Joe Fischer, a fabricator working with chassis for Performance Unlimited, (address), Ringwood, laughed, “Once you get me talking about cars it’s hard to get me to stop.”
It wasn’t just the incredible depth of knowledge Fischer brought to Performance Unlimited’s Tech Presentation Sunday where racers and fans of the sport learned the fine art of fine tuning suspensions and steering for maximum performance, it was also the passion for the subject vividly flashing in Fischer’s eyes as he described how balancing the weight of a racecar at each tire is a process that has to account for fuel consumption, spring compression in turns and road temperatures while racing. In fact, Fischer said the timing of these factors is also crucial in racing as the goal is to have the car operating at its optimal weight and balance late in a race.
“You’re not going anywhere early when the cars are all packed in tight together,” Fischer said. “You want your optimal weight late.”
To achieve the optimal balance of weight, Fischer said they can add weight in different areas of the car. However, adding weight becomes counterproductive. By maintaining the chassis at the lowest possible weight, they have more flexibility to modify weight distribution.
Prior to Sunday’s event, Mike Wolf, a race engineer with the Paul Menard Car 27 (more) spoke of all the minute details required to give a NASCAR racer the best opportunity to win. Fischer echoed those sentiments. However, he also pointed out that most people don’t have millions of dollars for the kinds of equipment the ‘NASCAR boys’ use. In the case of measuring and adjusting the car’s weight at each wheel, NASCAR has a 7-post shaker that simulates the effect on weight distribution while going around the track.
“Obviously, we don’t have that capability,” Fischer said. “We use a bump-steer system – meaning the way we determine what the steering does with travel.”
Fischer demonstrated how they set the bump-steer equipment up to the spindle with the tire and wheel removed. With a floor jack, they raise the spindle through its range of travel. The dial indicator on the equipment shows how much steering the car has while driving. As Fischer explained, bump-steer is just that; the car hits a bump and, as the springs compress, the wheels pull one way or the other. The goal is to reduce the amount of pull, or steering, that occurs when going over bumps.
Fischer said everything comes down to one simple equation – how much tire can they put on the pavement.
“The bottom line in racing, in any way, shape or form – it always comes down to tires on the ground … the contact patch,” he said. “Everything you’re doing with the chassis is to achieve the most contact patch on the track.”
He said that a car with a 600-horsepower engine will lose every time to a car with 150 horses if the prior is running on bicycle tires and the other has a good set of road shoes.
The minutia of detail extends to the level of measuring the temperature of tires. Fischer described how they take three temperature readings across the surface of the tire from outside to in. The variation in temperature tells a lot about how a particular tire is running. Even the temperature from tire to tire is informative.
“Ideally, you would have 140 – 140 – 140 (degrees) across the front left tire,” he said. “The left rear might be a little hotter because it’s the drive tire.”
For instance, Fischer said that, if a tire had readings of 110 – 50 – 110 (degrees) that would indicate there is not enough air in the tires. If the middle temperature is highest, there’s too much air. Other readings can indicate whether the camber is too positive or negative, as well as other factors.
Approximately 25 racers and enthusiasts attended the event last Sunday. The attendees brought varying levels of knowledge about the subject matter but all came away with a better understanding of the myriad of influencing factors involved in trying to tweak a racecar to its ultimate performance.
One thing that makes tuning a suspension and steering so difficult is that everything is interrelated. As Fischer explained, when they make an adjustment in one area of the car’s chassis, it tends to effect adjustments in other areas. Sometimes, identifying a problem isn’t all that easy either.
Fischer was driving a car in a race for another owner a few years ago.
“For the first 10 laps, I was dominating the field,” he said. “No one could touch me.”
But, after a yellow flag, Fischer discovered that the steering had become extremely loose; when he went around turns the rear wanted to slide out. He said that, every time they ran the car, it was the same thing. Fischer said he was talking to the owner of the car a short time after the race.
“He told me, ‘We found it,’” Fischer said.
It turned out the problem with the chassis was related to the header (exhaust manifold) requirements for the particular engine in the car – a Ford power plant. There wasn’t enough room for the headers to fit around a round brace that connected the center of the chassis to the right front of the chassis. To solve the problem, the car’s crew cut the bar out and replaced it with an aluminum alloy that was bolted in so they could remove it to fit the engine in and slide it through the headers afterwards to reconnect it.
“The thing about aluminum is that, at about 700 degrees, it turns to butter – it loses its rigidity,” he said.
When the bar, which was designed to help stabilize the chassis, became soft, the entire handling of the car changed dramatically.
Fischer said there are also differences in how they tune and balance a chassis that depend on the type of racing the car runs in. Short track racers, like Fischer, run on a circular track, always turning to the left. But, road racers run on a track with multiple turns to right and left. The optimal balance for the road racers is generally more equalized.
They also have to consider the qualifications for their type and class of racing.
“We want to be more than 58 percent (of the weight) on the left side of the car,” he said. “But, if you’re 58.2 percent to the left you’re disqualified. That’s illegal.”
In fact, the specifications change based on what type of motor a car has. Teams that choose a bigger carburetor are penalized on weight. He said that, as soon as a race is over, the top four or five finishers drive straight to the garage where they are checked to ensure they qualify. If they fail the test, they’re stripped of their winnings.
All of this translates to tuning and balancing the chassis as close to the allowable standard without crossing the line. Fischer described it as a quest.
“No matter how good you are, you’re always looking for more,” he said. “You try different things and, if they don’t work, you go the other way.”
For every improvement, the car receives what Wolf called “free speed.” And Fischer agreed that, ultimately, that’s what drives racers and their crews to continue challenging the envelope.
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