also what is the proportioning valve????

this is a real doozy.......

i have just done a stanza front end conversion......i have machined the discs and re-kitted the calipers

when the car is off and i put my foot on the brakes, the brakes feel very spongy....and pretty much just sponge all the way to the floor....
but after a few pumps they feel great and will stay like that ....UNTIL

when i take off and then go for a drive, the brakes will loose all pressure and it will feel spongy and again will pretty much sponge down to the floor.....

if i pump it while driving it will feel great ...but after driving for about a km the brakes will disappear again...and sponge down to the
floor.....

me and my mate have bled and bled and bled the brakes...and we are 100% sure we cannot get anymore air outa it......

i was also told that maybe i didnt tension my wheel bearings properly and the brakes have to try and squeeze the disc back into place.....anyways we checked that and they are fine.....


does anyone have any damn idea what is goin on....cause 3 brake shops have no clue......

pleeeaaaseeee help