So a car that originally had all drums is upgrades to disk all the way around will not need the proportioning valve changed ? Not even gutted? What master cylinder is used ? The drums one or a disk brake one?
all drum systems do not use a proportioning valve. That is handled by wheel cylinder size, shoe size, drum size or a combo of those factors. A properly setup all disc system will account for it in rotor sizing, caliper bore size, pad size or a combo of those factors.
An aftermarket all disc setup will most likely need a proportioning valve because most of them are NOT properly setup.
All that "valve" is in an all drum setup is a splitter and in some cases a brake warning light switch. To which you will most likely need to add an adjustable aftermarket proportioning valve to adjust the aftermarket all disc setup to work properly. As in the rears don't lock up first.
