ORIGINAL: P Zero


Sorry to say you are wrong, sir. Every car since like 1965 has em. On factory vehicles theyre self adjusting. The way it works is - lets say you nail the brakes hard, the front end dives, in order to keep the back brakes from locking up it reduces line pressure to the back wheels. Then lets say you load your car down to the point the *** is squatting. The proportioning valve will increase pressure to the rear to help slow the vehicle faster and more evenly.
-P.