A bigger rotor may come with a weight penalty, but its ability to absorb and vent heat wit
A Matter of Balance
A brake bias adjuster can be an incredible tool for a knowledgeable racer. A bias adjuster can easily change the amount of braking pressure sent to the front brakes versus the rear. As fuel burns off or the track changes with the setting sun, you may prefer to change the brake bias more to the front or to the rear. A bias adjuster within the driver's reach is perfect for that, but it is often too tempting to use the bias adjuster to cover other handling sins.
Carl Bush of Wilwood Engineering agrees that the balance bar should only be used for fine adjustments to compensate for tire wear, fuel burn-off, or changing track conditions. The key is finding the car's balance, the correct front/rear bias with the balance bar centered, or neutral. "Typical asphalt stock cars run on average at about 70 percent front brake bias," Bush says. "A big-block dirt Modified will use nearly the exact opposite. Dirt Late Models fall somewhere in the middle. If a racer is always adjusting the balance bar completely to one end of the car or the other in an attempt to correct the handling during braking, you probably need to re-evaluate your component mix."
Your options for changing what's called the static bias, or brake bias, without the use of the balance bar are numerous. They include rotor diameter, caliper piston size, master cylinder piston size, and even brake pad compounds. Increasing rotor diameter increases the braking power, or bias, at that tire.
You should try to have your brakes in this range with the bias bar centered. As conditions change at the track, the bias bar is available to you to make changes. If the bias bar is cranked all the way to the front or to the back to make up for a poor setup at the drop of the green flag, you've lost it as a tuning tool.
Caliper technology is constantly advancing. One of the biggest advancements for the guy ra
Spencer recommends spending a little testing time at the track to find a well-balanced braking setup. Tracking brake temperatures just as you track tire temperatures can tell you a lot about what your car is doing. On asphalt, Performance Friction representatives say they generally like to see front brake temperatures 150-300 degrees higher than the rear. If it's greater, then you are probably not getting the full potential from your rear brakes. This will result in the front brakes being overworked, and the fluid in the calipers will boil, which will seriously degrade your ability to slow down in the turns. If the split is less than 150 degrees, you probably lose on entry under hard braking.
Choosing the Right Combination
Finding the best combination of parts for your braking system can be daunting. If you are racing a series that does not place many restrictions on what you can run, your options are nearly unlimited. One of your best options is to choose a manufacturer or dealer you trust, preferably one that will work with you closely and not just from behind the parts counter, and start with their recommendations.
Bush assists racers with their brake setups at every level and recommends relying on a manufacturer's experience. "Wilwood has been deeply involved with racing for 27 years," he says. "In many cases, not only do we have a recommended baseline for a particular type of car or series, we also have a baseline for the specific track you plan to run. That information can be used as a starting point, but car style, driver preference, and chassis setup can all require adjustments."
As we mentioned earlier, a larger-diameter rotor will increase braking force. This is because the pads are moved farther from the axle centerline, and that essentially increases the leverage the brakes have on the wheel. There are several other advantages of a tall rotor, but racers by and large tend to avoid putting large rotors on their race cars because of the additional weight.