Factory vs. Aftermarket Control Arms — Which Are Right for Your Subaru?

What Do Control Arms Do? Understanding Their Role in Your Subaru's Suspension

Control arms are the backbone of your Subaru's suspension system, serving as the critical link between your wheels and the vehicle's chassis. They allow the suspension to move up and down over bumps while keeping the wheels precisely positioned relative to the body. Without properly functioning control arms, your alignment, handling, and tire wear would suffer dramatically.

Front vs. Rear Control Arms

Subaru vehicles use control arms in both the front and rear suspension, though their designs differ based on the suspension architecture:

• Front Lower Control Arms (FLCAs) — On McPherson strut setups (WRX, STI, BRZ, Forester), the front lower control arm connects the steering knuckle to the subframe. It influences camber, caster, and roll center geometry.
• Rear Lower Control Arms (RLCAs) — The rear multi-link suspension uses lower control arms to locate the rear hub/knuckle. These arms are the most commonly upgraded component for lowered Subarus because they directly control rear camber.
• Rear Upper Control Arms — Found in the rear multi-link setup, these arms work with the lowers to manage camber and provide vertical wheel travel.

Why Control Arms Matter for Alignment

Your control arms dictate the suspension's geometry—specifically camber (the vertical tilt of the wheel), caster (the forward/rearward tilt of the steering axis), and toe (whether wheels point inward or outward). When you lower your Subaru on coilovers or lowering springs, the suspension geometry changes:

• Rear camber typically goes more negative (wheels tilt inward at the top)
• Stock arms often cannot adjust far enough to correct this
• The result is excessive inner tire wear and compromised handling

The Connection Between Control Arms and Handling

Beyond alignment, control arms influence how your Subaru behaves in corners and under braking:

• Bushing stiffness affects steering response and feedback—soft rubber bushings absorb road feel, while spherical bearings transmit every input directly
• Arm rigidity determines whether the suspension flexes under load—stamped steel can twist, while billet aluminum stays true
• Geometry adjustments like roll center correction can reduce body roll and improve cornering balance

Understanding these fundamentals helps you appreciate why upgrading from factory arms to adjustable aftermarket units can transform your Subaru's handling—especially once you've lowered the car or started pushing it on track.

Factory (OEM) Control Arms: Pros, Cons & When They Make Sense

Subaru's factory control arms are engineered to balance comfort, durability, and cost-effectiveness for the average driver. They're designed to work flawlessly at stock ride height and deliver thousands of miles of reliable service. But like most OEM components, they come with trade-offs—especially for enthusiasts who modify their suspension.

How OEM Control Arms Are Built

Factory Subaru control arms share several common characteristics across WRX, STI, BRZ, Forester, and Impreza platforms:

• Stamped steel construction — Cost-effective to manufacture and adequately strong for street use, but heavier than aftermarket alternatives and prone to minor flex under hard cornering
• Rubber bushings — Compliant bushings absorb road imperfections and NVH (noise, vibration, harshness), prioritizing ride comfort over precision
• Fixed length — No adjustment for camber or toe; alignment is limited to what the eccentric bolts at the subframe can provide
• Rust-prone — In harsh climates with road salt, stamped steel arms can corrode over time, weakening the structure

The Advantages of Sticking with OEM

Factory control arms aren't without merit. For certain builds and driving styles, they remain the right choice:

• Ride quality — Rubber bushings isolate the cabin from road harshness, making daily commutes more comfortable
• Warranty preservation — On newer vehicles, keeping OEM suspension components avoids potential warranty disputes
• Lower cost — Replacement OEM arms are typically less expensive than quality aftermarket units
• Stock height compatibility — If your Subaru sits at factory ride height, OEM geometry works exactly as Subaru intended

Where OEM Control Arms Fall Short

The moment you start modifying your Subaru's suspension, factory control arms reveal their limitations:

Limited Adjustment Range

When you lower your WRX, STI, or BRZ on coilovers, the rear camber shifts heavily negative. Factory arms rely on eccentric cam bolts at the subframe mounting points, which typically offer only ±1.5° of adjustment. On a 2-inch drop, you may need 3° or more of correction—impossible with stock hardware.

Bushing Deflection

Under aggressive cornering, rubber bushings compress and twist, introducing slop into the suspension geometry. This "bushing deflection" means your carefully set alignment changes dynamically under load, reducing consistency and driver confidence on track.

No Geometry Correction

Lowering a car doesn't just affect camber—it alters the roll center, anti-squat geometry, and suspension motion ratios. OEM arms can't address these changes. Aftermarket arms with spherical bearings and adjustable mounting points can.

OEM Control Arms: The Bottom Line

For Subaru owners keeping their car at stock height and prioritizing a smooth daily driving experience, OEM control arms are perfectly adequate. But if you've lowered your car, plan to track it, or want sharper handling response, it's time to look at what the aftermarket offers.

