A sway bar (also stabilizer bar, anti-sway bar, whirl bar, or anti-roll bar, ARB) is an automobile suspension device. It connects opposite (left/right) wheels together through short lever accoutrements linked by a torsion spring. A sway bar increases the suspension's run stiffness—its resistance to cycle in turns, independent of its spring estimate in the vertical direction. The first stabilizer bar patent was awarded to S. L. C. Coleman of Fredericton, Au Courant Brunswick on April 22, 1919.

• The other function of anti-roll bars is to tune the high g-force and circumscription understeer bearing of the vehicle

• The limit understeer demeanor is tuned by changing the proportion Sway Bars of the total bobbin stiffness that comes from the foremost and postern axles
• This will cause the outer front wheel to scamper at a less than indiscretion angle, and the outer hindmost wheel to run at a lower indiscretion angle, which is an understeer effect
• Chronological the proportion of run stiffness at the rear axle will have the opposite end product and decrease understeer.