Shocks Vs. Struts: Here's The Difference

The terms "shock" and "strut" are often colloquially used to refer to the same part, perhaps because they both operate within a car's suspension apparatus. Structurally, however, they are distinctly different. A strut is the assembly of components that provide both shock absorption and structural support to the chassis at large, while shocks are individual parts that perform primarily the former. If one were to liken a car to the human body, a strut would be the whole leg and a shock just the knee.

Here's another way to think about it: as professionals, Michael Jordan and Michael Jackson served virtually the same societal function. They both had wildly successful careers entertaining the public for high pay. Yet their individual methods of doing so were different. It's the same deal with shocks and struts — both are crucial components of a car's suspension system, both show up on a list of Jalopnik users' biggest car part expenses, and like the Michaels they even have similar names. In reality, though, they perform closely related functions differently.

A well-operating suspension is imperative for a car to be comfortable, properly steerable, and safe. The suspension keeps the car planted firmly on the road and maintains a smooth ride while supporting the car's frame as part of its chassis. The suspension's components accomplish this by absorbing and smoothing the feel of bumps and road imperfections a car's tires encounter.

Suspension systems typically include a combination of coil springs, shocks (also called shock absorbers), control arms, and ball joints. A "strut" refers to the assembly of a coil spring, shock, and other components including bearings into one functional unit. Coil springs within a suspension system, which help directly absorb the feel of bumpy terrain, are traditionally made of steel, although in recent years some automakers have proposed plans for implementing plastic springs. Shock absorbers work in tandem with coil springs to limit their impact and maintain the car's contact with the road. Control arms are joined with ball joints, connecting shock-absorbing parts to the chassis and steering components.

There are different types of suspensions, such as coil spring, leaf spring, torsion bar, and air, so the exact configuration of parts like shocks and coil springs (and the inclusion or exclusion of other parts, like air springs) depends on the vehicle's intended purpose and individual needs for safety, handling, and comfort.

Shock absorbers manage impact and rebound by the movement of hydraulic fluid through a piston. Struts are often composed of shock absorbers as well as coil springs, and are connected to lower control arms and a ball joint via a steering knuckle. In addition to absorbing shock and impact, struts actually bear weight within the vehicle's frame. To revisit the anatomy example, a shock absorber is like the knee that absorbs impact from walking, while the strut is like the joints (including the knee), tendons, and muscles all working together to bear weight, absorb shock, and steer the body.

However, it's important to note that not all cars use struts, and ride control can be maintained with a configuration of separate shocks and coils only. All wheels will be connected to either shocks or struts, but this can vary even between wheels on the same car. Jalopnik readers consider suspension high-priority for preventative maintenance, and knowing whether your car has shocks, struts, or both, and maintaining them properly can preserve drive and ride quality as well as overall safety.