as you guys may or may not know I brought my truck to the body shop a few weeks ago, on the way there I hit the pedal and it turned into mush, no prob I figured, just air in the lines, I can bleed them when I get it back. Got it back, bled the brakes, still mushy, bled them again, still mush. I figured the master went to hell so I replaced that, still no brakes. I replaced both front calipers, still no front brakes (ended up rebuilding the whole front end....again) Now I just replaced the proportioning valve and I still got no front brakes. The rears lock up and the front dont do ****.

WTH is wrong with this thing!

 

Check your brake pistons, the dust caps as well. They may very well be shot.

All mine went at once.

 

If I have someone step on the brakes I can hear the rears move back and forth so I know its not that, I think im gonna take the master back to napa and get a new one

 

when you bleed the fronts, have you got strong fluid pressure (squirt) at the calipers ?

just a thought. the proportioning valve somehow magically ? senses the pressures from the rear, and is supposed to balance the front vs rear. manually adjust the rear shoes up good and snug and see if that helps any.

another thought. if the rubber brake hoses on the front are old and soft, they can swell and absorb the pressure, robbing the calipers/wheel cyl of the pressure they need to operate. my old chevy did this.

 

plus one on the flex lines, mine went but they would lock up not absorb.

i had a squishy pedal for the longest time and i would bleed it and it would be hard for a few days then it would get squishy again. it turned out to be the line that goes in the frame over the gas tank, it was just rotten enough to let air in and fluid out but not enough to burst to let me no a line broke. pissed me off cuz it wasnt wet under the truck anywhere.

 

Check to make sure one of your rear wheel cylinders isnt blown, I was working on a chevy the other day that I couldnt get the air out of the lines for ****, I pulled the rear drum and the cylinder was leaking everywhere.

 

well, master cylender number 2 didnt fix it. checked the rubber lines going to the calipers and there is no swell going on at all, and when the fronts are bled there is strong fluid coming out of the bleeders. Im gonna jack the rear up and check the adjusters...again, but Im positive that they are already correct. Both rear wheel cylenders are working fine.

If you go down a blacktop road and lock the brakes up (just a quick smash on the pedal) it seems like they will alllock up, but than fade to nothing in the front and locked up in the rears

Makes me sick, i think im gonna buy a uni-mog

 

mine did that too. could not find the problem anywhere.

keep us posted on what you find. I ended up replacing all the brake lines, except the flex lines, the calipers, master cyl, propotioning valve, rear wheel cylinder's, and it still did it.

 

hard for me to check by myself, but if someone could I would appreciate it. When you step on your brakes does your vacuum booster move? When I step on the pedal, the booster seems like it moves out about 2-3 inchs

 

So something happened from the body shop? What work did they do?
It sounds similar to when I had my rear shoes on backwards. I had the front shoe on the back and the back shoe on the front. (I hate working on drum brakes.)