental setup?

Hamlin admitted he borrowed setup ideas from 23XI Racing, the team co-owned by Michael Jordan and Hamlin himself, after struggling at Iowa in the past. He said he wanted to lean on a proven setup from a team that had run well at the track.

“I can't hit my ass with both hands at this racetrack so put someone else's setup in that has been pretty good,” Hamlin said bluntly.

He insisted this wasn't an experiment for the Chase for the Championship. He simply wanted to try something different from what his own team had been running.

Safety concerns and NASCAR's brake pad rule

Both Gayle and crew chief James Small of the No. 19 car suggested NASCAR needs to revisit its brake pad replacement policy for safety reasons. Hamlin agreed, even as he understood why the rule exists to prevent teams from swapping pads for competitive advantage.

“And that's their argument, right,” Hamlin said. “We do not want 36 teams having a qualifying brake pad and a race brake pad.”

Hamlin said he would have accepted any reasonable penalty to fix the problem before the race. He even asked what would happen if he changed the pads anyway.

“They said, 'Well, we would make up a penalty and it would be worse than what it would be if you just came in and changed them under green.' And I was like, 'oh, well, I guess I just need to go slower then.'”

Hamlin warned that if he lost brakes entirely, he would simply putter around the track and end up laps down rather than risk a dangerous crash.

What this means for Iowa racing fans

For Iowa race fans, the incident highlights ongoing tensions between safety rules and competitive fairness in NASCAR. Hamlin's public push for common sense in rule enforcement resonates with a state that values straightforward, practical solutions.

Despite the brake troubles, Hamlin and Briscoe wrestled their cars to top-six finishes at Iowa Speedway. Hamlin remains the Cup Series championship leader, but the brake scare raises questions about whether NASCAR's rulebook needs updating to prioritize driver safety.

As Hamlin put it: “This is to hopefully keep my car from blowing a rotor or going into a corner dead straight and wiping someone or myself head on into the wall.”