How do I know if my back struts are bad?
The short answer: look for a bouncy ride, rear sag, fluid leaks on the struts, unusual noises, and reduced stability. If you notice any of these, get a professional check to confirm whether you need replacement. This guide explains what rear struts do, how they fail, how to spot the signs, and what to do next.
What rear struts do and why they fail
Rear struts (often called shocks or shock absorbers, sometimes integrated with coil springs in a single unit) dampen vertical wheel movement and help keep tires in contact with the road. Over time, wear, leaks, and impact can reduce their ability to dampen, leading to a less controlled ride. There are two broad types to consider: suspension struts for the rear of your vehicle, and trunk/hatch gas struts that hold open the tailgate. They fail for different reasons and show different symptoms, which this article distinguishes to help you diagnose accurately.
Signs your rear suspension struts may be failing
These are the most common indicators that the rear suspension struts are worn or damaged. Look for multiple symptoms rather than relying on a single clue, and consider having a professional inspection if you notice any of the following.
- Excessive bouncing or a wallowy feel after hitting potholes or rough roads. A good shock should limit rebound; persistent bounce indicates worn damping.
- Rear-end sag or uneven ride height, especially when the car is empty or loaded. If the back end sits lower than normal or noticeably dips under acceleration or braking, the struts may be worn.
- Leaks or noticeable oil stains around the strut body or near mounting points. Leaking dampers are a clear sign of failure and should be replaced.
- Unusual noises such as clunks, bangs, or squeaks when driving over rough surfaces or going over speed bumps. These sounds can point to worn bushings, mounts, or failed struts.
- Reduced stability and increased body roll in corners or during lane changes. You may notice the car feels less planted at highway speeds or during quick maneuvers.
- Tire wear that looks uneven or faster-than-expected on the rear wheels. Worn shocks can alter alignment and tire contact with the road.
- Visible damage to the strut assembly or mounting hardware, including bent mounts, cracked housings, or corrosion.
- Car sinking or dipping when braking or accelerating, not just when parked—a sign the damping system isn’t keeping the chassis under control.
These symptoms can overlap with issues in other parts of the suspension or steering system. If you notice several of them together, a professional inspection is usually warranted to confirm whether the rear struts are the sole cause or if other components need attention.
How to test rear struts at home
Before you head to a shop, you can perform a few basic checks to gauge whether the rear struts might be worn. Use caution and ensure the vehicle is on level ground and supported safely if you raise it.
- Visual check: Inspect for oil leaks on the strut body and around the mounting points. Look for damaged boots, corrosion, or bent parts.
- Bounce test: With the car on level ground, press down firmly on the rear corner and release. A healthy shock usually returns to its position smoothly with minimal bounce. If the car keeps bouncing more than once or twice, the damping may be worn.
- Ride height and load test: Compare the rear ride height to the front or to a known baseline, and note whether the rear end sags with or without a load. A significant, unbalanced difference can indicate worn struts or weak springs.
- Noise observation: Drive slowly over rough surfaces and listen for clunks or squeaks that could signal worn mounts or bushings.
- Tire wear check: Inspect rear tires for unusual wear patterns, such as cupping or feathering, which can be linked to improper damping.
- Mounting integrity: Check all bolts and mounting points for looseness or movement. Loose hardware can mimic or mask strut problems.
Home tests can point you toward a problem, but they can’t diagnose every cause of poor ride quality. A professional inspection will assess not only the struts but also related components such as springs, control arms, bushings, and the overall alignment.
When to replace rear struts and what to expect
Replacement decisions depend on the extent of wear, symptoms, and your vehicle’s specifics. In general, you should consider replacing rear struts if there is visible leakage, persistent poor ride quality after addressing other potential causes, or if a technician confirms reduced damping capacity. Replacing struts in pairs is often recommended to maintain balanced handling, even if only one side shows wear.
- What to expect in terms of cost and timing: Parts can range from around $50 to $200 per strut, with premium or specialty units costing more. Labor often runs around $100 to $300 per strut, depending on the vehicle and shop rates. A typical rear axle replacement might run from roughly $300 to $900 total, with wide variation by model and location.
- DIY vs professional installation: If you have the right tools and experience, you can replace struts at home, but many vehicles require a hydraulic spring compressor and safe jacking procedures. A professional installation ensures proper torque, alignment, and warranty considerations.
- After replacement: Expect improved ride quality, better handling, and restored stability. If you had other suspension components worn as well, consider a coordinated inspection to prevent premature wear on new parts.
Bottom line: most drivers replace rear struts when symptoms are clear or leaks are present, and many opt to replace both sides to preserve even damping and predictable handling on the road.
Trunk/hatch gas struts: a different job, different signs
If your “back struts” refers to the gas-filled supports that hold up a trunk, hatch, or tailgate, the symptoms and fixes are different from suspension struts. These gas struts don’t dampen road shocks; they simply lift and hold the hatch. When they fail, you’ll notice the hatch won’t stay open, opens slowly, or sags under its own weight. You may also hear a hissing or see oil around the strut seals.
What to look for with trunk/hood struts
Key indicators that trunk hatch gas struts are failing include:
- The trunk or tailgate won’t stay open on its own or requires you to hold it up manually.
- It opens slowly or feels weak when lifting the hatch.
- Visible leaks of gas or oil around the ends of the strut.
- Hinges feel stiff, or the hatch drifts downward over time.
In most cases, gas struts are relatively inexpensive and straightforward to replace. Replacing them in pairs can help preserve balanced opening on both sides of the hatch, if your vehicle uses two struts, and installation is typically a quick, tool-free process.
Quick takeaways
To recap: for rear suspension struts, look for persistent bouncing, rear sag, leaks, noises, and reduced stability; perform a basic home assessment, and consult a mechanic for a definitive diagnosis and replacement. For trunk/hatch gas struts, focus on opening/holding performance and any signs of leakage. When in doubt, a professional inspection will identify whether the issue is with the struts themselves or with related components.
Summary
Your rear struts—whether the suspension type or the trunk-hold open kind—play a critical role in safety and comfort. Signs of trouble include changes in ride quality, leaks, noises, and misbehavior under load. Start with a visual check and a cautious bounce test at home, but rely on a qualified technician for a definitive diagnosis and proper replacement. Replacing struts in pairs is common practice for even handling, and understanding the specific type of strut in question will help you shop for the right parts and service.
