We were always educated about how “Power is nothing without Control”, hence we chase after the one aftermarket part that not only stops the vehicle, but also looks good on the picture; brakes. However, the picture is still pretty much incomplete. There are also other factors that contribute to shorter braking distances without breaking traction. Even with good tyres, there is one thing that many forget; Brake Bias.
Brake Bias is the distributed amount of total brake force applied to the front and rear of the vehicle’s braking system. To put it simply, it is the amount of braking pressure distributed to the front and rear brakes respectively. Why is that done so? Read on…
To fully understand brake bias, the fundamental step is to understand how a brake system works. When the brake pedal is depressed, the pressure applied on the car’s master brake pump cylinder, which then forces brake fluid to pressurize until it matches the brake balance bar’s preset pressure. This pressure is then applied onto the caliper’s pistons, causing it to squeeze the brake pads onto the brake rotors.
The brake balance bar’s determined pressure controls the amount of pressure for the front and rear brakes accordingly. Most vehicles have brake balance bars that apply more pressure to the front than the rear, because when a driver steps the brakes of his vehicle, the decelerating motion will cause the weight from the rear of the car to shift to the front of the car. This weight transfer causes the front brakes to work harder due to the additional stresses of weight transferred from the vehicle’s rear, hence the need for greater braking bias on the front.
When larger brake calipers are used, the amount/size of the caliper pistons greatly increase. Brake/tyre lockups then occur easily whenever the brakes are applied. Since the brake balance bar’s pressure for the front and rear of the brakes have not been readjusted to suit the larger, more powerful brakes, the amount of pressure applied is simply overkill for the larger calipers, since it assumes that more braking pressure is required for the stock calipers to slow the car down.
This then transmits into improper braking distances, sometimes even to the point of extending the braking distance. In worse case scenarios, the braking bias for the rear and front is simply too different from the stock brake setup, causing the rear to lock up, or the car’s rear weight to throw forward and laterally too aggressively. These might then cause over-steering or a floating sensation, which is detrimental for the vehicle that is about to enter a corner, or avoiding an obstacle, where maximum grip is of utmost importance. However, some owners deliberately setup strong rear brake bias to induce certain vehicular motions, such as the throwing of the vehicle’s rear out as it enters a corner. This is a common technique used to induce over-steer, which is common in vehicles setup for drift.
To solve this problem of immoderate braking, there are aftermarket brake balance bars that allow for adjustment of brake bias settings. If that is an expensive and complicated process while still wanting to enforce an upgrade, one should find a brake kit that complements the weight of the vehicle. Lightweight vehicles should aim for lighter, smaller brake upgrades while bigger brake upgrades should go to larger vehicles. Basically, do not overdo on the brake selection. Larger does not necessarily mean better.