Calipers are self adjusting. When you remove the old pads, the piston(s) in side the calipers will be extended from their cylinders. They make a tool to shove the piston back in the caliper, but I'm sure since your asking that you don't have one of these. If you just open the bleeder screw and use the handle of a hammer, you can carefully push the piston back in. Then tighten the bleeder screw. Put it all back together and bleed the system, starting with the caliper on the passenger side, then the drivers side. If your going to do all four wheels, then bleed the right-rear first, left-rear second, right-front third, left-front last. After the system is bleed, the calipers squeeze the rotors and after you release the brake pedal, they back off just a couple hundereths of a inch. I hope this helps.