Open Wheel Suspension - Sprint Car Technology

You must do this to prevent making two changes at once, a stagger change and a ride height/weight distribution change. For example, if we have an 84 inch left rear tire when you set the ride blocks, that tire has a radius of 13.37 inches. If we change to a 94 inch LR tire that has a radius of 14.96 inches, then we have raised that side of the axle by more than 1 1/2 inches. That would increase the RF to LR weight percentage considerably.

If a dual change is desired, then OK. But we need to realize just how much of a change is being made. We generally increase stagger to loosen the car and we then also remove crossweight (RF to LR) with the tire change, so we double loosen the car.

The handling balance for a Sprint Car needs to be a dynamic balance just as in a stock car. All four tires need to be in contact with the racing surface and have the most load ending up on them as possible. If we have a truly balanced setup, the LF tire will carry a decent load and the car will turn better.

For a winged Sprint Car, it would make sense that our spring rates, side to side, would be the same. Spring split on a solid axle suspension has a dramatic affect on roll tendencies. Since the cars roll first to the right on entry and then left at mid-turn due to the aero forces on the wing, we need to have the same roll stiffness in both directions. If a stiffer RR spring (over the LR spring) promotes roll stiffness in a roll to the right, then the reverse would be true for a roll to the left.

Our handling can be much different from corner entry to mid-turn if we run different rate springs on each side for winged Sprint Cars. The Panhard bar height, or Watt's link moment center height, must also be tuned to the spring stiffness as well as the spring base. The idea is to develop a setup for your Sprint Car that has the same roll characteristics for the front and rear of the chassis so that the handling balance is equal all of the way through the turns. Again, this has been tried and proven to work.

The setups for the winged Sprint Cars vs. wingless Sprint Cars is necessarily much different due to the high amount of downforce produced by the wings. The spring stiffness must be more for the winged cars, especially on asphalt. The speeds are much greater when Sprint Cars are racing on asphalt with wings attached.

More loading means more traction and the lateral g forces go up considerably with the increased speed through the turns. This necessitates a higher overall spring stiffness and in some cases, a spring split with the right side springs being more rate than the left sides.

Here too, we see a definite need for chassis setup balance. We really want all four tires to carry maximum load. At the LF, we need for that tire to carry load to help the car to turn. Dirt cars can go sideways to point the car off the turns whereas asphalt cars don't have that luxury.

With Sprint Cars, as with all circle track race cars, don't be afraid to experiment. Use the manufacturer's baseline to start with and then branch out and try different setup parameters. When something works, keep it. When something doesn't work, note it and don't try it again. Racing technology has evolved since the early days and we don't want to stop that process now.

Everything that will make you faster has not been discovered. That's one of the things that make racing so much fun. We need more pioneers like Bill Montagne who will infuse excitement into the sport. I see no reason why we can't experiment with the car's designs so long as it's safe to do