Brake Bias For Your Track Car
Brake bias is not a term that is used about stock cars very often. It is a technical term that is used on racing cars and sometimes street vehicles when they are used for track days. A track day is when an owner takes their car to a race track for some hot laps. If this is something you will be doing very often, then this information will be helpful.
As you step on the brakes the front brakes and the rear brakes are not applied with the same power. In some cases, depending upon what you are doing and how well, you might decide to change the factory setting. But do so with a great deal of caution. The term brake bias means the balance of how much braking the front and rear brakes contribute to slowing down a car. Brake bias is often written as a percentage or a ratio such as 65/35. This ratio would mean that the front brakes receive 65% of the available brake power and 35% is sent the rear.
In almost all racing cars and sometimes in modified production cars you can adjust this ratio. The control for this adjustment may be in the driving compartment and sometimes it is outside near the brakes. Adjusting the brake bias can be important to a winning race car or a faster track car.
Depending upon the race track layout you sometimes want the adjustment to make the front brakes work harder and on a different track with other conditions you need the adjustment to favor the rear brakes. When adjusting the brake bias you change the car’s handling characteristics when braking. For example, how does the car handle when you enter a corner? Adjusting the brake bias towards the front brakes makes the car feel tighter and more stable while braking and you begin to enter a turn. Adjusting it toward the rear makes the car looser while braking and entering a turn. A tighter car can cause understeer which means that the front end of the car does not turn in very easy. A looser car can cause oversteering, where the front turns in too fast and the rear end swings out too far.
When a car slows down there is a weight transfer towards the front of the vehicle and the front tires load up, while the rear tires lose some weight on them. This is the reason front brakes typically are larger and have more initial brake bias set than the rear brakes, since they are used more. However if you applied too much bias to the front brakes, they will lock up. This means you will can’t effectively slow the car as the rear brakes are helping very little in slowing down the car. On the other hand if you have too much rear brake, the rear tires can lock up as the weight transfers forward and makes the rear end of the car lighter.
In general it is always recommended to start with your brake adjustments so that it ranges between 70/30 and 80/20, as your initial trial setting. You can adjust your brake bias within this range and see which particular setting allows you to complete a lap faster. Make small adjustments to start.
Normal passenger cars will not come equipped with a brake bias adjustment capability, however it can be added. But if it is done, it should be done by a brake professional who knows what they are doing. Brake bias changes to your settings should only be utilized while on a race track. There were very excellent reasons why your car manufacturer choose your particular car’s initial settings. Modify this brake ratio at you own peril.