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Summary
  • A sway bar is a torsion spring with short lever arms at both ends. The solid metal bar’s lever arms connect to the left and right wheels in the front or rear suspension. Sway bars prevent body roll when a vehicle is making turns or driving over uneven roads.
  • Sway bars counteract body roll by returning the tires to the same level. When one of the wheels rises to a higher level than its partner during a turn, the bar twists to compensate for the rise.
  • When sway bars are worn, they can make strange sounds, cause poor handling, and make the steering wheel feel loose.

When you make a sharp turn, you might feel your body moving in the opposite direction you’re going. Your vehicle is also undergoing a similar rolling motion. Fortunately, sway bars help prevent potentially dangerous rollovers, keeping you and your passengers safe on and off the road.

But what are sway bars, exactly? What do they do, and how do they work? And how can you tell if they have worn out and require replacement?

What Are Sway Bars?

A sway bar is a torsion spring with short lever arms at both ends. The solid metal bar’s lever arms connect to the left and right wheels in the front or rear suspension.

, What Are Sway Bars? How They Work, Common Issues, and More

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Many SUVs have both front and rear sway bars to increase vehicle stability.

Modern vehicles will have at least one sway bar in either their front or rear suspension. Many models feature both front and rear sway bars for improved performance.

Other names for sway bars are anti-roll bars, roll bars, anti-sway bars, and stabilizer bars.

undercarriage of a car showing the suspension components
A solid metal bar with lever arms connected to the left and right wheels in the front or rear suspension, the sway bar’s role is to prevent the car body to roll while making turns or driving over uneven road surfaces.

What Do Sway Bars Do?

The primary role of the sway bar is to prevent body roll while a vehicle is making turns or driving over uneven road surfaces. Also called body lean or swaying, body roll is the vehicle’s tendency to rotate on its axis toward the outside of a turning movement.

The sway bar prevents body roll, which improves your vehicle’s handling while making turns. It thus contributes to your safety on the road by keeping you in control.

Sway bars also keep the wheels in the correct alignment. They prevent the twisting motion that can misalign the wheels.

Additionally, sway bars contribute to tire traction. Body roll can decrease the tire surface area touching the road surface, which reduces the tire’s grip and increases the risk of slipping. The sway bar prevents that from happening, ensuring the tire stays in contact with the road.

How Do Sway Bars Work?

When your vehicle makes a turn, force and weight shifts to the outside and away from the direction into which you are turning. If you go right, the force goes left. Conversely, going left means the force travels to the right.

As force travels outward, it raises the outside tire above the level of its inside counterpart. The uneven levels cause the vehicle to roll toward the direction it’s turning. If the vehicle leans too hard, it can fall onto its side or rollover completely like a turtle.

SUVs, trucks, and similar taller, larger vehicles are more vulnerable to this phenomenon, although lower vehicles will also experience this.

The sway bar is a heavy piece of spring steel fixed to the frame with metal straps and rubber bushings. The outer ends of the sway bar are connected via insulated links to the lower control arm.

The sway bar counteracts body roll by returning the tires to the same level. Like a torsion spring, it can twist its ends along its axis. When one of the wheels rises to a higher level than its partner during a turn, the bar twists to compensate for the rise. It returns the wheels to the same height and restores your vehicle to a level position.

If the vehicle doesn’t experience body roll, the sway bar doesn’t twist.

Bad Sway Bar Symptoms

Sway bars are sturdy parts with long service lives. Usually, the sway bar bushings or links fail, while the bar itself remains fine. However, sway bars can wear out and break down. Since they are crucial to stabilizing your vehicle, you will quickly notice the warning signs of a sway bar failure. Usually you’ll notice clanking noises while turning.

Here are the most common bad sway bar symptoms:

Suspension Makes Strange Sounds

Does your vehicle’s suspension make clunking, knocking, popping, or rattling sounds when you drive over speed bumps or rough patches of the road? These noises are the most common indicator that something has gone wrong with the sway bars, specifically the links that connect the torsion spring to the suspension.

If you hear these sounds, listen carefully to determine the exact location they are coming from. The sway bar is between the wheels, so if the noises originate from that area, it might indicate a bad sway bar.

worn out sway bar link and a new replacement
A worn out sway bar link and a new replacement | Image Source: Richard McCuistian

Poor Vehicle Handling

Sway bar links keep the sway bar connected to your vehicle’s suspension. If one of the links breaks, the bar partially detaches from the suspension.

A detached sway bar degrades your vehicle’s handling. You might experience more severe body rolls, especially when you turn around a corner at high speeds.

Furthermore, you might experience handling issues like reduced responsiveness to your inputs with the steering wheel.

Looseness in the Steering Wheel

The steering wheel connects to the front sway bar. Understandably, if something goes wrong with one of the connected parts, the other might follow suit.

A bad sway bar can make the steering wheel feel loose. A loose steering wheel might develop issues like too much free play that leads to overturning, forcing you to micromanage the controls.

Tips For Repairing a Bad Sway Bar

Replacing a bad sway bar is a big job. You must raise the vehicle off the ground to access the bad part. Some issues will also require specialized tools. For example, you will need an oxyacetylene torch to cut out a sway bar link that rusted over or seized up.

If you have sufficient experience in DIY car repair and access to specialized tools, you can replace the sway bar. Otherwise, contact a certified mechanic.

Sway Bar Replacement Cost

When the sway bar or one of its parts fails, you will need a sway bar kit to repair it. A kit contains the components you need to restore the suspension part’s performance to like-new level. A sway bar kit can cost anywhere between $50 and $2,060.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

File Under : Suspension , DIY Tagged With :
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