How do you know when your control arms need to be replaced?

The suspension under your vehicle consists of a series of shock absorbers (or dampers), coil springs and control arms. The latter is of utmost importance because control arms do more than just “control” wheel and suspension movements. Those curved pieces of metal form the anchor points between the chassis and the front wheel structures. Your car may have one or two wishbones, depending on whether your car has a MacPherson front strut or double wishbones. Rear suspensions typically have three to five wishbones or links. Cars with a torsion beam axle (which is simple, reliable, yet not fully tunable) do not have control arms. In this article we will focus more on the front control arms.

Control arms have bushings that connect to the chassis and ball joints that attach to the wheel structure. This arrangement allows the handlebars to turn left or right and the suspension to move up and down. That said, the wishbones contribute significantly to the ride comfort, handling, cornering and steering feel of your car.

When the steel or cast iron body of the arms is bent or broken, or when the bushings and ball joints wear out, you will feel steering shake or vibration, difficulty keeping the vehicle straight, rattling or clicking noises when accelerating or braking, and uneven wear on the front tires. Most symptoms are related to the telltale signs of bad suspension, but it’s worth checking the control arms first as they typically need to be replaced every 80,000 to 120,000 miles.

That said, your car may remain drivable with bad control arms, but it all depends on the severity of the damage. If you suspect that your rattle has developed bad control arms while driving, turn on your hazard lights, reduce your speed (preferably less than 30 mph), steer gently, and try to avoid bumps and potholes that could aggravate the problem. Because the control arm hooks the suspension and steering to the chassis, there is a distinct possibility of the wheel becoming loose from its mounting and causing the car to crash if not repaired immediately.

You could end up paying less for a do-it-yourself control arm replacement, but you’ll need the right tools and skills. Some things you will end up using are a jack, jack stands, a torque wrench, a socket set, and special tools such as a ball joint separator. In addition, it is better to replace the control arms on the front and left side at the same time, even if they are still reasonably intact. This returns the steering and suspension geometry to factory specifications, ultimately leading to a smoother ride, safer braking and competent handling.