How To Tell If My Struts Are Bad

So, you're suspecting your struts might be on their way out? Smart move to investigate. Worn struts can seriously impact your ride quality, handling, and even braking performance. This article will equip you with the knowledge to diagnose strut issues like a pro, covering everything from visual inspections to performance tests.

Purpose

Understanding the condition of your struts is crucial for several reasons:

Safety: Degraded struts compromise vehicle stability, especially during emergency maneuvers or on uneven road surfaces. This directly impacts your safety and the safety of others on the road.
Performance: Worn struts can lead to increased body roll during cornering, nose dive during braking, and generally sloppy handling. Replacing them restores a tighter, more responsive driving experience.
Tire Wear: Bad struts can cause uneven and premature tire wear. Think of it like this: your tires are constantly bouncing rather than maintaining consistent contact with the road.
Component Longevity: Compromised struts put additional stress on other suspension components like ball joints, tie rod ends, and control arm bushings, accelerating their wear. Addressing strut issues early can prevent more expensive repairs down the line.
Ride Comfort: A smooth ride is a comfortable ride. Faulty struts transmit bumps and vibrations directly into the cabin, creating an unpleasant driving experience.

This knowledge empowers you to make informed decisions about repairs, potentially saving you money by catching problems early and allowing you to confidently tackle strut replacement yourself (if you're so inclined and have the appropriate tools and experience).

Key Specs and Main Parts

Let's break down the anatomy of a typical strut assembly. Knowing the parts and their functions is the first step in diagnosing problems.

Main Components:

Strut Cartridge/Insert: This is the heart of the strut. It contains the hydraulic fluid and valving that dampen oscillations and control suspension movement. Think of it as a shock absorber housed within the strut body.
Strut Housing/Body: The structural component that supports the vehicle's weight and connects to the suspension system. It also houses the strut cartridge.
Coil Spring: Provides the springing action, absorbing bumps and maintaining vehicle ride height. The spring rate (measured in lbs/in or N/mm) determines how stiff the suspension is.
Strut Mount: Connects the strut assembly to the vehicle's chassis. It often incorporates a bearing or bushing to allow for steering movement (in front struts). A worn strut mount can be a significant source of noise and vibration.
Bump Stop: A rubber or foam cushion that prevents the suspension from bottoming out during extreme compression. Degraded bump stops can result in harsh impacts.
Dust Boot/Bellows: Protects the strut rod and seal from dirt, debris, and moisture. A torn boot allows contaminants to enter the strut, leading to premature failure.

Key Specs (Examples, Varies by Vehicle):

Strut Length (Extended/Compressed): Important for ensuring proper fitment and suspension travel.
Spring Rate: Specifies the stiffness of the coil spring. Higher spring rates generally result in a firmer ride.
Damping Force (Compression/Rebound): Describes the strut's ability to control suspension movement. Measured in Newtons (N) at specific velocities.

You can typically find these specifications in your vehicle's repair manual or from online parts catalogs when searching for replacement struts. Always verify compatibility with your specific make, model, and year.

How It Works

Struts are a crucial part of a vehicle's suspension system. They combine the function of a shock absorber and a suspension support. Here's a simplified explanation of how they work:

Compression: When the wheel encounters a bump, the coil spring compresses, absorbing the initial impact. The strut cartridge simultaneously resists this compression through its valving, preventing excessive bouncing.
Rebound: As the spring rebounds (extends), the strut cartridge controls the speed of this extension, preventing the vehicle from oscillating excessively. The rebound damping is usually more aggressive than the compression damping to ensure a stable ride.
Damping: The strut cartridge contains hydraulic fluid and valves. As the suspension moves, the fluid is forced through these valves, creating resistance and dissipating energy. This damping action is what controls the suspension's movement and prevents it from bouncing uncontrollably. Different valve designs and fluid viscosities result in varying damping characteristics.
Support: The strut housing provides structural support, connecting the suspension knuckle (or hub) to the vehicle's chassis. This helps to maintain wheel alignment and control vehicle handling.

Real-World Use - Basic Troubleshooting Tips

Okay, let's get practical. Here's how to diagnose strut issues:

Visual Inspection:

Fluid Leaks: This is the most obvious sign of a bad strut. Look for oil streaks or wetness on the strut body. A leaking strut indicates that the hydraulic fluid is escaping, reducing its damping ability.
Damaged Dust Boot: A torn or missing dust boot exposes the strut rod to contaminants, leading to premature wear and failure.
Corrosion: Rust on the strut body or spring can weaken the components and lead to failure.
Deformed or Broken Spring: Inspect the coil spring for any signs of cracking, bending, or breakage. A damaged spring will significantly affect ride height and handling.
Worn Strut Mount: Look for cracks, tears, or excessive play in the strut mount bushings. A worn mount can cause clunking noises and vibrations.

Performance Tests:

Bounce Test: Push down firmly on each corner of the vehicle and release. Observe how many times the vehicle bounces before settling. More than two or three bounces indicates weak struts.
Ride Quality: Pay attention to how the vehicle handles bumps and dips. A bouncy, unstable ride is a sign of worn struts.
Handling: Notice any excessive body roll during cornering, nose dive during braking, or general instability.
Noise: Listen for clunking, rattling, or squeaking noises coming from the suspension. These noises can indicate worn struts, strut mounts, or other suspension components. Clunking is often heard when going over bumps.
Tire Wear: Inspect your tires for uneven wear patterns. Cupping or scalloping can be a sign of bad struts.

Safety

Working with struts involves significant risk due to the compressed coil spring. Never attempt to disassemble a strut assembly without proper spring compressors. The stored energy in the spring can cause serious injury or even death if it's released unexpectedly.

Spring Compressors: Use high-quality spring compressors designed for automotive use. Follow the manufacturer's instructions carefully. Ensure the compressors are securely attached and that the spring is properly supported before attempting to disassemble the strut.
Eye Protection: Always wear safety glasses or a face shield when working with suspension components.
Gloves: Wear gloves to protect your hands from sharp edges and chemicals.
Proper Support: Use jack stands to securely support the vehicle before working on the suspension. Never rely solely on a jack.
Disconnect ABS Sensors: If working near ABS sensors, carefully disconnect them to avoid damage.
Torque Wrench: Use a torque wrench to tighten fasteners to the manufacturer's specified torque. Over-tightening or under-tightening can lead to component failure.

If you're not comfortable working with compressed springs, it's best to leave strut replacement to a qualified mechanic.

Conclusion

By understanding the function of your struts and knowing how to identify the signs of wear, you can proactively address suspension issues and ensure a safe and comfortable driving experience. Regular inspections and prompt repairs will help maintain your vehicle's performance and prevent more costly problems down the road.

We have a detailed diagram of a typical strut assembly available for download. This diagram provides a visual representation of all the key components and their relationships, making it even easier to understand the strut's construction and function. Understanding strut operation will assist with learning, repairs, or modifications. Contact us to receive this valuable resource.