TDI Golf IV brakes

I've only 5000+ miles on my TDI Golf IV, but love the car and hate the dealer already. Has anyone else had a problem with the brake pedal going almost to the floor in a panic stop? The ABS pulses the pedal and the car stops very quickly but it uses a lot more pedal travel than I'm used to. If I'm waiting at a signal and put incresing pressure on the pedal I can drive it almost all the way down. I took it to the dealer and they replaces the master cylinder. The loaner/rental TDI Beetle did the same thing. When I got my car back it was unchanged. I know they replaced the cylinder because they left the air box floating and the relay box open, with a liberal splash of brake fluid all around.

It's hard to believe that this is normal, but with the loner and my "repaired" Golf both doing the same, I have to wonder. Caliper flex, balloning lines, extra strong boost due to the vacuum pump?

They probably should have replaced the brake booster. There have been other members with similar problems and that was the solution, IIRC.

The brake fluid may dissolve the paint too.

Um, I'm not sure, but I would be willing to bet that by pressing as hard as you have on the brake pedal with the vehicle not moving, you will see some warpage in your front rotors in the future. The reason I say this is the master cylinder in this car, along with the vacuum assist generates a tremendous amount of pressure that as you said, balloons lines, flexes calipers, and in severe cases, can take a vented rotor like we have in the front, and slightly "crush" just one small section of it. While the vehicle is in motion, this flexing is normal, and applied to the entire surface of the rotor with each revolution of the tire. But, if it's stopped, and pressure is applied, the rotor deforms much more than normal, and may retain that property to a certain degree. It may not be noticable now, but after several cycles of heating and cooling, the rotors may begin to pulse as the deformed area loses its ability to return to a flat shape.

I believe what you have experienced is normal (even the dealership experience of brake fluid all over the place!) for these cars. The brakes, as you have seen, stop extremely well!

Good luck-

-Rich