Brake rotors come in many different types. Before you can purchase a fresh set of brake rotors, you should understand each of these different types, what sets them apart, and what are the pros and cons of every style. The four kinds of brake rotors are:
- Blank or Smooth (OEM replacement- most vehicles)
- Diamond Slotted
- Drilled and Slotted
Why Choose Blank Brake Rotors?
Best for: Street, Autocross/Track, Towing/Hauling, Off-Road
Far and away, most new cars come with blank rotors installed both for maximum effectiveness across driving conditions and for cost effectiveness. If you do not drive aggressively, have a luxury car, or seek a brake rotor that is quiet above all, smooth rotors can be the right choice for you.
A top choice for endurance racers who need a brake pad that can hold up through a long race, as well as an overall inexpensive brake rotor choice, smooth or blank brake rotors can work very well for many needs. They tend to be the longest lasting overall, while also produce very little dust and are quiet to operate. It is precisely the plain nature of these brake rotors that makes them last longer: Without any drill holes or slots there is little room for cracks to develop.
There’s not much cons to having a blank rotor. Some drivers have a misconception that they should choose slotted or drilled rotors over blank rotors for superior performance. This is not necessarily true, so do not feel the need to select a particular type of brake rotor over the misunderstanding that it is better than another style of brake rotor. It all depends on how you drive your vehicle and how you would like it to stop.
Why Choose Drilled Rotors?
Best for: Street Performance
If you live in an area that experiences a lot of rain, drilled rotors are a very good choice. They perform well in rainy climates by offering a good “wet bite,” hold up well over the life of the rotors, and deliver more friction and more bite than their slotted counterparts. The bite is better with these brake rotors because the drilled holes give the water a place to escape, thus drying off the braking system components when water is present. Less water means a better bite and improved brake rotor performance.
While drilled rotors have a lot to recommend them, they can wear unevenly and may develop cracks when used in racing vehicles due to the heat and temperature extremes of a race. Drilled brake rotors also tend to wear in concentric grooved styles, which can look funny when the rotors are aged if the drilled hole patterns are not staggered. While this does not impact the performance of the brake rotors, it can affect the vehicle aesthetic and sensitive drivers may prefer to select a different style of brake rotor or else change out their rotors more often.
Drilled rotors are also a poor choice for race cars. They cannot withstand repeated heat and cool cycles very well, and will fail sooner rather than later as a result. Drilled brake rotors are fine for general use in street vehicles.
Why Choose Slotted Rotors?
Best for: Street Performance, Autocross/Track, Towing/Hauling, Off-Road
Slotted rotors work very well for heavy trucks, SUVs, off road vehicles, tow trucks, and competition cars. It is particularly important to choose high quality brake rotors when picking a slotted style. If the brake rotors are not properly machined, from the inner to the outer edges, they can crack sooner than they otherwise would or should. Dodge prefers this type of rotor with its Brembo high performance braking systems, found on SRT and Scat Pack models.
2009 Challenger SRT
This style of brake rotor delivers improved consistency with every stop, by reducing the friction in the brake pads. Over the long run the slotted rotors also perform well: As the slots shave down glaze from overheated brake pads, they expose fresh material every time you brake. As a result, you can rely on these pads to deliver effective, non-fade braking even in heavy duty vehicles.
Slotted brake rotors are not without their disadvantages: They tend to have a shorter life compared with other types of brake rotors, and may shorten the life of brake pads, as well. When you are coming to a stop from a high speed, you may feel a rumble from the brake rotors. They will still perform safely, but the noise may be annoying.
Why Choose Drilled/Slotted Rotors?
Best for: Street Performance, Towing/Hauling, Off-Road
Drilled/slotted rotors offer the benefits of drilled and slotted rotors together. They work well for wet climates, where frequent rain is a consideration.
They perform well, although not necessarily better than other styles of brake rotors. These newer brake rotors are starting to appear on some luxury cars, including Mercedes and BMW. Car owners looking to be consistent with maintenance may prefer to stick with the drilled/slotted rotors if these were original to their vehicle.
These rotors do work particularly well for tow vehicles, trucks, and other cars that carry heavy loads. Heavier vehicles require more energy to come to a stop safely, and this type of brake rotor excels at delivering it. Drilled/slotted brake rotors are also are fine for general use in street vehicles.
Drilled/slotted rotors are not recommended for performance racing since the drilling makes them vulnerable to cracking.
Unless you have an exotic car with carbon-ceramic brakes, then your rotors are most likely made out of cast iron, which is prone to rust. Iron oxidizes easily, and rust will form on the surface of the discs if they are exposed to water or even moisture.
Besides being an aesthetic thing, rust really isn't a problem on brake rotors. On the braking surface itself, the worst rust could do is slightly modify the friction coefficient for a period of time before it was worn down. You won't notice it. Though, with one or two stops, your brake pads will rub off the rust.
However, because oxidation and rust eat away at the metal, it is important to drive your car regularly and engage the brakes in order to wipe off the accumulated oxidation on the surface of your rotor. Surface rust becomes a problem once it gets deeper and starts pitting the disc.