Double Down Motorsports has a lot of track experience, especially in production based cars, and even more specifically in Nissan's 350Z. I thought it would be good to pass some general suspension tuning knowledge along to my fellow Z enthusiasts.
Lets start by going over the different adjustable parts of suspension systems and their function.
Ride Height: Lowering a car's ride height, lowers its center of gravity resulting in less body roll and better handling. Beware though, because lowering your car also changes its alignment specs. Lowering your car will affect the amount of camber on your tires. Lowering your car can also affect toe, which can be very dangerous if not set properly.
Dampening: Most aftermarket coilovers are dampening adjustable. There are two basic types of dampening adjustments, compression and rebound. Then further into that is high and low speed compression/rebound. Compression adjusts the rate that your dampers (aka shocks) compress themselves, or basically the rate they soak up bumps in the road. Rebound is the opposite. It adjusts the rate your dampers rebound from being compressed. The best example I can think of off the top of my head is a memory foam matress. You put your hand in it and when you remove it, it slowly goes back to its original state. That would be a much exagerated version of a really slow suspension rebound.
Spring Rates: Spring rates can either be linear or progressive. Linear spring rates remain the same as they are compressed. Progressive spring rates get progressively stiffer as it compresses. Linear springs are better for performance, while progressive springs offer a better ride quality.
Camber: Camber is defined as the angle of the tire in relation to the road surface. When looking at the front of the car, if the top of the wheel is inward more than the bottom of the wheel, that is negative camber. If the top of the wheel sticks out farther than the bottom, that is positive camber. Camber adjustments are dialed in to achieve even tire wear for the type of driving you are doing.
Caster: Caster is like a shopping cart wheel. The wheel is forward or behind the lower ball joint. Positive caster is when the wheel sits behind the lower ball joint point (like when you are pushing a shopping cart normal). Negative caster is the opposite (like if you were to turn a shopping cart wheel backwards). Caster affects stability at speed and steering response.
Toe: Toe is how the wheels are pointed in relation to eachother and are measured sepearate front and rear. Zero toe means that the two front or rear wheels are perfectly parallel to each other and are facing perfectly forward. Toe in, is like someone who is pidgeon toed. The front of both wheels point in towards each other instead of pointing directly ahead. Toe out, is the opposite. Toe can affect tire wear, how the car rotates in a turn, and on the front wheels, it can affect how the car turns into a corner.
Sway Bars (or anti-roll bars): Sway bars are desingned to combat body roll by transferring force to either side of the car in a turn. It is basically a device that helps with weight transfer while turning.
Tire Pressure: Tire pressure can have an effect on the handling of your car by adjusting the tire's contact patch.