Rear brakes locking up before fronts

[LostMy65]

I've added an adjustable proportioning valve to the rears, everything was working fine when I had drums up front.
I've turned the adjustable proportioning valve all the way down for the rears, and I still can't get the fronts to grip.
I know for the rears you can adjust the shoes in or out, but is there a way to adjust discs?
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[ole dollor]

this is very common on all wheel drum brakes, try adjusting the front brakes tighter than the back, this will help alot, also adding weight to the bed will help.
the front brakes should always grab first. the back brakes grabbing first will cause the truck to try a swap ends, front disk brakes are the way to go, and all wheel disk brakes is the best of all, but going to disk brakes is very costly .
if you have no leaks in the back, try readjusting the brakes, front tighter than rear....