Originally Posted by PirateDunk
The spring washers help to increase the clamping stresses of the rivets.
I work with and design aircraft components. If a rivet or bolt gets slop it has zero fatigue life.
i.e. If you stick a 6mm bolt in an 8mm hole it can carry zero load. Simples.
I apologise for being too fussy. I have a syndrome called self preservation. I've noticed Hardly-Worthit drivers don't have this basic human instinct.
Not being too fussy.
Your bolt example is dead-on. However, I can't tell you how many iron, Brembo race rotors I've heard rattle, to include new, out-of-the-box examples. Brake Tech iron rotors do the same. They float freely, without spring washers. IDK, I'm not an engineer. But, I'd think the engineers, who specialize in these components, have a pretty good idea what they're doing. In fact, before floating rotors became mainstream, they didn't have spring washers. When nearly every sportbike started coming with them, people started complaining about the rattling.