What is a sway bar and how does it work?

When you hear sway bar, you assume it has something to do with swaying. You’d be on the money. Also known as an ‘anti-roll bar’, it helps to distribute weight transfer and reduce body roll during cornering. It is a fairly simple idea but the engineering boffins make it an excellent one.

A sway bar is critical to your cornering and stopping, therefore it’s a great idea to know what a sway bar is and how it works.

What is a sway bar?

A sway bar, or anti-roll bar, is made out of a metal or strong composite material. It is shaped into a cross bar that connects one side of the car to the other. Sometimes having small bends to fit snugly and improve strength.

It is usually mounted close to the wheels, or rear axles, and tucked up into the floor pan. It has bushings where it mounts to the body to help reduce vibration and disperse energy. Sometimes even mounted to the same mount surface as the coil overs.

Most modern cars generally have a front and rear sway bar. This ensures that the weight transfer and torque is controlled and mitigated. The control of this turning and twisting is where it gets another one of it’s nicknames. Anti-roll bars are often called torsion bars, as they control the torsion.

The bushings and size of the sway bar depend on application. The front sway bar is larger than the rear, this is because the front wheels turn and the engine is swinging around up there. Manufacturers specially design these components to work with the suspension system to improve ride quality and handling.

How does a sway bar work?

When your car moves, the weight it possesses moves too. So when you corner, the top of the car rolls to the outside of the turn, that’s the lean that you feel. Imagine that one side leans up and the other side leans down. The weight ‘sways’ to the side of the car where the load is.

A sway bar, by being connected to both sides of the car helps mitigate this roll. This helps keep the inside tyres more planted and reduce roll to the sidewall on the outside tyres.

Imagine now that as one side goes up and across, it is pulling the other side to do the same. This means that when you have weight transfer, the sway bar helps the transfer to the sides to cancel out.

Some car makers even go a step further. They have adjustable or active anti-roll bars. So now when that weight is being transferred, the anti-roll bar actively manages just how much force is required to cancel the roll out. An active bar will constantly manage your car’s weight transfers. Adjustable sway bars will require you to set it up depending on what to expect.

A larger sway bar will stop more body roll than smaller ones. You don’t want a massive sway bar because the load transfer helps improve cornering grip. Manufacturers look for a goldilocks solution, not too big, not too small.

What can go wrong with a sway bar?

Given that sway bars are made out of really strong materials, there isn’t a lot that can really go wrong with them.

The most common issue is usually picked up on Warrant of Fitness inspections, bushings. The sway bar bushings are what dampens the load transfer, add in the fact that they’re exposed to the elements and they wear out. If they are cracked or split, they’ll need replacing.

If your sway bar bushings need replacing or you just need a cheap WoF, click here.