What Are Drilled Brakes and How do They Work?
There are two major types of high-performance brake rotors — drilled and slotted. We’ll discuss the drilled rotors here and move on to the slotted rotors on the next page. Drilled brake rotors, as the name implies, have holes drilled in them. Having a holes drilled into any of your brake parts may seem counterintuitive, especially the brake rotors — after all, a rotor full of holes means that there’s less surface area for the brake pads to grab and stop the car — but there are a few reasons drilled rotors make sense.
The first is heat. When the brake pad grabs the rotor, it creates friction, which creates heat. If that heat can’t escape, it leads to brake fade, which reduces the brakes’ stopping power. The second reason is gas build up. This actually isn’t much of a problem any more; however, the materials used in some older types of brake pads caused gas to build up between the rotors and pads. That gas also limited stopping power. The last reason is water. If a car drives through a puddle, a carwash or even a rainstorm, the brake rotors can get wet. A wet brake rotor is slippery and difficult for the brake pads to grab. Having drilled holes on a brake rotor makes it easy for heat, gas and water to be quickly moved away from the rotor surface, keeping the brake performance strong.
The downside of using drilled rotors on your vehicle is that all of those holes tend to weaken the rotors — just like punching holes in the wall of a house would weaken the wall. After repeated stressful driving, the rotors can even crack.
But what if you’re into driving performance? Are drilled rotors right for you, or should you consider another kind of brake part for your spirited driving?
Slotted brake rotors use slots carved into the flat metal surface to move gas, heat and water away from the surface of the rotors. Motorcycle brake rotors work much in the same way as car brake rotors. The rotors spin along with the wheel, and when the brakes are applied, the brake pads grab the rotor to stop the wheel from spinning. On a motorcycle, however, the front and rear brakes usually operate independently of each other, in contrast to car brakes, which work to slow or stop all four wheels at once. Most motorcycles have independent, hand-operated controls for each brake — front and rear. The front brake tends to be more effective; delivering the lion’s share of the stopping power, with the rear brake assisting to slow or stop the bike. Obviously, motorcycle brake rotors are considered a key component of motorcycle safety.
Most street driven motorcycles come equipped with drilled brake rotors; however, most high-performance or on-track bikes will typically use slotted rotors. Since motorcycle brake rotors are more visible brake parts than car brake rotors — especially on the front wheel of the bike — the drilled brake rotors often provide a custom look. In fact, many custom cycle builders use decorative drilling or shaping of their rotors to make their bikes stand out.
Some brake parts get less attention than others. That’s just the way it is. For example, high-performance brake pads tend to get a lot more attention than high performance brake rotors. As we mentioned earlier, when you’re talking about high performance rotors, slotted, not drilled, rotors are the choice of most racers. The benefit of the slots is that they allow hot gases, water and other debris to move off of the face of the rotor; however, they do tend to wear the brake pads down faster. That’s likely not a problem for most performance drivers. Most probably already have ceramic or carbon fiber brake pads which are pretty long-wearing anyway.
High performance brake rotors are also vented to allow even more heat to dissipate away from the braking system and prevent brake fade. While the slots in slotted brake rotors are carved into the face of the rotors, the vents run around the edge of the rotor. As the rotor spins, the heat escapes through the vents. Without the extra heat, there’s less of a chance for brake fade, which makes the car perform better on the track.