Brake Disc Mot Failure
A brake disc worn close to or below its minimum thickness results in an advisory note or a major fault during an MOT test. A worn brake disc close to its minimum thickness is not considered a failure, while a brake disc worn below this minimum thickness is an MOT failure.
Yes, according to the UK's Ministry of Transport (MOT), worn brake discs that fall below the minimum thickness standard will result in an MOT failure. However, if the brake disc is worn close to the minimum thickness, it will only be marked as an advisory note and not lead to a failure. It is essential to maintain your vehicle's brakes and ensure they meet the safety standards to pass the MOT test.
Are worn brake discs an MOT failure?
Worn brake discs can result in an MOT failure if they are worn below the minimum thickness, which is considered a major fault. If they are worn close to the minimum thickness, it will only result in an advisory note.
Why are my discs distorted when I brake?
Discs may become distorted when braking due to overheating or run-out brakes. To prevent this, use engine braking and avoid excessive use of brakes when driving down long hills. If your brakes are worn, it is important to have them replaced to ensure safe driving.
Can a pitted disc fail an MOT test?
According to current MOT guidelines, pitted discs should not fail the MOT test unless they have become seriously weakened. However, the final decision on whether a pitted disc is deemed unfit for purpose and needs replacement rests with the MOT inspector.
Do I need to replace my brake discs?
Brake discs may need replacing if early symptoms are ignored, such as juddering through the brake pedal or warped discs due to uneven heating and cooling. Thinner or more worn discs are more likely to warp.
Worn brake discs can result in an advisory note during an MOT test but will not cause failure if they are above the minimum thickness. However, brake discs that are below the minimum thickness will be considered a major fault and result in an MOT failure.
How much wear should a brake disc have?
Brake discs can have 2-3 millimetres of wear before needing to be changed. A burr can be felt at the rim when a disc is worn, and the more pronounced the burr, the worse the wear is.
Do brake discs and brake pads wear out over time?
Brake discs and brake pads are subject to wear and tear as they convert kinetic energy into thermal energy through friction over time. Careful drivers can get up to 100,000 kilometres from one set of brake pads, while those who prefer a speedier style will need to replace them sooner.
What are the parts of a brake disc?
The parts of a brake disc include metal discs that rotate with the wheel, brake pads that cause friction when the brake pedal is pressed, and brake calipers that contain the piston and brake pads and clamp onto the disc when braking.
During MOT testing, brake discs that exhibit pitting are evaluated to determine if they will hinder the effectiveness of the braking system. Should the pitting be deemed as having no significant impact on braking performance, the MOT tester may suggest replacing the brake discs in the near future. However, if the pitting is found to be excessively severe, the brake discs will need to be replaced for the vehicle to pass the MOT test.
Brake Disc Worn, Pitted, or Scored but Not Seriously Weakened?
The "brake disc worn, pitted, or scored" advisory is given during MOT inspection when there is a problem with brake discs that do not yet require replacement. This does not indicate a serious weakening of the brake system.
Should pitted brake discs be on my certificate as an advisory?
The inclusion of pitted brake discs on an MoT certificate as an advisory will depend on the severity of the damage.
What causes a car to fail the MOT test?
The criteria for passing the MOT test changed in 2018, with defects now being classified as Dangerous or Major instead of marked as a pass or fail. A car cannot be driven with a Dangerous defect. It is important to note that word of mouth regarding what will cause a car to fail the test may be out of date.
Front brake pads necessitate more frequent replacement as they tend to wear out faster than rear brake pads (which could be either disc or drum brakes). Replacement is essential when the pads become too thin, particularly if they display signs of wear.
Should I replace my brake pads and discs?
It is recommended to replace both brake pads and discs at the same time to prevent damage and improve overall brake performance.
Do you need to replace brake rotors every time?
Brake rotors do not need to be replaced every time brake pads are replaced. However, when replacing rotors, brake pads should also be replaced for safety reasons.
How do I know if my brakes need to be replaced?
To check if your brakes need replacing, visually inspect the brake pads and look for less than 3mm of visible pad. If your car vibrates as you brake, it may indicate abnormally worn or thermally damaged brake discs.
Can You Replace Brake Pads Without Replacing Rotors?
In short, brake pads can be replaced without replacing rotors as long as the rotors are still in good condition and have no significant damage or wear.
The MoT tester must inspect the brake pads during the inspection and fail the car if the brake pads are worn down to the wear indicator or below 1.5mm. Some brake pads have metal wear indicators that create a squealing noise upon contact with the disc.
Should a MOT tester inspect brake pads?
According to Ask Honest John, a worn brake pad should be inspected by an MoT tester and the car should fail the test if the pad is worn down to the wear indicator or below 1.5mm. However, it is unclear if the tester in question performed this inspection, as one of the front brake pads on the car disintegrated within 100 miles of passing the MoT.
Are brake discs serviceable?
Yes, brake discs are serviceable, but they have a limited lifespan and will eventually need to be replaced. Regular maintenance and inspection can also help prolong the life of brake discs.
Do rear brakes fail Mot?
It is possible for rear brakes to fail an MOT test if they are found to not meet the required standard for effectiveness and safety. This can include issues such as excessive corrosion or wear on brake discs, insufficient braking force, or other factors that could compromise the vehicle's ability to safely stop. It is important to ensure that all aspects of a vehicle's braking system are in good working order in order to pass an MOT.
Are all brake rotors worn?
No, not all brake rotors are worn. The degree of wear on brake rotors/discs depends on various factors such as the driving conditions, vehicle usage, and maintenance. In some cases, brake rotors may require replacement due to excessive wear, warping or damage, while in others, they may still be within the acceptable threshold for safe use.
Car brake judder can occur due to various reasons such as poorly-fitted brake discs, dirt or rust on the disc, excessive tightening torque, distorted hub or incorrectly fitted alloy wheels. Extreme disc overheating and distortion, as well as disc thickness variation (DTV), can also cause brake judder.
What causes disc brakes to go bad?
Disc brakes can go bad due to various reasons, including overheating, wear and tear, contamination, and problems with the brake pads or calipers. Heavy or prolonged braking can cause the brake pads to overheat, leading to glazing and reduced performance. Over time, the friction material on the brake pads wears down, requiring replacement. Contamination from oil or grease can also affect the brake pads' grip on the rotors. Additionally, seized or damaged calipers can prevent the brake pads from pressing against the rotor, leading to poor braking. Regular maintenance and timely repairs can prevent disc brake problems and ensure safe and reliable braking performance.
How to avoid distorted discs?
One can avoid getting distorted discs by utilizing a lower gear and engine braking when driving down lengthy hills. This can prevent excessive brake usage and overheating. If the brake pedal feels soft, this could indicate an issue with the brake fluid.
What do you need to know about disc brakes?
Disc brakes can be damaged by overheating, which is the most common cause of rotor damage. Cross-drilled rotors can help dissipate heat, but they may also create stress cracks due to intense heat. Overheated rotors are more likely to warp.
Why is my brake caliper sticking?
A brake caliper may stick due to various reasons such as the accumulation of dirt and debris, rust, lack of lubrication, or a damaged or worn out piston seal. This can result in uneven brake wear, reduced braking performance, overheating, and even brake failure. Therefore, it is essential to have the brakes and calipers regularly inspected and serviced by a qualified mechanic to diagnose and address any sticking caliper issues promptly.