Why a Stiff Swaybar Might Make a Car Corner Slower

October 31, 2012

Swaybars or anti-rollbars are often misunderstood and often neglected as a part of vehicle modification. Any seasoned race mechanic will tell you that a properly sorted suspension system, which includes the coil springs, shock absorbers and swaybars will result in better handling and more predictable vehicle behavior especially on demanding turns.

How a Swaybar Functions

To make things simple, a swaybar is connected to the left and right side of the vehicle suspension to counteract forces that are applied to each side at any given situation. The swaybar is designed to lift the inside wheel on any turn to help the car corner flatter. The outside wheel on any turn loses traction, as the wheel is lifted, and the swaybar aids in this action by trying to lift the inside wheel. 

Swaybars could be installed on either the front or rear suspension but most automobiles have swaybars on both the front and rear suspension for better cornering. Understanding how a swaybar works will give you an idea on how a stiffer swaybar will yield significant benefits in cornering performance and tactile feel on the steering wheel.

Other people might note that adding stiffer swaybars might contribute a harsher ride but since swaybars are normally attached to pivots they could move in conjuction with normal suspension behavior, as it would on stock diameter swaybars.

Stiff Swaybars

This discussion could spew hundreds of both proven and unproven theories regarding stiffness of swaybars. Manufacturers utilize different methods, techniques and metals that claim to enhance swaybar stiffness for better handling. But as a general rule, regardless of the material used, an increase in overall diameter will result in an overall increase in stiffness. Without getting too technical in the discussion, understand the fact that swaybar stiffness will increase as the fourth power of a diameter. This means that swaybar stiffness will yield a significant increase with just an increment of difference in diameter.

If your vehicle utilizes a 23 millimeter swaybar, then the stiffness could be calculated to be 279,841 units (23 x 23 x 23 x 23) and changing to a 26 millimeter swaybar will yield an increase in stiffness of 456,976 units (24 x 24 x 24 x 24) even though the difference is only 3 millimeters in diameter. This means that using a 26 inch swaybar will produce a significant difference in overall vehicle behavior.

Cornering Effects

As mentioned before, adding a larger diameter swaybar will aid in better cornering as there is more control over extreme load transfers and suspension movements, but too stiff of a swaybar will yield a negative effect and make your car corner less aggressively. Front wheel drive cars with excessively flat cornering abilities offer less control and require a slower entry speed when negotiating a sharp turn for better control. On wet conditions, this will make the car prone to slide as opposed to using less stiff swaybars.

The trick is proper suspension tuning and this could be achieved through numerous testing in the confines of a safe track. Remember that a big change will occur in vehicle behavior by simply using a larger millimeter sway bar, and getting accustomed to the change in dynamics is required when assessing overall performance. 

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