These, in car suspension use, tend to be used to replace suspension bushes on the ends of suspension arms in fast-road and especially race use. These are solid metal spherical bearings that will allow the arms to move in their specified arcs just as intended from the factory, but while totally eliminating the flex the rubber bush gives. The main advantage of getting rid of the flex is improved precision of suspension and steering feel, but the side effect is a stiffer ride and a much shorter life span than production rubber joints.
These are the items that locate the top of the suspension strut in the correct position on the car’s chassis. From the factory they tend to basically be a large rubber bush that absorbs the stress and vibration that would otherwise be transmitted to the chassis from the suspension. Uprated items tend to be made of either polyurethane, or solid metal with a rose joint to mount to the shock absorber, to improve handling response and control. Some aftermarket top mounts, as well as being solid with a spherical bearing, allow the shock and spring position to be relocated a few cm within the suspension towers, giving you a decent amount of camber and sometimes even castor adjustment.
On standard production cars these are the rubber mounting points on the vast majority of standard suspension components, and they allow two metal parts to be connected without actual metal on metal contact. This drastically reduces the vibration and noise that would exist if the components were connected with a solid metal joint, and decreases wear too.
On tuned cars these soft rubber bushes are commonly replaced by stiffer polyurethane items, reducing movement and improving suspension response. On full-on race cars many bushes are replaced by solid metal mounts to totally eliminate flex, but this is at the expense of noise, comfort, and long-term wear; all things that aren’t much fun on a road car, but not an issue on a racer.
Not all cars have these, as some have the suspension arms mounted directly to the chassis, but subframes are the solid frames that the suspension arms are connected to on the front or rear of many cars. Subframes are specially designed so the suspension arms are connected at the perceived perfect position for the standard production vehicle, but on a modified version of the car these positions are often far from perfect.
Unfortunately modifying a subframe is no easy task and it’s rarely done outside of hardcore race cars, but on some vehicles, custom tubular subframes that not only save weight, but mount the arms in optimal position for race use do exist; if you can afford them that is!
Static suspension designs
Over the last century there has been a countless variety of suspension setups, though many of them (which tended to have serious, even dangerous, downsides), have fallen out of fashion. These days there are just a few designs still in regular use, and while all of them have advantages and disadvantages, they can all be very effective on the road and track. Here’s a run down on the most popular designs…
This is the most modern and complex suspension design. In theory, this makes it the best, but the complexity means it needs sophisticated 3D computer simulations to accurately design, so it’s not as common on specially made race cars as you might imagine. Multi-link setups have three or more arms per wheel, which means every possible arc of movement can be individually designed without it affecting another. For example, if they wish, the camber can change as the wheel moves up and down without it affecting toe or castor like it tends to with other suspension designs.
In reality, getting suspension geometry perfect is incredibly complex and manufacturers spend millions using sophisticated computer programs to try and get it right. But once the car is modified beyond its original intentions, these things are likely to be less than perfect once again. Having said that, multi-link – provided you have fully adjustable arms – gives a tuner an incredible range of geometry changes at their finger tips, and while some racers may consider it overly complex, it does allow an almost infinite range for you to tweak the geometry to your heart’s content.