Sway Bars and Coilovers: When to Add One
Sway bars control body roll by tying the left and right wheels together, while coilover springs hold the car up and control bounce. Add a bar when the car still leans more than you like. Add one when you want to shift its balance without raising spring rate.
Plenty of people fit coilovers, drive the car hard, and still feel it lean into a fast sweeper. The first instinct is to order stiffer springs. Sometimes that is right. Often a sway bar is the tool for the job, because it works on roll and leaves the ride over straight-line bumps mostly alone.
What Sway Bars Do That Springs Do Not
A sway bar, also called an anti-roll bar or stabilizer bar, is a length of spring steel. It runs across the car, mounts to the body in two bushings, and connects to each side's suspension through end links.
Whiteline puts it plainly: the stiffer the bar, the more force it takes to move the left and right wheels relative to each other. That is the whole trick. In a corner, the outside wheel moves up and the inside wheel moves down. The bar twists and resists that difference, so the body leans less.
When both wheels rise together, over a speed bump you hit square, the two sides move the same way. The bar barely twists. So a bar adds roll stiffness without adding much stiffness in plain bounce.
Springs work differently. A coil spring resists every movement of its own corner, bounce and roll alike. Raise the spring rate to cut roll and you also firm up the ride over every bump. That is the key difference between the two parts.
Sprung or unsprung?
A sway bar mounts to the body, so most of its mass is sprung. Changing it does little to unsprung weight, which is mostly the wheel, tire, hub, brakes and knuckle, plus part of the arms, damper and spring.
How Coilovers Change the Picture
A coilover kit gives you adjustable ride height, and most give you adjustable damping. If your kit's springs are stiffer than the factory springs, they already cut some roll. Lowering drops the center of mass, but it also moves the roll center, so the net effect on roll depends on the car. For many street cars the stiffer springs are enough, and the factory bar can stay.
Coilovers also let you pick a spring rate. BC Racing and Fortune Auto both build with custom spring rates. On BC Racing kits, Swift Springs SPEC-R springs are an upgrade option on most fitments. That freedom matters here. If you want a compliant ride, you can choose a softer spring rate and let sway bars handle roll control.
Damping plays a part too, as it does in any performance suspension setup. Damping controls how fast the car rolls, not how far. The BC Racing BR Series gives you 30-click simultaneous compression and rebound on one knob. KW V3 adjusts compression and rebound independently. Slowing the roll with damping can make a car feel tighter even when the final lean is the same.
A coilover kit also lets you set ride height at the lower mount on full-length designs, with a locking collar holding the setting. One thing lowering always changes: end link geometry. Drop the car and the bar arm and the control arm sit in a new spot relative to each other. We cover that below.
When to Add a Sway Bar With Coilovers
Add a bar when you have a reason you can name. These are the common ones.
The car still leans too much at a spring rate you like. You chose the springs for ride quality and do not want to go stiffer. A bar adds roll stiffness without firming up straight-line bumps.
You want to change the balance. Whiteline's guidance by drivetrain: on front-wheel drive, increase the rear bar to reduce understeer. On rear-wheel drive, increase the front bar to reduce oversteer. On all-wheel drive, increase the rear bar first, then the front, to fine-tune.
You run autocross or track days. Quick direction changes reward a car that settles fast. An adjustable bar also lets you tune balance at the event without touching the coilovers.
Change one thing at a time. If you fit coilovers and new bars on the same weekend, you will not know which part did what. Drive the car on coilovers first, then decide on bars.
When to Leave the Factory Bar Alone
A stiffer bar is not free. Because the bar links both sides, a bump under one wheel twists it and pushes on the other side too. On rough, broken roads that can make the car feel busier and less settled.
Leave the factory bar in place if the car feels balanced and you mostly drive on the street. Leave it if the ride is your first priority. A bigger bar on a car that already pushes or already rotates well can tip the balance the wrong way. If the car feels good, keep the parts list short.
Also check the basics first. Worn bushings, loose end links and a bad alignment all feel like roll or vague handling. Fix those before buying new parts. Our guide to suspension bushings covers what to look for.
Adjustable Bars: How the Settings Work
An adjustable bar has more than one place to bolt the end link on each arm. Whiteline explains that moving the link changes the length of the lever arm, which changes the bar's stiffness. You tune roll stiffness without buying a new bar.
