Alright this is the second time that this has happened. 1987 Quattro 5000cs turbo. Has been driving fine for months from when i got it, but about a month back this same brake issue happened again. Same types of things have happened each time. Im driving highway, 5th gear for a while, when the wheel gradually starts to shake more and more. As i slow the shakin does descrease so this probably does not have to do with the brakes but who knows. I get my destination, shut the car off do what i gotta do come back, turn the car on, start driving then my brake pedal goes straight to the floor. The first time i pulled over and checked fluid, lines and everything, no leaking no nothing. I wait it out and the brakes come back and i make it back home. S Second time same shakin occurs (not sure if its even realted) but the brake goes to the floor once again. I keep going (being in a development) and expierment. The brake goes very far down until its mabey about an inch from the floor until it starts to slow the car down. If i pump the brakes it comes up and works closer and closer to were it should, but once i start going again, it goes back to the one inch away working type deal. As i keep driving the brake gradully comes back to normal. Once again there was no leaking (although i did notice a but around the cap where u pour the fluid in and a bit around the seam of the fluid resovoir tank, (but a very minimal amount, may have just been there from when i filled up weekes ago)but the lines looked fine, fluid was full. Im completely baffled. Does anyone have a clue of whast going on?