NASCAR’s Standardized Stock Car Has Room for Modifications

In the wake of racing legend Dale Earnhardt Sr.’s death in the last lap of the 2001 Daytona 500, NASCAR officials set out to engineer a safer race car.

They also sought to develop a vehicle that offered racing teams more cost-effective development, fabrication and maintenance. To do this, they crafted precise technical specifications for all racing teams. In essence, NASCAR has created the same car for all teams in the competitive Sprint Cup Series – the Car of Tomorrow (CoT), which took its first competitive laps in March 2007 at Bristol Motor Speedway in Bristol, Tenn., during the Food City 500 race.

NASCAR’s Car of Tomorrow is the culmination of seven years of planning, development and design at NASCAR’s Research and Development Center in Concord, N.C. The organization’s old rules allowed racing teams to fabricate cars on a variety of templates that differed among specific manufacturers. All Cars of Tomorrow – no matter if they are Ford, Dodge, Toyota or Chevy – now are required to fit the same set of design specifications and undergo inspection to ensure compliance on a standard blueprint. The larger, boxier CoT design standardizes numerous components across racing teams, ranging from sections of the frame to crumple zones, among other factors.

While Sprint Cup Series racing teams no longer are building completely different cars for different tracks, they’ve learned there’s still room for some chassis customization through competitive-minded construction tweaks that suit a particular driver’s style or even the length of the track.

“The CoT narrows the competitive technology gap among teams, but it still exists,” says Shane Love, head fabricator at Joe Gibbs Racing, a Toyota team and former home to two-time Sprint Cup champion Tony Stewart. “Racing team fabricators are adding customization to the Car of Tomorrow to boost a team’s competitive advantage. It comes down to the chassis. The cars have standard frames and safety features, but there definitely is a small amount of room for tweaks. Welding plays a huge role in that.”

Standard Template

Safety remains the No. 1 reason why the organization sought to build a more standardized Sprint Cup racing vehicle, but NASCAR also quickly realized such a car could improve competition and allow teams to be more cost efficient – with room to personalize the cars to the required style of various drivers and tracks, notes Don Krueger, lead fabricator at NASCAR’s Research & Development Center.

“The public perception that these things are so locked in with an assembly line production mindset is overplayed,” Krueger says. “These cars still are built one at a time. Yes, the Car of Tomorrow specifications have made it a little more ‘assembly line,’ but each car is unique, and teams are making minor changes within the parameters. You certainly don’t crank out chassis on an assembly line.”

Under the Car of Tomorrow’s detailed specifications, all Sprint Cup Series stock cars must meet the same dimensional specs for the wheelbase (110 inches), body width (74.0 inches), body length (198.5 inches) and height (53.5 inches). The driver’s seat is 4 inches closer to the center of the car. The roll cage is 3 inches closer to the rear. The roof height is 2.5 inches more than what Love calls the “cars of yesterday,” while the greenhouse is 4 inches wider. The driver’s side on all CoT vehicles now features double frame rails. The drive shaft is now encased in a steel tube to prevent it from piercing the floor pan and impaling the driver in a crash.

NASCAR tests the chassis/rollcage assembly for each team, recording the location of each joint, component and measurement. Every joint and mating of the rollcage and other components must fall within tolerances outlined in the CoT construction plans developed at the NASCAR R&D Center. While the CoT is highly standardized through specifications and certification testing, the fabricators on the various racing teams aren’t really as locked in as one might think, Krueger says.

“We control the big pieces, but there’s a lot of flexibility in terms of suspension geometry and how components are attached to the chassis. There is room for manufacturer identity. The pick-up points on the chassis are regulated only for asymmetry requirements,” Krueger says.

Love and his counterparts on other racing teams admit there isn’t much “wiggle room,” but also acknowledge Car of Tomorrow specifications do allow for strategic modifications.

“It was a challenge at first,” Love says. “But we stopped objecting to the concept and started to think creatively inside the box. We decided we needed to find ways to get the most out of the Car of Tomorrow design requirements.”

Welding within the Box

Welding is one of the great dividers when it comes to customizing the Sprint Cup Series Car of Tomorrow among racing teams and automotive manufacturers.

“Each car gets a personality through the slight variations of tubing thickness, the alloy, the welding method and even the welder who worked on it. One guy welds differently from the next one,” Krueger points out.

A stock car chassis requires thousands of welds. Some chassis are completely MIG welded, while others feature a combination of MIG and TIG welds. Some teams even tinker with the concept of using only the TIG welding process for their chassis, Kreuger says.

TIG welding, while time consuming, also produces a cleaner weld and uses lighter-weight materials than its MIG counterpart. These factors have caused NASCAR fabricators to take an increased interest in TIG welding, even if the welding process takes longer.

