I started off with a 94 drum brake rear end which I had replaced the brakes on. After bleeding it the pedal would be kind of soft but after a week or two the pedal would almost hit the floor. Now I have upgraded to an 87' fully rebuilt disk brakes and I got the pedal height a little bit higher but no where near it is supposed to be.

I have a master cylinder on order but I need opinions if this is the problem or not. I do not have a vacuum bleeder, just two people, one pumping brakes, one bleeding.

First things first: http://www.popularmechanics.com/cars...enance/4213448
to make sure you're doing it correctly (not saying you aren't, just, you know...)

Second, when the pedal is getting 'spongier/softer', have you bled them again to see if there is air in the lines?

Your seals for the master cylinder piston(s) could be bad and causing pressure to leak past the seals, but it's odd that it gets better when you bleed the brakes and then a couple weeks later it gets worse again. But, that's assuming that each time you bleed the brakes, it gets better, but I don't know that that's what is happening. The master cylinder is cheap and the more likely culprit assuming you aren't leaking fluid somewhere. So I would replace that and see where that gets you.

Sorry, finally finished working on my friends problematic ford ranger. Got master in at about 12 and bled all brakes. Problem is fixed and brakes are tighter than my 06 trailblazer so I'm happy with it. Thanks for the input!

Trying to figure out why new was $109 and remanufactered was $24.99? Obviously went with reman, works good, no complaints