[Jack21]

A proportioning valve is used to adjust the front - rear brake bias. Front - rear weight distribution, front - rear tire size, front - rear rotor size, front/rear brake pad area, front/rear caliper piston area, front/rear master cylinder bore (area) all affect front - rear brake bias, we install a proportioning valve to fine tune this. (Since all these variables are already sorted out for you on a normal car, you don't need a prop valve unless you dramatically change something) Once you've selected and installed all your components, and dialed in your brakes, you shouldn't need to adjust it again unless you change one or more parameters, e.g. install a larger rotor/different caliper on one end of the car.