Hello all. I have a 99 F-150, 4 wheel disc, 4X4, 5.4 with terrible brakes. I don't drive this truck much, only 4k miles since last June, and I've had problems with pads getting stuck due to rust. I recently replaced all rotors, pads and front calipers due to poor performance, but I still seem to have a problem. I can not get the brakes to lock, or abs to come on, when braking on pavement. ABS will come on in gravel or grass. When the truck is running, I can push the pedal to the floor. I have constant resistance, but it doesn't take much effort to get it to the floor. I have bled the brakes until I had clean fluid at all wheels, I've made sure the calipers slid smoothly, and the pads weren't binding. I think I'm looking at the booster or the master cylinder. Does anyone out there have any suggestions?

 

to me it sounds like the master cylnder is leaking in the inside of the housing so you are not loosing the fluid out . there is a little rubber cup that tends to go out quite often on thoses. but if the booster was out it would take a lot of effort to push the pedal to the floor. also check to see if there is a leak some where on the break lines

 

I picked up a new master cylinder today at NAPA, only to find out when i got home that it is 1 1/16 and mine is 1 1/4. Maybe mine is bigger because of the tow package?
Also, I checked for leaks, there are none that I could find. The fluid level in the resevoir has never gone down.