A suspension control arm is used to connect a drive wheel to the body of the vehicle with the help of bushings, while allowing for controlling the movements of the wheel. A properly operated control arm can pivot up and down, helping the wheel to tackle road imperfections, while staying secured to the frame. When mounted in the front, it is a part of both suspension and steering systems, which is why it is crucial for your handling, steering, and driving safety. As a rule, it is connected to the steering system with ball joints, making it possible to turn the wheel when necessary.
Made from iron, steel or aluminum, a control arm can be found on each front and rear wheel on vehicles with a strut-type suspension. On some vehicles, there are two control arms per wheel, called upper and lower control arms. Such suspension designs are named double wishbone. Depending on the vehicle you drive, you may also find control arms under a different name. The possible options are a-arms, track control arms and wishbones.
Control arms are maintenance-free items which usually don’t draw your attention until something happens. However, their failures are very dangerous and can put your life at risk if not addressed properly and in time. Being a part of both suspension and steering systems, a bad control arm can cause a loss of driving control on the road, which may lead to an accident.
Made from durable materials, control arms can last a lot of years and even the lifetime of the vehicle. However, improper towing, corrosion, collisions, road imperfections and worn-out ball joints or bushings can shorten the service life of your control arms. If this happens, you will notice one or more of the following signs:
- Abnormal noises, including knocking, squeaking, clunking, popping, or snapping, when going over bumps
- Strange sounds when steering, accelerating or braking
- Wandering steering or other steering issues
- Uneven tire wear
- Excessive vibrations you can feel through the steering wheel
Control arm troubleshooting and replacement
A control arm is a non-repairable suspension part. If it fails due to excessive wear or damage, it must be replaced with a brand-new part. In some cases, you may just need to replace the bushings if they are the root of the problem. This will require a special tool and involve additional labor, which is why your mechanic may offer you to go with a complete control arm replacement.
To remove a bad control arm, your mechanic will need to lift the vehicle to access the faulty part. He or she will also inspect the entire suspension and steering systems for damage and signs of wear. All damaged or worn-out hardware, ball joints, bushings and other related parts must be replaced together with a bad arm. It is also a good idea to replace both left and right control arms at the same time. When the fix is done, a four-wheel alignment is also recommended for smooth as safe steering.
We do not recommend you to replace a bad control arm yourself. It is crucial for both steering and suspension systems, and requires special tools and equipment to deal with, which is why replacing control arms should be left to a professional.