Being competitive in today's racing environment means that every aspect of a race car must be scrutinized for optimum performance. Serious competitors don't have the luxury of leaving even the smallest detail to chance. This is true for the Saturday night warrior or a Winston Cup team. Because of this, a number of new sciences have developed in the racing community, which serve as a testament to the specialized nature of race car building. Among the most advanced sciences is that of chassis building.
There can be little argument that chassis design has reached a pinnacle of importance never thought possible as few as five years ago. With a world of technology available, today's chassis builder has an extraordinary amount of information on which to base any new scheme. With such an abundance of resources it seems impossible that it can all come together to produce a superior race car platform.
Speaking with three chassis experts, we wanted to know how different builders approach chassis building. Our goal was to understand how a race car foundation moved from a theoretical concept to reality. Along the way, we also looked for information or new ideas or concepts that might provide some insight into the direction chassis building is headed.
Eddie Dickerson, Director...
Eddie Dickerson, Director of Chassis Engineering at Hendrick Motorsports
First, we took our questions to Eddie Dickerson, who is director of chassis engineering at Hendrick Motorsports. Dickerson and his staff have been at the cutting edge of chassis design for 11 years and are well known for their successes with the #5, #24, and #50 Winston Cup cars.
Beginning with the basics, we took a look into materials used in the building of the Hendrick chassis. From a materials standpoint, NASCAR mandates the basic components. The rules set the material types and minimum material sizes. As an example, framerails are required to be a minimum of 3x4-inch rectangular tubing with .120-inch thick wall. The main structures (cages) are constructed from 1 3/4-inch-diameter .090-inch-wall seamless tubing. Other materials are always being investigated, but NASCAR has tightened up the rules so not much room is available for big changes. As a matter of fact, Dickerson told us that many of the chassis rule changes came about because of the #24 car the Hendrick stable ran in Charlotte in 1997. That car, known as T-Rex, was legal, but because the design pushed the envelope a bit too much, the NASCAR rulemakers changed some things to try to standardize chassis making. Dickerson said, "Chassis design has some tight baseline standards today, but you have to be on your toes looking for areas to improve your system."
From a philosophy standpoint the Hendrick organization takes the approach of maximizing the performance of the chassis before making any big changes for performance gain.
NASCAR mandates chassis materials...
NASCAR mandates chassis materials used in the Winston Cup Series. Many other series require the same material use for strength and safety.
"Except for the T-Rex, our basic chassis is similar to the ones run in years past," Dickerson said. "It has been a slow and evolving process over the years. The changes have been a little here and a little there. Our basic foundation is based on the same points as the Ronnie Hopkins and Mike Laughlin cars. Taking those points as the standard, we have developed our chassis based on incremental changes. Making big changes can be very tough, because for every alteration you want to make you are faced with other things that may make it impossible to try something new. The basic packaging of the race car does not leave a lot of room for radical changes. Our philosophy is to get 110 percent out of what we have before we go to some different ideas. Of course, that does not mean that if we see something that can give us a superior setup we won't pursue it. We didn't just fall of the turnip truck-our engineer and staff are constantly providing us with new things to look at."
There are a lot of ways to work and re-work a chassis to search for things. Today, Hendricks is looking more in the area of the snout.
"We have developed a short-track snout and an intermediate-type speedway snout that works pretty well for us," Dickerson said. "When it comes to changes, the front suspension seems to be where we can find more. The rear tends to be an area that provides less opportunity for improvement."
Driver comfort is still a part of the chassis mix. Each of the Hendrick drivers-Gordon, Labonte, and Dallenbach-have a certain feel they want with their cars. That means Dickerson and company must provide changes here and there to accommodate the style of the drivers.
"Fortunately for us, we have 15 people on site that are always thinking to come up with new things," Dickerson said. "Some of what we do is an educated guess, but you still have to get on the track to do the good-ole-boy testing. Even after you have built the best chassis, something as simple as tire compound or sidewall rigidity in track testing can give you very different driving characteristics than what was expected. It's always a challenge."
Hess Racing Products
Billy Hess, owner Hess Racing...
Billy Hess, owner Hess Racing Products
Billy Hess is owner of Hess Racing Products in Charlotte, North Carolina. The Hess enterprise is well respected in the chassis field and builds platforms for virtually all types of circle track cars. The Hess organization builds its own design concept, but it also has the versatility to adapt to ideas and theories from outside of its own process.
"Ninety-five percent of everything we build is from a typical order where the buyer knows what we build and that's what he wants," Hess said. "On the other hand, some of what we build comes to us in other ways. For instance, some teams have engineers but don't have a way to build the chassis, while others have ideas but don't know how to carry it out. We process their proposals in our system to see what will and what won't work. Then, taking the ideas that work, we build the total package, incorporating their ideas along with our experience to put the design on four wheels."
Like the Hendrick staff, Hess uses a sophisticated computer design system that can take the variety of information and make changes to produce an on-screen race car chassis. With a few keystrokes the entire characteristics of a car can be changed, allowing Hess to see the results of ideas well before any construction begins. Being computer jockeys gives the chassis experts today an enormous advantage over builders just a few years ago. Now, new ideas can pass muster on a theoretical basis before the first piece of steel is cut and welded.
