When to change brake discs? Replacement is performed when the working surface of the part is significantly worn. It is also necessary to change the brake discs if beating or vibrations are felt when braking.
How to understand? The thickness of the brake disc indicates a greater degree of wear, the parameter is measured with a caliper. If the disc was overheated, it may warp. In this case, turning is unlikely to help, it is better to replace it.
How To Understand That It Is Necessary To Change Brake Discs
It is very important to understand when to change brake discs, because they are a critical element for the safety of all road users. Some people prefer to restore the discs by turning them, but this method requires a separate discussion. It is important to know the main signs that signal the need to replace brake discs in order to avoid possible risks.
Very Small Thickness
Do not forget to change the brake pads and discs. Over time, they wear out, which leads to a decrease in the thickness of the rotor part and its destruction. Manufacturers indicate the minimum permissible thickness of the disc on its surface or packaging. You can also view the full characteristics of the new disc in online catalogs.
This is done for the convenience of mechanics so that they can quickly find the information they need, for example, when the inscriptions on worn disks are hidden under a layer of rust.
Is it necessary to change brake discs when the thickness of the rotor part reaches or approaches the critical minimum? The disc is generally capable of withstanding braking after the ultimate thinning, but this entails serious risks that should not be ignored.
Auto repair specialists can easily determine the wear of a brake disc by using a caliper to measure its thickness – the process is not complicated.
The measurement should be taken along the working surface of the disc where the pad is located, and not along its edge, since this will not give an accurate idea of the condition of the part.
Beating During Braking
If you feel vibrations when pressing the brake, this is the second sign when you need to change the brake discs. They can be worn out even without reaching the critical thickness. In the future, the disc may lose shape due to frequent overheating.
Uneven disc thickness can also be the cause of vibrations, indicating possible problems with the calipers or their guides, which could have become stuck or not work correctly. If vibrations are detected, the cause may not only be in the disc, so it is better to contact a reliable car service.
Problems can arise in several cases:
- Low quality discs. When you change the brake discs on your car, consider buying better quality parts.
- The driver’s habit of driving carelessly, constantly overheating the brakes, can also cause problems.
- Sometimes a general “disease” characteristic of a certain car model appears. Solutions include installing either original disks from a reliable supplier to avoid counterfeits, or a complete replacement of the brake system.
Visible Damage To The Surface
In wet weather, light rust on the brake discs is not considered a defect. However, if deep corrosion is detected on the surface or serious rust accumulation in the ventilation slots, it is recommended to replace the disc. This is especially true for cars that have been idle for a long time.
Certain signs will help you understand at what level of wear the brake discs need to be replaced:
- If the brake pedal behaves unusually, for example, it falls significantly, this may indicate not only problems with the discs, but also problems with other elements of the brake system, such as worn pads, a faulty brake cylinder, or a brake fluid leak. It is still important to inspect the brake discs for wear.
- If you experience vibration or jolting when braking, it may indicate that the disc is warped, skewed, or worn unevenly. In this case, you should also check the condition of the brake pads.
- Whistling sounds when the vehicle slows down often indicate that it is time to change the brake discs. If they are completely worn out, there is a risk of damage to the disc due to contact with its metal base. Check the general condition of the disc.
If any of these defects appear, it is important to carefully inspect the brake system and its components, paying particular attention to the brake discs.
What Affects the Time to Replace Brake Discs
Below are some factors that will help you understand when it is time to change your brake discs.
- The type of gearbox affects. Cars with automatic or robotic transmission are less susceptible to disc wear, since the engine helps with braking, unlike cars with a manual transmission, where wear is 1.5-2 times greater.
- The location plays a decisive role. The discs on the front axle wear out faster due to the high loads during braking, their service life is limited to 80,000 km, while on the rear axle they can serve up to 120,000 km or more.
- ABS in a car improves the distribution of braking forces, making the wear of brake discs slower by 20%.
- Depending on the weight of the vehicle, it is also determined how often the brake discs need to be changed: in heavy vehicles such as trucks and buses, they wear out faster than in passenger cars.
- Driving in the mountains significantly accelerates the wear of brake discs, requiring replacement after 30-50 thousand km, unlike flat terrain, where the discs last longer.
- Aggressive driving style. Sharp starts and stops contribute to rapid wear and warping of the disks due to constant temperature fluctuations, making replacement inevitable even with sufficient thickness.
- The compatibility and durability of brake components are highly dependent on their hardness. When discs and pads are ideally matched to each other in this parameter, service life can be increased threefold. Too hard pads or rotors made of hard metal can lead to rapid wear of the opposite element in one cycle of work.
The serviceability of the brake mechanism affects the service life of the parts. Problems such as cylinder oxidation and guide jamming reduce the service life of the discs. It is especially harmful when hot water gets on the discs, which can lead to cracks and distortion of their shape, reducing braking efficiency.
What Is Better, To Sharpen Or Replace Brake Discs
Brake discs wear unevenly, with grooves, ridges and scratches forming on their surface over time, which can be seen visually and felt by touch. Many factors contribute to this, including the use of low-quality brake pads, corrosion, and dirt or sand getting between the disc and the pads. In addition, overheating can cause discs to warp.
Unevenness on the disc reduces braking efficiency and causes inconvenience when braking. Should you change the brake discs when faced with such a problem? If the disc is still in relatively good condition, it can be repaired by turning it.
