First off i replace from the valve back with new lines. My bleeder screws and rusted BAD and couldnt seem to get them out. So just thinking off the top of my head i unscrewed the end of the new line and bled it like that. How effective is this? It could be i still have some air in them but the back seemed good. Do i need to bleed the front as well even if i just did the back ones? Need some help as im not to familiar with brakes. Thanks all