The brake balance or brake bias of a

vehicle A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), wa ...

is the distribution of

brake A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. Background ...

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a p ...

at the front and rear

tire A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineering), t ...

s, and may be given as the percentage distributed to the front brakes (e.g. 52%) or as the ratio of front and rear percentages (e.g. 52/48).What Is Brake Bias And How Do I Adjust It? – FLOW RACERS
/ref> The braking balance affects the driving characteristics in terms of how fast the vehicle can brake, how the vehicle can take corners, and

tire wear A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which t ...

. The optimal brake balance can vary between circuits, weather conditions and driving styles. On race cars, the brake balance is often part of the

racing setup In motorsport, the racing setup, car setup or vehicle setup is the set of adjustments made to the vehicle in order to optimize its behaviour (performance, handling, reliability, etc.) for specific conditions. Vehicle setups are variable for a vari ...

, and in

formula car An open-wheel single-seater (often known as formula car) is a car with the wheels outside the car's main body, and usually having only one seat. Open-wheel cars contrast with street cars, sports cars, stock cars, and touring cars, which have thei ...

racing it is regularly adjusted during the course of an entire lap. In some cases, the brake balance may be adjusted to match the traction (grip) of the vehicle during braking, which usually means distributing a greater braking force to the front (for example 55/45). In other cases, it may be desirable for the brake balance to be the more similar at the front and rear (e.g. 50/50) for the tires to last longer, which may be beneficial in endurance racing. Adjustment of the brake balance is often done by adjusting a proportioning valve which determines the distribution of the brake force between the front and rear brakes. The adjustment can be made via mechanical couplings or with the help of a small electric motor.

Front and rear wheel drive

Road cars with

front-wheel drive Front-wheel drive (FWD) is a form of engine and transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel drive vehicles feature a transverse engine, rather than the conventional longit ...

can typically have a brake balance of 80% front-wheel bias, while road cars with

rear-wheel drive Rear-wheel drive (RWD) is a form of engine and transmission layout used in motor vehicles, in which the engine drives the rear wheels only. Until the late 20th century, rear-wheel drive was the most common configuration for cars. Most rear-wheel ...

typically have around 60-70% front-wheel bias.

Changing the brake balance

Sometimes the brake balance can also be adjusted individually between the left and right tires, such as in systems for

electronic brakeforce distribution Electronic brakeforce distribution (EBD or EBFD) or electronic brakeforce limitation (EBL) is an automobile brake technology that automatically varies the amount of force applied to each of a vehicle's wheels, based on road conditions, speed, lo ...

and

cornering brake control Cornering brake control (CBC) is an automotive safety system introduced by carmakers BMW and Mercedes-Benz (ESP Dynamic Cornering Assist and Curve Dynamic Assist). It is a further development and expansion of the anti-lock braking system, design ...

. In racing cars without such systems, a

limited-slip differential A limited-slip differential (LSD) is a type of differential that allows its two output shafts to rotate at different speeds but limits the maximum difference between the two shafts. Limited-slip differentials are often known by the generic tr ...

can perform some of the same tasks, and this is also commonly adjusted as part of a

Advanced forms of adjustment

Brake migration is an advanced adjustment of brake balance where the brake balance changes dynamically through a turn as a function of the force on the brake pedal. This function is made possible with

brake-by-wire In the automotive industry, brake-by-wire technology is the ability to control brakes through electrical means. It can be designed to supplement ordinary service brakes or it can be a standalone brake system. This technology is widely used on al ...

systems. For example, it can be useful to use less distribution on the rear brakes when entering the corner in order to stabilize the car, and progressively increase the rear-brake distribution as the apex approaches.Formula One Brake Systems-f1chronicle.com
/ref> On Formula One cars, the amount of brake migration can be adjusted using a rotary switch on the steering wheel.

References

{{Reflist Auto parts Motorsport terminology

Front and rear wheel drive

Changing the brake balance

Advanced forms of adjustment

See also

References