I took advantage of the truly awful weekend weather to change the rear brake pads on my W8. There are a few good write-ups on the Web dealing with this topic. I especially like this one in Google Docs. An extract from a ClubB5.com thread. I am not going to document the process again, however I do want to share how incredibly useful was to have a caliper piston retraction tool at hand to speed up the job. Mine came from Harbor Freight. It is a bit expensive but I can use it in my other vehicles. Notice also the handy "caliper suspension system", namely a short bungee cord attached to a fastener in the body. Even with the tool, it does take quite a bit of force to turn it. I used a short piece of pipe placed over the handle to get some leverage. I also opened the bleeding valve to drain some of the fluid to prevent back pressure in the system as I read it is not healthy for the ABS system. If you are wondering about the rust on the disk surface, it is the by-product of spending the time to clean the rear suspension as well.
Piston retractor in action
Caliper Service Kit
I also removed the liner and gave the wheel well and suspension a decent cleaning.