Hi all, Here the deal, I have the original 4 piston front brakes and the original non-power master cylinder with the separate PP valve for the front brakes only. This is all factory original. I rebuilt the master and replaced the pp valve with the original replacement part. Bleed the system several times. The brakes work fine, but when you first get in after several days or a week of not driving it, the pedal goes to the floor. You can pump it a few time and it regains pressure and is then fine while driving it. There are no leaks and the master is full. Why is it is this way????
Even though you rebuilt the master it still sounds like that is probably where your problem lies. If you're properly bench bleeding, (zero bubbles) and that much air is getting into the system that quickly (without even driving), it really couldn't be anything else. Try to get a professionally rebuilt one or even a new one if possible. if that dog won't hunt, I would bail on that setup. It's notorious for having problems. I had a set on my 68, pulled them off and went with the 69 single piston setup about ten years ago. Double piston's have been sitting in a box in storage ever since. Have never had any issue's with the 69's. Have wildwood disc all around on my 69 bird. It needs the extra stopping power though.
