the brakes are wearing me out

[tphsmith]

I cant seem to get my brakes working properly. I have no panic brakes. the truck has disc on the front, pads have lots of pad, rotors are smooth no grooves .the rear brakes are drum the drums are smooth no grooves, the pads have lots of pad. I have had this issue for too long. while trying to find the problem, I have replaced the M/C and still no change, brakes are soft and no panic brakes. the trucik has a power booster. the line for the PB has vacuum build up because I can remove the line to the PB and I can hear the air release from the booster. I canot see any moister on the rubber sections of the brake lines. and I'm sure the steel lines are not seeping, leaking either. I have bleed the brakes so many times starting from the farthest rear line working my way to the closest to the M/C still I dont have panic brakes. could it be that the rear drums are larger then I think they are and Im running out of brake travel?. I WANT GOOD BRAKES!!!!!!!!!!!!!!!!!