What does a Subaru control arm do?

In short, a Subaru control arm is a suspension link that connects the wheel hub to the vehicle’s chassis, guiding the wheel’s up‑and‑down movement while helping keep the wheel aligned. Across Subaru’s lineup, especially with Symmetrical AWD layouts, the control arm is a foundational component that supports stable handling, ride comfort, and predictable steering. This article explains the control arm’s role, how Subaru uses it in front and rear suspensions, signs of wear, and what to expect when replacing one.

What is a control arm and how does it work?

The control arm is a rigid or semi-rigid linking piece that pivots at one end on the chassis via bushings and at the other end on the wheel hub via a ball joint (in most designs). As the wheel travels up and down with road irregularities, the control arm allows vertical movement while limiting unwanted fore‑aft and lateral motion. This helps maintain the wheel’s camber and toe angles relative to the vehicle, preserving alignment and steering feel. In many Subaru models, the front suspension uses a lower control arm as part of a MacPherson strut setup, while the rear suspension may employ multiple links to better manage wheel position through suspension travel. The control arm also bears forces from braking, acceleration, and cornering, transmitting them to the chassis through its bushings and joints.

Front suspension configurations

Most Subarus use a MacPherson strut front suspension that includes a lower control arm as the primary link to the wheel hub. This arrangement provides a compact design with adequate geometry control for everyday driving and AWD performance. In some models or trims, additional steering knuckle components or stabilizer links work in concert with the front control arm to refine handling and ride quality.

Rear suspension configurations

Rear suspensions in many Subaru vehicles use multi‑link or trailing arm arrangements. In these setups, one or more rear control arms connect the wheel hub to the vehicle body, allowing the wheel to maintain proper alignment while the axle or independent suspension flexes. The design aims to balance ride comfort with responsive handling, particularly on uneven surfaces and during cornering in AWD conditions.

How it affects Subaru handling and AWD performance

The control arm’s primary job is to translate road forces into controlled wheel movement without letting the wheel geometry drift out of alignment. In Subaru’s AWD platforms, accurate control arm function contributes to balanced weight transfer, consistent tire contact with the road, and predictable steering response. Worn or damaged control arms can compromise camber and toe control, which may lead to increased tire wear, pulling, or a wandering feel—especially at highway speeds or during cornering.

Common signs of wear and failure

Symptoms of a worn control arm or its bushings/ball joints can overlap with other suspension issues. If you notice any of the following, have the suspension inspected by a qualified technician.

• Clunking, knocking, or banging noises when going over bumps or potholes


• Pulling to one side or uneven steering response


• Visible tire wear that is uneven or excessive on one edge


• Vibration or jitter in the steering wheel at certain speeds


• Slack or looseness in the wheel hub area when checked by inspection


• Cracked, cracked‑soaked, or deteriorated bushings or ball joints (often visible with undercar inspection)

Note: A similar set of symptoms can originate from related components like tie rods, ball joints, sway bar links, or strut mounts. A professional inspection is necessary to confirm a faulty control arm.

Replacement considerations

If a control arm is worn or damaged, replacement decisions involve several factors, including parts quality and overall suspension health. Consider the following when planning a replacement on a Subaru.

• Replacement options: You can replace just the control arm, or pair it with new bushings and/or a new ball joint. Some repairs use a complete control arm assembly for easier installation and reliability.


• OEM vs aftermarket: OEM parts provide exact fit and clearances; quality aftermarket arms can offer cost savings but verify warranty and compatibility with Subaru AWD systems.


• Ancillary components: Often, it’s wise to inspect and possibly replace related components (sway bar links, tie rods, alignment camber bolts, and strut mounts) to avoid repeat labor costs.


• Alignment: After replacing a control arm, a professional wheel alignment is essential to restore proper camber, toe, and caster settings and to protect tire life and handling.


• Expected costs: Labor is a significant portion of the total cost; parts vary by model and whether you use OEM or aftermarket parts. A shop can provide a precise quote after inspection.

Engaging a technician familiar with Subaru AWD platforms helps ensure correct installation torque specs, bushing preload, and alignment settings tailored to your model’s suspension geometry.

What to expect during replacement

Replacing a control arm typically involves lifting the vehicle, removing the wheel, detaching the old arm from the chassis and hub, and installing the new arm with proper torque on mounting bolts and ball joints. After installation, a wheel alignment is performed to correct camber/toe angles. Depending on the model and the shop, the job may take a few hours and should include a road test to verify steering response and ride quality.

