What Are Slotted Rotors? Do I Need Them?

The brake rotors are discs that are connected to each wheel. They are designed to transform motion or kinetic energy into thermal energy or heat. When you step on the brake pedal, a signal will be sent through the master brake cylinder to the calipers to squeeze the brake pads together against the rotors. This slows the rotation of the wheel and stops the car’s movement. When your brake rotors are due for a replacement, there are a number of options when it comes to choosing a new one. You might’ve heard of slotted rotors that lead you to ask, what are slotted rotors and do I need them? Slotted rotors are rotors that have long slots or lines in the metal surface.

Slotted rotors are designed this way in order to draw more air between the pad and rotor surface. If you ask, Do I need them? Slotted rotors will be a good choice if you want a great performance brake system. This type of rotor is usually used for SUVs and heavy-duty trucks, especially the ones that need enhanced stopping power when hauling or towing. While it is a great choice, it has some cons and one of which is that it increases pad wear. What are slotted rotors? If you still ask, “what are slotted rotors?”, continue reading. We will go through each of the frequently asked questions about this type of rotor and everything you need to know!

What are Slotted Rotors? –  Are Slotted Rotors Actually Better?

Rotors play a very important role in your car’s brake system. They are large metal discs connected to each of your car's wheels by its axle, two in the front and another two in the back. You may be able to see the rotors depending on the design of your hubcaps.

The brake rotors work with the brake pads and when it comes to halting your car, both are very important. The brake rotors spin with the wheel and when you step on the brake pedal, the brake pads squeeze or clamp down the rotor so your car can slow down or stop.

When the rotor is still new, it has an even and smooth surface. However, as it is being squeezed by the brake pads day by day or when you are driving your car and applying brakes, the rotors tend to lose their smooth finish and they become worn. When this happens, you may notice that your stopping distances are increased and your car’s braking performance has decreased.

You will know if your rotors are already worn when you experience vibrations or shaking when you apply the brakes, hearing grinding, squeaking, or squealing sound when you brake, or you notice grooves worn into your rotor. If your brake rotor is due for a replacement, it has to be done immediately since driving on damaged rotors is very dangerous.

But when it comes to replacing brake rotors, there are a number of options being sold in the market today and you have to decide what type of rotor you will use in your car. You might have heard of slotted rotors before that led you to ask, what are slotted rotors? Before we answer this question, let us go through the different types of brake rotors first.

You need to understand that not all brake rotors are the same and not all of them are right for your car. So when you are replacing your brake rotors, make sure that you choose the right type of rotor which your car needs. The different types of brake rotors are:

• Black and smooth rotor.

This type of brake rotor is generally found on most passenger vehicles. This rotor has a smooth, blank metal surface all throughout the rotor.

• Slotted rotor.

What are slotted rotors? Slotted rotors are designed with long slots or lines in its metal surface.

• Drilled rotor.

This type of rotor has drilled holes around its metal surface.

• Drilled and slotted rotor.

Drilled and slotted rotors are designed with a combination of drilled holes and slots. This is done to improve its braking performance.

When selecting the right brake rotor for your car, you need to see your car’s existing rotors and start from there. However, if you want to make a “brake upgrade”, there are some things you need to consider. Bear in mind that not all rotors can be used on your car. If you ask, what are slotted rotors and are they actually better, then here’s what you need to know.

• If you are not a super aggressive driver and are driving a basic passenger car, then using a blank and smooth rotor will be the best choice for you. Original equipment-specific brake rotors usually have 2 choices, the basic one and the premium one. The basic ones are generally made from recycled steel and might not perform as good as your car’s original brake rotor.

• If you own an SUV or a heavy duty truck and you need to enhance your stopping power for hauling or towing, then using slotted rotors for your car will be a great choice. The long slots or lines found on slotted rotors are made to draw more air in between the pads and rotor surface. The grooves that are machined across the rotor’s face allow excess dust and gases to escape, keeping the brake pads in contact with the rotor and improving the friction. That is why slotted rotors are usually chosen for most performance brake systems.

• Although slotted rotors are great during heavy braking, decrease the risk of brake fading, and help maintain consistent stopping power, this type of rotor has some drawbacks and one of which is that it can negatively affect your brake pad’s life. Slotted rotors also do not last as long as the others.

• Now, when it comes to drilled rotors, this type of brake rotors have drilled holes throughout their surface which allows dust, water, and heat to be dispersed easily off the rotor’s surface. Drilled rotors will be a great option for drivers that live and drive in an area with wetter climates since they can help improve your brake’s stopping power in wet and rainy driving conditions. If you want a car with a great braking system, for performance use, then slotted rotors will better suit your car since drilled rotors don’t work well in high-heat conditions. It tends to fail pretty easily when used in a race-like driving condition.

