Sway Bars 101: What They Do and How To Choose The Right Setup

If you want a meaningful handling upgrade without tearing the car apart, start with sway bars. Also called anti‑roll bars or stabilizer bars, sway bars connect the left and right sides of your suspension to manage body roll so the car stays flat, planted, and predictable when you turn in or change direction. That flatter stance translates to more grip you can feel from the driver’s seat.

The simple physics behind a big difference

A sway bar works like a torsion spring. When one wheel rises and the other falls in a corner, the bar twists and resists that motion. The resistance adds roll stiffness without making your main springs stiffer in straight‑line ride, which is why a quality sway bar upgrade improves cornering precision without trashing daily comfort.

Put simply, less roll means better tire contact and more confidence in rapid transitions, slaloms, and evasive maneuvers. After installing a swaybar many drivers describe the result as a more planted feel. This is a direct result of better weight distribution and traction.

Not only does it feel good, it offers big benefits:

• A car that’s more planted through a turn allows for better rotation and more control
• A car that’s more planted lets you get back on the gas sooner, resulting in quicker acceleration out of the turn

With the right sway bars on board, you’ll soon be taking familiar corners at higher speeds than you used to -- and grinning a lot more too.

Is Stiffer Always Better?

The short answer is an ambiguous yes and no. Handling balance is about how much front versus rear grip you have at different points in a corner. Changing front or rear roll stiffness with sway bars shifts that balance. Generally, stiffer is better for a handling -- to a point. But we won’t tell you that installing a swaybar is the right thing for all drivers vehicles and situations.

• In most cases, an aftermarket sway bar is going to be stiffer than the factory sway bar
• In most cases, this is going to improve the performance and handling of the car
• For most drivers, these improvements are going to make them happy and they’ll quickly adjust to the improved handling characteristics of their car

Often, consumers assume the stiffer the bar the better but often that is not the correct course. Balance is paramount for anything suspension.

For instance, suppose you’re looking to improve the handling of your daily driver and you install a sway bar rated at 200% stiffer than stock. Rather than improve, your cornering performance, ride quality and traction will suffer on real world road surfaces. Potholes, mid-corner dips, and road kill will all fight against your uber-stiff setup.

Say your left side front wheel hits a bump mid-turn. Stock suspension or a moderately stiff aftermarket sway bar will transfer some of the energy to the passenger side front wheel – no biggie.

But an extremely stiff sway bar will transfer much more of the energy – maybe enough to unsettle the suspension and reduce traction by creating tire lift on the inside wheel and excessive sidewall flex on the outside tire. The swaybar you installed to improve handling is now working against you.

STILLEN bars are engineered to take advantage of this balance and not be overly stiff simply to have a higher number. We take the guessing out of the equation so you can enjoy better handling without ill effects.

Understeer vs Oversteer: What your sway bar choice changes

The majority of vehicles on the road today, for safety purposes, are set up from the factory to understeer a little. The reason for this is liability and safety. Auto manufacturers have to build their cars for typical drivers who aren’t trained to handle a car in high-stress situations.

When the average driver experiences understeer, their natural reaction is to panic, let off the gas, and apply the brakes. Conveniently enough, this is exactly how to counter understeer. With less gas and more brake, the vehicle will slow down, the tires will regain their composure and the vehicle will resume traveling in the desired direction.

Too bad, because one of the biggest advantages of a rear wheel drive car like a Z is the ability to power through turns. With the factory setup favoring understeer, this advantage is lost. All that beautiful power going to the rear wheels is pushing the car in a direction you don’t want to go.

For the vast majority of drivers using their vehicles for daily driving, canyon carving or occasional track use, sway bars that impart a moderate increase in stiffness are the best choice. The incremental stiffness will retain factory-like ride quality while offering improved handling in the corners and slaloms.

For even more versatility and fine-tuning, adjustable sway bars might be your best option.

The more adjustability a sway bar offers, the more you can fine tune your suspension to suit your needs and preferences.

What’s more, adjustable sway bars allow you to set up your suspension to favor:

• Oversteer - when a car turns more sharply than desired by the driver
• Understeer - when a car turns less sharply than desired by the driver
• Neutral Handling - when a turns exactly as desired by the driver

Handling balance is about how much front versus rear grip you have at different points in a corner. Changing front or rear roll stiffness with sway bars shifts that balance.

• Increasing front roll stiffness generally adds understeer.
• Increasing rear roll stiffness generally adds oversteer.
  

There are exceptions and real‑world tuning always comes back to testing.

Solid vs Hollow sway bars

Both solid and hollow (tubular) bars can deliver the roll stiffness you want. What changes is weight and packaging.

• Hollow bars can match or exceed the stiffness of a smaller solid bar while saving significant weight. The material farthest from the center does most of the work in torsion, so removing the core reduces mass without gutting stiffness when diameter and wall are chosen correctly.
• Solid bars are straightforward and durable. For harsh environments or expected curb strikes, the extra wall thickness can be a plus even if the bar is heavier.

The right choice depends on goals. If you care about reducing front weight and improving response, a tubular option is smart. If ultimate robustness is your priority, solid can be the simple answer.

Adjustable holes, end links, and real‑world tuning

Many STILLEN sway bars include multiple end‑link holes so you can fine‑tune rate. Moving the end link inward increases effective stiffness. Moving outward softens it. That quick change lets you dial in balance at the track or after a tire change without swapping hardware.

Upgraded adjustable end links help remove preload and noise while making bar changes more repeatable. After any adjustment, evaluate turn‑in, mid‑corner balance, and exit traction before making the next tweak.

How to choose the best sway bar for your car

Choosing the best sway bar is about matching the bar to how and where you drive, your tire, and the rest of your suspension.

1. Define primary use
   Daily driver, canyon carver, autocross, track day, or towing or off‑road. A balanced street setup that reduces roll without upsetting ride will differ from a time‑attack build that prioritizes mid‑corner support and fast transitions.

2. Start with the weak link

• • If the car understeers, consider more rear roll stiffness or a softer front setting to bring the balance toward neutral.
  • If the car oversteers, add front roll stiffness or soften the rear to stabilize the rear axle.
    Always test in a safe environment before committing.

1. Pick a rate and the adjustability you need
   A moderate front and rear upgrade with adjustability is the most flexible path for mixed street and track. You can run the soft holes for daily use, then click stiffer for events.

2. Choose solid or hollow based on goals
   If weight and response matter, look at tubular. If you need simplicity and toughness, solid is fine. The bar’s diameter, wall thickness, and arm length together set the true rate.

3. Use quality bushings and lube correctly
   Polyurethane bushings sharpen response but need proper lubricant. Use silicone or lithium‑based grease designed for polyurethane and avoid petroleum products that attack rubber. Reapply as needed to stop squeaks and reduce wear.

4. Integrate with springs, dampers, and alignment
   Sway bars are part of a system. On some cars, reducing roll with bars can let you use friendlier spring rates for daily compliance. Complement the setup with appropriate camber and tire pressures.

Why STILLEN sway bars

STILLEN sway bars are engineered to deliver real, repeatable grip gains with fitment and adjustability tailored to each platform, and they are made right here in Costa Mesa, California. Our process, materials, and quality checks are the same ones trusted by private‑label and OEM programs, so you can install with confidence.

For many popular models, you can choose front, rear, or matched kits with adjustable holes to fine‑tune balance as your driving evolves. Explore current applications and specs on our sway bar product page