The Axle Nut...
I recently had an issue where I found that my driver's side rear axle nut was loose (freely spin by hand). Some one told me to check it after I have been hearing what could be a bad bearing. Tightened it up, wheel no longer shake when it's off the ground but on the ground.... it wobbled and for sure the bearing died. I had the bearing replaced as well as the two seals. Plus I had to replace the hub, I'm guessing the bearing somehow started wearing into hub since the inner races we're able to separate.
My question is, how does the axle nut come loose? I don't do burn outs or anything. Occasionally I take turns and exits fast because I like how the car takes the turns.
There is a castle cap and cotter pin over the axle nut but there's some wiggle room between the cap and nut.