Rex Stump, Hendrick Motorsports...
Rex Stump, Hendrick Motorsports engineer and General Motors University graduate, uses a state-of-the-art suspension kinematics program to develop new chassis designs. Along with many other pieces of information, programs such as this will reveal what the suspension is going to do when the body travels down and rolls. It also provides information on things like what kind of camber or steer will be created.
Once a design is set, the computer spits out all the specifics for a builder to go by in constructing the chassis. As good as any design may appear on the computer, the ultimate test is on the track. Hess pointed out, however, that with the combination of experience and new computer technology, the art of building excellent race cars has moved to a more reliable level.
"Chassis design has a lot to do with what a driver wants. Today, the biggest difference we see between driver requests comes on the basis of how quick a front end turns," Hess said. "For instance, right now the big rage is what we call the low snout. It's a totally different package that has a different roll center and camber gain package from a standard build, all of which has to do with how aggressive the front wheels are. The snouts are built in standard height, 3/4-inch drop and 1 1/2-inch drop. Each version gives a significantly different feel to the car, and from driver to driver the comfort level for each one can be affected. The snout example is just one of many variations that we take into account in building a chassis to a driver's specs."
Here is the 90-degree chassis...
Here is the 90-degree chassis design. Notice that the chassis suspension system is built parallel to the framerails, which produces a 90-degree suspension-mounting system.
Typically the 90-degree setup...
Typically the 90-degree setup calls for a coilover shock and spring setup like the one shown here.
Much of the work going on...
Much of the work going on in chassis design is in the front snout. Here, Josh Gibson, chassis fabricator for Hendrick Motorsports, begins to build the front snout to engineering specifications. Gibson is one of the 34 people Hendrick employs in chassis building for the #5, #24, and #50 race cars.
Steve Pearson, owner Pearson...
Steve Pearson, owner Pearson Racing
Steve Pearson of Pearson Racing in Athens, Georgia, is a former Busch car builder and now builds Saturday night race cars in the form of trucks and late- model sportsman race cars. Although this shop does not at this time employ computer design (computer technology is in the works) in the building of its products, the sophistication and quality level is high. As in any high-quality building process, the cars are based on plenty of historical documentation, and the accumulated information of individual car and track data serves as the basis for building the Pearson products.
Pearson, like the other builders we spoke with, began his short-track chassis building based on historically accepted standards. Today, however, his method has adopted some changes that have brought more Winston Cup-like characteristics to his platforms. These changes have occurred primarily in the front end of the chassis.
Instead of using the typical 90-degree coilover chassis design, Pearson has moved to a more flexible 60-degree design. This provides the flexibility and freedom for quick and easy shock and spring changes to be made, because a 60-degree system allows shock and spring mounting to be independent of each other.
Taken at the Bill Hess Race...
Taken at the Bill Hess Race shop, the view on this screen is typical of how a computer design begins. All the necessary data, such as upper- and lower-arm measurements, is keyed into the computer in preparation to view the dynamics of the resulting design. Information displayed on this computer screen can be easily changed, so many configurations can be considered before the actual construction begins. This kind of simplicity allows the designer much greater flexibility to design a chassis that works well on the track and also fits the "feel" a specific driver wants. Programs like these are in large part responsible for much of the refined chassis building available to racers today. This also is a tool to fix chassis problems. By placing the existing measurements of a chassis into the program, many problems can be easily spotted, which makes finding solutions quicker and simpler.
"All of this design is not new," Pearson said. "But, like many ideas, they cycle in and out of use as other ideas come along. This is an idea and process whose time has come again, and we think this is the future for the Saturday night short-track racer, both car and truck."
Changes in chassis building, like the 60-degree system, have improved the characteristics of power transfer from the engine to the ground as well as improved car handling. The improvements in race car foundations have put a renewed focus on engine tuning.
"The sophistication of the chassis has reached a level where chassis tuning is getting most of the engine power to the ground, so now engine tuning is once again becoming the focal point of getting around the track," Pearson said. "That's not to say that a chassis doesn't hold some power secrets, because it does. It's just that today's chassis are better than they were as little as five years ago, and so more engine power is being transferred to the ground than ever before."
The 60-degree version uses...
The 60-degree version uses indepen-dently mounted shocks and springs, not unlike Winston Cup cars. Configured this way, shock and spring changes are quick and simple.
This is what the designer...
This is what the designer sees after all of the data has been entered. The computer reveals all of the geometry that results from measurements entered in the first step. A process like this gives builders an enormous amount of information and detail, such as all front and rear geometry, wheel information, center of gravity, and much more, on which a race car platform design can be based. By replacing measurements in previous data screens, changes to the chassis geometry are made quickly and easily. The effects of this technology is clear, and it has a lot to do with the advances in chassis science in recent years. With this kind of engineering tool, hundreds of configurations can be reviewed in a fraction of the time it once took, and it can all be done without cutting or welding any materials.
Pearson Racing has moved away...
Pearson Racing has moved away from the 90-degree coilover chassis design to a 60-degree system. It's called a 60-degree setup because the suspension is mounted at 60 degrees to the framerail. This system offers new flexibility with shocks and springs.