Carbon copy
By Larry Cothren, Stock Car Racing Magazine
November 28, 2001
10:23 AM EST (1523 GMT)
Whenever a Winston Cup driver finds a particular race car he likes, his teammates go about duplicating that car with the precision of a watchmaker. From scanning bodies with laser scanners to precisely measuring the placement of suspension parts with digitizing arms, building and maintaining cars in Winston Cup has become a refined art.
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Digitizing arms can be used to assess damage to chassis components and to assist with the placement of body parts.
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It remains, however, an imperfect art, one that relies largely on the skills and limitations of human hands, even as motorsports technology continues to expand.
"These guys are building them by hand, so there's no way to get them identical, not every little inch of it," says Mark Fryar, shop foreman for Bill Davis Racing, which fields two cars on the Winston Cup circuit. "We try to get them as close as possible. We've got all these measurements and we try to make everything as close as we can, but being identical is about impossible by hand."
And drivers, of course, can be a finicky bunch. While the cars they use in competition are often unpredictable, pinpointing every minute detail in the duplication process is another factor that's next to impossible.
"Why one car is better than another car, I don't know," says Fryar. "We've had cars that were really good in the wind tunnel but didn't run that well on the racetrack. That's why racing is such a challenge, I guess, because you never know. We've got engineers, a lot of smart people, all the teams do, but nobody can make each car run like the best car.
"Every driver I've ever heard of, from Ward Burton to Mark Martin to all the different drivers I've worked with and people who've worked with different drivers, they all say 'so and so' has a favorite car. I heard one guy talking one day that they built a road race car for Mark Martin, supposedly a copy of the car he won all the races at Watkins Glen with, that it was identical to that one, and he went out and drove it and he didn't like it at all."
While there are a multitude of adjustments on a Winston Cup car, even the slightest of changes can greatly alter the way a car handles.
"Whenever you say a driver wants an exact copy of a car, once you change too many things, like shock motion ratios or effective spring rates, you're going to change it for him, so you've got to strive to keep everything as close as you can," says Scott Houston, projects manager at PPI Motorsports.
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Two damaged cars on track.
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Even when a team re-creates a car that closely resembles a driver's favorite machine, there's no guarantee that the components will remain stable enough to ensure having two quality products of similar characteristics.
"The thing is so pliable and so flexible that it's always changing," says Houston of race cars in general. "It's never in the same shape for any given period of time. As far as creating a carbon copy of a particular one they're racing, I don't know that we'll ever be able to. The thing would have to weigh a million pounds. But for what we have, we can at least keep it in a tolerance and that's what we try to do."
Toward that end, Houston and his co-workers at PPI, as well as other Cup teams, have worked in recent years to upgrade their quality-control standards in-house. At PPI, that includes taking precise measurements and keeping computerized records of essentially every part that goes into building a race car. The team has also worked to weigh everything that goes into building a PPI Motorsports car, including nuts, bolts, washers, and so on.
"Just to list that stuff took three months," says Houston. "You think you could just sit down at the car and do it, but you can't because everything is categorized."
Kent Day, a vehicle dynamicist at PPI, has taken the process a step further by developing computer software that aides teams in setups and in making cars as similar as possible.
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Computer images of actual race cars can be generated using laser scanners or digitizing arms.
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"It allows the crew chiefs to basically simulate what they're going to do at the racetrack before they go," says Houston. "They can run the setup that they're going to use. To make that program as accurate as possible, what we do is take each of the components, starting with the big stuff like the rear-end housing, trailing arms and spindles, and we measure the stuff. We measure it with a (digitizing arm) that will give you the x, y, and z coordinates of all the points.
"Take a spindle, for instance. It's basically the same as scanning a spindle. Then you compare it with a standard we've set for it. Then the measurements of that spindle are put into a database under the name of that spindle. So when the race engineer or crew chief gets ready to go to a race, the mechanics who bolt this stuff on the cars present him a report that tells exactly which spindle, which steering arm, which trailing arm, and he loads all this stuff and electronically bolts it onto a car."
The work, though tedious, pays off by offering PPI, which fields the No. 32 Winston Cup Ford, a level of quality control previously unattainable.
"We have a master serial number sheet. The mechanics and the guys who actually assemble the car verify that the spindles and the hubs and stuff are the ones going on and this stuff has been measured," says Houston. "A lot of the variations get taken out right there. We measure, for example, the upper and lower A-arms, measure the pivot points of that from when the car is built. We measure them again after, say, two or three races. If we take a hit, we measure them and then correct them."
Mike Dubowicz, an engineer for Melling Racing, says a digitizing arm is a valuable piece of shop equipment. One of its advantages is that it's much less expensive than other methods, such as using a laser scanner, yet it allows teams to measure chassis and body components in the quality-control process. That includes checking new parts for correctness and assessing damage to parts off of wrecked cars.
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Even with the technology found in NASCAR, countless hours are spent hand-fabricating stock cars.
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And if the team has a particular car that performs well enough to duplicate, the digitizing arm allows team members to begin the duplication process.
"What we would do is go through and digitize all the chassis points," says Dubowicz. "From there we can use that information to help reproduce the car."
The team imports information from a digitizing arm into a computer program, such as CAD (Computer Assisted Design) or FEA (Finite Element Analysis), to create a 3-D computer image of the vehicle.
With the tools available to ensure precise work, the body of the race car is generally considered the area easiest to duplicate.
"Our fabricators are excellent at doing that," says Nick Ollila, director of engineering for Roush Racing. "If we get a car we like and want to mass produce them for, say, Jeff Burton, it's not a problem. They all come out like coming out of a cookie cutter."
"The body stuff, while it's expensive for the inspection equipment, that is probably going to end up being the easiest because you're just dealing with one basic shape and the location of the nose and the greenhouse and the tail," says Houston.
Body scans have been used on Winston Cup cars in recent years. The technique employs laser scanners to scan lateral lines across bodies. The information from the scans is then imported into computer software to give team members a three-dimensional image of the body. Ollila says that before cars get to that point, however, a technique can be used to build race cars that is nearly as old as automobiles themselves.
"First of all, you keep extremely accurate records when you're building the car, when you're hanging the body, the placements of the door tops, etc., not just in one dimension, but in all three axes, x, y and z," says Ollila. "You don't need to have a [digitizing] arm or a laser scanner to do it.
"You can do it the way they used to back in the '30s when they were building production cars. They had bucks they made. When they had a car they wanted to duplicate and put it into production, they would make these egg crate templates, if you would, off of a body panel, and then fabricators would shape that metal until it fit that egg crate buck. Then they had an exact match.
"Like the corner of the roof, you would measure its vertical location, measure its lateral location relative to the framerails, and you would measure its fore and aft location relative to whatever point of origin you wanted it to be, whether it's the firewall or whatever."
Once cars are completed at Roush Racing, the next step in the process is to take them to an R&D lab. "Its primary function is for every car that gets built to go back to that room to get scanned," says Ollila. "At that point it's strictly a matter of quality control and it's validating that the fabricator put the body panels in the position he was supposed to put them in."
In the end, however, duplicating a winning race car involves so many components and so much input from so many different sources that the effort is never perfect.
"The suspension is all the same and everything we have now is all precision measured, and we build everything the same, but the driver doesn't like every car, for some reason," Fryar says. "Whether it be the setup, or the way the body is on, or the way the chassis is built ...what it is we don't know. If we could figure that out, we would be rich people.
"There are so many variables, not only with the car and chassis and stuff within our team, but also the tire compounds, engine combinations, gears and transmissions, even the driver, so many different things make these things run good every week."
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