The construction of a single coilovers is relatively simple. They get their name by placing the coil or spring over the shock absorber, thus the name coil OVER. The spring is responsible for holding the weight of the vehicle while still allowing the wheels to move up and down in response to the road. The coil is able to be adjusted with multiple structures called spring perches; these hold the spring in place around the shock absorber and allow the user to change various aspects of the ride. You can move these perches with a special wrench that is supplied with your new set. When you loosen or tighten them up, you are changing the height of the car.
For further instructions on how to adjust your coilovers follow the link here.
Next is the actual shock absorber of the component. This is responsible for keeping the spring from making the ride bouncy. They are critical to the ride of the vehicle. At the top of a pair of full coilovers, at the strut towers is the adjustment knob, with this you can change the ride from being firm to soft. It is extremely easy to change and takes about 30 seconds to do. On a stock set up, simply adding new shocks can change the handling characteristics of the vehicle. But the problem with OEM shocks is that they are not capable of being adjusted and the user is forced to stick with that set up no matter if they are on a track, a country drive, or going to the grocery store. Wouldn’t it be nice to have the ability to change your ride whenever you wanted? And how could your vehicle even approach being deemed a “great handling car,” without a set of suspension necessities like this?
Many supercars as well as virtually all touring, rally, autocross, drifting, and to many other racing classes to list have adopted suspension set ups like this. They have seen the value in using this suspension and have not opted to take any short cuts. You don’t see Ferraris driving down the road with 55 different kinds of braces under, over, and inside a car and no coilovers. This is a testament to how there is truly no other single modification you can make to a car that will make as drastic a change as this.