It’s no secret that brakes are one of the most important components in your car. It is vital to set your brakes up differently for different applications. The brakes on your street car for example aren’t under the same amount of load as they would be in something like a rally car. As a result, cars prepared for motorsport require a very different braking setup than that of your daily driver.
You might be wondering what actually happens in your brake system when you apply the brakes. When you push on the brake pedal, it presses on a piston which goes through a brake booster and a master cylinder. This pushes brake fluid out through the brake lines and out to the brake caliper which pushes the pads into the rotors causing friction which slows the car down. The brake booster is oftentimes the first thing people remove from the braking system when they build a race car. This is because the brake booster operates off of a vacuum. When you are left foot braking, and using throttle and brake at the same time, you don’t have a vacuum. This causes the brake pedal to become very hard. As soon as you let off the gas, the brake goes very soft. This inconsistency is not something you want when you are driving at the limit which is why most people take the brake booster out for performance applications.
Moving down the brake system, from the master cylinder, there is a set of brake lines that go to the front brakes and a set that goes to the rear brakes. These brake lines are routed through the anti lock brake system (ABS) pump and module. The ABS system reads the wheel speed sensors to determine when individual wheels are locking and respond by modulating the brake pressure to prevent the wheels from locking up. In a streetcar ABS can be a good thing to have, in a rally car or a track car, you don’t want ABS. Disabling ABS is fairly simple in older cars, usually involving pulling a fuse or unplugging the module. One thing to keep in mind is that disconnecting the ABS module can have other effects. You might disconnect your ABS module and find that your speedometer doesn’t work any more. On more modern cars, your wheel speed sensors might operate through the ABS module so disconnecting it may cause other things to stop working. A way around this is to run the brake lines past the ABS pump but leave the ABS module plugged in. This way the electronics still do their job but ABS does not function. Make sure you research your specific car because every car’s ABS system operates a little differently.
From there, your brake lines will run to the calipers. In some cars, the brake lines are routed through the cabin but in most cars, they are run on the undercarriage. This is not ideal for a rally car as you might expect so it is recommended to run your brake lines on the inside of the car. This will keep them protected from road rash, salt and if the car bottoms out.
When you build a dedicated race car, all the braking components except the calipers and rotors are inside the vehicle. For example, race cars often have an upgraded pedal box which has the master cylinders mounted directly on it. One goes to the front brakes and one goes to the rear brakes. Racing cars usually have adjustable brakes where the driver can alter the brake bias from front to back on the fly. The other benefit to keeping everything in the car makes it easier to install a hydraulic handbrake. From the master cylinder on the pedal box, you simply route the brake lines to another master cylinder on the hydraulic hand brake.
Hopefully that gives you an understanding of how street car brakes differ from race car brakes. If you want to learn more about preparing a rally car, click here!
