Exhaust mounting tips (should the muffler be loose?)

Hey everyone, noticed that my muffler has quite a lot of side to side play, even though the rear bolt was fully done up. Realised that this was because of where the threads run out on the bolt, it doesn't grip it fully.

But before I rush out get some washers to sort it - is it supposed to be like that? Muffler's pretty heavy, is it supposed to have some play in it so you don't get metal fatigue in the mountings from going over bumps, or some such thing?

 

should be nice and tight.

scooters have a floating exhaust, its mounted to the motor because it moves with the suspension. so it needs to be bolted down nice and tight, that goes for the muffler/end can to

 

Great thanks for the info