Are you hearing a bumping or clunking sound from one side of your car, even when you are driving on smooth roads? Can you push in or pull out the top of your wheel and tire when the car is parked? Is your steering wheel shaking at 50mph? If you answered "yes" to any of these questions, you might have a failing or broken control arm. The instability caused by an old or worn out control arm is more than just an inconvenience; it's dangerous and means they need to be replaced. Even if you think you may only have an alignment problem, or that your tires may just need to be rotated, don't rule out considering getting your control arms checked. There is no manufacturer's suggested replacement interval for this part, however regularly harsh driving conditions or a collision could damage valuable suspension parts. A good mechanic or repair shop can spend less than an hour under your car and tell if your control arm bushings, ball joints, or both are past their prime.
Some automotive parts have been around since the birth of cars; however the control arm was actually an improvement on the beam axle design of the early 20th century. This new technology offered each wheel independent vertical movement and travel, something that a beam axle and kingpins did not. Control arms are usually found in pairs on each front wheel; one upper and one lower. Both connect to the steering knuckle, usually through a ball joint which allows the spindle to pivot (or steer) left and right. There are usually a set of bushings located at the points where the arms mount to the car's frame or chassis. Often times, the control arms will also be connected to other suspension components such as the sway bar links and struts. More advanced suspension systems may have up to four arms on each side which helps stabilize the car under cornering while still giving each wheel the freedom to move quickly. These multi-link systems are usually more expensive to maintain, but provide a superior driving experience.
Replacing your control arms, bushings, or ball joints is not an easy task. It requires some machinery that can usually only be found in a repair shop, however a trained and experienced mechanic can make easy work of it.