COBB Control Arm Subaru WRX / WRX STi (2015-2021) Front Lower - Standard Alignment or Offset Caster

Fitment Information

• Subaru WRX / WRX STi (2015, 2016, 2017, 2018, 2019, 2020, 2021)
• Subaru WRX STI Type RA (2018)
  
• Subaru WRX STI S209 (2019)

Specs & Features

• Unsprung Weight Diet: Constructed from high-strength Lightweight Alloy that is significantly lighter than the heavy OEM steel arms, allowing the suspension to react faster to bumps and road imperfections.
• Precision Steering: Pre-installed 94a Durometer Bushings replace the mushy factory rubber, eliminating unwanted deflection and keeping the tire contact patch flat during hard cornering.
• Two Geometry Options: Available in Standard Alignment (for a factory reset) or Offset Caster (to add positive caster for better stability).
• Streetable Performance: Engineered to provide race-car stiffness without ruining the ride quality—minimal increase in NVH (Noise, Vibration, Harshness) means it’s still comfortable for the daily commute.
• Stronger Than Steel: The alloy construction isn't just lighter; it provides superior structural rigidity, handling the high G-forces of track days without flexing.

Product Description

The front lower control arm is the backbone of the Subaru front suspension. Unfortunately, the factory WRX arms are made of heavy stamped steel with soft rubber bushings that squirm under load. This leads to vague steering and a suspension that feels "slow." The COBB Tuning Alloy Lower Control Arm Kit solves both problems instantly. By switching to aluminum alloy, COBB reduces "unsprung weight"—the mass that the shocks and springs have to control. Less weight means the wheel can track the ground better, giving the driver more grip and confidence.

The Bushing Factor - Stock rubber bushings act like a sponge, absorbing energy that should be going into turning the car. COBB pre-installs 94a Durometer bushings that are stiff enough to prevent deflection but forgiving enough to absorb road noise. This means when the driver turns the wheel, the car reacts immediately.

Standard vs. Offset Caster: Which do you need? COBB offers this upgrade in two flavors, and the difference is all in the geometry:

• Standard Alignment: This is a direct geometry replacement. It retains the factory wheelbase and caster settings but adds the benefits of alloy construction and stiffer bushings. Perfect for the driver who likes the stock feel but wants more precision.

• Offset Caster: This is for the handling perfectionist. The rear bushing assembly is offset (moved inboard), which pushes the mounting point of the arm outboard. This geometry trick sweeps the arm forward, relocating the knuckle and adding approximately 0.5° of positive caster per side. Why does that matter? Positive caster improves straight-line stability at highway speeds and increases "dynamic camber" during turns, giving the front tires more bite when cornering hard.

Why does that matter? Positive caster improves straight-line stability at highway speeds and increases "dynamic camber" during turns, giving the front tires more bite when cornering hard.

This is one of the most effective suspension upgrades available for the Subaru chassis. It’s not just a replacement part; it’s a transformation. By combining weight savings, increased rigidity, and optimized bushing stiffness, COBB allows the WRX to punch well above its weight class. Whether chasing lap times or just enjoying a favorite back road, these arms provide the feedback and control that the factory left on the table.