The dealer was very confident the noise was the belt slipping. I was instructed to check belt tension from the bottom, not the top. There should be roughly 10mm deflection when pushed fairly hard. When checked from the bottom my belt deflection increased to 1.5-2". I have now tightened the belt to the dealer recommended 10mm deflection and the loud bang/gunshot sound has stopped. I'm now worried the I may have tightened too much. The bevel box was whisper quite before but now makes a very distinct sound during deceleration. It sounds like a generator winding down.
I think 10mm is on the tight side. It will cause the bevel box to whine just like a generator as well as increasing the load on the bearings and seals. Somewhere between what you had before and what it is set at now will be the sweet spot. I've been keeping mine at around 20mm deflection and can almost twist the belt 90 degrees. Have never slipped once. The people at Super Max recommend the belt being on the loose side but not too loose so as to ratchet (slip a tooth). Once there it should stay. The belt might stretch a bit when new but they are extremely tough and should not have to be adjusted at all afterwards.
