Understanding the Suspension System of the VA WRX

The Subaru WRX has long been celebrated for its all-wheel-drive traction and turbocharged performance, but the third-generation VA chassis (2015–2021) benefits greatly from targeted suspension upgrades. While the factory suspension is competent, it is tuned for a balance of comfort and affordability, leaving room for improvement in cornering stability, body roll control, and steering feel. Before selecting aftermarket components, it’s essential to understand how the suspension interacts with the chassis during cornering, braking, and acceleration.

The VA WRX uses a MacPherson strut front suspension and a double-wishbone rear setup. Key forces during cornering include lateral load transfer, which causes the chassis to roll toward the outside of the turn. Sway bars (anti-roll bars) resist this roll by connecting the left and right sides of the suspension, while strut supports reinforce the chassis structure to prevent flex. Together, these upgrades reduce unwanted movement, allowing the tires to maintain better contact with the road surface.

The Role of Sway Bars in Handling

Sway bars are torsion springs that link the control arms or struts on each side of an axle. When the car leans into a corner, the sway bar twists, resisting the motion and transferring some of the load from the inside wheel to the outside. This action reduces body roll and helps keep the car flatter through turns.

How Sway Bars Work

A sway bar is essentially a U-shaped piece of spring steel with arms that connect to the suspension. The bar’s stiffness is determined by its diameter, wall thickness (if hollow), and material composition. When one wheel moves upward relative to the other—as during cornering—the bar resists that difference, creating a counteracting force. The result is less lean and a more neutral balance between understeer and oversteer.

Benefits of Upgrading to Aftermarket Sway Bars

Stock sway bars on the VA WRX are designed for a compliant ride and predictable understeer. Aftermarket options offer significant improvements:

  • Reduced Body Roll: Increased stiffness cuts chassis lean by 30–50% in many cases, making the car feel more planted and stable.
  • Improved Cornering Speeds: With less roll, the tire contact patches remain flatter, generating more lateral grip and allowing higher speeds through turns.
  • Adjustable Balance: Many aftermarket sway bars feature multiple adjustment holes. This enables fine-tuning of understeer/oversteer tendencies to match driving style or track conditions.
  • Better Traction During Transitions: Stiffer sway bars reduce weight transfer during lane changes or slaloms, helping all four wheels stay in contact with the pavement.

Types of Aftermarket Sway Bars

Not all sway bars are created equal. Common variations include:

  • Solid vs. Hollow Bars: Solid bars are heavier but offer consistent stiffness. Hollow bars are lighter with similar strength when properly engineered, reducing unsprung mass for slightly better ride quality.
  • Fixed vs. Adjustable: Fixed bars have one stiffness setting. Adjustable bars provide two or three holes that effectively change the lever arm, altering roll resistance. For a street/track dual car, adjustable bars are highly recommended.
  • Front vs. Rear: Upgrading the front bar mainly reduces overall roll; upgrading the rear bar has a greater effect on corner-exit oversteer. Many owners start with a rear bar to dial out understeer.

Popular aftermarket brands for the VA WRX include Whiteline, Cusco, Perrin, and SuperPro. These manufacturers offer direct-fit bars with polyurethane bushings for improved durability and response.

Enhancements with Strut Supports (Strut Braces)

While sway bars control suspension movement, strut supports (also called strut tower braces or strut bars) address chassis flex. The VA WRX unibody, though rigid from the factory, can still twist under heavy cornering loads, especially in the front and rear strut towers. This flex reduces steering precision and allows unwanted camber changes.

Chassis Flex and Its Impact

When the strut towers move relative to each other during cornering, the suspension geometry shifts, causing unpredictable handling. The driver feels vagueness in the steering wheel and a delay in turn-in response. Strut supports physically connect the top of the strut towers, creating a triangulated structure that resists this movement. The result is a tighter, more connected feel.

Key Benefits of Strut Supports

  • Increased Chassis Rigidity: A strut brace locks the towers in place, reducing flex by 20–40% depending on design. This maintains suspension alignment angles under load.
  • Sharper Steering Response: With less chassis compliance, steering inputs translate directly to the wheels. Turn-in becomes immediate, and mid-corner corrections feel more precise.
  • Improved Stability at High Speeds: A stiffer front end reduces wobble and wander, particularly during high-speed sweepers or under hard braking.
  • Complementary with Sway Bars: Strut supports and sway bars work together: bars control roll, braces control chassis compliance. Using both maximizes handling potential.

