FAO those with rear strut braces

Was out in the cup yesterday for a good 2 hour drive, longest I've done since fitting the strut brace, and noticed that occasionally going over bumps etc, I get what I can only describe as a metallic rattle. Took it off today, went for a drive, sound gone, put it back on, same drive, sound is back. Any clues? Oh and its not that the strutbrace is loose?
 
Was out in the cup yesterday for a good 2 hour drive, longest I've done since fitting the strut brace, and noticed that occasionally going over bumps etc, I get what I can only describe as a metallic rattle. Took it off today, went for a drive, sound gone, put it back on, same drive, sound is back. Any clues? Oh and its not that the strutbrace is loose?

Metal colar inside the rubber thingies that go on top?
 
its because its bolted to the top of the dampers - which are mounted with the rubber bushes these flex and will cause the bar to move also - it should be bolted to the strut tower
 
Cup racer cage is mounted the same pal!

it wont be bolted to the dampers - as these are not ridgely mounted - it will bolt to the top of the damper towers surely and the dampers then bolt through this ?
 
its because its bolted to the top of the dampers - which are mounted with the rubber bushes these flex and will cause the bar to move also - it should be bolted to the strut tower


its 100% not that, sound is completely wrong. its also like a washer is loose on the top of it.