Brakes acting up 76 c10 2wd

[aleighs1990]

I have a 76 c10 2wd with manual brakes, and a problem i'm not sure how to diagnose. Recently when i will press my brake pedal to stop it will go most of the way down with no pressure and then there is some pressure in the last little bit of pedal travel. Sometimes if i just pump it i will get the full pressure back, and sometimes i have to pull the pedal up quickly with my left foot and press again to get good pressure. The pedal will usually return to normal position on its own after a couple seconds without pulling it up, but when driving obviously it is not smart to wait on that. I would say I experience this problem about 70-80% of the time while driving. I have not found any leaks yet, and no change in fluid level (although a bit low, i assume from normal pad wear). Could it be that I'm too low on fluid, or need to bleed the brake system? Or do I need to look into getting a master cylinder?

[VileZambonie]

Check to ensure your wheel cylinders and calipers are dry, check all lines etc. If no leaks then yes replace the MC. While you are at it, convert to power brakes.

[aleighs1990]

Is there any instructions I can get for replacing the MC? And what would it take to make an upgrade to power brakes?

[Captain Swampy]

The adjusters on the rear brakes might be froze. When they get out of adjustment it increases pedal travel.  Could be a combination of this, a leak, or a bad master cylinder.

[aleighs1990]

Would frozen adjusters be a wd40 or lube fix, or full on repair?