“Weight always has been an issue, even pre-Car of Tomorrow,” Krueger says, adding that the total weight of cars on the track today is mandated by CoT guidelines. “Teams always are trying to save weight at the top of the car. Anywhere you can take even an ounce off the chassis, you do it. If a TIG weld saves an ounce or two of weight, it might be worth the extra hours.”

At Joe Gibbs Racing – a Lincoln Electric-only shop – Love and his team try to incorporate as much TIG welding into chassis construction as possible. “We want the best-penetrating, most-consistent weld we can make,” he says. “Obviously there is a time issue in motorsports, but we want everything to be perfect, too. TIG is my preference, but I also think the highest form of motorsports should perform with the highest form of welding.”

Love’s team uses Lincoln’s Precision TIG® 375 Welder, which offers the widest welding range in its class – 2 to 420 amps for both AC and DC – and TIG pulser heat input control for any weld. Love uses the Precision TIG® for any special metals – titanium, aluminum, chrom, moly and stainless – for such jobs as tailpipes and front suspension, as well as other external parts, to name only a few.

The Gibbs shop also recently acquired the new Invertec® V310-T, a technologically advanced portable AC/DC TIG welder is designed expressly for such applications as serious motorsports. The Invertec® V310-T features an LCD screen with Dynamic Display™, making all relevant parameters visible at a glance. The the V310-T allows users to customize the arc through its adjustable AC frequency and selectable waveshapes. And, with its soft, crisp and AC stick modes, it provides exceptional welding performance on all electrodes.

“We’re still experimenting to find the best areas where to use it. Right now, I’ve been using it for a lot of our parts,” Love says. “So far, the aluminum aspect of it has been great. It has some new technology that makes aluminum exciting to weld. The size of the machine is great and can be used anywhere in our trucks or around the car.”

While TIG welding plays a major role in the construction of any Joe Gibbs Racing car, that’s not to say MIG welding doesn’t have its place in the team’s fabrication shop. The crew uses MIG welding – a number of Lincoln’s MIG welders, including the Power MIG 215 and Power MIG 255 – for support tube and body fabrication.

“The Power MIG is our workhorse,” Love says.

Because the Car of Tomorrow is still a relatively new concept that requires regular refinement and tweaking, constant testing of vehicles is a must to make them race-day ready. Joe Gibbs Racing drivers, including Joey Logano, Kyle Busch, Denny Hamlin and Marc Davis, regularly track test the car, sometimes weekly. This allows the team to improve on performance issues and also tailor cars to individual driver preferences – within the parameters of the approved Car of Tomorrow specifications.

“There are some places on the car that could stand to be lighter,” Love says. “The lighter you build the car, the more you can adjust your racing conditions. There is room to ‘legally’ tweak it for smaller race tracks or super speedways – we’re still learning what those ways are through trial and error. The longer we run this car (the Car of Tomorrow) on different tracks, the more we will find ways to make those changes. You can’t rush it. We have to take our time on the decisions. It all comes down to winning a race in the end.”

Rigorous Chassis Certification Levels the Playing Field

While each racing team puts is own stamp on NASCAR’s Car of Tomorrow (CoT) design blueprint, each car’s chassis must undergo an intensive certification process before it can enter competition. Additionally, any chassis that has been involved in a crash must also undergo re-certification before it can be used again on a track.

Racing teams bring their chassis to NASCAR’s state-of-the-art Research and Development facility in Concord, N.C. Technicians there use a system comprised of two sophisticated, portable coordinate measuring machines to inspect more than 220 locations on the chassis before qualifying it for certification.

The system, developed by Romer Inc., creates a three-dimensional data representation of each chassis to compare its features with NASCAR’s CoT design rules. The machine consists of a seven-axis rotating arm, a steel platform with drill holes places in a unique pattern that is certified by laser and special operating software.

Chassis undergoing inspection are rolled onto the platform and locked into place. The articulating measuring arm, once activated, uses a ball probe that matches to the drill holes to identify the specific location on the system’s grid and accurately determine the X, Y and Z coordinates for any location on the chassis to be certified.

NASCAR technicians certify the chassis for adherence to height and width tolerances using the Romer arm. They also use an ultrasound probe to check sheet-metal thickness.

Once a chassis gains certification at the NASCAR R&D Center, it is fitted with 10 radio frequency identification (RFID) microchips placed on various locations throughout the chassis. Each of these chips matches a unique serial number that is placed on the chassis’ interior roll bar.

NASCAR inspectors at the track can then check RFID chips to determine a chassis current certification status and history, ensuring that only certified chassis compete in races.

“Post race, we also bring in the winner and at least one other car and re-inspect on site, too,” notes Don Krueger, lead fabricator at NASCAR’s Research and Development Center. “We keep close tabs on every chassis and their condition.”

The entire initial inspection takes less than two hours and is provided by NASCAR at no cost to the racing teams. More than 2,000 chassis have been certified or re-certified since the end of the 2006 racing season, with a success rate of 90 percent.