bled front breaks after replaceing old ones break peddle goes almost to floor not like they used to why

I'm assuming that you did refill the brake fluid ... it may have droped the first time the pump started .... keep it full and it will probable return to normal ,,, Always remember that if your brakes do fail that you can use the emergency brake to limp home with

If you replaced brake pads and you had to compress the calipers cylinders back in and before doing that you removed the master cylinder brake fluid cap while doing. I am just trying to figure out when did air get into the lines. Did you also replace the master cylinder/calipers/wheel cylinders or the break lines too, the master needs bench bleed before doing line bleeds if it had been replaced or allowed to drain fully. If you had just did the pads/shoes and did not open the lines by replacing those parts listed above or allow the master drain fully, bleeding them would be not needed or very little, otherwise if you did open up the lines a vacuum pump will be helpful to pull bubbles out of lines and bench bleeding the master will take care of it, this assuming the master is still good itself, check to see if there is any leaks including at the wheel cylinder and loose bleed valves and line bolts to calipers/wheel cylinders. If doing bleed the old fashion way as we use to do, its pump pump pump break pedal hold down until told otherwise, someone else quickly opens & closes bleeder valve starting with the most farther rear brake valve and helper hold foot down until you close valve then do the other rear and then the off drivers front the last the drivers front all while adding brake fluid to insure it never gets low enough to have to pull the master for a bench bleed. If master was dry then bench bleed it like shown on this URL copy & paste it: http://www.superchevy.com/how-to/brakes/0509sc-bench/