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Creating Championship-Winning NASCAR Dodge Truck Chassis

by Ian Sharp

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When Dodge went into the NASCAR truck series, Lou Patane was running motor sports; his friend, Francois Castaing, had put him into that position. Lou Patane didn't know a thing about almost any kind of motor racing, including drag racing, despite having sponsored a team.

Over the past twenty years, until Francois Castaing arrived, Chrysler Motorsports had not been a priority for staffing; Castaing tried to change that, in the European and Japanese mold where the brightest and boldest flourished.

I heard through from a third-party source that Bob Lutz wanted the best racing guy in Chrysler to do the NASCAR program. I had a spotty record then, because I'd upset most everybody in the company trying to do what was I felt best for the company, product, etc. - all altruistic motives, misinterpreted in the corporate environment. However, they asked me do the truck racing program. My last chance, I think.

I met with Lou Patane, and he said, "We want you to make the body structure really integral and make the car handle."

Lou Patane had operated several Arizona dealerships when, in 1994, he joined Dodge. Mr. Patane rose to vice president of motorsports operations, leading the new NASCAR Craftsman Truck and Winston Cup efforts. He returned to retail in 2001.

I replied, "But the body structure's just sheet metal that's hung on a tube frame chassis. It does nothing for the stiffness of the vehicle; I mean zero." He didn't understand that and insisted that we approach it this way. This was ignored as it was illogical and nothing more was said of this again.

During this meeting with Lou I was with Paul Brown from Reynard. We looked at each other and scratched our heads. . . and because Patane was a drag racer, we talked about drag racing. He made the statement that "the more load you put on the engine" the faster the drag car would go. Paul Brown said, "Does that mean you open the parachute on before you start it should go faster?" Typical English laconic logic, and that sort of flustered Lou for an answer. I am sure that there was some truth in that from Lou's empirical experience, but there has to be a point where that reverts back to being drag/grip limited.

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"I drove the car before Lanier - I laid two black tire strips up the yard, as the guys were egging me on to open it up! So you could say I was the first NASCAR driver, when Chrysler came back to racing...."

I went to a NASCAR Craftsman Truck race to take a look at the chassis, and said, "We need to do something better than that," not really understanding the NASCAR philosophy of total control of all aspects of every parameter. It smacked to me of a frightened organization, afraid of managing technical issues. I looked in the rulebook and there was nothing in there to say you couldn't do this or that. You could do whatever you wanted, by omission, which is the European philosophy……or so I mistakenly thought.

A Richard Petty NASCAR frame, an old one they hadn't used, was sent down to us at Jeep-Truck Engineering on Plymouth Road, and we set up a little development area in the back of the Jeep development shop with a surface plate. We got some experienced people in who I knew were really good, including Frank Christalaw, who is an excellent fabricator. We started, with Reynard's help, to make the chassis frame efficient in stiffness, weight, and, especially high-up weight.

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I was running on all the favours I could muster within the Jeep engineering organization, and had Les Koltvedt in the measurement lab digitally scan all the chassis tubes into CAD for the FEA, and Reynard model work. I recruited the help of Chris Marth, a young engineer who was a good FEA and structural engineer working on contract at Jeep, so on his free time he ran CAE computer model of the structural members of the chassis we had scanned and put into CAD.

Truck series driver John Nemechek lost his life by the car spinning 180 degrees before Dodge joined the series. He hit his helmet directly on the concrete barrier, and had a fatal concussion.

For few weeks, Paul Brown at Reynard had been asking me why the driver was not more centrally positioned in the car for safety, and I had scoured the rule book and could not give him and answer, but this solidified why a driver should be repositioned in the vehicle. This was long before the NASCAR Car of Tomorrow, which based on almost the same principles we used for engineering the Dodge Truck chassis.

We put the driver closer to the center to make that less likely that any part of his body could contact the outside world in the event of a crash, logical stuff from European racing. We included a crush structure in the doorframe, by putting in some honeycomb. It didn't add weight, as the chassis were loaded with ballast to get to the minimum weight anyway.

Someone at Reynard rakishly put it: "All the added weight in the chassis was to ensure a bigger accident, that went further around the short oval tracks so all the spectators got an even opportunity to look at a crash." To this day I am not sure why a NASCAR car or truck has not gone into the crowd, with all that mass they carry, piercing the light fencing structures.

Because none of us, including Reynard, had any experience with NASCAR, we muddled along with the rule book as a guide, but since there wasn't much in it, we were really only guided by common sense and a sound engineering education. Little did we know that neither common sense nor engineering were the most important guiding features of chassis design by NASCAR.

