The brake disc rotors of your BMW are discs connected to each of the wheels against which the brake pads press when you press the brake pedal. Alongside the brake pads, they are one of the parts in your braking system that see the most wear and tear and will thus need to be changed more frequently than others.
The Function of BMW Brake Disc Rotors
Role in the Braking System
Your BMW has four brake disc rotors, one connected to each wheel. When the brakes are activated, the brake pads press against the brake disc rotors, converting the wheels' kinetic energy (movement) into thermal energy. Thus, friction slows the wheels' rotation.
BMW Brake Disc Rotor Design Types
There are a variety of brake disc rotors for your BMW, and the type of brake disc rotors used can even vary in the same year, so ensure you get the correct one for your vehicle. These can be a combination of slotted or drilled, solid and vented.
Solid
Solid brake disc rotors feature a smooth surface around the rotor. Because they are not as efficient at dissipating heat, they are commonly only found in light passenger vehicles whose brakes are not subject to high levels of heat stress.
Vented
A vented brake disc rotor has a hollow vent between the front and rear surfaces for heat dissipation capability. These are usually the standard for performance models.
Slotted
Slotted brake disc rotors come with long slits or vents on the surface around the rotor. The slots have a higher friction coefficient than standard discs and are able to disperse water and gas to deliver better braking performance.
Drilled
Instead of slots, drilled brake disc rotors have drilled holes in the surface. The drilled holes offer similar benefits as vents over the standard smooth surface.
Slotted and Drilled
Some brake disc rotors will come with a combination of slots and drilled holes which offer even better heat, water, and gas dissipation and are thus used in performance vehicles. However, not only do the many exposed edges wear down brake pads faster, but the reduction in material in these brake disc rotors also makes them more susceptible to cracks.
Signs of Worn or Damaged Brake Disc Rotors
Common Brake Disc Rotor Issues
Brake disc rotor issues usually result from wear and tear with regular use but could also be caused by warping due to overheating, rust damage, or cracks. These are some of the most common brake disc rotor issues:
1. Shaking or vibrating steering wheel
2. Screeching or loud noises when braking
3. Reduction in braking performance
4. Pulsing brake pedal
5. Scratches on the brake disc rotor surface
Impact on Braking Performance & Safety
Faulty and/or worn out brake disc rotors can adversely affect the braking ability of your BMW and compromise the safety of you and your passengers. Any suspected issues should be dealt with immediately before driving your BMW again.
Maintenance Tips for BMW Brake Disc Rotors
Proper Driving Habits
Proper driving habits can lead to fewer instances where you will need to apply your brakes heavily. Heavy braking is one of the leading causes of premature brake disc rotor failure since the large amount of heat produced suddenly can cause warping.
Using High-Quality Brake Pads
The quality of the brake pads has an impact on the braking performance of your brake disc rotors since the rotors are in direct contact with them. Higher quality brake pads can lead to better stopping power, increased lifespan, and reduced dust and noise.
Proper Cleaning
Cleaning the brake disc rotors of buildup of dirt and grime can increase their braking power. You can also apply an anti-rust spray to prevent rust, which can lead to an uneven surface, vibrations, and noise.
Replacing or Resurfacing Your Brake Disc Rotor
Your brake disc rotors may need to be replaced if they are cracked, warped, or worn down to a certain point. Your mechanic will inspect the rotors if you are having trouble or whenever you send your BMW for a brake pad replacement. The rotor thickness and runout are measured, and if the rotor falls below the minimum thickness, it needs to be replaced. Otherwise, it can be resurfaced and reused.
Sourcing BMW Brake Disc Rotors (OEM vs. Aftermarket)
Brand new BMWs come with Original Equipment Manufacturer (OEM) brake disc rotors made by their authorized manufacturers. BMW brake disc rotors made by third-party manufacturers and usable in BMWs fall under the "Aftermarket" parts category.
We recommend investing in original BMW brake disc rotors to return your car to its original level of performance. Because of the more stringent levels of manufacturing, you'll likely get better braking performance and more use out of an OEM replacement. While aftermarket brake disc rotors may be cheaper, installing them may void your BMW's warranty and even cause damage to your car. Moreover, they might not have the same braking capability or even fit into your BMW properly. With safety-related parts like the brake disc rotors, it's prudent to avoid taking chances and to go with the original.
Are BMW Brake Rotors Expensive?
Continental car parts are generally more expensive than average. BMW brake disc rotors can be pricey, and the price will vary according to the type of brake disc rotors. For example, the front brake disc rotors are usually more robust and will be more expensive.
Where to Buy Genuine BMW Brake Rotors Online
Brand-new genuine BMW brake disc rotors can be obtained from your country's BMW dealers and OEM parts retailers. For a more affordable alternative without much trade-off, choose second-hand brake disc rotors that are in good condition. We recommend purchasing them from a trusted dealer like BE FORWARD Auto Parts.
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