Control arm: problems, when to replace, repair cost

September 7, 2015
Control arm
Control arms "hold" front wheels, allowing up and down movement
of the front suspension.

The control arm is an important part of the front suspension. It connects the steering knuckle (the part that holds the front wheel) to the vehicle's frame or body, see the photo. To allow the up and down movement of the suspension, the control arm is attached to the vehicle's chassis or body through flexible rubber bushings called control arm bushings. To allow front wheels to turn, the outer end of the control arm is connected to the steering knuckle though a ball joint.

In most cars and trucks, a control arm is made in the shape of letter "A" or "L" with two ends attached to the chassis. In some cars, a control arm is a single link with a ball joint on one end and a rubber bushing on another end. Control arms have a very important role holding both front wheels on the road. If a control arm is worn out, damaged or bent, the vehicle is NOT SAFE to drive.

Control arm problems

Separated ball joint
Owner of this car was very lucky that the ball joint has separated
while driving at slow speed

There are a few reasons why a control arm may need to be replaced. in many cars, a ball joint is built into the control arm as one piece and cannot be replaced separately. In this case, the whole control arm will need to be replaced if a ball joint shows some wear.

A ball joint is an extremely important component. If it wears out, the front wheel can separate from the lower suspension causing the vehicle to lose control. In this photo, a ball joint has separated while driving, although the owner was very lucky that it happened at slow speed. If this had happened on the highway, the outcome could have been much worse.

Worn out or torn control arm bushings is another reason a control arm may need to be replaced. In some cars, control arm bushings can be replaced separately, but it involves higher labor costs. Often, the whole control arm is replaced if the bushings are worn out.

The control arm is the most common part that bends in a collision involving one of the front wheels or after hitting the curb. A bent control arm must be replaced.

How a control arm is inspected

Technician checking the suspension of the vehicle on the lift
Technician checking the suspension of the vehicle on the lift

Control arms, as many other suspension components, cannot be properly inspected at a drive-through fast-lube place. The only way to inspect control arms is when the vehicle is lifted on a hoist. This is what happened to the owner of the vehicle in the photo above: for the last year, he visited only a fast-lube shop and they didn't catch a worn-out ball joint earlier.

Are there any symptoms of a bad control arm bushings or a ball joint? You might hear some popping or clunking noise when driving over bumps, or when accelerating and decelerating. In some cases, a car may feel unstable and "wander" during braking or when driving over bumps. Often, however, the symptoms might not be present.

This is one of the reasons why it is important to have your vehicle inspected at least once a year in a repair shop by a skilled mechanic with the vehicle lifted on a hoist.

Control arm replacement

New control arm
New control arm

Replacing a control arm can cost from $160 to $390 for one arm. It's not necessary to replace both control arms if one is bad, however, if one is worn out, it's reasonable to expect that another control arm will likely need replacement soon.

After one or both control arms are replaced, the wheel alignment procedure must be performed (another $60-$120).

In some cases, worn out control arm bushings can be replaced separately. Control arm bushings need to be pressed in with a special tool or press.

Is a control arm easy to replace at home? On the difficulty scale from 1 to 10, replacing a control arm is 7 or 8. In the shop, it takes about 1-1.5 hours to replace one arm.

You might also be interested: