my brake suck, i really need help

[the nitro man]

i'm working on my wife's 85 monte carlo that has a bone stock 305 in it. every thing is stock.

about two years ago i change front rotors & pads & it just didn't seem right. well i lived with it, but about a month or so ago i change front pads & rear shoes. the back brakes started locking up a little in my gravel driveway going down hill. i had never put rear shoes on it so i put them on too thinking that might fix that. well it still does it. after i go down the road about a 1/4 mile the rear brakes stop locking up. i checked them & loosened them up, made sure they were clean & they were clean other than brake dust. no grease or brake fluid on them at all.

the brake pedal just sucks. it has for two years now. the pedal will go down about half way & then it starts getting real hard to mash. i can mash it hard & the car doesn't slow down that much. i can slam them & they wont grab hard like they should. they will not lock up at all. i changed the brake booster tonight & that was a waist of time, just as bad as it was.

can the master cylinder do this? what about the proportioning valve?

 

[454RAT]

could be a prop valve. try gravity bleeding all of them. also put it up on 4 jack stands and have some one see if you can test the brakes by manually turning the front tires with someone holding the brakes, same goes for the rear. Also might look at your rubber hoses. they could be collapsing under pressure.

 

[Ole yeller]

as far as the rear brake locking up. its probably cheap shoes on the rear. seen it happen many times. gets alot of brake dust and bites too good. genrally you can clean them with brakekleen and the will work good for a while.
as far as the pedal i would buy a good mater, flush the system good and make sure you bleed all the air out.

 

[the nitro man]

well here it is a few years later & the car is still locking up on the rear brakes. i've changed, the master cylinder, brake booster, proportioning valve, rear shoes, & rear rubber line.

could it be the front brakes not working worth a damn causing this?

 

[Doober]

Is it humid there? I seem to remember reading/hearing moisture can cause that, I had a Sonoma that did the same thing. Also are the wheel cylinders in good shape? That may cause it too, but you'd possibly see fluid loss over time.

 

[the nitro man]

no not real humid. i changed shoes again today & everything looks good. i left the rear adjusted pretty loose. i guess i'll try it for a day or two & if it still does it i think i'll start on the front next with new rubber lines & rebuild the calipers. that's all that's left.

 

[44-bu]

are the brakes vac-assist ? maybe not getting any vacuum to the booster. just a thought.

 

[the nitro man]

it has power breaks, i've changed boosters, & checked the vacuum line. it's all good. i think break dust might be getting caught up in the drum. the front breaks are nothing to brag about, i think i'll change calipers when i get the extra money, or just rebuild the stock ones. ever done that?

 

[Doober]

You could also try braided lines to get rid of some of the spongy pedal feel.

 

[the nitro man]

that is a good idea.