We should think of the turns...
We should think of the turns as three distinct phases or segments. In doing so, we can evaluate what to do to the car so that each phase is faster without hurting the other phases. We generally tune to the middle handling balance and then work on entry and then exit performance.
As the driver enters the turn, backs off the throttle, and applies the brakes, he (or she) begins to turn the steering wheel and must turn it sufficiently for the front end to come around. If the car is actually set up too tight, the driver will need to turn the wheel further than what would normally be necessary in a car that is neutral in handling balance. When the driver has turned too far, the traction balance reverses from tight to loose as the front traction begins to exceed the rear traction. At this point, the car will start to feel loose. This can happen so quickly that the driver will swear that the setup in the car is loose.
Just past mid-turn, the car will definitely feel loose to the driver. The exit performance off the turn will also suffer as the driver gets on the throttle and the car gets looser from power-induced rear wheel spin. The average temperatures of the rear tires will then probably be hotter than the average of the front tires due to spinning the tires with the loose-off condition. The crew will many times read this as a loose condition and think the car needs to be tightened up. It is already tight, and so a lot of valuable time is wasted searching for solutions to this basic problem.
A great way to quickly discover just what the handling balance really is for your car is to have the driver roll through the turn below the maximum speed. The amount of steering input needed to just drive around the turn should be mentally noted. The crew chief can view the location of the driver's hands from the fence or the top of the hauler. Then, the driver should take the turn at full speed as he would in the race. Again, note the amount of steering input by asking the driver or looking at the position of his hands at mid-turn. If the steering wheel is turned more than when the car was rolled slowly through the turn, the car is set up too tight. Many drivers are very surprised at the outcome of this test. A lot of time can be saved by doing this simple exercise.
We can see where the driver's...
We can see where the driver's hands are located when the car is normally turning the corner well under speed.
We are often in search of more bite off the corners. One way to accomplish that is to soften the right-rear spring. If your car is too tight in the middle, the rear springs may be too soft or the spring split may be wrong for the type of racetrack you are racing on. A softer right-rear spring than the left-rear spring can make a car very tight if other components are not set to balance the car.
There are many ways to promote more bite off the corners rather than by putting excessive rear spring split in the car. Often, a small amount of spring split will do the job while helping to maintain balance setup for mid-turn performance.
The front springs may be too stiff or the spring split may be wrong, causing an unbalanced setup. A stiff right-front spring can make the car too tight by not allowing the front to roll to work with the rear.
In this example, when at speed,...
In this example, when at speed, the driver's hands are well below the top of the door sill, showing that a lot more steering input is being used. This car is very tight.
The way the front springs are arranged as to stiffness is dependent upon the track configuration and banking angles. If the track has a long and larger radius entry combined with a lower banking angle, you can run a softer right-front spring than the left-front spring. This serves to improve turn entry and helps make the front end more efficient at mid-turn. This will not work with a tighter entry combined with a higher amount of track banking angle.
For tracks with medium banking and normal entry characteristics, you can run even spring rates across the front with good results. As the track banking angle increases, so should the right-front spring rate over the left-front spring rate.
Sometimes, we may play with the upper control arm angles and lengths to see if we can improve the way the front end works. When we do this and do not track the moment center (often referred to as the roll center) location, we can drastically change the dynamics of the front suspension for the worse. There is no telling where the moment center (MC) might be located after we make our changes.