Now lets get into some handling dynamics and how these parts can cause or cure them.
The handling of a vehicle is all about weight transfer. Controlling the amount of weight transfer to specific tires is essentially what suspension tuning is all about.
Ride Height: Ride height can affect many other handling dynamics. If your car is too low, it can result in too much camber gain. The camber changes as your coilovers compress. Remember the lower your car the more negative camber. This theory, depending on the suspension geometry of your car can multiply on itself the lower your car is. For example, a car with stock ride height might gain -1 degree negative camber in a turn. A car which is lowered already might gain -2.5 degrees in a turn. So there is a point where you can be too low. Rake can also play havoc on your aerodynamics. If your car is higher in the front than in the rear, your car essentially becomes a wind catcher at speed causing lift and ultimately dramatically less grip.
Dampening: Compression and rebound are a main staple in handling and is constantly being adjusted on race cars. The ideal setup is a coilover system that can move along with the undulations in the road without upsetting the weight balance of the chassis. You can also use it to dial in or out understeer/oversteer. For example, if you are experiencing understeer softening the front dampening and/or stiffening the rear dampening can help dial that out. The opposite is true for oversteer. There is a trade off though. The softer you go, the more body roll is experienced, but the better your car absorbs undulations and bumps in the track.
Spring Rates: Spring rates are not something that is easily changed at the track for most. Spring rates can also change the handling dynamic of your car. The front to rear split of your springs can also aide in how a car rotates through turns. If you have too much spring in the rear, it will result in oversteer. Too much spring in the front and it will result in understeer. It is also very important that your dampers are valved correctly for your spring rates.
Camber: Camber is adjusted to help keep maximum contact patch on the ground resulting in maximum grip. Drag racers should run 0 camber in the rear to maximize contact patch in a straight line resulting in the most forward grip. Road racers on the other hand have to adjust for lateral as well as forward grip. This is when negative camber comes into play. Negative camber helps maximize contact patch when turning yeilding in higher corner speeds. The trade off is less contact patch for forward acceleration when driving in a straight line. The most accurate way to tell if you have the right camber settings is by taking tire temperatures on the outside, middle, and inside of each tire while they are still hot from a lap around the track. Taking tire temperatures can also help you determine weather or not you are running the correct tire pressure.
Caster: It is rare to find caster adjustment in a car or even aftermarket setups. The problem you don't want to run into is having too much negative caster. Negative caster is very unstable at high speeds. It also amplifies steering wheel input to a point where it is not helping your turn in. Think of a shopping wheel cart again. If you were to turn the wheel backwards, then start pushing the cart, that wheel will immediately flip back to the regular position of positive caster. That is essentially what your car wheel will do in a negative caster situation, except without the ability to be able to actually flip around into positive camber. You can also have issues if you are running too much positive caster. Caster also affects camber gain when turning the wheels. Although you won't have any stability issues at speed, too much positive caster will result in too much camber gain and less overall grip.
Toe: Toe is one of those things that minute adjustments can completely change the characteristics of the car. Toe out in the front can help the car turn in crisper. Toe out in the rear can help the car rotate through the turns better. Toe in, can help keep stabilize a car that may have worn out bushings. There is a fine line though before toe settings can become dangerous. Too much toe out and your car can become virtually un-controllable. Generally speaking, you want to keep your toe at 0. Sometimes front or all wheel drive cars can benefit from a tad toe out to get the car to rotate. If you are drag racing, you will want nothing other than 0 toe.
Sway Bars: Sway bars are sometimes adjustable and can be used to help dial in or out understeer/oversteer without affecting dampening or alignment settings. Stiffening the bar in the rear will help dial in oversteer, while softening it will help dial it out. The same goes for dialing in/out understeer in the front. The sway bars are probably the simplest part of suspension adjustment.
Tire Pressure: Tire pressure can be used for fine tuning a car's handling characteristics. Again though, there is a fine line. If you are suffering from mild oversteer, lowering the rear tire pressure can help. The same goes from understeer and front tire pressure. The opposite is also true that if you are suffering from oversteer, adding tire pressure to the front can help, and if you are suffering from understeer, adding pressure to the rear can help. There is a catch though. If you are running too much or too little tire pressure, your tire's contact patch will shrink. Too much tire pressure and the middle of the tire starts ballooning, too little and the middle of the tire starts caving in.
