Aftermarket brake rotors of both the slotted and drilled variety are available for most vehicles. Both slotted and drilled rotors provide better performance than the stock rotors on a vehicle. The main differences between the rotors are small but are important if you are considering them for reasons other than safety.
Differences In Material
A drilled rotor has less metal content than a slotted rotor. The holes in the rotor help to get rid of excess water in the rotor when driving in the rain. When less metal is used in the construction of a rotor, it has less stopping power than a rotor with more metal content in its construction. Slotted rotors have more metal than a drilled rotor. Slotted rotors are more efficient at moving water away from the rotor when it rains. Slots also help to keep your brake pads clear of debris.
Slotted Rotor Advantages
A slotted rotor has approximately twice the life of a stock rotor. The design of the slotted rotor does this by expelling excess heat out of the slots even during excessive braking. This cuts down of the wear of the rotor. When slotted rotors are used, a car will have a smoother and shorter stopping distance when braking than a drilled rotor due to its heavier weight.
Drilled Rotor Advantages
Rotors which are cross drilled can expel more heat than a stock rotor but not as much as a slotted rotor. The unique spacing of the drilled holes in the rotor gives the drilled rotor better weight distribution than a slotted rotor. The lighter construction of the rotor means that it will stop later than slotted rotor due to its lighter weight.
Both slotted and drilled rotors result in a shorter stopping distance. Aftermarket rotors are less prone to failure than stock rotors and carry their own warranties.
Neither drilled rotors or slotted rotors are necessary to add to your vehicle. They are used by people who wish to have improved performance and are often used in racing and other motor sports. Drilled or slotted rotors should be used when a shorter braking distance is desired and cannot be achieved with the stock rotors on your vehicle.