Dinan Adjustable Anti-Roll Bar Set BMW M2 | M3 | M4 F8X 15-20
Hamann 30mm Front and 25mm Rear 2 Way Adjustable Sport Stabilizer Bars BMW M4 F82 | F83 15-20
aFe POWER 440-503001-N aFe Control Sway Bar Set BMW M2/M3/M4 (F80/82/83/87) 14-20
aFe POWER 440-503001FN aFe Control Front Sway Bar BMW M2/M3/M4 (F80/82/83/87) 14-20
Sway bars, also known as anti-roll bars, are one of the most important components in your suspension system. While your springs help manage overall body movement, sway bars strictly deal with side-to-side movement. More importantly, they can either make your vehicle understeer or oversteer, since reducing body movement over one axle can effect grip on that axle.
The Purpose of Your Sway Bars
The entire purpose of a sway bar or anti-roll bar is to decrease body roll. With excessive body roll, the outside tires can experience excessive load which decreases total grip, however, excessively stiff sway bars can also decrease grip. In many vehicles, the stock sway bars aren’t designed to handle the cornering grip of sticky tires and can’t properly control body roll, thus creating the need for aftermarket sway bars.
A sway bar is actually inactive once the car is not on the verge of leaning towards one side. However, the moment it does begin to lean, the sway bar will apply force to the suspension on both sides. This includes upward force on one side and downward force on the other to counter the leaning force.
Why Upgrade Your OEM Sway Bars?
Aside from improved performance because of the reduced rate of body roll, sway bars likewise enhance the weight allocation between wheels. Because your vehicle is cornering more level, there is less weight being transferred to the outside wheel.
While a sway bar’s primary function is to decrease body roll in cornering, it can impact overall handling as well. More specifically, aftermarket sway bars can drastically change under-steer and over-steer. Many aftermarket sway bars are adjustable, which means you can easily tune over-steer and under-steer depending on what road or track you’re driving on.
In most applications, a stiffer rear sway bar results in more over-steer, while a stiffer front sway bar will result in more under-steer. Over-steering on throttle can typically be managed with softer spring rates or softer damping in the rear, however, over-steering off throttle or while coasting can easily be managed with a softer rear sway bar.
Tuning over-steer and under-steer not only improves overall cornering speed, but it makes the vehicle much more predictable and easy to drive. With an unpredictable car, you can never push your driving skills to the limit because of the potential for an unexpected change in handling.