If you own a car, you've probably heard of shocks and struts. But like so many other automotive parts, you may not know much about these components. Thankfully, we've got the information you need to get up-to-speed.

What is a strut or shock absorber?

Struts and shocks are both designed to do the same thing: dampen oscillations from the car's springs while driving over bumps and potholes. Both components contain a piston inside a tube. The tube is typically filled with hydraulic fluid, though gas may be used in performance applications.

As the car's spring moves up and down, the piston inside the shock or strut works against the hydraulic fluid. Although some of the fluid escapes through tiny holes in the piston, the amount is so minimal that the piston is still forced to slow down. That, in turn, slows the oscillations from the coil spring as well.

What is the Difference Between Shocks and Struts?

Although shocks and struts are similar, there is one major difference: Each strut is integrated into an assembly with one of the car's coil springs. Shocks, however, are stand-alone components.

Also, because the struts are combined with the springs, they provide support for the vehicle's suspension. Furthermore, some front struts attach to the car's steering linkage and act as a pivot point when the wheels are turned. Shocks, on the other hand, are not involved with either of these tasks.

Struts are more expensive than shock absorbers.

What are the symptoms of bad shocks or struts?

Worn struts or shocks can cause several problems. Some of the most common include:

    • A bumpy ride: Worn shocks and struts don't properly dampen the oscillations from the suspension springs. That translates into a bumpy and uncomfortable ride.
    • Tire wear: Worn shocks and struts can lead to tire "cupping" - a term for recessed spots in the tire tread. Additionally, bad struts can throw off a car's wheel alignment, leading to abnormal tread wear.
    • Noises: Shocks and struts that need to be replaced may also make a clunking noise while going over bumps.
    • Abnormal steering wheel feedback: Because bad shocks or struts can throw off your car's alignment, they can also cause abnormal steering wheel feedback, such as pulling and wandering.

How do you diagnose shock or strut issues?

Shocks and struts can be more difficult to diagnose than you might think. That's because many other suspension parts can mimic the clunking sound associated with bad shocks or struts. Also, all too often, the old-school "bounce test" your grandpa taught you doesn't work well on modern vehicles.

So, what can you do?

Well, to start, you can check the shock or strut for fluid leakage. A little grime build up is normal, but actual oil on the tube of the component is a clear indication it's time for replacement. Check the tires, too. If you find the tread is cupped, there's a very good chance you need new shocks or struts.

If you think the shocks or struts may be making noise, you can hook up a ChassisEar brand (or equivalent) wireless stethoscope to the vehicle. Attach one of the tool's leads to the suspect dampener (or close to it) and go for a ride. If you can hear the clunking noise directly through the tool, chances are you're due for a shock or strut replacement.

Keep in mind, however, that noises can often reverberate off the vehicle's chassis. As such, trying to pinpoint the problem with a wireless stethoscope can sometimes be misleading.

Finally, if you've got an older car with traditional fluid-filled shocks, you can give the bounce test a try, even though it's not very precise. Start by pushing down on the bumper of the vehicle at one corner - if the car bounces up and down more than once, the shocks or struts are worn and should be replaced.

What causes a strut to break?

Shocks and struts don't usually break unless the car has been in an accident. Rather, these components wear out over time and eventually start to cause issues, such as those mentioned earlier.

How often do struts need to be replaced?

Shocks and struts are considered wear items that eventually need to be replaced. Some strut manufacturers and auto repair professionals recommend replacement every 50,000 to 100,000 miles or whenever you start to experience symptoms.

Replace your shock absorbers or struts in pairs.

How much is it to replace struts and shocks?

Getting new struts or shocks isn't cheap. isn't cheap. Most experts recommend replacing shocks or struts in pairs - a job that costs anywhere from around $500 to upwards of $1500 (including labor costs running from $100 to $200). If you need to get all four, the shock and strut replacement cost could be well over $2,000. Expect to pay even more if your car has adjustable struts or some other type of advanced suspension system.

Can I replace shocks or struts myself?

Replacing a set of shocks or struts is a job best left to a professional. Each strut is integrated with a suspension coil spring - which is under extreme tension - and that makes the task more dangerous than most. If the strut assembly is taken apart incorrectly, the spring may launch forth, causing extreme injury and even death. So, don't try this at home and go to your trusted repair shop.