How do you improve on something that's good to begin with? The Evo is blessed with one of the best standard equipment brake systems found on any production car. In stock form the Evo has big Brembo four-piston front and two-piston rear brakes and big ventilated rotors on all four corners. With the normal brake modifications, such as high-temperature fluid, braided lines and upgraded brake pads, the stock brakes can handle just about any situation you would likely find on the street, including spirited driving in the twisties. With an aggressive high-temperature brake pad, the stock brakes can also handle abusive track duty, even with R-Compound tires. The stock brakes even look good. No wonder many Evo tuners overlook the brakes when building fast Evos.
Why in the world would we mess with our brakes then? Since our plans for Project Evo IX include some serious track use, we considered the idea of upgrading our brakes. With the stock Evo being relatively heavy at close to 3,200 pounds, the stock brake pads must be exchanged for some aggressive heat-resistant pads for track use with sticky R compound tires to avoid fade. The trouble with these kinds of brake pads is that they aren't streetable.
The aggressive friction material of racing brake pads has a high metallic content, including materials like powdered iron, bronze, and copper with friction modifiers like ceramic and carbon powders used to maintain a high coefficient of friction at the near metal melting temperatures that brakes sometimes see at the track. Naturally, this sort of brake pad is very abrasive.
So race pads don't instantly wear out the rotors, they depend on high temperatures so they can develop what is called a transfer film on the rotors. A transfer film is a thin layer of metallic oxides that bonds to the rotor. The transfer film is formed under the high temperatures and pressures of brakes being pushed to the limit. The aggressive pad material rubs on the transfer film instead of the bare iron of the rotor, and the film protects the metal from rapid wear. Think of the transfer film as a wear-resistant coating for the rotor that exists at high temperatures.
When used on the street, the temperatures don't get high enough for a transfer film to form and the abrasive pad material does a handy job of machining your nice rotors down to nothing in a shockingly short time. We've seen race pads completely ruin a set of rotors in 200 street-driven miles. We won't say who did this (ahem), let's just say we have up close and personal experience with this. Another minus is that race pads generally don't work well when cold, as in the type of cold that's seen in your first few stops in the morning or when driving on the highway for miles without touching your brakes. This might lead to dangerous situations when the brakes are cold. Finally, racing pads give off obnoxious, sticky, cleaner resistant and corrosive brake dust. This gummy black powder just loves to eat up polished alloys or burn through powdercoat if it isn't washed off frequently.
Driving to the track and switching the pads before starting out is not that big of a deal but the hassles of registration and mandatory drivers meetings make race mornings somewhat hectic without having to scramble to switch pads. After all most of us don't have a pit crew to help out on track days. What we wanted were some brakes that had enough capacity so that we could drive to and from the track and run on the same set of pads. To stop 3,200 pounds of Evo with streetable pads meant going big, real big.