When people speak of a vehicle’s suspension, they usually mean coil springs, shock absorbers or struts. The latter is actually a shock absorber mounted inside a coil spring, which performs the functions of both devices at the same time. A strut supports the weight of the vehicle and dampers the shock that the suspension system receives when moving over bumps or handling other road imperfections.
Unlike shock absorbers that never come as a part of a steering system, struts belong to both steering and suspension systems. In addition to their primary function of supporting the vehicle’s weight and absorbing body rolling, struts assemblies can pivot, allowing your front wheels to turn in a desired direction.
What most of us call a strut is actually a MacPherson strut. It is named after Earle S. MacPherson who was the first to combine a coil spring and a shock absorber into a single unit. This strut design allows for reducing the weight of the suspension system, eliminating the need for upper control arms. Besides, it is more compact compared to other suspension designs, which makes it perfect for small cars and lightweight trucks. Although, a MacPherson strut is not the only type of suspension struts. There are also modified front suspension struts, which are based on the same design, yet allow for a lower ride height.
No matter what type of suspension struts you have, their failure can turn your driving into an uncomfortable and dangerous experience. Fortunately, before your struts fail to do their job properly, you’ll notice several warning signs, such as:
Knocking and/or thumping noises
If you notice any strange noises when going over bumps, your front struts could be worn-out or damaged. In some cases, you may hear a popping noise when cornering, which usually says about bad strut bearings.
Since your struts also perform the dampening function, worn-out or damaged struts can lose their ability to absorb shock. As a result, you can experience a rough ride when driving over uneven road surfaces. The front or rear end of your vehicle can also dip down when braking hard or accelerating rapidly.
Body rolling when going around a turn
Because bad struts can’t support the weight of the vehicle as they should, you may experience body rolling when cornering. This can be accompanied by other steering and handling problems.
Uneven tire wear
Abnormal tire wear can be an indicator of failing struts. In most cases, bad struts cause a cupped wear pattern. However, they can also affect your wheel alignment, resulting in difficult or wandering steering.
Hydraulic fluid leaks
Just like shock absorbers, your struts are filled with hydraulic fluid. If the strut housing or seals are damaged, the fluid can escape from the strut.
Wandering steering or pulling
Your struts are a part of your steering system. That’s why faulty struts can affect your vehicle’s alignment, which, in turn, can lead to steering problems.
Longer braking distance
Bad struts can cause a bouncing effect when braking, which will increase the stopping distance of the vehicle.
Struts troubleshooting and replacement
Suspension struts are not the only source of suspension and steering problems. Bad strut bearings or bushings can mimic similar symptoms as bad struts. That’s why we recommend you to have your entire suspension system properly diagnosed before replacing struts.
Strut bushings and bearings should be replaced along with struts. In most cases, they serve as long as your struts. A four-wheel alignment is also required if struts, bearings or bushings are replaced.
Even if the only one strut is faulty, both struts in the front or the rear should be replaced together.
If a strut is in good shape, but its coil spring is damaged, you can replace the coil springs on both struts without replacing the entire strut assemblies.
Unless you’re a professional mechanic, we do not recommend you to work on the suspension system yourself. Your mechanic has all necessary equipment and experience to do the job safely and quickly. He or she will remove the old strut assemblies and replace them with new ones, or just replace the struts or coil springs if necessary.