Aftermarket Control Arms: Adjustability, Materials & Performance Gains

Aftermarket control arms solve the problems that OEM arms can't—excessive camber on lowered cars, bushing deflection under load, and fixed geometry that doesn't adapt to your build. Whether you're correcting alignment after installing coilovers or building a dedicated track weapon, quality aftermarket arms unlock your Subaru's true handling potential.

Key Features of Aftermarket Control Arms

Premium aftermarket control arms differ from OEM in several critical ways:

Adjustability

The most important upgrade is the ability to fine-tune camber and toe independently of factory eccentric bolts. Aftermarket arms use threaded rod ends that allow precise length adjustment:

• Rear Lower Control Arms (RLCAs) — Adjust rear camber to compensate for lowering; typically offer ±3° or more of adjustment range
• Rear Upper Control Arms — Fine-tune camber further or adjust toe depending on design
• Front Lower Control Arms (FLCAs) — Adjust caster and camber; some designs include roll center correction
• Toe Arms / Trailing Arms — Dial in rear toe independently for stability tuning

Spherical Bearings vs. Rubber Bushings

Most performance-oriented aftermarket arms replace rubber bushings with spherical bearings (also called rod ends or heim joints):

• Zero deflection — Spherical bearings don't compress or twist, maintaining alignment under hard cornering and braking
• Instant feedback — Every steering input translates directly to the wheels with no delay
• Increased NVH — The trade-off is more road noise and vibration transmitted to the cabin

Superior Materials & Construction

Aftermarket control arms are built to withstand the demands of aggressive driving:

• Billet aluminum — CNC-machined from solid aluminum blocks; lightweight, strong, and corrosion-resistant
• Chromoly steel — Stronger than stamped steel with thinner wall thickness; ideal for high-stress applications
• Anodized or powder-coated finishes — Protect against corrosion and add a clean, purposeful look

The result is arms that are often lighter than OEM while being significantly stronger and more rigid—reducing unsprung weight and improving suspension response.

Performance Benefits of Aftermarket Arms

Proper Alignment on Lowered Cars

This is the number one reason Subaru owners upgrade their control arms. When you lower your WRX, STI, or BRZ by 1.5–2.5 inches, rear camber can exceed -4°. Adjustable rear lower control arms let you bring camber back to a streetable -1° to -2° range, saving your tires and restoring balanced handling.

Consistent Geometry Under Load

With spherical bearings eliminating bushing deflection, your suspension geometry stays exactly where you set it—whether you're cruising on the highway or attacking an apex at 1.2g lateral load. This consistency builds driver confidence and makes the car more predictable at the limit.

Weight Reduction

Billet aluminum arms can shave 1–3 lbs per corner compared to stamped steel OEM units. While this sounds minor, it's unsprung weight—mass that the suspension must control. Reducing unsprung weight improves ride quality, grip, and transient response.

Geometry Correction

Some advanced aftermarket arms offer roll center adjustment or anti-squat tuning. By relocating the pickup points, these arms can restore factory-intended geometry on a lowered car or optimize it for specific driving styles (more rear grip for time attack, more rotation for drifting, etc.).

Popular Aftermarket Control Arm Brands

SubiMods carries control arms from trusted suspension specialists known for Subaru-specific fitment and quality construction:

• SPL Parts — Premium billet arms with sealed spherical bearings; popular for street/track dual-duty builds
• Whiteline — Australian suspension experts offering adjustable arms with various bushing options
• ISC Suspension — Affordable adjustable arms that pair well with their coilover systems
• Voodoo13 — Known for drift and stance applications with aggressive adjustment ranges
• GKTECH — High-quality arms with excellent spherical bearings; drift and grip applications
• Racer X Fabrication — Chromoly construction for maximum strength in high-power builds

OEM vs. Aftermarket: Side-by-Side Comparison

Aftermarket control arms are one of the most impactful suspension upgrades for any lowered Subaru. They transform a compromise (excessive camber, inconsistent geometry) into an opportunity to fine-tune your car's handling to your exact preferences.

Choosing the Right Control Arms for Your Build

Not every Subaru needs aftermarket control arms, and not every aftermarket arm is right for every build. The key is matching your control arm choice to your suspension setup, driving style, and tolerance for trade-offs like NVH. Here's how to make the right decision for your Subaru.

Step 1: Assess Your Suspension Drop

Your ride height is the biggest factor in determining whether you need aftermarket arms:

Step 2: Define Your Driving Style

How you use your Subaru should guide your bushing and construction choices:

Daily Driver / Street Build

• Priority: Ride comfort, low maintenance, minimal NVH
• Best choice: Adjustable arms with polyurethane or rubber bushings
• Why: You get the camber correction you need without the harshness and noise of spherical bearings. Poly bushings are stiffer than OEM rubber but still absorb road imperfections.

