A vehicle braking system bias adjuster which includes a brake bias adjustment knob assembly which enables the driver of the vehicle to quickly and easily set, adjust, and visually and quickly determine the relative front to rear (or right front to left front) brake bias or brake bias setting of the vehicle before and while driving the vehicle. The brake bias adjustment knob assembly visually indicates the exact amount of brake bias, or if there is no bias at all. The ratio is expressed in numbers to enable the driver to reset the brake bias to a known value of ratio as needed for track conditions and vehicle weight changes. The value in numbers is reproducible. The present disclosure also provides a method and apparatus for retrofitting an existing vehicle with a brake bias adjustment knob assembly which enables the driver of the vehicle to quickly and easily set, adjust, and visually determine the relative brake bias or brake bias setting (i.e., the ratio of front to rear brake biasing or the ratio of side to side brake biasing) of the vehicle before and while driving the vehicle.