At the competitive edge of every professional sport, the margins of victory are tiny differences in energy, efficiency, skill and physical configuration. Over time, this gives rise to elaborate regulations governing competitors’ behavior, their contests, component designs, and the unending attempts to create a winning edge by stretching the rules. In response, NASCAR adopted more sophisticated methods to verify a racecar’s dimensions at its research and development facility in Concord, NC. After using Hexagon Metrology’s (North Kingstown, RI) proprietary GridLOK technology, NASCAR officials felt confident they could inspect a car to tighter tolerances. With the introduction of the Car of Tomorrow (CoT) in 2007 (see Sidebar 1), adopted in response to safety concerns, fair competition and cost management, the implementation of new standards necessitated a more rigorous means of enforcing specifications with tighter tolerances as compared to prior generations of racecars. 

Metrology became an essential part of the build process once NASCAR brought tighter tolerances into play. To replicate verification procedures right down to the equipment used, Hendrick Motorsports (Concord, NC) (see Sidebar 2) invested in 12 ROMER portable coordinate measuring machines (CMMs) of varying styles and sizes from its official partner for dimensional metrology products and services. The arms are used for both tactile probing and laser scanning of the car bodies to guarantee they fall within NASCAR’s required tolerances. Though most measurements are taken with touch probes to verify specific points, Hendrick Motorsports also equipped some of the arms with the CMS108 laser scanner to inspect complete car bodies. Careful to stay within the required specifications, the four Hendrick teams max out tolerances to gain every possible ounce of performance.

GridLOK Drives Accuracy

Hendrick Motorsports implemented the GridLOK system to guarantee its portable measuring processes precisely match those of NASCAR. GridLOK is a spatial coordinate system configured to work by treating its entire workspace as a large invisible coordinate system, effectively creating a giant CMM. To initially construct this CMM, engineers install numerous small (5/8 inch diameter) conical seats in a grid pattern which typically spans 4 meters by 6 meters. The seats are either mounted in a concrete floor or steel plate—Hendrick Motorsports chose the steel plate option. Once installed, engineers feed their coordinates into the inspection program using a precision laser tracker as a guide. The grid contains a volumetric repeatability of ±0.002 inch, and the stage is now set for the articulating arm.

To measure an object in the GridLOK system, an operator takes the arm and touches any three conical seats. The arm recognizes its position in relation to other seats, locks onto a common origin and assigns the proper 3D coordinates. Once a section of a part is measured and the data is imported into the software, the operator then moves to the next section. Points are acquired from three other conical seats and the arm “understands” where it is relative to the previous set of points. Data from that section is imported into the software, and the process continues until complete. Hendrick Motorsports uses 13 GridLOK plates for chassis manufacturing, body manufacturing, racecar setup and final racecar body measurement before loading the car for an event. 

Framework for Precision

In order to compete in NASCAR Sprint Cup’s rigorous 36 race schedule, each Hendrick Motorsports team has 14 cars in its fleet. Each of these 56 cars is repeatedly measured to check dimensional accuracy. In years past, internal components were measured as a means of quality control. With the implementation of portable CMMs, quality control expanded into body components, as well as fabrication, assembly and reverse engineering. Hendrick Motorsports has evolved the use of the arms to the final suspension set up of the racecar in preparation for competition. The use of the portable CMMs and the GridLOK system has increased the accuracy of the racecar assembly. 

“Hexagon Metrology helps us optimize every area of the car and engine, which drives results on the track,” says Vice President of Development Doug Duchardt. “The race engineers are confident that measurements made with the ROMER arms are more accurate than those gathered with previous inspection techniques.”

In-house measurements also are taken to guarantee Hendrick Motorsports’ proprietary chassis are built to the design intent and will pass NASCAR’s inspection. To enforce CoT specifications, a rigorous chassis certification process checks more than 220 specific points. All points measured need to be within ±70 thousandths of an inch of NASCAR’s nominal figures. Every Sprint Cup chassis must be certified for the race, and, in the event of an accident, recertified before being approved to return to competition at the racetrack. The high-tech inspection process allows NASCAR to identify and maintain records of each unique chassis.

Once the chassis is officially certified, ROMER arms are used to assist in precisely attaching the body panels to the racecar and verify the completed car itself will conform to NASCAR’s tolerances. A completed chassis fitted with body panels is delivered to the Nos. 5 and 24 shop or the Nos. 48 and 88 shop. After the body and chassis arrive at each shop, measurements are taken throughout the finish fabrication and painting process. Each shop has four dedicated operators (two per car) to measure external features. Ensuring quality standards is a rigorous job when there are millions of dollars on the line. As Chris Spaulding, engineer for the Nos. 5 and 24 Chevrolets, says, “It is very serious if the tools you use are not accurate. This can have some extremely costly ramifications. Fortunately, our engineering team is confident in the results the arms give. The results ensure all our cars are racing at peak performance, gaining every fraction of a second possible when on the track. There is a definite reason we partnered with Hexagon Metrology -- their tools have not let us down.”

Only the First Lap

The decision to adopt the measurement system was a twofold process. Hendrick Motorsports had been measuring internal components, such as engines and transmissions, using bridge CMMs, but realized more data was needed on the car bodies. Then, when the CoT was introduced, this cemented Hendrick Motorsports’ decision to adopt the system to mimic NASCAR’s capabilities. Once the organization discovered the applications supported by the GridLOK system and portable arms, Hendrick Motorsports started formulating ways to improve the entire car’s performance. 

The expanded use of the arms to perform final suspension setups of the racecars has helped the Hendrick Motorsports teams in two primary ways.  First, the technicians are able to precisely meet the crew chiefs and team engineers desired setup and tolerances.  Second, these accurate datapoints allow Hendrick Motorsports to assess and correlate its analytical tools. Hendrick Motorsports employs two Brown & Sharpe Global Advantage CMMs to measure results as they relate to key engine components. Though the arms are used throughout the assembly process, several parts, including engine components, are measured on the bridge CMMs since high precision measurements are essential in their manufacture and assembly. For example, Hendrick Motorsports assembles approximately 700 engines each year to power its 56 racecars, as well as those of various customers. The company has built the engines for the last six Sprint Cup champions, including 2011 winner Tony Stewart. 

Enhancing performance even carries through to the driver’s seat. During carbon-fiber seat fabrication, a mold is poured while the driver sits in the frame so the liner conforms to his body. The liner is then laser scanned and a custom 3D model is created to duplicate the liner as many times as needed. When driver Kasey Kahne joined the team, he brought seat liners from his previous team. Since that time, NASCAR mandated a change to the seats which modified the thickness of the material and affected the way it came out of the mold. The narrower seats were uncomfortable around Kahne’s ribs, and the crew found the discrepancy by scanning the liners to make the necessary adjustments. 

Metrology has proven itself to be a critical tool in the Hendrick Motorsports toolbox. Spaulding confirms the widespread usage. “Most of the time you think of CMMs and portable CMMs and you visualize inspecting parts to a print to verify it is within tolerance.” Spaulding says. “We use them for almost everything.” Given the fact that Hendrick Motorsports operates in a highly competitive industry, the teammates are challenging themselves constantly to engineer a performance edge using creative solutions. When that performance meets the racetrack, the results are nothing less than amazing.

For More Information, Contact: 

Hexagon Metrology Inc.
North Kingstown, RI
800-274-9433
www.HexagonMetrology.us