Diagnosing a Faulty Suspension Control Arm

Most modern cars have at least two control arms, one behind each front wheel and some even at all four corners. Depending on suspension design, there may be both upper and lower control arms, or just lower control arms. Front control arms typically connect to the vehicle’s frame at one end, and the steering knuckle at the other.

The control arm has two functions, to allow the car’s wheel and tire assembly to move up and down while traveling over bumps and limiting the movement of certain steering and suspension components. Each front control arm also has a built-in ball joint. The ball joint allows the steering knuckle to pivot when the driver turns the steering wheel.

Control arms rarely fail as they are basically just big hunks of metal, of course that is if it suffers a direct impact like a collision. The most common reason for replacements for control arms are due to its bushings or ball joints wearing out, which sometimes are non-serviceable. However, most of the time, it’s more efficient and cost-effective to just replace the entire arm instead of replacing individual joints and bushings.

There are several signs that you may have faulty control arm/s.

First you should diagnose with a visual inspection. Check the actual control arm for issues such as major rust, distortion or cracks. Also inspect the bushings for major cracks or tears, and the ball joints for torn grease boots and/or other damage. Another inspection would be checking both the bushings and ball joints for significant play.

For bushings, place a pry bar on the control arm near the bushing then move it back and forth, up and down with little force. A slight amount of movement is normal but free movement is typically an indication of worn bushings. A general rule of thumb is 1/8” of movement or more indicates a rubber control arm bushing is worn and should be replaced.

For ball joints, it depends on the type of suspension your vehicle is equipped with. Generally, the procedure involves checking the joint for radial and axial play by pushing and prying on the wheel/tire. Some manufacturers suggest pulling on the control arm itself. Like bushings, significant play means the joints are worn and needs to be replaced. Remember to consult your vehicle’s factory repair information to determine the type of suspension your car has to properly check the ball joints.

If you have determined that your control arms need to be replaced, Complete Car Parts has the solution for you. We offer TOR premium control arms for thousands of vehicle applications. They’re designed after OE specifications for exact fitment and to out-perform original parts.

If you need assistance with fitment, installation or if you simply have an inquiry, simply contact us and we’ll be more than happy to help.