Today I replaced the "bobbins" on my K1100lt. I bought Grimica steel version from Motobins in England for about 1/2 the price of BMW...About $86.00 with shipping.
Now that they are on, the bike is much quieter. Its amazing how much racket the loose discs made.
So now I want to say a few words about the installation process for those who will be doing the job in the future.
The stock bobbins are aluminum so I found that it was easiest to just cut the heads from the outside of the discs - I used a chisel but a dremel or drill would also work as well or better - and then just whack the barrels with a large screw driver and hammer before installing the new ones.
It took a couple of hours excluding going to the Home Despot for some tools.
Some pics below...
