71 c10 rear brakes not working

[cblock]

I recently bought a 1971 c10 that sat for about 10 years. the previous owner took arround the block once every couple of months, so when I drove it the rear brakes where sticking , I put new shoes, turned the rotors and rebuilt the wheel cilynders. now I'm not getting any pressure to the rear , I bleeded the master cylinder and theres pressure there. theres another unit under the master cyl but the lines are preety stripped, so I couldnt loosen them. whats this unit and whats its purpose? thanks

[jessemthompson]

The other unit under the master cylinder is the proportioning valve. Sometimes when they sit for a while they get stuck. On mine there was something like a plunger valve on the end of it. I tapped lightly on it with a hammer and it freed it up and my rear brakes started to work again.

[cblock]

thanks for the advice, I'll try it and go from there