It doesn't take a new race team long to learn that brakes are right up there, in terms of overall importance to performance, with the engine. A quality braking system isn't just for avoiding crashes or making sure you don't run off the end of the trailer, it's also important for controlling turn entry, loading the front wheels to help the car turn, and on dirt tracks helping control the car's pitch as it slides through the turns. In short, better and more consistent stopping power usually translates into faster lap times and improved performance on the racetrack.

Of course, like everything else in racing, there's more to it than simply buying the best parts and bolting them on. Along with the tires and valvetrain, the braking system probably requires as much time and attention as any other single component on the race car.

And the main reason for that is primarily the brake fluid. Everything else, from the pedals to the pads, can be pretty hardy and resistant to abuse. Other than knocking the glaze off of a set of pads or checking to make sure the rotors haven't warped from heat, the rest of most braking systems are quite dependable. The problem with brake fluids is they are hydroscopic, which is simply a fancy word for "absorbs water like a sponge."

Avoid the H2O
Hydroscopic materials (some may also call them "hygroscopic") include salt, sugar, and obviously, brake fluid. These materials will attract water so strongly they will actually pull it out of the moisture in the air around them. That's why salt will often "cake" if not kept in a sealed container. With brake fluid, the results of exposure to moisture aren't as easily seen. In fact, in street cars it may not even be noticeable.

Like brake fluid, and 99 percent of all other liquids, water is non-compressible, so it actually works quite well as a hydraulic mechanism to transfer the force from the driver pressing the brake pedal to the pistons in the calipers pressing the brake pads against the rotors. The problem with water is it has a depressingly low boiling point (212 degrees F). When moisture is present in brake fluid it drastically lowers its boiling point, and we all know that one of the main byproducts of the friction between the brake pads and rotors used to slow the car down is heat. When the moisture reaches its boiling point, it turns to steam right there in the brake lines or caliper. That steam, in turn, produces air in the system which is easily compressed and you wind up with the dreaded "spongy pedal."

There is also another byproduct of boiling brake fluid. When that moisture turns to steam, it not only creates compressible air in the system, since steam also takes up more volume than the water it came from it also creates pressure. Think about the steam engines on trains in the old cowboy movies. This excess pressure can grow enough to actually push out the pistons on the brake calipers, causing the brakes to drag.

It all adds up to a recipe with all the wrong ingredients when it comes to racing. Race car braking systems produce extreme heat, making it more likely to boil the brake fluid and produce a spongy pedal. And that loss of performance and pedal feel will force the driver to apply the brakes earlier and stay on them longer in order to get the same result, giving the brakes less time to cool off before the entry to the next turn. You can see where it goes from there. The driver not only gets poor pedal feel and pitiful braking performance, but the brakes are also dragging all the way around the track, killing horsepower at the wheels.

New Tool for an Old Job
That's why race teams must flush the brake system as part of their regular maintenance schedule. Of course, not only must the brake lines and calipers be flushed of the old brake fluid, you also have to be careful not to allow air bubbles to be introduced into the system at the same time, which is easier said than done. After all, the entire goal is to keep air out of the system to ensure a nice, firm pedal and lots of brake response.The old-school method, which works fine and many racers swear by, is to crack open the bleeder on the caliper, pop the top off the master cylinder and activate the brakes to push the old fluid out of the lines. The problem with this is it requires two people: one to work the brakes and a second to open and close the bleeders and also keep the fluid in the master cylinder topped off. You can only do one caliper at a time, so it's also a bit time consuming. As CT's Project G.R.E.E.N. team recently found out.