How NASCAR drivers keep their cool in 140-degree cockpits

By Kelly Crandall

The introduction of the cooling shirt into the world of NASCAR racing was initially something of a puzzle. Many drivers weren`t sure how it started, while others speculated it must have originated with **Hendrick Motorsports**, particularly crediting **Jimmie Johnson**, known for his pioneering approach to fitness and driver well-being.

“I was the first driver to wear one,” Johnson revealed, “but the individual responsible for its inception was **Chad Knaus**.”

Johnson explained that his former crew chief, Knaus, constantly sought out new technologies and embraced a comprehensive view of performance, which included optimizing Johnson`s physical condition. Given Johnson`s history of struggling with cramps and sensitivity to heat, Knaus acquired a cooling shirt and decided to rigorously test its effectiveness.

“In the past, when we painted cars, one bay would be heated to 100 degrees Fahrenheit to accelerate paint curing,” Johnson recounted. “[Knaus] literally instructed one of our team members to enter this bay wearing the shirt, connect it to the power source, and sit there simulating being in a race car to test it. I vividly remember Chad calling me, exclaiming, `You won`t believe it, this cool shirt truly works! I`ve got so-and-so in the spray bake booth, I`m roasting him in there, but he`s wearing the shirt and feels great!`”

Johnson started using the shirt around 2018 or 2019. Initially, only his teammates were aware; he wanted to keep it a secret from competitors to maintain a competitive edge on the track. Over time, however, it became public knowledge, leading to other drivers adopting the technology following Johnson`s lead – a classic case of “monkey see, monkey do.”

**Joey Logano** breaks into his characteristic wide smile and hearty laugh when discussing the device.

“It`s like diving into a swimming pool on a hot summer day,” the reigning NASCAR Cup Series champion enthusiastically stated. “It feels amazing. It`s fantastic.”

At its core, the system is a shirt embedded with cooling technology. It contains small tubes through which chilled fluid circulates. This innovation has fundamentally changed driver comfort levels during races.

**Erik Jones** reflected, “I recall years ago, we used ice packs in our suits and ditched them during pit stops. In terms of endurance on a hot day, this is simply a game-changer. There were races where you`d finish completely depleted and exhausted, regardless of how much you trained. Now, it`s transformed things to the point where even on a 90-degree day, I don`t think heat inside the car is a primary concern for anyone anymore.”

Methods for keeping drivers cool have continuously evolved. Previous techniques included ice packs, fans, and the helmet hose (which still blows cool air onto a driver`s head). However, the helmet hose doesn`t offer the widespread cooling effect provided by the shirt covering a larger surface area. Today, it`s rare to find a driver in the field who isn`t wearing a cooling shirt.

Jones wasn`t the only driver to label the cooling shirt a “game changer.” **Michael McDowell** linked the increased adoption of the shirts to the debut of the **Next Gen car** in 2022. Teams quickly realized during testing that these new cars retained significantly more heat, making the cooling shirts far more essential and appealing.

“The shirts were available before, but they often malfunctioned or weren`t very cold,” McDowell explained. “You`d hesitate to use them, unsure if they`d help or fail on a given day. But now, although there are still occasional issues, it`s incredibly helpful for keeping your core cool, protecting vital organs, and lowering your heart rate by reducing heat stress. That`s a huge benefit.”

Some drivers, like **Shane van Gisbergen**, go a step further and freeze their shirts beforehand for enhanced cooling. This ritual is so crucial that his public relations representative has a recurring calendar reminder: “put cool shirt in freezer an hour and a half before the drivers` meeting.”

Not all drivers wear the shirt every weekend; the decision often depends on the weather forecast. **Ross Chastain** is one such driver, noting there are instances when he actually *wants* to sweat.

“At Martinsville, I had to use the bathroom because I wasn`t sweating sufficiently,” he remarked.

While inside the car, the cooling garment (either a shirt or vest) worn beneath the fire suit connects to a pump. According to **Cesar Villanueva**, the interior specialist for Kyle Larson at Hendrick Motorsports, the pump can be installed virtually anywhere.

The pump circulates a mixture of water and antibacterial/antifungal fluid. This keeps the system clean and prevents clogging. If the fluid doesn`t flow, the pump won`t function. However, system failures during a race can occur for various reasons beyond just clogging.

**Austin Dillon** described the situation when a system fails: “You`re simply stuck in a bad predicament. There`s really nothing you can do except turn it off, and maybe drain the water if possible, but it feels like a lifeline. It`s genuinely important to have it working.”

A system failure means the driver`s temperature rapidly escalates. The circulating fluid heats up, and without the ability to dump the hot water, there`s no immediate relief.

“It`s fantastic until it isn`t,” Logano commented. “But more often than not, it performs well. Honestly, they`ve significantly improved the whole system. It used to be quite heavy, which deterred many drivers, but now it`s a relatively efficient setup. If it can provide a mental edge at the end of a race by keeping you physically fresher, you`ll use it.”

“No matter how good your physical conditioning is, you`re going to experience fatigue after 400 or 500 miles,” he added. “If you can stay even slightly fresher, it`s likely worth the effort.”

Of course, the weight of the system is a considerable factor. While driver comfort is crucial, car performance is equally vital, and added weight slows lap times. Despite this impact, accepting the weight penalty associated with the unit – which Villanueva estimates to be around 6½ to 7 pounds – has become necessary.

“I believe we`ve accepted some weight disadvantage for wearing it,” **Chris Buescher** stated, “because you absolutely need to be as fresh as possible to compete effectively at the finish of these races.”

**Tyler Reddick** began using a cooling shirt in 2021 after losing weight. He noticed that his core temperature became difficult to regulate quickly without the previous “insulation” his weight provided, leading him to need the technology.

Reddick`s assessment perfectly encapsulates the significance of the cooling shirt in modern NASCAR.

“Many drivers utilize it,” he said. “In terms of keeping the body cool, I think it`s probably the most effective tool we have available.”