Brake Guru\'s, Need some Help!! My brakes have had issues ever since I did the 3/4 ton swap last year. It seems as if my Master Cylinder is always going bad, well thats according to the brake shop. No matter how hard I try I can not get a pedal back and always have to take it to a shop to get power bled. In fact my master cylinder went out on me 3 weeks ago and after I was unsuccesful in bleeding the brakes I had to take it to the shop, they powerbled it and got me some pedal but in no way was the braking what it should have been. Well 2 weeks ago my rear passenger drum just completely locked on me, so instead of fooling with the drums I went ahead and purchased the parts to do a rear disc brake conversion. Well I finally had a chance to switch it over last night, everything went great except for the fact that I have no pedal again. I bled and bled and bled the system. I cannot find any air in the lines or master cylinder. If you push the pedal down it's just a nice smooth stream of brake fluid that will spout out from any of the bleeding points. And to top it all off I cant get the brakes in the rear to work... I can mash the brake pedal to the floor and the rear tires will still spin by hand, but at the same time they are currently getting plenty of brake fluid to them, I can open the bleeder nipple and press the pedal and a stream will flow out. I'm at a loss, it seems as though something is really wrong. I forgot to mention that in the past I have had trouble with not getting any fluid to the rear brakes. I could open the bleeder nipple and push on the pedal but nothing would come out. Obviously I can understand why this would have happened last night but when I bled them 3 weeks ago it was happening too, which doesn't make sense because it had been driven for about 6 months with out anyone even touching the brake system. So should I try a New master cylinder instead of a rebuilt one? I know the rebuilt ones are junk anyway but I would have thought they would last longer then 3 weeks. Do you think the booster or proportioning valve could be causing the fluid to barely reach the rear and give me no pressure?