Making your car handle is a really complicated task, if you think about it. Ride frequencies, roll centers, camber curves, scrub radii, it's enough to make you build show cars instead. So here's an easy solution: ignore all that stuff. Odds are you can make your car handle better than most by knowing only five things.
The first thing to know about handling is that your tires are by far the most important thing. A set of sticky tires can make even a tragic suspension fast, and the best, most perfectly tuned, aligned, and corner-weighted track car will be a disaster on Costco economaster treadlife supremes.
So how do you pick the right tires? That's a tough one. The tire industry seems determined to make tire choice as difficult as possible. Which do you think is stickier, a Pirelli P7000 or a P7000 Super Sport? Wrong, the plain P7000 is far more super. Here's a hint that can help you on that one: The Super Sport has an M+S marking on the sidewall. That means Mud and Snow, which simply means the tread blocks are small and full of cuts that are good at grabbing onto sloppy surfaces. Such a tread is terrible when pushed hard on dry pavement. In the Pirelli example, sticking to the P7000 will give you much more grip without major sacrifices in ride, wet weather handling, or any of those ordinary concerns. So look for-and avoid-the Mud-and-Snow-rating if you drive like we do.
OK, so the tread pattern is the key? Not really. In general, performance tires will have bigger tread blocks, since they're physically stronger and less likely to be ripped apart by hard driving. Performance is fashionable, though, and despite all the hype about tread stability, water evacuation and the like, tread patterns are largely dictated by fashion. So tires like the Yokohama Parada, Nitto NeoGen, and BFG Scorcher are designed to look like race tires, but offer the longer tread life necessary to make them affordable to a fashion-conscious mass market. They offer plenty of grip to get bumpstop-thumping show machines home, but have no place on the track.
What about treadwear rating? Isn't a tire with a treadwear rating of 40 far grippier than one with a 400? Probably. The treadwear rating is a decent indicator, but don't nitpick it. A 160 treadwear is not necessarily stickier than a 200. The more modern a tire design, the higher its treadwear rating can be while still being sticky. In the end, experience is the best tool for picking a tire. If you don't have enough experience, use somebody else's. See who's fast and ask what tires they like. The Tire Rack's Web site, www.tirerack.com, is also a good source of info, though they don't carry several of my favorite tires. Ignore the advice of the guy at the local tire shop. The second thing to know about handling is that having enough travel is almost as important as having good tires. Think about this when you're fantasizing about how low you want your car to be. Some cars, like an '88-to-'00 Civic, have so much travel that you can be in the weeds and still have plenty. Others, like a first-generation Neon or SE-R, can hardly be lowered at all before they start pounding the bump stops.
How much travel you need is determined partly by the terrain you're driving on, and partly by your suspension setup. Stiffer springs mean your suspension will move less, so you don't need as much travel. The same is true if you have a lot of low-speed damping from your shocks. And get this: You'll need more travel and/or a stiffer suspension if you have really sticky tires. The reason is simple: More grip means more body roll, which uses more travel. The simplest travel solution, though, is simply not to lower your car so much. Sorry.
Speaking of handling balance, how to adjust it is the third thing you need to know about handling. This is really simple if you remember that more load at one end of the car will make that end start sliding earlier. Say you have a nose-heavy, front-drive car and you want to reduce understeer. The first thing you should do is think about the problem differently. Instead of reducing understeer, think about increasing oversteer.
More oversteer comes from putting more load on the rear tires, and that comes from a stiffer rear anti-roll bar, stiffer rear springs, or stiffer rear shocks. If you want more understeer, try stiffer stuff at the front. If you're already too stiff, go softer at the opposite end.
When making these adjustments, remember that, assuming you're starting with a reasonably competent setup, a change in anti-roll bar diameter will make the most dramatic change in handling balance. Changing spring rates is probably second. Changing the lever arm on an anti-roll bar (switching settings on an adjustable bar) is around third in the level of adjustment, and turning the knob on adjustable shocks is a distant fourth, being best for fine-tuning an already good setup.
Just beware: If you haven't properly addressed suspension travel, your tuning attempts might do exactly the opposite of what you want. A car that understeers because the front suspension bottoms out in hard corners could actually get less understeer from a bigger bar because the bar would reduce roll, which would lift the outside front suspension back off the bump stop. That's why the suspension travel thing is the second thing you needed to know, and this is the third.
The fourth thing you need to know about handling is that dampers are voodoo. Just like the black arts, they are both extremely powerful and virtually impossible to figure out without years of study. Good dampers can make a car ride and handle beautifully, and bad ones can render your every attempt at adjustment useless. Since the real tuning in a shock is done at the design level, the best you can hope to do is buy the right ones. Figuring that out is harder than figuring out tires. Sorry.
Finally, the fifth thing you have to know about handling is that your alignment matters a lot. It's also confusing. Here's what you need to remember:
* Toe-in in the front improves straight line stability and makes turn-in sluggish.
* Toe-out in the front makes your car darty in a straight line, darty on turn-in (some people like that), and tears up the inside of the front tires.
* Toe-in in the rear suspension promotes understeer.
* Toe-out in the rear makes you crash.
* More camber means more cornering grip and less straight line (acceleration and braking) grip. Put more camber at the end where you want more cornering grip.
There will be a quiz.