Setup specialists strive to have all parts working in harmony
Keeping four tires firmly planted on the ground requires creews to choose shock absorbers and springs working in concert with each other and with specifications geared toward particular tracks.
When a Sprint Cup team sits down to plan what components will be used for power and the suspension in a race car chassis they have chosen to race at a particular track, they have a variety of decisions to make concerning what power band they want the engine to perform in, what gearing they will use to transfer that power to the track and what combination of suspension parts they will select to help keep the car glued to the track as consistently as possible.The goal of the setup specialist or engineer is to establish and maintain a consistent, and therefore reliable, tire contact patch that the driver can be comfortable with and feel confident in while he is racing. The specialist needs to determine how much rake and tilt he wants to run at a particular track and also select the truck arms, track bar, sway bars, spindles, springs and shocks, etc. to run to support that decision. And, he needs to decide what caster, camber and toe, etc. he wants to design into his setup to complement the other parts he has selected. The correct selections and settings will, hopefully, result in a setup that will provide optimum and consistent performance throughout the race. For example, he would want to run more front wheel camber on a shorter and flatter track such as Martinsville than he would at a high-banked superspeedway like Daytona. The lateral (inertial) forces and potential body roll would be greater on the flatter and tighter turns at Martinsville than they would be on the steeper banking and sweeping turns at Daytona. The oval track racer is constantly thinking "low and left" when he builds a race car to keep his center of gravity and therefore his roll center as low and left as possible. This will reduce body roll and help to keep all four tires firmly planted on the track's surface. He can help to achieve that goal by selecting suspension parts that will also minimize body roll. If the static weight (the weight of an object at rest) is 3,000 pounds then it is pushing down on the Earth -- because of gravitational pull -- at the rate of 3,000 pounds. If you divide the weight by four then it is pushing down at the rate of 750 pounds per tire if the weight is distributed equally -- which, on a race car, it is not. This is where the racer tries to fool Mother Nature by redistributing what weight he can so it will push down disproportionately on the left side tires so they will have more grip in the corners when the car has inertial forces acting upon it and trying to roll it over. This is where the sway bars, track bar, shocks and springs come into play in the setup formula. Your street car probably has similarly rated springs on all four corners but a race car will have stiffer and softer springs combined to achieve a redistribution of weight when the car is experiencing inertial loads in the corners. Keep in mind that all the selected components need to work harmoniously together to achieve the setup specialist's goal. You would not, for example, run a shock with a soft bump or compression cycle with a stiff spring (on the front end) because they would not work in concert with each other to maintain a consistent tire patch. You might, however, run a soft spring and a shock with a softer bump and a stiffer rebound cycle so the shock and spring would compress more easily and then the shock's stiffer rebound cycle would hold the compression of the spring down longer and thus keep the nose of the car lower for a longer period of time. That is what they are doing when you hear the term "coil binding" used by crew members or analysts.
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