Summary

The control arm is a fundamental suspension link that connects the wheel hub to the vehicle body, steering the wheel’s vertical motion and helping maintain correct alignment. In Subaru vehicles, front and rear control arms work with the brand’s AWD platforms to deliver balanced handling and ride comfort. Worn control arms can cause clunks, pulling, uneven tire wear, and vague steering, and replacing them usually requires new bushings or joints, possible wheel alignment, and consideration of related suspension components. Routine inspection during services can catch wear early, helping preserve safe handling and tire life.

Final takeaway

For Subaru owners, understanding that the control arm is a key alignment and motion‑control component helps explain why suspension wear can feel inconsistent or harsh over time. If you notice symptoms described above, seek a professional evaluation to confirm whether the control arm or related components need attention, and plan for proper alignment after any replacement.

What happens when your control arm goes bad?

When a control arm goes bad, you'll experience issues like clunking noises, poor handling and steering, and uneven tire wear. In the worst-case scenario, a failed control arm can lead to the suspension collapsing or the wheel separating from the car, resulting in a loss of control while driving. 
Common symptoms of a bad control arm

• Noises: You may hear clunking or knocking sounds when going over bumps, as the worn bushings allow the arm to move excessively. 
• Poor handling: The vehicle's steering may feel erratic, pull to one side, or "wander" on the road, especially when hitting bumps. 
• Vibrations: Excessive vibrations, especially in the steering wheel, can occur due to improper wheel alignment and play in the suspension. 
• Uneven tire wear: The alignment issues caused by a bad control arm can lead to accelerated and uneven wear on the tires, often on the inner or outer edges. 
• Instability while braking: The vehicle may feel unstable or "lurch" forward when you brake, and your braking distance could be longer. 
• Rough ride: The control arm's ability to absorb impacts is compromised, resulting in a rougher ride over bumps. 

What to do if you suspect a bad control arm

• Do not drive the vehicle, as a failed control arm can cause an accident. 
• Have the vehicle inspected by a qualified mechanic to confirm the problem. 
• When replacing a control arm, it's often recommended to replace both on the same axle, as the other is likely to wear out soon as well. 

What is the main function of a control arm?

Control arms play a crucial role in the suspension system of a vehicle. They help to keep the wheels aligned and maintain proper tire contact with the road, which is essential for safety and stability. The inboard (chassis) end of a control arm is attached by a single pivot, usually a rubber bushing.

How much does it cost to replace a control arm?

The average cost for a control arm replacement is between $350 and $1,000, though it can range from $80 to over $650 per arm depending on the vehicle, parts, and labor. This price includes parts and labor, and an alignment is often recommended afterward. Luxury or high-end vehicles typically have higher costs than standard models.
 
This video explains the factors that influence the cost of replacing a control arm: 58sLearnToDIY360YouTube · Jul 28, 2025
Cost breakdown

• Parts: The cost of a new control arm can range from approximately $80 to over $650, depending on the vehicle's make and model, as well as the type of part (e.g., OEM vs. aftermarket). 
• Labor: Labor costs are often the largest part of the total price, as control arm replacement can be a complex job that can take several hours per side. 
• Alignment: It is highly recommended to get an alignment after replacing a control arm to ensure your car's suspension is properly adjusted, which adds to the overall cost. 

Factors that influence cost

• Vehicle Make and Model: Luxury or high-performance cars have more expensive parts than standard models. 
• Parts Type: The cost varies depending on whether you choose Original Equipment Manufacturer (OEM) parts, aftermarket parts, or heavy-duty parts. 
• Labor Rates: Shop labor rates vary by location, with higher rates in some areas and for certain types of shops. 
• Additional Repairs: If other suspension components, such as ball joints, bushings, or shocks, need to be replaced at the same time, the total cost will increase. 

How to save money

• Shop around: Compare prices from different auto repair shops. 
• Consider aftermarket parts: These are often cheaper than OEM parts, but be sure to research the quality of the brand. 
• Ask for a combined quote: If you need other suspension work done, ask if it can be done at the same time to save on labor costs. 

What is a Subaru control arm?

The control arm or A-arm is the link between the chassis and wheel hub in your Subaru. It lets your wheels go up and down while keeping them from moving forward and rearward.