Parking Brake Failures & Your MOT Test

The MOT test is a crucial annual check designed to ensure your vehicle is roadworthy and safe. While many components are scrutinised, the parking brake, often referred to as the handbrake, plays a surprisingly significant role. A failure in this seemingly simple system can lead to an immediate MOT rejection. This article will delve into what happens if your parking brake fails an MOT, exploring the reasons behind such failures, the specific test procedures, and what steps you can take to prevent it.

Understanding the MOT Parking Brake Test

The MOT test isn't just about visual checks. For the parking brake, a series of practical tests are performed to ascertain its effectiveness. Testers will use a dynamometer, a rolling road, to measure the braking force applied by the parking brake. This is done both on the front and rear wheels, depending on the vehicle's configuration.

Key Test Parameters:

• Braking Force: The parking brake must be capable of holding the vehicle stationary on a gradient of 1 in 6. On the rolling road, this translates to achieving a minimum braking force.
• Lever Travel: The handbrake lever should not travel too far. Typically, it shouldn't be possible to pull it up to its maximum limit. Excessive travel indicates worn cables or brake shoes/pads.
• Pedal Travel (Foot-Operated Parking Brakes): Similar to the lever, the pedal should have a reasonable amount of resistance and not go to the floor.
• Engagement: The parking brake should engage smoothly and hold the vehicle without significant juddering or noise.

Why Might a Parking Brake Fail an MOT?

Several factors can contribute to a parking brake failing its MOT inspection. Understanding these common culprits can help you maintain your vehicle proactively.

Common Causes of Parking Brake Failure:

• Worn Cables: The most frequent cause is stretched or corroded cables. Over time, these cables can lose their tension, meaning they don't pull the braking mechanism with enough force. Rust can also impede their smooth operation.
• Sticking Calipers/Wheel Cylinders: If the components that the cables operate (calipers for disc brakes, wheel cylinders for drum brakes) are seized or corroded, the parking brake won't engage effectively. This is particularly common if the vehicle is left unused for extended periods.
• Worn Brake Pads/Shoes: While the primary service brakes are tested separately, the parking brake often uses a separate mechanism or a portion of the main braking system. If the shoes or pads are excessively worn, the parking brake will have less material to grip against, reducing its effectiveness.
• Corrosion: All braking system components are susceptible to corrosion, especially in areas with harsh weather or where salt is used on roads. Corrosion on the brake discs, drums, or the mechanism itself can prevent proper engagement.
• Improper Adjustment: The parking brake system requires periodic adjustment to maintain optimal performance. If it hasn't been adjusted correctly, it might not provide sufficient braking force.
• Damaged Actuating Mechanisms: The levers, linkages, and springs that actuate the parking brake can become damaged or worn, leading to reduced efficiency.

What Happens if Your Parking Brake Fails?

If your parking brake fails during the MOT test, the vehicle will receive a refusal of an MOT certificate. This means your vehicle is deemed unsafe for use on public roads and cannot be legally driven until the issue is rectified and a re-test is passed.

Implications of an MOT Failure:

• Immediate Rejection: The vehicle will be issued with a 'Dangerous' defect notice, meaning it must not be driven until repairs are completed.
• Repair Required: You will need to take the vehicle to a qualified mechanic to have the parking brake system repaired or adjusted.
• Re-test: Once the repairs are completed, the vehicle will need to undergo a partial re-test of the parking brake system. In many cases, if the failure was solely related to the parking brake, the rest of the MOT isn't re-tested, but this can vary depending on the extent of the repairs and the garage's policy.

Preventative Maintenance for Your Parking Brake

To avoid the inconvenience and potential cost of an MOT failure, regular maintenance of your parking brake is essential. Think of it as another vital part of your car's overall health.

Tips for Maintaining Your Parking Brake:

• Regular Use: Even if you primarily use an automatic transmission, make a habit of engaging the parking brake when you park, especially on inclines. This helps to keep the cables and mechanisms lubricated and free from seizing.
• Occasional Full Pull: When safe to do so (e.g., on a quiet, level road), occasionally pull the handbrake up to its maximum recommended position and hold it for a few seconds. This can help to clear surface rust from the brake drums or pads used by the parking brake.
• Listen for Unusual Noises: Pay attention to any clicking, grinding, or stiffening sensations when you apply the parking brake. These could be early indicators of a problem.
• Check Cable Tension: While you might not be able to adjust it yourself, a mechanic can check the cable tension during routine servicing.
• Inspect for Corrosion: During wheel changes or brake servicing, visually inspect the parking brake cables and mechanisms for signs of rust or damage.
• Professional Servicing: Ensure your parking brake is checked as part of your vehicle's regular servicing schedule. A competent mechanic will be able to identify and address potential issues before they become MOT failures.

Can You Drive a Car with a Failed Parking Brake?

If your car fails its MOT due to a parking brake issue and receives a 'Dangerous' defect notice, you technically cannot drive it on public roads. The only exceptions are driving it to a pre-booked MOT test centre or to a place of repair. If you are stopped by the police and your vehicle is deemed unsafe, you could face penalties.

Frequently Asked Questions (FAQs)

Q1: How much does it cost to fix a parking brake for an MOT?

The cost can vary significantly depending on the nature of the fault. Replacing worn cables might cost anywhere from £100 to £300. If calipers or wheel cylinders need replacing, the cost could be higher, potentially £200-£500 or more per axle. It's always best to get a quote from your local garage.

Q2: Can a garage adjust a parking brake?

Yes, most garages can adjust a parking brake. This is often a relatively straightforward procedure that can resolve issues with excessive lever travel. However, if the cables are stretched or corroded, adjustment alone may not be sufficient.

Q3: My parking brake seems fine, why would it fail the MOT?

The MOT test is very specific. Even if your parking brake feels okay for everyday use, it must meet the precise braking force requirements on the rolling road. It's possible your brake is working, but not to the stringent legal standard required for road safety.

Q4: Is the parking brake tested on all vehicles?

Yes, the parking brake system is a mandatory part of the MOT test for all passenger vehicles, including cars, vans, and motorcycles (where applicable). The specific method of testing may differ slightly based on the vehicle type.

Q5: What if the parking brake warning light is on?

A constantly illuminated parking brake warning light, even when the brake is fully released, is usually indicative of a fault within the parking brake system or a low brake fluid level. This would likely result in an MOT failure.

Conclusion

The parking brake is a critical safety feature, and its proper functioning is non-negotiable for passing the MOT. A failure in this system can lead to an immediate rejection, rendering your vehicle illegal to drive. By understanding the testing procedures, common causes of failure, and implementing regular preventative maintenance, you can significantly increase the chances of your vehicle passing its MOT with flying colours, ensuring both your safety and compliance with the law. Don't underestimate the importance of this often-overlooked component; a well-maintained parking brake is a hallmark of a safe and roadworthy vehicle.