Types of Strut Supports

Strut braces for the VA WRX generally fall into two categories:

  • Front Strut Tower Brace: Installs across the engine bay, connecting the two front strut tops. Many are hinged or two-piece for easy installation without modifying the engine bay.
  • Rear Strut Tower Brace: Mounts in the trunk area behind the rear seats, connecting the rear strut towers. This brace reduces flex at the rear, improving traction and rotation.

Materials vary from steel (heavy, strong, affordable) to aluminum (light, moderate strength) and carbon fiber (premium, very light, minimal gains over aluminum for street use). For most drivers, a steel or aluminum front brace offers the best value.

Selecting the Right Components for Your VA WRX

Choosing aftermarket sway bars and strut supports involves more than just picking the biggest bar. Considerations include driving goals, budget, and compatibility with other modifications. Below are key factors to evaluate.

Material Considerations

For sway bars, spring steel is standard. High-end bars use chrome-silicon steel for fatigue resistance. For strut braces, aluminum is a popular choice because it’s lightweight and corrosion-resistant, while steel offers the highest rigidity at a lower price. Avoid poorly made braces that flex under load—check reviews and brand reputation.

Adjustability and Tuning

An adjustable rear sway bar is one of the most effective ways to change handling balance. Softer settings (using the hole farther from the end) promote understeer; stiffer settings promote oversteer. This allows fine-tuning for different tires, track layouts, or wet vs. dry conditions. For the front bar, adjustability is less critical because it primarily affects overall roll rather than balance.

Strut braces are typically non-adjustable, but some feature a quick-release or hinge design for easy removal during engine bay work. This is worth considering if you frequently access your turbo or intercooler.

Brand Reputation and Compatibility

Stick with manufacturers that specialize in Subaru performance. Whiteline, for example, offers comprehensive kits with sway bars, end links, and bushings designed for the VA chassis. Cusco and Perrin are also well-regarded. When purchasing, confirm that the bar diameter matches your chassis year and whether the kit includes polyurethane bushings and heavy-duty brackets. Whiteline has specific VA WRX sway bar sets with adjustable rear bars and upgraded end links. Perrin offers a wide range of braces and bars for the VA chassis. Cusco is known for high-quality strut tower braces.

Installation Guide and Tips

Proper installation is critical for safety and performance. While many enthusiasts install sway bars and strut braces at home, following a systematic approach ensures the best results.

Tools Required

  • Floor jack and jack stands
  • Socket set (10mm, 12mm, 14mm, 17mm, 19mm common)
  • Torque wrench (required for final tightening)
  • Breaker bar for stubborn bolts
  • Penetrating oil (e.g., WD-40 or PB Blaster) for rusty hardware
  • Pry bar or ratcheting strap (to maneuver sway bar into position)

Step-by-Step Overview

Front Sway Bar Installation:

  1. Raise the front of the car and secure it on jack stands. Remove both front wheels.
  2. Disconnect the stock end links from the sway bar using a 14mm socket. Note that the ball joint may spin; use an Allen key to hold the stud if needed.
  3. Remove the sway bar brackets (two per side) holding the bar to the subframe. Typically these are 12mm bolts.
  4. Lower the old sway bar out from underneath. You may need to disconnect the steering rack or remove a heat shield on the driver side for clearance.
  5. Install the new sway bar with bushings and brackets. Apply grease to the bushings as specified by the manufacturer. Hand-tighten bracket bolts.
  6. Reattach the new end links (if replacing) with the car’s weight on the suspension or with the suspension loaded to avoid preloading. Torque all fasteners to spec (typically 30–45 ft-lb for bracket bolts, 25–35 ft-lb for end link nuts).
  7. Reinstall wheels and lower the car. Repeat for the rear bar.

