Race car suspensions and setups have gone through many changes in recent years. Ever since the onset of the "Big Bar Soft Spring" era, racers have found themselves trying to go softer and softer with their suspensions to achieve that perfect balance. Everybody is doing it, and if the Cup guys are doing it must be better, right?
Much of the time, however, racers are disappointed with the results as the cars just don't seem to react logically. If the car is tight, you soften the front springs even more...right? This time that doesn't seem to work, so confusion and frustration usually set in, sending you back to your traditional setups.
Magically, the car's feel is back, and it's fast again. So what was missing? They say "Why didn't it work for me?" In my experience it's all about the understanding of one basic dynamic that most racers don't have the ability to measure: Dynamic Wheel Load Distribution.
Bump rubbers come in various...
Bump rubbers come in various densities and sizes. The idea is to produce a "spring" rate that will work in conjunction with the other springs in the car to produce a balanced setup with soft initial travel and then a much stiffer spring rate in the turns.
Dynamic Wheel Load Distribution is the distribution of loads on the four tires as the car turns and all of the load transfer has taken place. If we can gain this one piece of missing information, the puzzle will begin to unfold, and you will begin to understand why your race car reacted the way it did with the new style setups.
Many have said that the Big Bar Soft Spring setup only achieved its gains from the added downforce created from a better, lower, and flatter body attitude. While those advantages definitely have merit, they are still overlooking the very reason aero downforce makes a race car faster. Here again it all comes down to wheel load distribution.
So, now you can begin to see that when previously trying the Big Bar Soft Spring setup, the real culprit to the failure was the redistribution of wheel loads. In actuality, this is a lack of or reduction in those wheel loads as you went softer and softer on the front springs. The solution to this problem can be solved in several different ways so that you can have the advantages of better aero downforce, as well as maintain a neutral balanced setup.
This rubber represents a much...
This rubber represents a much stiffer rate that is close to, but not really a packer. This can be used in conjunction with the round rubber design.
Bumpstops are one of the best methods of achieving this balance. When using bumpstops, you install a stack of properly selected bumpstops on one or both front shock shafts. You then select a front spring and sway bar package that will give you the best on-track body attitude.
Now, the key is knowing and achieving the proper wheel load in critical parts of the corner to balance the chassis handling. We do this by selecting different hardness ratings in the bumpstops themselves, and by adding spacers or packers to alter the timing and engagement points of the shock body to the bumpstop stack.
This in effect creates a specific amount of wheel load for each wheel, based on a given amount of suspension travel to achieve that optimum body attitude and optimum distribution of wheel loads at the same time.