Project EVO IX: Part 4, In search of the Ultimate EVO Brake System
By Mike Kojima
How do you improve on something that is really 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 4 piston front and two piston rear brakes and big ventilated rotors on all 4 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.
The big 355mm Brembo rotor dwarfs the stock one piece rotor. Even though the Brembo part is much larger, the alloy center hat makes it lighter.
Why in the world would we mess with our brake then? Since our plans for Project EVO IX include some serious track use, we first started to consider the idea of upgrading our brakes. Since a stock EVO is a relatively heavy car at close to 3200 lbs, 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 are not streetable.
The 6 piston monoblock caliper is compared to the stock 4 piston part here. The primary advantage of the monoblock caliper is that it uses a brake pad twice the size of the stock part. The monoblock caliper is much stiffer due to its one piece construction and the center bridge shown here in the picture.
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 they do not instantly wear out the rotors, race pads 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.
These tension spring clips are what keeps tension on the full floating rotors so they are free to move but do not rattle like typical racing full floating brakes.
When used on the street, the temperatures do not 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 have seen race pads completely ruin a set of rotors in 200 street driven miles. We won’t say who did this (ahem) but let’s say we have up close and personal experience with this. Another minus is that race pads generally do not work well when cold, as in the type of cold that is 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 powdercoating if it is not washed off frequently.
Our brake system installed. Overall the underpinnings of Project EVO look pretty trick.