The smoothness of the metal surface can be restored by removing a thin layer using specialized equipment. Some devices can be attached directly to the hub, while others require dismantling the parts for work. As a result of the treatment, 0.25 to 0.5 mm of metal can be removed, depending on the depth of the groove on the disk.
However, it is worth considering that cast iron parts are sensitive to sudden changes in temperature. This means that attempts to correct the deformation of brake discs caused by overheating may be ineffective. There is a high risk that after reheating the part will lose its shape again.
The discussion of the advisability of turning disks has been a hot topic for many years. Opinions are divided: some are sure of its usefulness, while others consider this action comparable to renewing the tread on tires by cutting it. Manufacturers believe that it is better to replace the part in advance than to decide to turn the support disk.
While resurfacing tired brake rotors can greatly improve the performance of your car, it is important to approach the process with caution and not overdo it.
When wondering whether you need to change the pads when replacing the brake discs, there are a few key points to keep in mind. You should not begin turning if the disc thickness is within 0.5 mm of the minimum, due to the risk of removing too much material. Both discs on the same axle must be treated, and the pads must be replaced immediately afterwards. It may also be necessary to replace the wheel bearing before starting the work, as its wear can negatively affect the quality of braking.
How To Extend The Service Interval For Replacing Brake Discs
By paying due attention to the maintenance of the brake system and careful driving, you can significantly extend its service life and ensure safety on the road. Following simple rules will help avoid unnecessary problems.
- When you change brake discs, buy only quality parts from trusted suppliers to avoid counterfeits, which, unfortunately, are flooded on the market. Give preference to goods from well-known manufacturers who value their reputation.
- It is important to use discs and brake pads from the same manufacturer to ensure optimal compatibility and efficiency of the braking system. When choosing parts, it is recommended to give preference to components from manufacturers whose products were used in the assembly of your car. This ensures that new parts will work in harmony with those already installed. Ignoring this advice can lead to deterioration in the efficiency of the braking system, wear and unpleasant sounds during operation.
- Replacing brake pads is not only about new parts, but also about caring for the condition of the entire brake system. Make sure that the pistons, calipers and pads work without jamming to avoid their rapid wear and deterioration of braking. Before installing new parts, clean the units from dirt and rust, and also use a special lubricant recommended by the manufacturer, which can often be found in the kit with pads of famous brands.
- When installing new discs, it is necessary to remove any remaining lubricant or friction agent from their surface before use, using a special cleaner for this purpose.
Frequently Asked Questions About Replacing Brake Discs
1. How To Properly Run In New Brakes?
Buying a new car or replacing components requires running in and bedding in the brake system to increase its service life and improve its performance. Bedding in is necessary to minimize the initial roughness of the brake discs and pads. This process, which includes about twenty soft decelerations from 80 to 30 km/h with cooling intervals, helps to increase the contact area of the parts.
The running-in process also allows the friction material of the pads to be brought to a state where it becomes harder, and therefore acquires better performance characteristics. To do this, it is necessary to heat it to a certain temperature, which causes the material to sinter.
It is important to avoid excessive heating to prevent damage to the not yet strengthened friction layer. During the first 300 km, you must not stop abruptly, overload the car or pull a trailer. During this time, a calm driving style is required. It is also worth avoiding mountain descents on the brakes, reducing speed using the engine.
Following these precautions will ensure optimum brake performance that can withstand even extreme conditions when required.
2. How To Choose The Right Brake Disc?
We remind you of the critical importance of selecting wheels for your vehicle in accordance with the manufacturer’s instructions. Using wheels that do not meet the requirements, such as replacing ventilated wheels with solid ones or using wheels from other models that seem suitable, will result in improper operation of the braking system and increase the risk of accidents.
When choosing disks, it is important to pay attention to parameters such as diameter and thickness, which can vary even for one car model depending on the year of manufacture and sales region. If you are not sure that you can choose the right parts, it is recommended to entrust this work to a specialized service or spare parts store.
On all specialized forums you can find a lot of opinions about pads and discs. They argue more about oil and rubber. In certain moments, most drivers are unanimous. In particular, only an experienced professional will be able to detect the difference between regular and perforated brake discs on the move, so it is not worth overpaying for this. There is also no need to buy composite discs, since they are more suitable for sports cars and are rare.
In today’s reality, it is hardly appropriate to recommend spare parts from any specific manufacturers, since most car owners sometimes buy what they can find or options that are affordable. However, it is important that the brake discs and pads are of the same brand. Reputable manufacturers test their products to ensure their compatibility, which minimizes the chance of noise when braking.
3. How Do You Know When It’s Time To Change Your Brake Discs?
How often to change brake discs depends on operating conditions and driving style. A careful driver can expect the part to last up to 100 thousand kilometers. However, when using the car in racing conditions, the discs wear out very quickly. Therefore, whatever the circumstances, the key point is to monitor the current condition of the brake system components.
4. Is It Possible To Change One Brake Disc?
Usually, brake discs wear out simultaneously, but problems with the caliper or damage to the pad can cause uneven wear. Sometimes, if a defect is found on a new disc or it is damaged during installation, it is permissible to replace only one part.
Regular inspection and timely replacement of brake discs and pads are critical to ensuring safety on the road.
