The mounting plate for my JCW broke in half so until I get that situated again I installed the factory backrest/luggage rack. But it's been years since I took it off, and now that I put it back on, it looks like I'm missing something. Check out these pictures. The allen screws clamp the rig to the grab bars, but then run into the support from the rack- in such a way that the threads are going to get destroyed if they stay like that. The support is not threaded, but it looks like there used to be a nut or something to catch that allen bolt. Anyway, can someone explain or show a picture of how it is supposed to look when installed?

I just took the rack off my dad's bike last week.  There is an acorn nut (maybe lock washer too) that is supposed to be there.