Once the track has developed...
Once the track has developed a black groove, we are fast on the way toward a slick track. The groove is usually narrow, and the area outside the groove becomes slick as the material dries out. The right-side springs are now softer than the left-side springs.
Evening up the front springs will help the car turn, and softening the RR spring, lowering the moment center, and raising the CG will provide better bite as the track dries out.
LM: We can now begin to change the spring rates at the RF, RR, and LR. The RF = 350; RR = 200; LR = 200 (375 pounds swing arm). We can move the Panhard bar over to the left side of the chassis with the heights at 11 inches left and 9 inches right. We can start moving weight over to the right side to provide a lower left-side weight of 52-54 percent. Now softer tires can be used with some siping. Slightly increased Ackermann and small amounts of rear steer (LR tire coming forward) will help the car turn through the middle.
The track has now blackened over and the edges of the groove are loosening up with the surface material turning to drier sand. Passing becomes difficult because of the one-groove nature of the track. The "slide job" works well here because as you go under a car coming into the corner, you pass and inevitably slide in front of the passed car. Once your car hits the black groove, it will grip and you can accelerate off from the passed car.
Now the track has gone to...
Now the track has gone to an overall slick condition that requires more imagination.
HS: When the track turns black, the surface has become hard with very little loose material. The moisture is evaporating off the first inch of material, and there will be less available grip without the surface becoming overly slick. We will still need to drive the car straight and try not to soften the right-side springs too much yet. We won't change the setup at this point in time, but the driver will need to think more about throttle control coming off the corners to prevent wheel spin.
LM: We will want to soften the setup a little more while the track is transitioning through this phase, and we need to reverse-split the front springs. We could continue to move weight up and to the right in the car to raise the CG about 1 inch and further decrease the left-side weight percentage. The LF spring = 375; RF = 350; LR spring = 185; and RR spring = 175.
We can utilize the entire...
We can utilize the entire width of the track for passing or to find the fastest groove. Bite off the corners will be at a premium.
The Panhard bar, mounted on the left side of the chassis, should be at heights of 12 inches left and 8 inches right. Tire selection should include a little more siping to help dissipate heat, as the tires will begin to spin slightly coming off the corners. There will be less grip, but not to the point of going overly soft on the springs or introducing great amounts of rear steer to turn the car.
The track has now dried up and the black is mostly gone. The surface has not come apart just yet, and passing is a bit more manageable because the entire width of the track is uniform in grip. If the track changes banking with more angle on the high side, then passing can be done on the outside more easily than down low if the car is handling well.
We have now reached the final...
We have now reached the final stage in the track's transition. The surface has dried out completely, and fine particles of material (sand) cover the surface, reducing the traction to very low levels.
HS: We can now soften the right-side springs, or pull out all of the spring rubbers. It is time to soften the car, move weight over to the right, and lower the rear moment center more. Change the RF spring to a 750-pound spring and the RR to a 175-pound spring. Raise the rear ride height one more inch, move weight up and to the right in the car, and soften all of the shocks. Reduce the air pressure in the tires by 2 pounds all around.
LM: It is time to go a little more radical in the setup. We will soften the RR spring and the front springs. LF = 350; RF = 325; LR = 200 (350 pounds swing arm); RR = 175 (325 pounds swing arm). Raise the Panhard bar by 1 inch to 13 inches left and 9 inches right. Increase the rear steer by changing the angles of the left trailing arm. Decrease the air pressure all around for more footprint area, and groove the tires for the most side bite with more grooves and a limited number of siping cuts.