Well hello there, I've been a lurker for quite a while, and finally feel the need to post. I have a 1969 FJ55 that I just put minitruck disc brakes onto. I'm using the hard parts and booster from a 1983 pickup. the rotors are from and 81 FJ40, and the Master cylinder and calipers are from a 1990 4x4. I'm also using the hard lines from the 1983 truck for the front brakes, and have maintained the original 1969 brake line for the rear circuit. I just finished getting everything together, and to my dismay, these brakes just don't aren't working too well. When the truck is not running, the brakes feel normal, but when the truck is running, there is very excessive pedal travel before the brakes are actuated. The brakes appear to work, but resistance is only felt once the pedal gets almost to the floor. This does not match the symptoms of a bad booster. Anyone have a guess of what is wrong? Is the 1" master cylinder too small to run this combo of brakes, does it have the wrong size residual valve? I have not tried driving it yet, as I am waiting on a machine shop to shorten and retap my relay rod.