When to replace sway bar links?
A sway or stabilizer bar prevents the car body from leaning too much and keeps the vehicle stable when driving in turns. Most of the cars have one sway bar in the front and another separate sway bar in the rear suspension. Some cars have only one sway bar in the front suspension. Sports cars have thicker sway bars for better stability when cornering.
A sway bar is connected via rubber bushings to the car body or frame in the middle. Outer ends of the sway bar are connected to the parts of the vehicle suspension that holds the wheel (struts or control arms). The part that connects the outer ends of the sway bar to the suspension component is called a sway bar link. In most cars a sway bar link has two small ball joints at each end. Over time, the sway bar link ball joints wear out. The first sign of a worn out sway bar link is a knocking noise from the suspension when driving slow over road bumps. Your mechanic can check the sway bar links while performing a regular service with the car on the lift. A worn out sway bar link will produce a knocking noise when pushed up or down. An extremely worn out sway bar link can separate. This will cause your car to lean excessively in turns and feel less stable and secure on the road. A worn out sway bar link must be replaced to keep your vehicle safe.
In a pickup truck, sway bar links have a slightly different design, see the lower photo. With this design, the rubber bushings that hold the sway bar link may wear out causing excessive play and "looseness" when driving over bumps or in turns. Is it necessary to replace both sway bar links if only one is bad? The answer is no, however your mechanic may recommend replacing both sway bar links because both links usually wear at the same rate and if one is bad, the other may go soon too. Do sway bar links have to be replaced whenever the struts or control arms are replaced? No, but in many cars an old sway bar link could be extremely difficult to remove without damaging it, as the threads could be rusted. Because of this, sway bar links are often replaced whenever a component (a strut or control arm) that the link is connected to is replaced.
Do sway bar links have to be replaced at a certain mileage? There is no need to replace a sway bar link if it's working properly and is not worn out. Replacing a sway bar link is not very expensive. Typically, it costs $75-$140 per side in a repair shop. If you want to replace the sway bar link yourself, soak the thread with oil or WD-40, as the nuts could be seized and very difficult to come out. Do sway bar bushings have to be replaced whenever the sway bar links are changed? No, the bushings are separate items and should be replaced whenever they are worn out or if they become noisy.