Everyone knows they need to maintain their car. Filters need changed, tire pressure checked, fluids topped off and, every few years, a new set of shocks or struts. But what about the parts that connect your wheels to the chassis? To keep your ride smooth, the suspension must move fluidly, but in control. That’s the job of a suspension control arm. Here are the major bad control arm symptoms and what you can do to fix the problem.
Control arms allow the suspension to move while keeping the wheels planted on the road.
Depending on the suspension design of the vehicle, you may have front and rear control arms. Some control arms are triangulated and shaped like an L or A, while others are simply a straight bar or tube. They can have round bushings, ball joints or even a combination of the two. Control arms do exactly as their name suggests—they control movement while still allowing freedom of motion.
Signs of a Bad Control Arm
If any of the following signs of a bad control arm crop up during your normal driving, you need to check your suspension for any looseness or worn-out components.
Driving down a rough road or hitting a speed bump shouldn’t sound like a drum solo. A bad control arm sound is typically described as a solid “clunking” noise. Driving over bumps or anything that jostles the suspension puts pressure on the control arm joints. If the joints are worn or loose, they will be unable to control the movement, which is typically followed by a “thunk” as the metal control arm slams into the bad control arm bushing. If a control arm joint is loose enough to allow components to slam together then it is time for a replacement.
Loose control arm joints can make steering seem loose or delayed. Steering linkage relies on pushing and pulling the wheel hubs to change the tire angle so you can go around corners. If a portion of that movement is absorbed by worn out control arm bushings, it won’t move the tires in a way the driver expects. Even if the steering wheel is held straight, looseness in the control arm joints can allow small changes in the steering angle without driver input. A worn steering box can also have the same symptoms, so it is worth getting both issues checked for good measure.
Irregular Tire Wear
If your tires are not getting held firmly to the rest of the car, then tire wear is potentially inconsistent. Ideally your tires should wear evenly across the entire width of the tread. But worn-out control arms can put more pressure on the outside edge of the tire, causing it to wear faster. This is also a possible sign of an out of spec alignment, so you should consider and inspect both as potential causes.
Engineers designed your car to drive a certain way and for suspension components to move in a very precise manner. Worn out rear control arms can prevent the rear wheels from staying in the same track as the front wheels. On a solid rear axle vehicle, the axle may move side to side or shift forward and backward, leading to a “loose” feeling when changing directions. The same feeling can happen for bad front control arms as the sloppy control arm joints allow the suspension components to wander around. The feeling is at times cumulative as multiple loose joints add up to greater amounts of movement that is out of tolerance.
How to Fix a Bad Control Arm
Some control arms are designed for servicing with replacement parts. You can remove bushings and press in new ones. Additionally, you can sometimes press out and replace ball joints or simply unbolt and replace them. However, some control arms are designed for replacement as an entire assembly once they degrade. You should replace control arms left/right pairs to prevent uneven handling. If one bushing or ball joint on a control arm needs replacement, then you should replace the others as well. The metal body of a steel control arm can corrode to the point of failure, but aluminum control arms are fairly robust. Once one control arm bushing begins to fail, the excessive movement it causes can make other connected bushings fail faster.
Replacing a control arm bushing usually requires a special tool to press the old bushing out and the new bushing into place. The same goes for replacing a ball joint. Both tools are readily available at your local NAPA Auto Parts store and are easy to learn how to use.
Choosing a complete control arm assembly can save time while also giving you the confidence of knowing the entire part is brand new. Simply disconnect the old control arm and slip a new one into place.
Keeping an ear and eye out for bad lower control arm symptoms and bad upper control arm symptoms will help keep your vehicle in good shape for the long haul. Ignoring these symptoms can lead to more damaged parts, short tire life and potentially dangerous driving situations. You can keep tabs on things yourself or have the experts at your local NAPA Auto Care inspect your vehicle at the first sign of trouble.
Check out all the steering and suspension parts available on NAPAonline or trust one of our 17,000 NAPA Auto Care locations for routine maintenance and repairs. For more information on the symptoms of bad control arm bushings, chat with a knowledgeable expert at your local NAPA Auto Parts store.
With an automotive writing career spanning over two decades, Brian has a passion for sharing the automotive lifestyle. An avid DIYer he can usually be found working on one of his many project cars. His current collection includes a 1969 Olds Delta 88 convertible, BMW E46 sedan, and a slant-6 powered 1975 Plymouth Duster.