What is a control arm and where is it located?

Your vehicle's rear and front control arms play a major role in your car or truck’s suspension system. Rear and front control arms hold everything together and help you maintain control of your car or truck. Generally speaking, a vehicle’s control arms act as the pivot point from the wheels to the road and the springs or struts to the frame or unibody of the vehicle. They keep the up and down motion of the vehicle’s wheels in relation to its body synchronized while holding the knuckles, spindles, and axles firmly onto the vehicle. Control arms also work in tandem with bushings, which are used to reduce friction and prevent any contact between the components that could cause damage. The vast majority of front control arms will also have a ball joint mounted securely to them, which also allow for the control arm to rotate up and down without binding up.

The number, type and location of control arms on a vehicle vary greatly and are dependent on the type of suspension system the car is equipped with. A vehicle with independent front suspension may have upper and lower control arms tucked behind each wheel, which are commonly referred to as "A-Arms." A vehicle with a MacPherson strut style suspension system in the front would only use lower control arms because the strut essentially takes the place of the upper control arms. In terms of construction, a front control arm can be made out of stamped steel, cast iron, or aluminum, and each material brings with it its own set of pros and cons. For an in-depth explanation of the various control arm setups that are possible on a vehicle and the different materials that they are made of, check out our control arms guide.

How do I know my control arm needs to be replaced?

The front control arms, like all control arms in general, are always being subjected to significant day to day abuse whether in an off-road terrain environment, or just bad road conditions on your daily commute. Front control arms can wear out where the ball joints attach, and the bushings attached to the other end of the control arms can also wear out or become loose. This is the most common reason for front control arm replacement because either of these scenarios can cause excessive tire wear, popping, or creaking in the suspension system, extra play in the steering system, and can pose a serious safety concern for you as well for others around you.

Although it is possible to replace the ball joint or the bushings themselves when they go bad, this can be difficult.  Replacing a ball joint, for example, may require specialty tools to press the ball joint to the control arm.  Since you will already need to remove the control arm to replace a ball joint or the bushings, you may as well replace the entire control arm.  

The front control arms themselves can also get bent over time, either from an accident or possibly from a tow job gone bad. All of these are great reasons to replace a front control arm.

Can I replace the control arm myself?

Front control arm removal usually requires a number of sockets and a ratchet, jack and jack stands, penetrating oil, hammer, and a torque wrench for reinstallation. The first step is to jack up the vehicle and secure it on jack stands. If you don't have the luxury of air tools, then you want to loosen the lug nuts on the wheel while the vehicle is on the ground, jack up the vehicle, and then remove the lug nuts and the wheel the rest of the way. Depending on the control arm, they usually require the removal of a castle nut and retaining pin or a simple nut that keeps the ball joint connected. If the control arm has a separate ball joint, after you've separated it, secure the knuckle in place to keep it from moving. Then remove the two bolts that keep the control arm connected to the vehicle. A lot of penetrating oil and a bit of hammering to loosen the control arm may be needed. Reinstallation is simply the reversal of the prodecure, but it can vary from vehicle to vehicle, so its recommended to follow a guide during the process. After completeing the repair, it's recommended to get an alignment.