My brakes have been feeling mushy for a while and it hasn't had much pedal. I bled all of the brakes and still didn't help. Then I checked the truck for leaks in any lines and came up dry. Sooo...I just put a new master cylinder on it I bled the master cylinder the proper way and put it on my truck my brakes feel the same way. I noticed that in the resivoir closest to the firewall still seems like it has air bubbles in it. I must have bled them 15 times. WHAT CAN IT BE?!?!?!?!? I have dana 60 and 14 bolt just wondering since the bigger calipers and stuff if that makes any difference I have not made any brake mods otherwise. Any help would be appreciated thanks!