In keeping with our desire...
In keeping with our desire for less rear steer, we moved the rear links to holes that would make them more parallel to the ground.
For springs, we needed to spring the car for North Florida Speedway, which would be our first race in the car. This speedway is a medium-banked track that I would estimate to be around 12 to 14 degrees. For this kind of banking, we would use a stiffer RF spring and a stiffer LR spring. Our layout (in pounds per inch) is: LF = 450, RF = 500, LR = 550 (220 equivalent), and RR = 650 (234 and 325 equivalent). The rates in parenthesis are the rate equivalent if the springs were mounted to a clamp on the rearend.
A note about the swing arm cars: A swing arm is one where the spring/shock is mounted on the control arm. This creates a motion ratio and a dynamic reduction in the rate the car "feels" equal to the spring rate multiplied by the square of the motion ratio. Our swing arms came with two holes and different lengths on each side. This created an opportunity for us to make changes to the spring rate the car feels just by moving the coilover to a different hole.
So, in the RR corner, we can start out the night with the coilover in the rear hole, which is the higher rate of the two, for an equivalent rate of 325 and then when the track goes slick move the coilover to the front hole for a 234 rate which provides more bite off the corners.
All of the other holes would...
All of the other holes would promote rear steer to move the right rear back and the left rear forward.
The final settings involve the weight distribution in the car. Our total target weight with the driver is 2,425 pounds with a 52.5 percent rear, 54 percent left side and 56 percent cross weight, or about 240 pounds of left rear distribution. Bobby won a heat race with that amount of LR weight and felt like this track could use a lot of LR load to help with bite off the corners. The option for a low range of cross is to go with 49 percent cross, or about 70 pounds of LR. We may well try that for tight conditions.
The rear percent is lower than a lot of the recommendations out there, but again, for this track we felt we needed to bring this car closer to a fifty-fifty distribution. The 54 percent left side is going to be good for tight conditions, but might be too much for a slick track. We might move more weight to the right side if the track conditions turn more towards being overly slick.
We had already moved all of the lead ballast to the middle of the car and some of it up higher to promote roll over and side bite. This might hurt us when the track is wet and heavy, but come feature time, it will be very helpful. Moving lead around is not so easy at the track and we will be developing ways to move weight up and down on a sliding tube to make changes to the center of gravity for changing track conditions.
At this point we are all set up to go racing. All we need now is to complete the installation of the body, fuel her up, and throw on some new tires. We want to thank all of our partners who have provided support for this project. We will be reporting on the results of our first race in the next issue, whatever the outcome.