Wow! I have the same problem with my £21,000 FLHTCU 2012 Harley Davidson. The bike was also delivered with rusty silencers (mufflers) . . . . . and Harley Davidson boast of pure quality??? When I apply the rear brake the back of the bike vibrates and in some conditions very badly. Feels really bad and unsafe to ride sometimes. Apply the front brake no problem. The discs have been checked by 2 dealers and both dealers tell me that all is “OK”. It’s not OK and I see from searching Google that other HD owners have the same problem. I have written an official letter of complaint to Harley Davidson UK and have asked . . . . Is this normal? . . . . . Is this part of the design? . . . . Is the bike safe to ride? I am waiting an answer. My HOG members tell me I should ask for my money back. I would appreciate any info/help especially if anyone has received an official response from Harley Davidson – Please!!!!!