By Bryan Redeker
This Sunday will be Racetech’s first autocross of the year. The event will be at GVSU, which is where one year ago, the Mustang suffered suspension failure and came home on a flatbed. This year should go better with a complete new front and rear suspension, very sticky tires, and improved suspension geometry. Brandon and I will also be running the Fiesta in HS.
Since the Mustang has completely new suspension geometry and tires, all of the tire pressure data from the past few years gets thrown out. We don’t have any data on the Fiesta either for tire pressures. Brandon and I will be going into this autocross blind, with no real idea how to set up the pressures on either car. Our assumptions are a low pressure on the back of the Mustang for grip off the line, but also lower front pressures than we have been used to in order to try and reduce potential understeer due to the higher front spring rate than is recommended. For the Fiesta, I am thinking about a very high rear tire pressure to decrease rear traction and promote rotation. The Mustang rotates with the touch of the throttle, while the Fiesta will need some left foot braking and high rear pressures. Going to look at the data from my ZX3 and see if that points me into a direction to start. I think I used to run 38 psi front and up to 42-44 psi in the rear. I also put the Koni’s on full stiff and a massive rear sway bar. There are none of those adjustments on the Fiesta, just tire pressure.
We do have a magical instrument that will help guide us to setting up the Mustang and Fiesta on course. I have a Longacre pyrometer that we can check the tire temps at the outer edges and center. That data will tell us either to decrease or increase pressure based the temperature spread between three points on the tire. Since we don’t have a compressor at the track, we will go high and bleed down from there. I am expecting the Fiesta will draw a large crowd around it when it shows up on Sunday. When you are trying to prep two cars for competition, trying to walk and learn the course, and find time to relax, having a crowd makes things hard. The group that will see the car in action this Sunday are the hardcore weekend warriors, and making a good impression in front of them is important. I am hoping that a few of them will make a change to the Fiesta next year after seeing it on course this weekend.