Rear Sway Bar Installation:

  1. Raise the rear of the car and remove the rear wheels.
  2. Disconnect end links from the bar. The rear end links often have a 14mm nut and an Allen key fitting.
  3. Remove the two bracket bolts per side. The rear sway bar is located above the exhaust. You may need to drop the exhaust hangers slightly for clearance.
  4. Slide the old bar out from the passenger side. Install the new bar with bushings and brackets. Grease the bushing contact points.
  5. Reattach end links with the suspension loaded (or with wheels on the ground if possible). Torque to manufacturer specs.

Strut Brace Installation:

  1. Front brace: Open the hood. Remove the plastic cowl cover if necessary. The strut top nuts are usually three or four per tower.
  2. Remove the top nut on each strut tower stud (typically 14mm). Do not remove all nuts—just loosen one per tower to slide the brace mounting plate underneath.
  3. Place the brace over the studs and reinstall the washers and nuts. Torque to the lower spec (typically 25–30 ft-lb for the brace plates; the strut top nut should be tightened to factory spec—around 35–40 ft-lb).
  4. For the rear brace: Fold down the rear seatbacks and remove the trunk trim panels. The rear strut towers are exposed. Follow the same process of loosening one top nut per side, mounting the brace, and retorquing.

Common Mistakes to Avoid

  • Not Preloading Suspension: Tightening sway bar end links with the wheels hanging can preload the bar, causing poor ride quality and unpredictable handling. Always have the suspension under load (wheels on the ground or use jack stands under the control arms).
  • Incorrect Torque: Over-torquing sway bar bracket bolts can crush the bushing or damage threads. Under-torquing leads to clunks. Use a torque wrench.
  • Cross-Threading Strut Nuts: Strut top studs are fine-threaded. Start all nuts by hand to avoid damage.
  • Ignoring End Link Upgrade: Stock end links are often plastic and may fail under the increased load of a stiffer sway bar. Consider upgrading to adjustable metal end links for reliability.

Post-Installation Testing and Fine-Tuning

After installing aftermarket sway bars and strut supports, the car will feel noticeably different. It’s important to test drive and adjust settings for your specific use case.

What to Expect on the Road

Initial impressions include reduced body roll, tighter steering, and a more connected feel. The ride may feel firmer over bumps, especially with stiffer sway bars on rough roads. Rear sway bars set to the stiffest setting can make the car rotate more easily on corner entry, which is desirable for track driving but might feel twitchy on wet roads. Take time to adapt to the new handling characteristics.

Adjusting Sway Bar Settings

If you have an adjustable rear sway bar, start with the softest hole. Drive on familiar roads and note the turn-in behavior. If the car understeers (pushes forward), move the end link to a stiffer hole. If the rear feels too eager to oversteer (spins out), soften the bar. Many autocross and track drivers experiment with two to three settings to find the sweet spot for their tire compound and alignment (e.g., -2° front camber, -1° rear on street tires). ScoobyTuner offers a solid guide to suspension tuning for the WRX.

Strut braces do not require adjustments after installation, but you may notice more creaking or flex under extreme load if the brace isn’t securely torqued. Recheck bolts after a few hundred miles, especially on the front brace near the hot engine bay.

Cost Considerations and Value

The price of upgrading sway bars and strut supports varies widely. A set of front and rear aftermarket sway bars from a reputable brand typically costs $250–$450, plus $50–$100 for replacement end links. Strut braces range from $100 for a basic steel front brace to $300+ for a carbon fiber pair. Installation labor, if done by a shop, adds $200–$400.

For the performance gain, this is one of the highest-value modifications for the VA WRX. A well-tuned sway bar and strut brace setup can transform the car from a competent daily driver to a sharp, track-capable machine with minimal impact on daily comfort—especially compared to stiffer springs or coilovers. Combined with an alignment and good tires, the upgrade delivers noticeable lap time improvements and increased driver confidence.

Conclusion

Upgrading your VA WRX with aftermarket sway bars and strut supports is a proven method to significantly enhance handling, steering precision, and stability. By understanding how these components work and selecting quality parts that match your driving style, you can tailor the car’s behavior to your preferences—whether that’s flatter cornering for autocross, sharper rotation for track days, or simply a more engaging daily drive. Proper installation and post-installation testing ensure you unlock the full potential of your chassis. With this foundation, your WRX will feel more planted, responsive, and enjoyable on every road.