Is the nut at the bottom sitting flat against the carbon top plate as it looks like its sitting at an angle. IIRC the carbon top plates have a steel insert bonded in where the nut sits? If it is at an angle then when the nut is tightened down the efect would be to try to bend the threaded part of the strut?
Its been loosened by me before the photo was taken! Normally it was flat against the metal insert as it should be.
Originally Posted by
focusv8
I seem to remember you fitted the carbon tops recently.
Same side that's sheared

yes but the carbon strut top only requires the top mount bolt to be removed, NOT the bottom spring cup bolt!
This is how it looks with bolt done up tight.

It snapped inside where the spring cup is so i dont see how fitting strut tops would have caused that.