2mm can be alot at 20mph+, add that to the 'pivot' front mount and that can add serious stress to your poor rear mount. Have you thought of getting a universal U-bolt type front mount? Can you change your current front plate for a U-bolt?
At least your case isn't snapping in half
If you have the tools, going to a larger bolt could work, just remember you're transferring that stress to your case then.