Going into a hard left-hand turn, weight is going to transfer on to the car’s right front. For the car to handle properly, it will need a sufficient spring rate to prevent collapsing the spring, yet not so stiff that it prevents suspension movement under varying types of loads such as bumps. Springs are rated in terms of the number of pounds of load required to compress the spring 1 inch. For example, a spring with a rate of 500 pounds per inch means that it requires a 500-pound load to compress the spring 1 inch. You can also think of the spring as the component necessary to allow the suspension to take a set in the middle of the corner at the point where maximum load is generally applied. If the spring is too soft, the car (in our left-hand turn example) will merely collapse the chassis down on the right front spring and hit the bumpstop, which effectively creates an infinite spring rate. At this point, the car will probably understeeer horribly because the front suspension effectively is solid, as if there were a solid link in place of the spring. If the spring is too stiff, it will not allow the suspension to compress enough to allow the suspension work and the car will more than likely still understeer badly. The way to tell the difference here would be in suspension travel. The undersprung car would compress several inches, while the too-stiff rate would compress or move very little. Many other factors come into play here, but you can see how important it is to establish a proper spring rate. Ironically, a compression-adjustable shock absorber can help you dial in the proper spring rate by looking at how much compression valving is required to help the spring do its job. The more compression stiffness that is required, the more likely it is that you need a stiffer spring. Conversely, if softening the shock’s compression valving helps, then the spring could be too stiff.