MOT Checks: Suspension System

The MOT test is a vital annual inspection designed to ensure your vehicle is safe to drive and meets environmental standards. While many people are aware of checks on brakes, lights, and emissions, a crucial component often overlooked is the suspension system. But does a suspension system need to be inspected during an MOT? The unequivocal answer is yes, absolutely. The condition of your car's suspension is a significant factor in its overall safety and roadworthiness.

Why is Suspension Important?

Your car's suspension system is a complex network of components that connects the vehicle to its wheels. Its primary functions are to:

• Ensure a smooth and comfortable ride by absorbing shocks and vibrations from the road surface.
• Maintain tire contact with the road, which is essential for steering, braking, and acceleration.
• Support the weight of the vehicle.
• Control the vehicle's handling and stability, especially during cornering and braking.

Without a properly functioning suspension, your vehicle's handling can be severely compromised, leading to longer braking distances, unpredictable steering, and an increased risk of losing control. This is precisely why it's a key area of focus during an MOT inspection.

What Aspects of the Suspension are Inspected?

During an MOT, a trained inspector will meticulously examine several key components of your suspension system. These include:

1. Shock Absorbers (Dampers)

Shock absorbers are critical for controlling the up-and-down movement of the vehicle's body. The MOT will check for:

• Leakage: Any signs of oil leaks from the shock absorber body or seals are a failure point. Leaking fluid indicates that the seals are failing, compromising the shock absorber's ability to dampen effectively.
• Excessive Wear or Damage: The inspector will look for any visible damage to the shock absorber casing, mounting points, or the shaft itself.
• Effectiveness: While not a precise measurement, the inspector will assess the general effectiveness of the shock absorbers. A worn-out shock absorber will result in excessive bouncing after the vehicle is pushed down, indicating a lack of damping control.

Worn shock absorbers can lead to a bouncy ride, reduced braking efficiency, and uneven tyre wear.

2. Springs

The springs bear the weight of the vehicle and absorb the initial impact from road imperfections. Inspections focus on:

• Breakage: Any signs of cracks or breaks in the coil springs are a definite fail. A broken spring can significantly alter the vehicle's ride height and handling, and can also be a safety hazard.
• Corrosion: Severe corrosion that weakens the spring's structure is also a cause for concern.
• Incorrectly Seated Springs: Springs must be correctly positioned and seated within their mounts.

3. Suspension Linkages and Mountings

This encompasses a range of components that connect the suspension to the chassis, including control arms, wishbones, ball joints, and anti-roll bars.

• Wear and Tear: The inspector will check for excessive play or looseness in ball joints, tie rod ends, and other pivot points. Worn components can lead to imprecise steering and instability.
• Damage: Any cracks, distortion, or damage to control arms, wishbones, or other structural suspension components will result in a fail.
• Corrosion: Significant corrosion that affects the structural integrity of these parts will also be flagged.

Ball joints, in particular, are critical for steering and are thoroughly checked for play.

4. Wheel Bearings

While not strictly part of the suspension itself, wheel bearings are integral to the wheel assembly and are checked during the MOT. The inspector will test for:

• Excessive Play: By lifting the wheel and trying to rock it, the inspector checks for any noticeable looseness in the wheel bearings.
• Noise: Grinding or rumbling noises from a wheel bearing, especially when turning, can also indicate a problem.

A failing wheel bearing can lead to the wheel becoming detached from the vehicle, a catastrophic failure.

5. Bushings

Rubber or polyurethane bushings are used at various pivot points within the suspension to absorb vibration and allow for controlled movement. The MOT will check for:

• Cracking and Deterioration: Aged or damaged bushings can crack, perish, or detach, leading to excessive movement and noise.
• Missing Bushings: If a bushing is completely missing, it will result in a fail.

Worn bushings can cause vague steering and knocking sounds.

Common Suspension Failures

Based on MOT data, some of the most common reasons for suspension-related failures include:

What to Look Out For Between MOTs

While the MOT is a thorough check, you can also be proactive in monitoring your suspension. Be aware of the following signs:

• Uneven Tyre Wear: If your tyres are wearing down more on one side than the other, it often indicates a suspension alignment issue.
• Pulling to One Side: If your car consistently pulls to the left or right when driving on a straight road, it could be a suspension problem.
• Excessive Bouncing: If your car continues to bounce for more than a second or two after hitting a bump, your shock absorbers may be worn.
• Strange Noises: Clunking, rattling, or knocking sounds when going over bumps or turning corners often point to worn suspension components, such as ball joints or bushings.
• Poor Handling: A noticeable decrease in stability, especially when cornering, or a feeling of the car being less responsive to steering inputs, can be a sign of suspension wear.

Addressing these symptoms promptly can prevent more serious damage and ensure your vehicle remains safe.

Frequently Asked Questions (FAQs)

Q1: Can a car fail its MOT solely on suspension issues?

Yes, absolutely. If any part of the suspension system is found to be worn, damaged, or not functioning correctly to the extent that it poses a safety risk, the vehicle will fail its MOT.

Q2: How much does suspension repair typically cost?

The cost of suspension repairs can vary significantly depending on the specific component needing replacement and the make and model of your car. Simple bushing replacements might be relatively inexpensive, while replacing a complete strut assembly or a more complex component can be considerably more costly. It's always best to get a quote from a reputable garage.

Q3: Should I get my suspension checked even if it's not due for an MOT?

It's highly recommended. If you notice any of the warning signs mentioned above, it's wise to have your suspension inspected by a qualified mechanic. Regular checks can identify minor issues before they become major, expensive, and potentially dangerous problems.

Q4: What is the difference between shock absorbers and struts?

While often used interchangeably, there's a technical difference. Shock absorbers are designed purely to dampen spring oscillations. Struts, on the other hand, are a structural part of the suspension system, often incorporating the shock absorber within the strut assembly, and also serve as a pivot point for the steering.

Conclusion

In summary, the suspension system is a critical safety feature of any vehicle, and its condition is rigorously assessed during the MOT test. From shock absorbers and springs to ball joints and bushings, each component is checked for wear, damage, and proper function. Keeping an eye on your vehicle's handling and listening for unusual noises between MOTs can help you identify potential problems early. Ensuring your suspension is in good order not only helps you pass your MOT but, more importantly, keeps you and other road users safe.

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