I am presently doing battle with BMW over this very issue!
My feeling is your bike is either a 2006 or 2007 model??
The rattle IS due to the springs in the clutch basket breaking & rattling, I think there is a total of 6 springs.
This is a known BMW clutch issue but it seems that no BMW official will go “on the record” about it.
The basket WILL have to be replaced; the total clutch, plates & all should be replaced under warranty as a WHOLE unit, don’t accept a partial replacement, either basket or plates…insist the WHOLE clutch be replaced.
There are other threads stating that the clutch push rod replaced for a re engineered unit, I would assume this will be replaced also, DO bring this into the equation.
Right behind the clutch basket is a drive cog for the OIL PUMP, there is also an issue with this making noise, BMW have revised the design of this to a THINNER cog….need I say any more? The new “THINNER” sprocket p/n is 11267675452
If you can, try get this replaced under warranty at the same time the clutch replacement is being carried out.
If BMW will not give you a “new THINNER cog” under warranty purchase the “THINNER cog” yourself its only around $40.00 then have the mechanics replace it for you while the clutch is out, also have them re-tension the OIL PUMP chain to the factory specifications, I suspect this re-tension will become an issue further down the line…
I would also recommend switching oils from traditional Dino oil to AMSOIL 10W-40 fully Synthetic oil. http://www.amsoil.com/a/synthetic-motorcycle-oil
dont forget a new oil filter!