Articles » Basic Mods Part 2

Finally, we come to braking. This is probably one of the most important things in your car. If you plan to do a lot of racing, especially freeway (no, I’m not promoting it. ;-) ) or auto crossing, you’ll definitely need to upgrade your stock brakes. There are several features that upgraded brakes have.

On the stock Si, it has just plain-jane brake rotors and single piston calipers. The rotor is the metal disc you see when you look in the wheel. It is just a simple flat piece of metal that the caliper (that metal box that is on part of the rotor) compresses on and creates friction turning the car’s inertia into heat. Most cars come with vented rotors though. If you looked at these rotors from the side, you’d see it looks like the rotor was split in half long ways and some metal plates were inserted in there perpendicular to the rotor. Well, that is basically the concept. The plates actually circulate air through the rotor to help keep it cool. The biggest problem that can happen with stock brakes is called brake fade. This is where the rotor and brake pads get so heated that they become glazed and actually stop working. When this occurs, your car become very difficult to slow down, if not impossible, until the rotors and brake pads cool back off. Vented rotors are an attempt to prevent this, but aren’t the best solution.

A slotted rotor is a modified vented rotor that has even better cooling capabilities. What they do is cut slots at about a 45-degree angle around the surface of the rotor. This allows better cooling and for the rotor to better adjust to various temperature changes. A cross-drilled rotor is similar in that it’s a vented rotor that has holes drilled straight through it. This allows very thorough cooling and is very suitable for high-speed racing or any type of racing that requires repeated braking. You can also have slotted and cross-drilled rotors all in one. The rotors that come on the Porsches are not cross-drilled, but rather forged holes. This means that the rotor was actually made with those holes in there instead of them being drilled afterwards. This stops any type of cracking around the holes that can occur with a cross-drilled rotor.

Next are the calipers. If you remember, I said that the stock Si comes with single piston calipers. What this means is that the caliper has a "piston" in it that moves to force the brake pads to compress onto the rotor. The brake fluid is what moves these pistons and that is of course activated by your foot depressing the brake pedal. The more pistons you have in your caliper, the easier it will be for your brakes to slow down your car. Most Porsches come with 4 or 6 piston calipers(4 piston slotted and cross drilled brakes are pictured above). Another feature of brakes is the size of the rotor. If you notice, the high performance cars always have larger rotors. The larger the rotor, the less work the brakes have to do to slow down your car. The reason for this is simple: the calipers have more leverage on the wheels. However, when you start upsizing the rotors on your car, you’re going to have to make sure you have a big enough rim to accommodate this increase in rotor size. So just check with the manufacture of that rotor as to what is the minimum size rim that can fit around it.

This concludes part 2 of my Basic Mods series. We have learned the various ways of making your car handle better and stop faster, both very key in racing. Part 3 will take us back to the motor and cover some more advanced engine modifications.