How Your Subaru’s Suspension System Works
Any car enthusiast knows a Subaru WRX/STI model for their impressive handling and connection to the road. This dynamic driving experience is largely credited to a finely tuned suspension system.
Understanding the mechanics behind this system is key for any owner looking to maintain or enhance their vehicle's performance. Learn how your Subaru's suspension system works, from its core components to potential upgrades, helping you gain a clear perspective on what makes your car unique.
The Role of Suspension in a WRX/STI
The suspension system in your Subaru WRX/STI serves a dual purpose: maximizing tire contact with the road for optimal grip and providing a comfortable ride for the occupants. It accomplishes this by absorbing imperfections in the road surface, such as bumps and potholes, while also managing the vehicle's body movements during acceleration, braking, and cornering.
In a performance-oriented vehicle like the WRX/STI, the suspension is engineered to strike a precise balance between sharp handling and ride quality. This keeps the car stable and predictable even at its limits.
Key Components of the WRX/STI Suspension System
A complex network of parts works in unison to deliver the signature Subaru driving feel. Each component has a specific job, and understanding them individually is the first step toward grasping the system as a whole.
Coil Springs
Coil springs support the vehicle's weight and absorb the initial impact from road irregularities. They compress and expand to allow the wheels to move up and down independently of the chassis.
The spring rate, or stiffness, determines how much the spring will compress under a given load. A higher spring rate results in a stiffer ride and less body roll during cornering, which is often desirable for performance driving. Conversely, a lower spring rate provides a softer, more comfortable ride.
Struts and Shocks
Struts are a primary structural component of the suspension, integrating a shock absorber and a coil spring into a single unit. They provide structural support and pivot with the steering system.
The shock absorber, or damper, inside the strut controls unwanted spring oscillation. It does this by converting the kinetic energy of suspension movement into thermal energy, which is then dissipated. This damping action is crucial for keeping the tires planted on the road and preventing the vehicle from bouncing excessively after hitting a bump.
Control Arms
Control arms are hinged links that connect the wheel hub and steering knuckle to the vehicle's frame. They allow the wheels to move vertically while restricting unwanted fore-and-aft movement.
A typical WRX/STI uses a multi-link suspension design, which involves several control arms per wheel. This setup provides engineers with greater control over suspension geometry, allowing them to fine-tune camber, caster, and toe angles for superior handling characteristics.
Sway Bars (Stabilizer Bars)
A sway bar is a torsion spring that connects the left and right wheels on the same axle. Its purpose is to reduce body roll when cornering.
As the car turns, the outside of the vehicle tends to drop, and the inside tends to lift. The sway bar resists this twisting motion, transferring force from the more loaded side of the suspension to the less loaded side. This action keeps the car flatter through turns, improving stability and tire grip. Upgrading to stiffer sway bars is a common modification for owners seeking sharper handling.
Bushings and Mounts
Bushings are small rubber or polyurethane cushions located at the suspension's pivot points, such as where the control arms and sway bars connect to the chassis. They absorb vibrations and minor impacts, preventing this harsh noise from being transferred into the cabin.
Suspension mounts, like the strut top hats, serve a similar purpose by isolating the top of the strut from the vehicle's body. Over time, these components can wear out, leading to suspension sloppiness and a less responsive feel.
Differentials and AWD Integration
While not exclusively a suspension component, the symmetrical all-wheel drive system is deeply integrated with how the suspension behaves. Differentials manage the distribution of power between the front and rear axles and between the individual wheels.
The suspension system must work in harmony with the AWD system to ensure each wheel maintains traction. This harmony is what gives the WRX/STI its renowned grip and stability across various road conditions. As the suspension keeps the tires on the ground, it allows the AWD system to effectively put power down.
Common Suspension Issues in WRX/STI Models
The Subaru WRX and STI face specific suspension challenges because of their high-performance design. Driving styles that include aggressive cornering or frequent track use place extra strain on the system. Rough or uneven roads can also be hard on key parts.
When the suspension starts to struggle, you might notice the car rolling more in turns or the steering feeling less sharp than before. Unusual sounds sometimes appear when bushings or mounts begin to wear out. If you sense changes in how the ride feels or how the car handles, it’s wise to check for issues early. This helps preserve your vehicle’s sharp response and overall handling quality.
Maintenance Tips for Longevity
Proper maintenance will extend the life of your suspension components and keep your Subaru performing at its best. Regularly inspect your suspension for any signs of strut leaks, cracked or worn bushings, or damage to any components. Keeping your tires properly inflated and balanced reduces unnecessary stress on the suspension.
Getting a professional wheel alignment check annually, or after installing new suspension parts, is also critical. Alignment ensures the wheels are angled correctly, preventing premature tire wear and maintaining predictable handling.
Upgrades and Modifications
One of the most appealing aspects of owning a WRX/STI is the vast potential for performance enhancement. Suspension upgrades can transform your vehicle's handling dynamics.
Coilovers are a popular choice, as they offer adjustable ride height and damping. High-quality 2015 WRX coilovers, for example, can significantly lower the car's center of gravity and enable precise tuning for track days or spirited street driving. Other impactful upgrades include stiffer sway bars to reduce body roll and adjustable control arms for dialing in custom alignment settings.
Whether you’re planning to modify your WRX/STI or want to keep it performing at its peak, taking time to understand how your Subaru's suspension system works directly influences your driving experience. If you’re considering upgrades or have questions about the best parts for your build, reach out to the experts at WRXDaily. We provide knowledgeable support and quality solutions so you can get the most out of every drive.