Online Automotive Magazine
Don't chase your tail. Find the perfect suspension setup the right way.
January 12, 2007
I'm assuming that if you're reading this that you've had trouble dialing in the setup on your car. I can't speak for anyone else, but when I first started tinkering with suspension setups, I made all of the classic mistakes. So in this article, I'm going to talk about some of those mistakes and tell you why and how to avoid them.
The first problem that I had was shear lack of patience. I would go to a race track, run just two or three laps and then stop to make some shock or sway bar changes. Then I would run another couple of laps and be unsatisfied with the way the car is handling. Once again, I would stop and make two or three other adjustments. It would go on and on like this for several hours, and I would never get the car dialed in. I would just seesaw back and forth between the car understeering and oversteering.
So here's the first rule: have patience! Especially if you're at a racetrack for the first time, you need to run many laps to become consistent, and only then can you make an accurate judgment on the way your car is behaving. In other words, you need time to find the best line on the racetrack and run that line for several laps. If you're using a completely different line each lap, you have no grounding on which to base your suspension changes.
I'm not sure where I heard it, but some drivers say that you need to run at least 500 laps on a racetrack before you make any changes to the suspension at all. And after getting some experience, I'm beginning to think that this is an accurate figure! The bottom line is that you need to know the racetrack like the back of your hand before you start any suspension tuning. Changing shock and sway bar settings will not make up for your poor driving on an unfamiliar track. So get out there and drive as many laps as you can with a base setup. It doesn't matter if your car is oversteering or understeering the whole time as long as it's drivable, of course. Preferably, set your car up for slight understeer by making the front suspension 50% stiffer than the rear suspension. Not only will you better learn the track by making these laps, but you will also improve as a driver by having to adjust to the handling characteristics of the car in order to turn the best possible laps.
So let's say the you now know the track and your car is not handling to your liking. As I mentioned earlier, you should have learned the track with a slightly understeering car. Naturally, you now want to loosen up the car to improve your lap times. Here's the second major lesson: change one thing at a time. I realized that this was a huge mistake of mine after racing for a decent amount of time. Since I was impatient, I would change a bunch of things at once so I wouldn't have to stop driving so often.
The biggest problem with changing a bunch of things at one time is that you end up not having any idea about which changes had good or bad effects. For instance, let's say that your car is understeering in low speed corners and in high speed corners. You realize that to correct the handling situation in high speed corners, you might want to adjust your rear wing (if you have one) to reduce rear downforce. That will let the rear tires slip more and give the car a more neutral feel in high speed corners. But you also want to correct the understeering in low speed corners so you stiffen the rear sway bar and soften the front shock settings.
You go back out on the racetrack and the car is oversteering like crazy everywhere! But you don't know exactly what adjustment caused the problem because you made three completely different adjustments. The right thing to do would have been to try to correct the handling condition in the low speed corner first since this involves mechanical grip. I have always felt that it is better to dial in the mechanical grip of the car first before fiddling with aerodynamics. Anyway, you could have, for instance, just stiffened up the rear sway bar and then gone back on the track to see how the car behaves. If it was still too tight, then you could make another adjustment. However, if it become too loose, you know exactly the adjustment that caused it, and you can act appropriately.
In essence, the two biggest mistakes beginners make in suspension tuning are not turning enough laps to accurately judge what the car is doing and making too many adjustments at a time. If you learn not to make these mistakes, you'll be a step closer to being a better suspension tuner and driver.