Did you ever wonder how your car’s tires can stay on the road when you go over potholes and other rough areas? Control arms are the answer. These pivot points in your car’s suspension system allow the wheels to move in proper relation to the body, and connect to the car between the suspension and the frame.

There are two different kinds of control arms. Double-wishbone utilizes A-shaped arms, typically two on each side of the vehicle – upper and lower. This is a more complex system than MacPherson struts, which use one, more rounded control arm in conjunction with an upper spring and telescoping strut.

Assemblies come in three different types

  • Unitized: this assembly has an integrated ball joint, so when one part goes, the whole thing gets replaced.

  • Bolt-in: MacPherson struts use these control arms, which typically come in the form a stamped body.

  • Press-in: these are usually used in larger vehicles and feature a larger ball joint than unitized.

When control arms go bad you’re going to know it. The car may squeak or make a knocking sound, or pull to one side or the other. You also may notice the tires wearing unevenly. This could happen due to normal wear and tear, or the bushing on the control arm may become compromised.

When shopping for your new control arm assembly you’ll want to look for sturdy enough materials at a price within your budget. This part endures quite a bit of stress so you want a durable product.

How to make sure you’re getting a good quality control arm assembly

  • Decide on materials. Cast aluminum control arm assemblies are lightweight and corrosion-resistant, however they tend to buckle more easily over rough potholes. Cast iron are exceptionally strong and are typically wishbone-shaped. Stamped steel were typically used on older cars. They’re more inexpensive but can easily fall prey to rust.

  • Look for OEM (Original Equipment Manufacturer) -comparable pieces if you’re going with aftermarket parts. High quality aftermarket parts can perform to the same level as OEM parts, just make sure to buy from a reputable seller.

  • Choose a control arm assembly that is powder coated or otherwise treated for corrosion resistance.

If you're still unsure of what to purchase, YourMechanic supplies top-quality control arm assemblies to our certified mobile technicians. Our mechanics can provide and install a new control arm assembly, or install one that you've purchased. Click here to get a quote for a control arm assembly replacement.

This article originally appeared on YourMechanic.com as How to Buy a Good Quality Control Arm Assembly and was authored by Valerie Johnston.


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