We didn't realize that, when we wanted to put a tube here, NASCAR could say, "We don't like it there; we like it half an inch the other way or a quarter of an inch the other way."

We ended up with some good work by Reynard and ourselves, where they said we can make the driver safer and improve the vehicle dynamics. We lightened the chassis and made it stronger, using good sound engineering principles and modern techniques.

We knew we couldn't do a lot to the basic frame, so we concentrated on designed a chassis and suspension, with a structurally best-practices chassis for weight and strength optimization. I even considered making the engine a structural member of the chassis, but was quickly dissuaded from going that route, albeit the most logical.

One of the problems with the NASCAR chassis was there was a lot of friction in the suspension movement. I noticed that when I first went to a NASCAR race. I saw one of the guys setting up the car by jumping on the front of it. Every time he'd jump on it, the car would go down and then it would stay there. And then when they grabbed it and lifted it, it came up 3-4 inches and stayed there. This was without the shock absorbers attached so all this could only be attributed to friction resistance in the suspension.

I thought, "That's not good. That's a lot of friction; we've got to get rid of that." We looked at it, and lo and behold not only was there friction and stiction but the geometries were fighting each other in the joints, This was nasty and stuff from a pure engineering standpoint.

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One of the things was we came up was within the front spring arrangement. I said to Paul Brown at the time, "We need to get a spring that's neutrally loaded, so it doesn't form part of its spring stiffness through the bending of the spring." It's called the Wahl Factor. So you just get pure torsion in the spring wire material, the twist action in the spring, with no hysteresis and stickyness.

A coil spring works as a length of wire and you twist it, and that gives you spring action. But also, in the NASCAR sense, it had a bending action to it from the fixed mountings moving through a poor geometry arc top to bottom, so that was also adding column bending stiffness to the total wheel rate.

The Craftsman Truck Series first started in 1996. Dodge did not win a single race in 1996, won two in 1997, and two more in 1998. Then, in 1999, Dodge won four (Dennis Setzer was responsible for three and finished third in points). For 1999, Setzer ended up in seventh place with one win. Dodge finally won back to back championships in 2004 and 2005 (Bobby Hamilton and Ted Musgrave). Chevrolet won 12 from 1995 to 2013; Ford won a single championship; and Toyota won four, starting in 2006.

We needed to get a purer suspension movements, so we came up with a suspension that was a lot more compliant, and the spring had a cup on the top that had a ball in it that was mounted inside the spring. It had a very deep cup on top of the spring that located the spring, and then a ball that sat into the spring about I would say two inches down into the spring that was the rotation point of it. That self neutralized itself and had no bending in it, so it just rotated on the ball basically. Simply put, it was a ball joint mounting of the spring. A simple, elegant design and I am not sure why it is not used on road cars today.

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That worked very well, but NASCAR said, "No, no, no, no. You can't do that; way too technical."

Reynard's Paul Brown said told me, "Ian, you're exactly what Chrysler needs, but you're exactly something Chrysler can't handle," meaning I was just a square peg in a round hole there….such is life. We wanted to do engineering, and NASCAR didn't want us to do engineering.

John Wehrly was brought in to oversee the project as John had a great deal of experience dealing with NASCAR, having been instrumental in the early Hemi days with the Pettys. John explained that to me, that he's doing basically what NASCAR wanted to do by negotiation.

John, I have to say, was a great person to deal with NASCAR and was a calming influence, and was the best person to take the project on. I understand NASCAR's business model, but it's entertainment over engineering and unfortunately that just doesn't sit with me. I do not understand why we would be involved in a series where engineering pushing the envelope for production vehicles was not what was required.

Well, you can't argue that NASCAR's not been successful as a business model, and has made a lot of people quite wealthy, from the suppliers, team owners, track owners, and everyone associated with it. That's the other way of looking at it.

Formula One is quite successful but other series have struggled. American LeMans (ALMS), which is probably the most technical, advanced series, certainly more advanced, I think, than Formula One, struggles to get viewership, and that's why it's been sold to NASCAR.

I hope it does not go the NASCAR Sprint Cup and Truck racing route by manipulating wins on the track by fiddling with the parameters that alter a cars performance on the day, but all indications have been so far that they will "for the show". This is called the BOP, or balance of performance calculations which alter the cars' performance at each race. This has a sobering effect on the smart and young engineers, and ultimately the spectators, as each come to realize that unequal advantages are applied to each car based on their previous race performance.

Coming: aero-tuning the NASCAR trucks

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