Different people drive differently. Some like keeping it slow and methodical up until they turn off the engine, while others prefer making their cars dart down the road like a bat out of hell. Legality and safety aside, you need the right kind of brake parts – especially rotors – to get the most out of your preferred driving style. Below is a detailed comparison of the common rotor types.
When it comes to disk brakes, the rotors form the actual discs that the brake pads clamp down on and create the friction necessary to deter wheel motion. Such rotors come in a range of designs, meant to match different budgets and driving needs. Every type, except ceramic and two-piece, comes crafted as single pieces of iron capable of withstanding and dispersing rapid heat buildup.
OEM style rotors come as standard equipment on almost all vehicles and are the most basic type of rotor available on the market. These feature smooth, groove-less surfaces that allow for limited heat dissipation. They suffice plenty for everyday driving needs, but for someone with an eye on more aggressive braking than is considered regular, one of the other rotor types would suit better.
These are designed for auto enthusiasts who prefer stronger bite from their pads, specifically while towing or driving aggressively. A slotted rotor has lines of shallow indentations on each side of the rotor, which lets heat, brake dust, water, and friction gases flow out more easily. That means it stays cooler than an OEM-styled one, and is much more suited to 4WDs hauling heavy loads as well as two trailers. The slots do not run too deep and allow the disc to retain its strength and mass without warping or fracturing. That said, pad life is lowered substantially, because a bit of material gets sliced away each time the brake pad contacts.
This type of rotor is an improvement over the slotted variety when it comes to performance. They carry holes running all the way the way through to the other side of the disc, which guarantees maximum dispersion of debris and heat, even under the most intensive use. Some drilled rotors come with a slotted design modification; even without that, they are a great option for vehicles that frequently get driven hard.
The main downside to drilled rotors is that they incur relatively more damage from aggressive braking and overhauling. Too much weight lugged or towed, or excessive rough driving, can easily cause cracks to form between the holes. One way to offset that risk is to go in for partially drilled (dimpled) rotors. These are less efficient at heat dissipation, but last a good while longer.
This rotor type involves a construction out of specifically blended porcelain compounds. Such rotors were originally intended for high-end performance in top-of-the-line cars, although you could get something to go in most regular streetcars. Ceramic brakes are a lot costlier than the other types, but that is easily justified by the heat durability, corrosion resistance, and stopping power they can bring to bear. They are expensive enough that is hard to get them as aftermarket parts.
For rapid brake response, you could do no better than getting ‘two-piece’ rotors for your car. Where most brake rotors come as one-piece units, this type has an aluminum section that is fastened to an iron outer section, with the latter taking brake pad contact. The aluminum center spares a lot of weight. The design is strikingly unique because you can always tell the two pieces apart. This is usually intentional – manufacturers often color the aluminum part slightly differently in order to make them more visually appealing. Two-piece rotors understandably cost a lot more than the OEM, slotted, and drilled varieties, and are most commonly seen on high-performance cars. If you can shoulder the expense though, these rotors are possibly the best way to offset heavyweight from your tires and wheels.
The key aspect of these rotors does not have to do with the face of the disc. Instead, it pertains to the area between the sides. If the “edge” contains a hollow section with variously shaped fins, then the rotor is of the ventilated variety. The fins pull in air from that area, which removes the heat clinging to the rotors. Dissipation in this manner can have a profound effect on braking performance, as well as preventing boiling and overheating of fluid. Most OEM front brake rotors are of the ventilated or “vented” type, and so are all performance brake rotors.
OEM rotors generally possess parallel cooling fans. Performance-oriented brakes, on the other hand, have curved fins that function much more effectively, but only in one direction. For that reason, these rotors are also called unidirectional rotors.