Rear brake A8 4D2 4.2

Hello, everybody.
I changed the brake bevel at the front and back of my A8. I found out that a surface (back-left, inside) had been very strong. After the installation of the new brake bellows, the wheel turns only heavy and the brake disc becomes much too hot, which matches the heavy-duty wheelwheel. I checked everything again and I don't see any "failure to install." The only thing I have seen is that there is a bulge on the inner and outer edge of the brake disc. However, I already had that on other cars and never had any problems about it. Is there any other idea that one of you might have?

Thanks for the answers ...