Street/Track Dual-Duty

• Priority: Sharp response on track, livable on the street
• Best choice: Adjustable arms with sealed spherical bearings
• Why: Sealed bearings reduce maintenance compared to open bearings while providing zero-deflection precision. The NVH increase is noticeable but manageable for most enthusiasts.

Dedicated Track / Time Attack

• Priority: Maximum precision, adjustability, and strength
• Best choice: Full billet or chromoly arm kit with high-misalignment spherical bearings
• Why: Every fraction of a degree matters. High-misalignment bearings accommodate extreme suspension travel without binding. Comfort is irrelevant—performance is everything.

Drift Build

• Priority: Extreme steering angle, durability under abuse, quick adjustment
• Best choice: Extended lower control arms (if available), heavy-duty spherical bearings, maximum adjustment range
• Why: Drifting demands geometry that factory suspension was never designed for. Aftermarket arms let you run the aggressive alignment needed for big angle while surviving repeated abuse.

Stance / Show Build

• Priority: Extreme drop with driveable alignment, clean aesthetics
• Best choice: Full adjustable arm kit with maximum adjustment range; color-matched or anodized finishes
• Why: Aggressive static drops push camber far beyond what any single arm can correct. A complete kit (lowers, uppers, toe arms) lets you achieve a streetable alignment even at extreme ride heights.

Step 3: Determine Which Arms You Need

You don't always need to replace every control arm. Here's a priority guide based on common Subaru platforms:

WRX / STI (VA, GR, GD Chassis)

1. Rear Lower Control Arms (RLCAs) — First priority; corrects the majority of rear camber on lowered cars
2. Rear Toe Arms — Second priority; allows independent toe adjustment for stability tuning
3. Rear Upper Control Arms — For aggressive drops or track builds needing additional camber range
4. Front Lower Control Arms (FLCAs) — For caster correction and roll center adjustment; typically a track-focused upgrade

BRZ / FR-S / GR86

1. Rear Lower Control Arms — Essential for lowered BRZs; the rear multi-link suspension gains significant negative camber when dropped
2. Rear Toe Arms — Fine-tune rear toe independently
3. Front Lower Control Arms — Roll center correction is popular on BRZ for improved cornering balance

Forester / Crosstrek / Impreza

1. Rear Lower Control Arms — Same multi-link rear as WRX; adjustable arms correct camber on lowered builds
2. Rear Toe Arms — Useful if you're running aggressive alignment or have worn factory toe arms

Step 4: Budget Considerations

Aftermarket control arms range significantly in price based on materials, bearings, and brand reputation:

For most street/track enthusiasts, mid-range arms offer the best balance of performance, durability, and value. Entry-level arms can work for budget builds, but be cautious of no-name brands with questionable quality control. Premium arms make sense for dedicated track cars or high-power builds where failure isn't an option.

Step 5: Don't Forget the Alignment

Aftermarket control arms are only as good as the alignment that follows. Budget an additional $100–$200 for a quality four-wheel alignment after installation. Find a shop experienced with modified Subarus—they'll understand the target specs for performance builds rather than just dialing in factory numbers.

Typical performance alignment targets for a lowered WRX/STI:

• Front camber: -1.5° to -2.5°
• Rear camber: -1.0° to -2.0°
• Front toe: Slight toe-out (0 to -0.1°) for turn-in response
• Rear toe: Slight toe-in (0.1° to 0.2°) for stability

Final Thoughts

Control arms might not be the flashiest upgrade on your Subaru, but they're one of the most important for anyone running lowered suspension. Without proper camber correction, you're fighting against geometry that's working against you—chewing through tires, compromising grip, and leaving performance on the table.

Here's what to remember:

• OEM control arms work great at stock height — Subaru engineered them for the factory ride height and typical driving conditions. If you're not lowered, there's no urgent need to upgrade.
• Lowering your Subaru changes everything — Even a 1.5-inch drop can push rear camber beyond what factory eccentric bolts can correct. Adjustable rear lower control arms are the solution.
• Match your arms to your build — Daily drivers benefit from polyurethane bushings; track cars need spherical bearings. Don't over-build for the street or under-build for competition.
• Start with rear lowers, expand as needed — For most lowered Subarus, adjustable RLCAs solve 80% of the problem. Add toe arms, upper arms, or front arms as your build demands.
• Always get a proper alignment — Aftermarket arms give you adjustability, but that adjustability is worthless without a quality four-wheel alignment from a shop that understands modified Subarus.

Whether you're building a weekend canyon carver, a dedicated time attack weapon, or a show-stopping stance build, the right control arms let you dial in your suspension geometry exactly where it needs to be. It's the difference between a car that fights you and one that does exactly what you ask.

Ready to correct your alignment and unlock your Subaru's handling potential? Browse our suspension collection to find adjustable control arms, coilovers, and alignment components for your platform. Questions about fitment or which arms you need? Our team is here to help—reach out anytime.