Many car companies don’t prioritize performance when choosing a suspension system for their vehicles. Although we won’t provide an extensive list of all possible configurations, rather, we will give you a summary of the most common types that you’ll encounter when modifying a road car for competition purposes.
As we go along, it is crucial to understand that these configurations have their own unique advantages and disadvantages. We already know that the priorities for road cars typically include low cost, easy mass production, packaging to optimise interior space, and passenger comfort. In motorsport, few of these factors matter to us.
MacPherson Strut Suspension
The MacPherson strut is one of the most conventional suspension types that you’ll find in road cars, particularly in the front. The upright or hub will be rigidly attached to the strut and have a single lower control arm attached by a ball joint or spherical bearing.
The damper body is one of the most important components in this design. The benefits include low cost and simplicity of construction, as well as being compact and light weight to an extent. The disadvantage is that the stiffness-to-weight ratio is low, stiction occurs as a result of the dampener’s side load and bending force. Mcpherson also has poor roll camber recovery.
Camber recovery is how much camber the wheels regain as the chassis rolls over obstacles. If there was no camber gain, it would mean that the camber of the tyres wouldn’t increase as the suspension is compressed. This generally speaking, while a MacPherson strut can be made to work somewhat adequately, isn’t well suited for motorsport use.
Multi Link Suspension
Next, multi link suspension will be discussed. In its fundamental form, it contains two members that are only in compression or tension- thus, no bending forces exist. The number of possible layouts is great; some include up to 5 different suspension members. An array of advantages come with this type including the high flexibility of kinematic design. This gives the designer more control over elements like camber curves and toe change as well as offering some leeway in packaging style.
The disadvantages include high manufacturing costs and complexity, as well as a difficult design and modelling procedure. A multi link system may be used in motorsports with certain changes from the factory layout.
Double Wishbone Suspension
Double wishbone suspension is another common automobile suspension setup. An upper control arm and a lower control arm are used to locate and regulate the upright’s motion. Strictly speaking, the double wishbone is a sub type of a multi link suspension but it’s such a popular layout, it’s worthy of its own discussion.
The name is derived from the form and top-down perspective, which resembles that of a wishbone. A coilover unit is generally connected to the upper or lower control arm, which is known as direct acting. Indirect acting is an uncommon technique in road vehicles. The coilover may be installed inboard and actuated by a system of push or pull rods and a rocker, which is another choice.
The benefits of a double wishbone system are that it’s very adaptable to the required kinematics, comes with good camber rollover properties and has a high strength to weight ratio. On the downside, though, it does take up quite a bit more space which can pose problems during packaging. Additionally, this type of suspension is more costly and time-consuming to produce than others. All things considered though, for motorsport use especially, a double wishbone suspension is usually an excellent choice.
Live Axle Suspension
Finally, Live axles aren’t nearly as popular as they once were. However, it’s still worth noting because these devices were utilized until the 1980s in some sports cars. In the rear of rear wheel drive automobiles, this suspension comprises of a solid link between both wheels.
The differential being integrated as part of the suspension has its pros and cons. Pros include relatively low cost and no camber change and heave but the cons for a live axle are big. There’s extremely high unsprung weight, the lack of independence of the suspension from one side to the other and zero camber recovery in roll.
In summary
Although there are various suspension types accessible for road cars, the ones we discussed here are the most frequent. Each has its own set of advantages and disadvantages. Unless you want to make drastic changes to your car’s suspension, you’ll likely have to stick with the type that the original designers chose. However, no matter what kind of suspension you’re using, there’s always room for improvement.
