I am having second thoughts about this recent 'looser' tension initiative. With this amount of vertical movement in the centre of the belt I am now getting loud 'thonks' from the back end on hard acceleration when changing up a gear. I believe it is the slack being taken up on changing up a gear and applying power. Normal driving/changes are ok. I only get it on hard acceleration and on applying a lot of power having changed up. If the weather improves I will tighten the belt slighty and retest.
Sounds as though the belt may be jumping a tooth during acceleration.
