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Imagine your car moving at constant speed on evenly paved asphalt. Your car frame and tires would be moving in tandem. But what happens when you hit a pothole, brake suddenly, accelerate quickly, or come around a bend in the road? Were your frame to stay synchronized with your wheel, you car would bounce up and down, dive forward, squat backwards, or roll with the curve, respectively.
The suspension in your car minimizes the impact of these sudden directional changes so as to maximize the contact between your tires and the road. This results in improved steering stability, surer car handling and better passenger comfort. Connected to the frame or chassis of your car, your suspension system coordinate the relative motion of your car to your wheels via springs paired with shock absorbers or struts.
When your spring, shocks, struts, or bushing begin to get worn or are past their useful life (typically 50,000 to 100,000 miles), the performance of your suspension will deteriorate and you’ll experience:
- Increased braking distance
- Choppier ride
- Reduced steering responsiveness
- Premature or uneven tire wear
- More swaying, rocking, diving and squatting
- More road noises and mechanical squeaking
Springs are part of every suspension system and absorb energy but do not dissipate it. To dampen the impact of the springs coiling and uncoiling, shock absorbers or struts are added to the suspension system. The terms “shock” and “struts” are used interchangeably and while similar, they are not the same thing.
A shock absorber is mounted directly to the vehicle’s frame and is basically an oil pump that changes the kinetic energy of suspension movement into heat energy via hydraulics and fluids. A strut is mounted inside a coil spring and in addition to performing this dampening function, it provides structural support for the suspension. Struts are pivot points for vehicles’ steering systems. Since struts impact wheel angles, an alignment is needed when replacing a strut. Both shocks and struts are speed sensitive, meaning that the amount of resistance increases or decreases based on how fast the suspension moves. A pair of struts could be double or triple the cost of a pair of shocks, but struts have greater functionality.
A car can have differing suspension systems on each axle. In other words, a car could have struts on the front axle but shocks on the rear. A rigid axle binds the wheel whereas an independent axle permits wheels to move individually. Trucks tend to have dependent shock systems whereas cars often will have independent strut systems.
If you drive specialty cars, such as racers or extreme off-road vehicles, there are more suspension variations that are more specific for your driving need. Some suspension systems can last as long as ten years, but the telltale signs indicated above, such as choppier rides or uneven tire wear, should prompt you to have your suspension inspected by a licensed mechanic with the vehicle off the ground.
In addition to mileage, cars that are five years or older should have the suspension system inspected annually since road hazards such as potholes, uneven pavement, large rocks, road salt and winter weather introduce damage and corrosion that shortens the suspension system useful life or effectiveness.
At Fred’s Auto Repair, we advise preventative maintenance and proactive replacement when warranted to keep your suspension operating its very best so that your ride is smooth, your handling sharp, and your braking crisp.
