Make sure you have the bleed screws at top of calipers. I had the rear calipers off my 450 SL to rebuild and put them back on the wrong side causing bleed screws to be on bottom. Could get not too bad pedal from bleeding but as soon as car was started pedal went to floor. Switched calipers back and was able to bleed right away and everything working fine. Discovered my mistake by reading article on brakes in May 2012 Hot Rod magazine. Impossible to bleed brakes with bleed screw on the bottom!
