Is the top plate aluminum?
Rule of thumb, a nut needs to have as much threads as the diameter of the bolt. SO a 10mm bolt needs a nut (or tapped hole) 10mm thick. In aluminum I would double that.
Helicoils in aluminum hold better than just tapping the aluminum.
2012 R1200R !
2000 R1100RT (parts for sale!), 1976 R75/6, 2014 Vulcan 900 Trike
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