Bushings are a white-hot topic of discussion on forums everywhere. Most of the debate is around stock, polyurethane, or spherical types, but there is one more layer to consider: geometry correction bushings. To me, this is the best bushing-related mod to do, and it’s much better than simply changing bushing material. Let’s dive into the why and how.
We must first familiarize ourselves with the mechanics of suspension bushings. Most of us understand them as tools for damping vibration and harnessing the suspension, usually with tuned bits of rubber between joints in control arms and often on subframe mounting points. Every rubber bushing has a spring rate as well as the vibration damping effect. The deflection of the bushing itself is a spring rate, which causes a secondary or tertiary motion as the suspension loads. Depending on the design of the bushing, it can also have a spring rate as the suspension compresses and expands. The effect is significant enough that automakers spend a lot of time tuning these bits of rubber.
On the whole, bushings act as an important cartilage to the car’s skeleton. You do not want a spherical-jointed race car on the street. But, like any other part of the suspension, we can modify it to our desire. Thanks to the cleverness of the aftermarket, we can choose several materials as well as redesigned parts that add more performance-oriented alignment specifications. Enter geometry correction bushings.
These bushings, which are typically made out of polyurethane or elastomer, are basically designed to change the alignment and kinematics of the suspension. Your typical correction bushing will influence caster, camber, and anti-dive on the front suspension. It’s rare for rear suspension parts to have this mod, so we’ll be focusing on the front. Most of the time, swapping bushings on the rear has the desired effect, and it most certainly affects steering feel and handling just as much as front suspension mods. Still, these bushings on the front can affect steering weight, feel, and handling in a subtle but significant way.
A typical front-end correction bushing replaces the rearmost lower control arm joint. It’s where the bushing can do the most work of actually changing suspension geometry by influencing caster and anti-dive while it can have a minor effect on camber. It’s simple: It moves the joint toward the outside of the car, pivoting the control arm on the forward control arm joining and effectively increasing the front wheelbase slightly. That wheelbase increase adds caster to the front suspension, which adds steering weight and self-centering.
Some of these bushings can get fancy, like on my 2010 Volkswagen Golf GTI. Instead of a simple press-in bushing insert, Whiteline redesigned the bushing housing to bring the control arm joint down away from the body as well as outward, adding anti-dive to aid braking, as well as anti-lift to aid acceleration. Then there are OEM plus solutions like the BMW Z4 M bushings that add significant caster with factory rubber that fits any E46-based vehicle.
The main reason these bushings exist is because of the lack of adjustability in modern cars, even performance cars. Most of the time, there is only toe adjustment with no camber or caster adjustment. Adding camber plates and a set of configurable bushings does a lot to wake up the feel of a car, as well as grip it up some.
One of these kits is a simple and effective mod with almost no penalty, though you may lose some ride quality depending on the material of the bushing – mostly a problem with polyurethane. Whiteline makes an excellent elastomer compound that preserves ride quality over harsh bumps (they didn’t pay me to say that). My thoughts on polyurethane bushings should be reserved for another blog, but my points about these corrective bushings still stand.
If you want small parts to tinker with or a way to hone a greater dynamic whole into something better, look into some options for your car. I’ve done them on a few of my cars and have always had noticeably great results, especially in steering feel and response.
It won’t add gobs of grip but it will add ever-elusive feel. That is worth much more than anything else in the modding world.