When it comes to suspension upgrades, many enthusiasts will immediately look to springs and dampers as the path to better handling. While these components certainly play important roles in a vehicle’s handling performance and can enhance its curb appeal with a hunkered-down stance, they aren’t necessarily the first place to start.

“Ideally, you’d want to upgrade the sway bars and springs together as a package because you want to ensure that they complement one another,” explains Holley Performance Prototyping Engineer Philip L. Munoz. “But of course there are situations where that may not be feasible, or even preferrable. For example, some autocross classes will require you to run a stock suspension, but they’ll have an exception for sway bars. And that’s where you can really see just how much of a handling benefit sway bars can provide by themselves.”

While sway bars like those offered by Dinan and APR affect the amount of body roll exhibited by a vehicle while cornering, they also alter handling characteristics in other important ways and can impact other aspects of suspension tuning.

“You can make pretty significant changes to a vehicle’s handling just with sway bars, and in some situations, bars can do things that springs cannot,” Munoz notes. “A big part of a sway bar’s job is to manage weight transfer from one corner of the vehicle to another.” And that, in turn, can have a substantial impact on the car’s tendency to understeer (a handling behavior where the front end of the car wants to continue traveling straight ahead as you turn into a corner) or oversteer (a situation where the back end of the vehicle wants to rotate around toward the front) during spirited or at-limit cornering.

Shop Dinan sway bars here.

“It’s another tool to support the chassis; another knob to turn,” he says. “I think a lot of folks look at sway bars as kind of this ‘voodoo’ element of suspension tuning. They might have a sense of what they do, but they don’t realize how well you can tune a car with them. And with an otherwise stock suspension, sway bar upgrades can make a huge difference in how your car handles.”

An Unsung Hero In Suspension Tuning

Sway bar upgrades tend to be a plug-and-play, direct-fit proposition, an aspect which makes the upgrade affordable and easy to install. But another positive aspect of sway bar upgrades that’s ultimately both a blessing and a curse is the fact that, generally speaking, sway bar upgrades do not significantly alter a vehicle’s ride quality. While most would consider that a feature rather than a bug, that’s not always the case.

Shop APR Roll Control Sway Bars here.

“I think that’s another blind spot for a lot of people,” Munoz says. “They’ll upgrade the sway bars on their street car, drive the car around every day, and then say, ‘I don’t really notice the difference.’ And the reason for that is because the bars aren’t working very hard in day-to-day driving; you’re just not utilizing what they can do in that type of driving. But if you take that same otherwise-stock car, put a set of bars on it, and then say, ‘OK – let’s go to the track,’ that person would immediately notice a huge difference in the way the car behaves in the corners. And that’s something you’re going to feel when you're hustling through the canyons or on your favorite back road, too.”

What To Look For In Sway Bar Upgrades

Munoz says that any sway bar upgrade kit should include bushings that are stiffer than the factory bushings, as the soft material that’s typically used for stock sway bar bushings can reduce a sway bar’s effectiveness. “A sway bar is a spring, and a stock bushing is going to absorb a lot of the bar’s spring rate. And you also want to look for adjustability.”

That adjustability often comes in the form of multiple mounting holes, like those seen on Dinan’s Lightweight Tubular Anti-Roll Bar set for the 2015-2020 BMW M2, M3, and M4, or APR’s Roll Control rear sway bar for the 2017-2025 Audi RS3, 2022-2025 Volkswagen Golf R, and other vehicles that are underpinned by VW’s MQB platform architecture.

“Those mounting holes change the pivot point, which in turn allows you to soften or stiffen the bar, depending on which hole you choose to mount the bar with,” says Munoz. “With some bars, you could add as much as 150lbs of spring rate just by moving from the softest setting to the stiffest, and that makes it a very useful tuning tool.”

He also points out that by using adjustable end links with upgraded sway bars, you can also “split” the settings from side to side if you prefer. For example, you might find that the car works best using the stiffest sway bar mounting hole on the driver’s side and the middle setting one on the passenger side. In a hypothetical scenario, changing both sides of the bar from the stiffest to the middle setting on a three-holed bar will change that sway bar’s effective spring rate by 50lbs, but using the aforementioned “split” settings would allow you to change its spring rate by 25-lb increments instead.

“Adjustable end links enable you to do things like that. And there are other situations where that adjustability really comes in handy. You have to keep in mind that a sway bar is effectively another spring in the suspension, and sometimes the bar will actually preload the chassis and shift the weight balance of the car if you don’t have any adjustability that allows you to correct that. In that situation, the sway bar is basically holding up part of that corner of the car all the time. And depending on the situation, that can either help or hurt a vehicle’s handling. A lot of circle track guys run pre-loaded bars, but many road racers do not.”

Adjustable end links offer the ability to dial that preload in to your preference, or eliminate it entirely. This design typically features a turnbuckle-style adjuster in the center that allows you to lengthen or shorten the overall length of the end link, which in turn affects how much pre-load the sway bar is putting on the vehicle’s chassis. “If you have the vehicle sitting at static ride height and you disconnect your end links, and you go to the next hole on the sway bar, the end links should just slide in perfectly – it shouldn’t require any effort to put it in. That’s how you know there’s no pre-load on the sway bar.”

Munoz also tells us that this adjustability allows you to tune a vehicle’s handling characteristics in ways that coilovers and other suspension tweaks cannot.

Shop APR end links here.

“One thing that’s really cool about sway bars is that you can use them to get the front and rear of the car to work together to improve handling. Let’s say you’re at the track and you’re seeing a little bit of push from the front end of the car, and you know the front sway bar in its stiffest setting. If you can move to the middle hole, you might find that the push has gone away because you’ve softened up your spring rate, which has allowed that tire to dig into the ground a little bit better. And the same goes for the rear – if you’ve got a car that’s got a little more oversteer than you’d prefer, you can soften up that rear bar and make the handling more neutral. Or if you like a looser car, you can stiffen that rear bar up to bring in more oversteer.”

For those just venturing into the complex world of suspension tuning, Munoz recommends looking for sway bar upgrades that have been vetted by other drivers or racers using the same vehicle platform, and avoid making dramatic changes right off the bat.

“Don’t go in blind – do the research and find out what the fast guys are running. In most situations, I would avoid going overboard with the rate and select something that’s 50 to 60 percent stiffer than stock rather than something that’s 200% or 300% stiffer than stock. And it’s important to establish some clear goals here. Is this going to be a daily driver, or are you building a dedicated track day car? That will affect the choices that you should make.”