Young Version — August 1999

The shock absorber is the hardest part to understand. So what exactly is a coilover? As the name suggests, it's a suspension system whose ride height can be adjusted. Apart from that, its functions and the names of its parts are the same as conventional suspension. Many of you probably already know this, but let's check the names and basic functions of the parts that make up the suspension. Starting at the top, there's the upper mount, which connects the body to the suspension. The main spring sits below it. You can see a thin piece of rubber between them…

…It's there to reduce noise and unwanted vibration. Next is the main spring—the part most people simply call the spring. It absorbs impacts from the road. Below that is the center seat, and some coilovers, like the one in the photo, also have a helper spring to support the main spring. Under that is the lower seat where the spring rests, held firmly by a lock nut. The position of the lower seat changes ride height; that's the basic idea behind a coilover. If you look at a photo or the parts themselves, it's fairly easy to understand what these pieces do. But the most complicated suspension part is…

…the shock absorber. From the outside it looks like a thick rod, but a car would behave wildly without it. The spring absorbs impacts, but after it compresses, it tries to extend again; once it extends fully, it compresses again. With springs alone, the car would keep bouncing. The shock controls that movement to a degree. The simplest way to do that is to create resistance. How is that resistance made? First, remember: oil doesn't compress under pressure, but gas (air) does. In the photo on the left, the shock has a rod moving up and down inside an oil-filled sealed cylinder…