Brake discs are an important car component – designed to help you slow down when you need to, from abrupt stops to gentle slow-downs. They are a vital safety feature, which is why it’s essential that they’re properly maintained and replaced when necessary.
How they work
To understand why your brake disc’s need to be replaced and how to know when they need replacing, it’s helpful to know how they work.
When you press down on your brake pedal it operates a brake booster and component called the master cylinder which contains brake fluid. The brake fluid is forced down your vehicle’s brake lines which makes a part called the brake caliper press your braking pads against your brake disc – this is what slows you down.
The friction and energy created during the braking process creates a lot of heat, which needs to be quickly dispersed. Brake discs are relatively quick at dispersing heat – much faster than drum brakes. If you think about how often you brake when travelling in your car, it’s easy to imagine why your brake discs and pads might need replacing or ’machining’!
Why you need to replace your brake discs
The key reason that brake disc’s need to be periodically attended to and replaced is because over time they can wear down and become a serious safety hazard.
Daily use means they can become grooved or suffer from uneven wear due to dust, contaminates or hard pad material. As a rule of thumb, it’s generally a good idea to replace brake pads before they have completely worked out.
Brake disc rotors will also need to be replaced or machined if they’re shimmying or pulsating when braking. It’s also worth noting that all car manufacturers have a minimum thickness for brake discs, and car owners must replace their brake discs when the minimum thickness has been exceeded.
How to know if your brake disc need replacing
There are some common signs to look out for that can indicate when brake discs have become worn or damaged. If you notice any of the following then your brakes may need replacement:
Squealing or scraping noises
A certain amount of squealing noise from your car brakes can be expected under normal circumstances, factors like the weather and the material of your brake pads can cause a little bit of noise.
Loud screeching sounds however are often a clear sign that brake pads are due for replacement. Many brake pads are designed with a wear indicator that will begin to screech, even when the brakes aren’t in use to indicate that the brake pads need replacement. If the car driver waits too long the pads can wear down completely and a scraping noise might be heard instead – often an indicator that it’s also time to replace the brake disc rotors.
Pulsation or vibration
If you notice pulsation or vibration of the steering wheel or brake pedal when using your brakes then this is often a sign that your brake discs have worn down or become damaged and require replacement.
Erratic stopping or movements
If it feels like your car jerks to a stop or pulls to the side then it could be a sign of worn brakes and could indicate that there is a problem with your brake pads.
Noticeable marks or cracking
It’s a good idea to regularly check the condition of your brakes – cracks or visible damage of your brake disc rotors is a clear indicator that it’s time for replacement. If your brake pads have been worn down to below 3mm then they will also need to be replaced.
Many cars are fitted with brake sensors which will indicate with a warning light when it is time to replace components like brake pads and brake discs.
How often do you need to replace your brake discs?
How frequently you will need to replace your brakes depends on factors like:
Your vehicle model
Driving style and
The conditions under which your car is being driven.
If your brakes experience heavy use for instance then you will need to replace your brakes more often. The recommended timing for brake replacements for the particular make and model of your car will be included in your car owner’s manual.
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