Hello Guys, trying to see if anybody has any input on my situation with my brake booster/brakes. I replaced my brake booster on my 72 scout II, it was making a hissing sound when I pressed the brake, I also changed the rear wheel cylinders and the shoes on it. Now that everything is in place my brake pedal is stiff and requires a little pressure, then it goes down a little too fast. Would it be that there is still some air in the brake lines and why would the pedal be stiff at first.