RanderCar: THE FINE ART OF
CHASSIS SETUP
By Perry M Merckx

Most race fans have heard drivers or crew members refer to the setup of the race car as too "loose" or too "tight". What exactly does that mean? To put it simply, if your car is too loose, the back end wants to slid out from under you causing you to hit the wall back end first. If your car is too tight it will be hard to steer through the corner and you will see the wall before you hit it. What can you do to help correct these conditions, and to maybe understand a little better the science of race car setup, is why I talked with Jim Randerson of RanderCar Racing Enterprises.

"The first adjustments that we make literally are in the construction of the frame," states Randerson. "We can build as much drivers side safety into the car as we can because we are allowed 58% of the total car weight on the left side." What this means is far more safety in the form of more bars in the drivers door and plating.

Frames are built on a "frame jig," which is a flat, level section of metal large enough to house the frame that is welded together piece by piece. The jig insures accurate positioning while the pieces are welded together.

Once the frame is completed more fine tuning of weight distribution takes place in the form of lead. "No matter how you build a car its not going to be as heavy as it needs to be raced at," informs Randerson. "Depending on the traction the race track has is where the weight is added." The frame is constructed of 3X2 inch metal channels and lead bricks, formed to fit exactly into the frame rails, can be placed precisely where you need to have weight added.

Now that the frame is completed, its time to bolt on the suspension. This is where it gets tricky. While its a simple procedure to attach the suspension components to the frame, adjusting these components is a whole different story. The different kinds of adjustments are almost endless. You have different spring and shock combinations which are almost unlimited just in themselves.

You have track bar adjustments, jack screws, camber and caster adjustments, tire stagger and air

pressure. This list goes on and on. You get the picture. All of these adjustments are basically, "To distribute the weight so each of the four tires is doing an equal amount of work when the car is in motion," cites Randerson.

"You better learn how to use all those adjustments, because everyone of them has a purpose. You wouldn't need them on a car if there wasn't a purpose for them," mentions Jim.

One critical adjustment on a race car is the Panhard bar or track bar adjustment. This part prevents the rear end from going side to side. The height of this adjustment will help dictate how the lateral force is divided on the rear tires. If the left rear tire is working to hard you can move this bar to transfer some of the mass in motion so the right rear tire is sharing some of the load.

This alignment will help correct a loose or tight condition. Also keep in mind that this adjustment will not change the four corner weight of a car when scaled. Simply put, you cannot change the weight of the unmoving race car, it adjusts how the weight is transferred when the car is in motion.

How hard a tire works has a lot to do with many adjustments. To determine how hard a tire is working, its a simple procedure of taking its temperature. The ideal temperature is between 210-230 degrees.

Anything over that the tire becomes too soft (tight condition) and that is not good. Any temperature under 210 and the tire will not stick to the track (loose condition) and that's not good either. "What you want to do is work the weights and the adjustments on the car so you don't have any one tire getting too hot, so that you keep all four tires working," says Jim.

When working with weight adjustments on the four corners of the car, getting the right combination of spring heights and shock rates is a craft in itself. You want to have more weight on the left side of the car because when the car is going into the turn, that mass in motion is going to want to shift to the right side of the car.

When you get the right setup all the tires are happy, and the car goes through the corner without knocking down the wall.

Without getting too serious about trying to explain chassis setup, which is something you could write a book on, keep this in mind. What works for you probably would not work for a different driver. And what works for someone else may not work for you. Its all in how you drive the car. How's that for an exact science?

Nevertheless, all cars obey the same basic laws of physics. The key to setting up your car is to first understand what you want it to do, then analyze what it's actually doing.

Working in such an imperfect world as chassis building, where temperature changes or track conditions can cause you to pull your hair out, you have to wonder why someone would want to do it for a living. "I just love it," remarks Jim. "I get paid to do something that everybody else has to do after their job."

Jim started helping his uncle Mike Randerson in 1976. Mike was selling a limited amount of racing parts for about five years and decided to start a small shop. RanderCar was established. Mike was still working a full time job but five years later, left U.S. Oil after 17 years, to go full time in his own racing business. During the next 11 years, Mike would have people like Dick Trickle, Ted Musgrave, Mark Martin and NASCAR champion Alan Kulwicki visit his shop. Kulwicki drove a RanderCar to the 1980 championship at WIR., and the next year drove a RanderCar in ASA.

Jim bought the business from his uncle in 1992 and has continued building RanderCar chassis' to the same high standards that his uncle did for so many years.

Mike started building race cars in 1960, and eventually would build cars for other people. The Randerson operation started out of his garage on Hillcrest Dr in Appleton.

Mike would soon run out of room and built a shop next to his property. The business grew to a point that soon after Jim bought out his uncle he would have to move to a larger location. RanderCar is located at 1008 Randolph Dr in Appleton, just outside of Little Chute. RanderCar is again experiencing growing pains. The once adequate shop is now to small again and plans are in the works to expand the existing shop.