Understanding Car Suspension and When to Replace Parts

Understanding Car Suspension and When to Replace Parts
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Ever wondered what it would be like to drive without a car suspension system? Even for a short drive, it would be bone-jarring for you and it wouldn’t take long for your car to quite literally come apart.

What is car suspension, and what’s included in it? Here’s what you need to know about the car suspension system and what symptoms of trouble to look out for.

What is car suspension?

A car suspension system bears your vehicle’s weight and dampens its motions to prevent a stiff, rigid ride. The components in the suspension absorb impact and vibration when you drive to make the ride more comfortable, but the system also prevents the car from being damaged due to impact with the road.

Think of it like a Nerf bat versus a solid maple Louisville Slugger. When you hit a fastball with the wooden bat, it sends shockwaves through your hands and forearms, all the way through your body. Hit a baseball with a nerf bat and the foam absorbs almost all of the impact, and it hurts less.

What parts make a car suspension system?

Designs vary between vehicle types, manufacturers and models, but parts in a suspension system largely fall into these different categories.

Shocks and struts

Shocks are typically found on solid axles and heavier duty car suspensions, whereas struts are used in independent suspension systems, but they serve the same purpose. Shocks and struts dampen the impact on your car by using fluid or gas inside a cylinder to slow the rate of rebound. You’ll have a shock or strut at each corner of the car at the wheel.

Coil springs or leaf springs

Whether your car has coil springs or leaf springs, their purpose is to maintain your car’s ride height. They’re heavy sections of spring steel that can bear your car’s weight. When you travel over a bump, the spring compresses and extends but when the motion is done, the car has returned to its original ride height.

Joints/bearings/bushings

A suspension system also maintains a vehicle’s wheel position on all three axes: vertical travel, longitudinal position and the steering. This requires pivot points: ball joints that maintain a wheel’s vertical position as the suspension goes up and down, the control arm bushings where the control arm pivots in the subframe, and the sway bar bushings that fasten the sway bar firmly to the chassis. Tie rod ends can be seen as part of the steering system, but they also allow the tie rod to pivot and travel as the suspension does its thing.

Rods and linkages

The sway bar is a rigid beam that stretches from side to side. It’s connected to the wheel knuckle or strut with a sway bar link and together they help prevent body roll when you’re turning corners.

CV shafts

You’d probably find constant velocity shafts, or CV shafts, most often in the drivetrain section, but they also contribute to suspension. The CV shaft transfers power to the wheel regardless of the wheel’s position. It moves up and down, forward and backward with the suspension to prevent the axle shaft from binding.

Tires

You might not realize it, but your tires are an important part of the suspension. Changing the inflation pressure, the sidewall height and even the stiffness of the tire compound can make a huge difference in how much road noise and impact transfers to the car body.

What does car suspension do?

A car suspension system effectively creates a disconnect between the car’s body and the wheel to improve driving comfort. These disconnects—points like the control arm bushings, struts and sway bar links—can neutralize vibrations and motion.

Another component to car suspension is often overlooked: the downforce on the wheels. Springs extend the shocks and struts as your car traverses rough roads to maintain the tire’s contact patch on the road.

Without suspension in your car, you’d have an extremely rough ride, and your wheels would lose contact as you drive. Also, the energy transferred to your car’s frame would make it susceptible to stress and damage.

Why is car suspension so important?

The benefits to a well-functioning car suspension are crucial to making your car enjoyable to drive and relatively low-maintenance. They include:

  • Better traction. When the suspension is working properly, your tires keep good contact with the road. That helps tires last longer by avoiding uneven tire wear.
  • A quieter drive. Driving a car with worn bushings or a loose sway bar link can be annoying, with loud rattling and clunking that transfers into the cabin.
  • Fewer repairs. From bolts coming loose to electrical connections getting jarred and disconnected, working car suspension eliminates costly repairs.
  • Controlled handling over bumps. This is the big one. Suspension keeps you in control when your car bounces, sways, rolls, accelerates and brakes.

How long does car suspension last?

Most of the components in a car’s suspension can be expected to last for years. They’re made of hard steel and durable rubber, but certain parts won’t last forever. Shock absorbers or struts are the only parts that have a recommended replacement interval based on an average life cycle, and manufacturers and shops suggest replacing them every 50,000 miles. Even then, it’s a preventative measure.

For sway bar links, control arm bushings, tie rod ends and other suspension components, it’s likely you’ll have to change parts occasionally. It’s done as needed, though, so deal with the repairs when symptoms are present. How long suspension parts last is far less impacted by the miles you rack up on the odometer than the conditions in which you drive. The harder you drive your vehicle, the more suspension work you can expect over the years.

What is suspension work on a car going to cost you? It can range from under $100 for a new sway bar link to $1,000 or more in parts and labor to change struts. And whenever you have suspension work performed, it’s strongly encouraged to get an alignment done, as well.

Signs you may need to replace your suspension

Sometimes it’s a surprise impact with a curb that causes a suspension problem, but it’s usually not a single moment that causes an issue. Most suspension problems are simply due to wear and tear over tens of thousands of miles. The following symptoms can show up suddenly or creep up over months—either way, it may be a sign to bring your car to the shop to get it checked out.

Pulling to either side

When you’re driving, your car’s alignment should hold you in a straight line without steering input. If your car pulls left or right, that can indicate the wheels are misaligned, typically because of a loose or bent suspension part. That might be a control arm bushing, tie rod end or strut.

Nosediving when braking

If your car dives down in the front when you hit the brakes, it can be a problem with suspension components. It’s due to weight transfer, meaning your car’s weight shifts forward when you’re braking, compressing the suspension closer to the ground. It causes low traction in the back wheels and can lock up the front brakes. This symptom could be from weak shocks or struts.

Continued bouncing after bumps

After you’ve gone over a bump, it can look or feel like your car keeps bouncing for a while. This indicates your springs are doing what they should, but your struts or shocks aren’t. When shocks aren’t dampening the movement anymore, you get that resulting bouncy motion.

Drifting through corners

If you’re feeling like you’ll lose control as you turn a corner, that’s often due to a condition called “body roll.” It occurs when a car’s weight is allowed to transfer from side to side more than it should, and it can actually make you slide out if the road conditions aren’t very good. Body roll happens due to weak shocks and struts as well as from broken sway bar links.

Excessive shaking/vibration

The feeling of the steering wheel shaking in your hands or the whole car chattering as you drive can be unnerving, and for good reason. That feeling can occur when there’s something loose in the suspension that no longer holds the wheel firmly. It could be the result of a loose or torn control arm bushing or ball joint.


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Disclaimer: The above is solely intended for informational purposes and in no way constitutes legal advice or specific recommendations.