When I apply my brakes they barely work and I have to pump them just to stop. I put new brakes on the back but the back brakes don't catch at all. I've bled the piss out of them and adjusted the back brakes where they need to be. What could it be? Is it the master cylinder?

 

Did you bleed the LSPV?

 

If you pump the brakes and it gets firm and STAYS FIRM, your master is fine, if it sinks it could be the master. If it sinks start with the master, if that doesnt fix it, or it doesnt sink, then replace the LSPV with a manual proportioning valve from summit. My LSPV went bad and I made the mistake of trying to hunt down junkyard LSPV's and that was a total bust. So im just running a union T back there, and no proportioning valve, but I should be running one.

Oh and if you pump the brakes and it holds also check your soft lines and see if they are expanding. as they get old they get weak and expand under preasure.

 

I looked up lspv in the repair manual but it didn't tell me where it is. I havn't a clue what it is. Can it be bled? I'll research summit for one.

 

Start at the drums and follow the lines up to the floor board. It is where everything plugs into and it has a load sensing arm that attaches to the axle itself. LSPV = load sensing proportiong valve