Whiteline lists 2 to 4 adjustment points on its adjustable bars, which in some cases gives up to 10 distinct stiffness settings. Its advice for setup is to start in a middle setting and adjust from there based on how the car feels.
Keep both sides on the same hole. Move one step at a time, and drive the same road or course after each change. Write down every setting, the same way you would log damping clicks on your coilovers.
Whiteline lists heavy duty blade adjustable bars in many sizes. Two examples are the Rear Sway Bar 22mm Heavy Duty Blade Adjustable (BTR86Z) and the Front Sway Bar 26mm Heavy Duty Blade Adjustable (BSF50Z). Whiteline also lists front and rear bar kits, such as kit BSK019. The titles do not name the car, so confirm fitment on each product page or call us with your VIN.
End Links and Bushings
A bar is only as good as its links and bushings. After a drop, the factory end link can sit at a steep angle or hold the bar under load at rest. Whiteline's advice is to use adjustable sway bar links to set the position and avoid any preload on the bar.
Set links with the car on its wheels, at ride height, ideally with your weight in the driver's seat. Adjust each link until it drops onto its mount with no push or pull. Then tighten it. Whiteline lists adjustable links such as the Universal Heavy Duty Adjustable Ball Joint Sway Bar Link Kit (KLC140-255). Measure your factory link before you order.
Check your factory links first. With the car on its wheels or on drive-on ramps, at ride height, undo one end of each link. If the ball stud lines up with its hole on its own, the factory link still works at your new height. If you have to push or pull the bar to line it up, the bar is preloaded, and an adjustable link will fix it. Repeat the check after any big height change. Our guide to what to order with coilovers covers when you can skip adjustable links.
Some coilover listings include end links. Fortune Auto's listing for the 2022 to 2024 Subaru BRZ (ZD8) includes front end links. Check your kit's listing before you buy links separately.
If you want to go further, the bar is one piece of a bigger chassis picture. Our guides to performance control arms and chassis bracing cover the next steps. Whiteline is the chassis-component brand in our lineup, with bars, bushings, alignment parts and bracing across a wide range of cars. Whiteline works alongside any of the coilover brands we carry, from BC Racing and KW to Fortune Auto and TEIN.
Frequently Asked Questions
Do I need sway bars with coilovers?
Not always. If the car feels balanced on coilovers alone, keep the factory bars. Add a bar if it still leans too much at a spring rate you like. Add one if you want to change its balance.
Should I upgrade the front or rear sway bar first?
It depends on the car. Whiteline's guidance: on front-wheel drive, increase the rear bar to reduce understeer. On rear-wheel drive, increase the front bar to reduce oversteer. On all-wheel drive, do the rear first, then the front.
Does a stiffer sway bar make the ride harsher?
Over bumps that hit both wheels evenly, not much, because the bar barely twists. Over bumps that hit one side, a stiffer bar pushes on the other side too. On rough roads that can feel busier.
Do I need adjustable end links with a new sway bar?
On a lowered car, usually. Lowering changes end link geometry. Adjustable links let you set the bar with no preload at ride height, which Whiteline recommends. On a mild drop, check the factory links first.
What setting should I start with on an adjustable sway bar?
Whiteline suggests starting in a middle setting and adjusting from there. Keep both sides on the same hole, change one step at a time, and note each setting.
Will a new sway bar change my alignment or ride height?
No. A bar mounts between the body and the suspension and does not set ride height or alignment. Do set the end links at ride height after you install it, so the bar sits with no preload. If anything binds or clunks, stop and check the links and bushings.
Can a sway bar replace stiffer coilover springs?
For roll, partly. A bar adds roll stiffness without firming up bounce. It does not help with squat under power, dive under braking or bottoming out. Those still come down to spring rate and damping.
Planning Coilovers and Sway Bars Together?
Tell us how the car behaves now, what you drive on and where you want it to end up. We will help you decide between springs, bars or both.
Call 1-800-460-9106 with your VIN. We carry BC Racing, KW, Fortune Auto, TEIN, Öhlins and Whiteline, and we will confirm fitment before you order. Free shipping across Canada on most kits.
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