Do My Struts Need To Be Changed?

One of the biggest changes in the mindset of today’s shoppers is the shift from a consumption mentality to a savings mentality. And that isn’t seen any more clearly than behind garage doors across America. According to research done at Polk, there are more than 247 million cars and light trucks on the road in the U.S. today at an average age of 11.4 years old. Considering that just a decade ago, the average was 9.6 years, it’s obvious that we’re all keeping our vehicles longer and trying to get more value out of them before trading in and buying something new. But the only way to get more value is to stay on top of maintenance items. You will keep your car running better longer and it is cheaper in the long run than getting by without service until major repairs are needed.

We’ve all been to the repair shop for a routine oil change and walked out with repair estimates for thousands of dollars. The question that crosses all our minds is, “What of this stuff really needs to be done?” To answer this question, let’s start with the basics of struts and what they do. Then we’ll talk how struts depreciate and what is involved when repairing them.

What Are Struts?

Struts are the main component of a modern independent suspension system – these are what “suspend” the body and frame of a vehicle above the wheels. All the weight of the vehicle rests on the struts, which shift the weight, via a few other components, to the wheels. Struts have a possible three components: a spring, shock absorber and the optional swivel mount.

The Spring

A spring is used to “suspend” the weight of your vehicle above the wheels — allowing the wheels to travel up and down on the road without causing possible damage to the body of your car by means of bumping up and down with every crack or pothole in the road. The spring is constantly trying to find the equilibrium to smooth out the impact of the road; but without a shock absorber it would cause the body of the vehicle to move up and down several times after each bump.

The Shock Absorber

Shock absorbers (shocks) absorb the shock of an uneven road before it reaches the body of the vehicle. Instead of all the force of a bump being conveyed from the spring to the body/frame of the vehicle, shock absorbers take the force and use most of it up themselves. The force that does make it way to push up the body of the vehicle is absorbed by the shock absorber when the vehicle comes back down for a smooth transition to equilibrium and a normal ride. A strut is a combination of a spring and shock absorber.

The Mount

Most smaller vehicles today, such as sedans, with independent suspension use what is called a “MacPherson” strut —named after its inventor. The MacPherson Strut throws the swiveling mount into the spring and shock absorber combination. They have to be strong enough to not only swivel when the wheels turn, but to also be able to bear the weight of the vehicle.

What Makes Struts Go Bad?

Wear and Tear

Struts need to be replaced if any of the three components mentioned above wear out. Unlike your oil filter, brakes or spark plugs, struts are not often thought of as a normal replacement item. But like your brakes or spark plugs, they are not made to last forever. Since struts are continuously in use when you drive, bearing all the weight of your vehicle, it should not be surprising that their components eventually wear out.

The shock absorber uses the force of a bumpy road to push a fluid from an internal chamber, through an orifice, and into another chamber. It does this as the internal piston is traveling up and down, and so it needs seals to keep the fluid where it is meant to be while parts are moving all around it. These seals eventually wear out, either by externally leaking fluid, or by internally leaking fluid, allowing too much fluid to pass too easily from one chamber to another, thus reducing the amount of force the shock absorber can use up.

The mount component uses a bearing to carry the weight of the vehicle while also allowing the wheels to turn. It also further dampens the vibrations by using molded rubber between the strut and the vehicle. The mount will need to be replaced if the bearing wears out or the rubber gets old and cracks or tears.

The spring should last the longest out of the three components since it is a solid piece of metal that is tempered to be able to extend and contract many times. But, if the shock absorber component is bad, then the spring is hit with much more force than is designed for it, and will eventually wear to become weaker than it should.

How To Tell

You may notice the vehicle sagging, or that the ride is not as crisp as usual if the springs have been subjected to excessive wear and tear. In places where rusting is a common problem, springs may break, causing awful noises when turning or on bumps, steering pull, or worse. More than likely though, you will not notice any signs as your springs fail because the changes are so gradual. And since the replacement of springs goes along with struts as an economical option in today’s world, they will most likely be replaced before they ever fail.

The most easily recognized is failing mounts because they usually make a noise. Failing mounts will often make a popping or clicking noise while you’re turning the steering wheel because the bearing inside is bad. Especially if you put your vehicle in park and the noise is still occurring while turning the wheel, strut mounts are your number one suspect.

Shock absorbers that failed are much harder to notice. With oil-filled struts, external leaks are easy to spot, especially if the leak is constant. But if the leak is slow, it may never be noticed, and with gas-filled struts, external leaks are not identifiable at all. Usually struts don’t fail completely though, and not all at once. The wear of shock absorbers creep up as the internal seals lose their sealing capacity slowly. The difference won’t be noticed from one day to the next, but there is probably a minute daily performance decline of your shock absorbers as they age.

Several problems may be noticed by drivers if the failure progresses to a severe stage. These include: excessive movement up and down, tire noise and vibration from cupping caused by excessive up/down movement, excessively harsh riding over bumps or noise on every bump from too much suspension travel. Most struts should be replaced before these symptoms occur.

How Long Do Struts Last?

There is no mileage interval that covers all shocks, and relying solely on your senses as a driver to tell when struts are bad can be deceiving since strut failure is usually so gradual you may never notice it at all. Having your struts inspected regularly, including a test drive by a technician, can be helpful to monitor your struts performance.

Does It Really Need To Be Done?

Although struts may not pose the obvious safety concerns that failed brakes might, or the obvious threat of damage that neglecting to change a timing belt on time might, they do affect both these areas, though in smaller ways. Bad struts means there is more wear and tear on all suspension parts, including the steering system as well. The obvious comfort factor of new struts being a more pleasant drive. Struts are more than a cosmetic or comfort concern though. They are an important part of the way your vehicle operates and neglecting them can cause more wear and tear on the rest of your car. Always take this into consideration and plan ahead, especially for those who are budget conscious.