Manufacturers design cars with a brake system to ensure safety while driving. The brake system consists of several components that work together to slow a car down at high speed. One of such components is the brake rotors, which are circular disks connected to the vehicle’s four wheels. There are usually four brake rotors installed in a car, one for each wheel.
Like other parts of a vehicle, rotors might develop faults and require replacement. If you need to replace your car’s rotors, some questions might come to mind. Questions relating to the purchase and replacement primarily.
This article addresses these questions, but it is important to understand how rotors work before delving into them.
How do rotors work?
Brake rotors should not be underestimated as they are one of the most important parts crucial to a car’s braking system. Once you press down on the brake pedal, the brake pads place pressure on the rotors to stop the car’s wheels from moving.
When the brake rotors are slowing down the car’s wheels, friction generates a large amount of heat. This is quite normal as the rotors are rubbing against the wheels to reduce the car from high speed to a stop. However, the rotors are designed with gaps that reduce the heat generated during the braking process.
When buying brake rotors for the first time, it can be confusing how many you need to purchase, considering that brake pads do come in pairs and rotors don’t.
Are rotors sold in pairs or singles?
Brake rotors are sold in singles and not in pairs. Therefore, it is easy to buy a single rotor if you only need one. However, if you intend to replace a particular rotor, it is best to check the state of the others as well.
Generally, it is not recommended to replace just one rotor, as this can cause braking issues. However, I will delve into this later in this article.
How do you know when to replace your rotors?
The brakes of your car work hand in hand with your rotor. Therefore, an issue with the braking system might call your attention to the state of your brake pads and rotors. If the brakes malfunction but loud noise is made, there is a chance that the rotors are damaged. However, not all noisy brake malfunctions indicate a faulty rotor.
Rotors should not be replaced only when they malfunction. Hence, during your usual maintenance, if you notice that your car’s rotors are rough or dented, they should be replaced immediately because rotors should be smooth. It is best to measure your rotors regularly to know when they need replacements.
Preventing potential malfunctions is cheaper and safer as faulty rotors can lead to crashes if they fail when driving at high speeds.
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How many rotors do I need?
If you notice any defect with your rotors, you will need to replace them in pairs. Hence, you will need to purchase at least two rotors even though just one needs replacing. It can happen that sometimes stones get stuck in between the rotor and the pad, causing damage to the rotor.
Unless you replaced the rotor less than 500 miles ago, it is recommended to replace both rotors situated on the same axle.
It is important to note that defective rotors are not the only kinds due for replacement. Rotors with the potential of failing should be replaced as well.
Can you buy just one rotor?
Yes, you can buy just one rotor as long as it’s just that one defective rotor. If you have more than one faulty rotor, buying just one rotor would be impractical; hence you need to buy enough to replace all defective ones.
As discussed above, unless you replaced the rotor recently, I recommend replacing them in pairs to ensure the proper functionality of your brakes.
How many brake rotors does a car have?
A car has four brake rotors, one attached to each wheel. They all work together to ensure that the vehicle stops when the brake pedal is pushed. Once pressure is applied to the brake pedal, friction is ignited, which progressively reduces the wheels’ speed.
Related content: Why does my car make a clicking noise when braking?
Should rotors be replaced in pairs?
Yes, rotors should be replaced in pairs for better stability during the braking process. The thickness of rotors reduces with time, which is very normal. However, if just one rotor is replaced, the difference in thickness might reduce stability when applying the brakes.
The higher the thickness of a rotor, the higher the mass it provides during the braking process. It absorbs and dissipates the heat generated by friction when the wheel rubs against it better than when thin.
When replacing, they should not only be of the same type as the original but should also be of the same or superior quality. There are different types of rotors, so the type should be kept in mind. There are:
Drilled and slotted
These are best suited for high-performance cars which require fast cooling. These rotors are a combination of heat dissipation and dirt removal features.
Slotted
These are often found in heavy-duty vehicles. These rotors cool faster than other types but don’t last as long.
Drilled
These are best suited for vehicles in wet climates. The rotors are designed not to accumulate dirt or debris, which might clog other rotors and slow down the braking process.
Blank and smooth
These are the most common types. They are also more affordable as their design is very simple. These rotors are used in different vehicle types and should not be mixed for safety and efficiency.
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How many rotors come in a box?
Rotors are sold in single units. However, since many manufacturers suggest replacing in pairs, you might find specific packages with more than one rotor. Some part dealers sell discount packages containing a pair of rotors and brake pads. If you find such packages for your vehicle type, you can save up money buying them as a pack rather than individually.
Closing thoughts
Rotors are very important parts of the braking system and must be checked often for damages or everyday wear. If a defect is observed, the affected rotor should be changed. Fortunately, brake rotors are sold singly, so you do not need to purchase more than what you need. However, it is still recommended to replace them in pairs, especially for rotors installed around the same time.
Just like brake pads, brake rotors do not last a lifetime, so they might need to be replaced from time to time. Therefore, whenever your brake pads are replaced, the rotors should be examined to ensure they are in good condition.
My name is Jeffrey Williams and I have been a car mechanic for over 35 years. I am currently working NYC Auto Repair Shop, in New York City and recently developed a strong passion about blogging. I decided to put together this blog where I will try and answer the most commonly asked questions I get on a daily basis from my customers.
