rear brake nitemare

[toast]

i have a 87 with jb5 brakes. well it had no rear brakes because of the wheel cylinders. so i rebuilt the drum brakes. new cylinders, springs, pads, lines and everything. so it tooks me 2 weeks to figure out my propationing valve had a reset switch . no i can get fluid to the rears but i cant get the rear to lock up when i slam on the brakes. i tried to use my parking brake to adjust them but it just gets stuck(super rusty). should i replace the parking brake lines and try again. and how do i get them adjust right enough to fix the self adjusting brakes. P.S. the rear brakes are self adjusting and there is no slit in the back of the drums. i have to take the tire off to get them to asjust

[79k30dually]

Try closeing the rear bleeder screws and open a front, then depress the brake pedal fast, just short of slamming it to the floor. This should shift the proportioning valve, it may take more than once. Normally the proportioning valve just sits there balancing fluid between the front and rear brakes, then when a line blows out or a wheel cylinder it shifts, cutting off fluid to the leaking part of the truck. Sediment collects in the proportion valve and sometimes it takes a shock to free it up. Good luck, Ron

[toast]

like hold the pedal down then open a front, let go then close. i dont understand.

[Desert1957]

Often when there is a sudden loss of fluid pressure the valve sticks because of the force causing it to shift in its bore.
If the proportioning valve is not stuck in one position, it should be re-centered just by pushing on the cap at the end of the valve.




red arrow points toward reset button

Desert

[joe231]

Applying the brakes while backing up will adjust the rear brakes if the adjusters are working properly and everything is installed correctly.

Why do you want the rear brakes to lock up?
Your rear brakes shouldn't be locking up with a properly functioning proportioning valve.
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[79k30dually]

What you're doing by opening a front bleeder screw and depressing the pedal is to reset the metering piston and the switch piston. Basically you're creating another leak so fluid pressure will recenter the valve. Ron

[Wrecked1982]

if the brakes are just about new give them time to break in new shoes on new drums needs a little time to stick well, if i can say that