• If you have asked, what are slotted rotors?, you might have heard about the drilled and slotted rotors too. This type of brake rotor is made for performance vehicles such as sports cars, that needs improved cooling and heat dispersion. It is common knowledge that where there is friction, there is always heat. Since the brakes on vehicles driven on off roads or tracks are usually exposed to constant force and heat, the integrity of the rotors will eventually be compromised.

To make sure that the negative effect of high performance driving will be decreased, the drilled and slotted rotors are designed with tiny holes and small trenches that are etched into the surface. These holes and trenches function as gutters for heat and water.  Although drilled rotors work great at dissipating heat, they also have some drawbacks. One, it is not as durable as the other types of rotors. Its edges tend to wear away brake pads quicker than the traditional smooth rotors since its material has been removed from the surface. This also decreases its health, which makes it more susceptible to cracks.

What are slotted rotors and are they better? If you have SUVs, tow trucks, heavy trucks, off road vehicles, or racing cars, then slotted rotors will be a great option. You just need to make sure that when you choose one, you will choose a slotted rotor that is known to be of high quality. If you purchase a slotted rotor that has not been properly machined, from its inner areas to its outer edges, it will most likely crack sooner than it normally would.

What are Slotted Rotors? – What is the Advantage of Slotted Rotors?

The different types of brake rotors each have some advantages and disadvantages. There are rotors with slots or drills which can help improve your car’s braking, but usually under different braking conditions. To help you understand what the advantages of the slotted rotors are or the other types of rotors, you need to know the heat transfer’s three forms.

• Conduction – Heat energy will flow from the area of high temperature to the area of low temperature when there is a temperature gradient within a body. This is referred to as conduction. Its heat will flow from the brake rotor’s edge through the hub bearing, and through the pad into the caliper.

• Convection – Convection is when air flow is dispersed from a body. In general, the higher the air flow over the brake rotor, the more heat will be taken away. The vanes of the rotor will function like a fan blade that will move the air from the rotor’s inside and direct it to the outside edge. This process helps get rid of the heat via convection.

• Radiation – This heat transfer form removes heat via infrared radiation. Once you stop your car and you pop up your hood, you will feel its heat above your engine with your bare hands even without touching it. This is the infrared radiation coming off from your car’s engine.

These three forms of heat transfer can happen when you step on your brake pedal. The heat transfer during an average stop is about 40 percent radiation, 35 percent convective, and 25 percent conductive. But for a high speed top with high temperature, the numbers will be about 45 percent radiation, 40 percent convective, and 15 percent conductive. You need to remember that during high speed, convection heat transfer is very crucial. That is why drilled and slotted rotors are usually used in this driving condition since they can help reduce the brake temperature.

So aside from asking, “what are slotted rotors?”, many people are also asking about the advantages of the slotted rotors.

The advantages:

• The slotted rotors are a great option for SUVs, heavy-duty trucks for towing or hauling, off road vehicles, and race cars.

• It is far better than the blank and smooth rotor in some ways. It has rotor grooves that provide two distinct advantages when under heavy braking. One for brake fade, and the other from high temperature brake pad outgassing, both can be reduced significantly and enable gases or air to exit through the slots. Its grooves can also shave off thin layers of brake pad material which can decrease glazing and enhance the braking consistency.

• The slotted brake rotor has a design that enhances the consistency with every stop. It lessens the friction in the brake pads.

• You will have peace of mind knowing that you can depend on your brake pads to effectively brake, slow down, or stop your car even in heavy duty vehicles.

The disadvantages:

• Slotted rotors have a shorter lifespan compared to the other rotor types. They also tend to shorten the life of your brake pad.

• You may also feel vibrations or hear noises from the rotors when coming to a stop from a high speed.

• If you want to have your slotted rotors machined, you may find it hard to find a shop that can machine your rotors.

Although slotted rotors do not improve the heat transfer, they can enhance the brake output by getting rid of the gas or dust that is trapped between the brake rotor and the pad. The gas and dust need to be removed since they can decrease the friction force by keeping the pad from fully contacting the brake rotor.

We have answered the question, what are slotted rotors? If you think that using a slotted rotor for your car is a great choice, then you can proceed and have it installed. However, there are some factors you need to consider when choosing what type of brake rotor you will use on your car. Aside from considering your personal preference or the style you prefer, you also need to consider how your car will be driven, and on what driving conditions.