What Are Struts on a Car?
Different types of cars have different types of suspensions. Most car owners have heard the term “strut,” but may not be clear as to what exactly the struts on a vehicle are or what they do.
Most straightforwardly defined, the struts are a structural component of most modern independent suspension systems and serve as a connection point between the wheel and the vehicle body. They are mounted at the top of the chassis at the front-end of most front-wheel-drive vehicles. However, struts are not limited to front-wheel-drive configurations. The primary purpose of the struts is to support the weight of the vehicle while also absorbing surface impacts and ensuring a smooth ride.
A strut assembly consists of two primary elements: the coil spring, which supports the height, weight and stability of the vehicle; and the shock absorber, which swallows bumps and dampens vibrations caused by irregularities on the roadway.
Other components of the strut geometry include the spring seats, the strut bearing, and the steering knuckle. Struts are typically installed in conjunction with the front wheels, but depending on a vehicle’s setup and driveline, they can also be mounted at the rear wheels. Just as there are different types of cars, there are different types of struts. The most widely used design by auto manufacturers is known as the MacPherson strut, which uses the top of a telescopic damper as the upper steering pivot. A MacPherson strut serves as a shock damper but is also engineered to handle significant lateral loads, such as when the vehicle is cornering. Other common strut designs include the coilover strut and the air strut. You can easily compare cars to determine which models have each type of strut.
“Shocks” and “struts” are terms often used together or interchangeably, but that can create confusion. There are major differences between the two components. Shocks, by themselves, have one primary function – to absorb bumps at each wheel – but they are not essential in the operation of a car or truck. Struts, on the other hand, have multiple functions (including shock absorption) and are essential for vehicle operation. Struts allow control and maneuverability of the vehicle.
When the struts are functioning properly, they will minimize the bounce a vehicle would otherwise undergo in normal driving. As a result, occupants experience a smoother and more level ride, free from most unwanted oscillations and jarring movements. Struts are important to overall vehicle operation because they are integral to both the suspension and the steering systems. In addition to general ride quality and load-bearing support, they impact brake performance, wheel alignment, and turning ability.
Some vehicles utilize a strut tower brace, a rigid bar installed across the top of the chassis to increase a vehicle’s stiffness. This kind of reinforcement will enhance the vehicle’s overall dynamics, especially through high-speed handling maneuvers and cornering.
Making sure your struts are in good working order requires periodic inspection by an authorized technician. Many mechanic shops and garages offer this service at no charge along with tire and brake inspection. For those living in climates with higher precipitation, it’s important to have struts checked specifically for rust and corrosion. General strut replacement is recommended between 60,000 and 80,000 miles, but sooner if your vehicle regularly carries heavy loads or drives on unpaved road surfaces. These conditions can cause struts to wear more quickly.
Aside from mileage and harshness of use, there are numerous indicators that your struts may need replacement. These include any of the following symptoms: an overall harsh ride, a noticeable vibration after riding over a bump, dull or unresponsive steering, sudden tire tread wear, wheel wobble during braking, swaying or excessive body roll when making a turn, or any evidence of a hydraulic fluid leak beneath the tire well.
One simple test a car owner can perform is to push down on the hood of the vehicle by hand to see if it comes back up and settles immediately. If it oscillates more than twice before settling, the struts are likely not functioning optimally.
If struts need to be replaced, the cost will generally be in the $750-800 range for parts and labor. Most technicians can complete the replacement within two to three hours. Whether replaced by a professional or done by the car owner herself, having well-functioning struts remains imperative for the proper operation, performance and safety of a vehicle.