[SlammedRanger]

Post a video of it. If you have play there either the axle lock nut isnt installed properly (99% of the time). Or someone replaced the bearings and didnt put the sleeve in between them and the bearing inner race pushed in. Thats my .02

 

[SlammedRanger]

Nope. The big one with the rounded side goes the opposite way you said(rounded part inside hex part toward outside). And the skinny one locks against it. Not toward the rotor at all. The skinny one is a jam nut. The other ones is the actual tensioning nut.

 

[SlammedRanger]

Best picture i could get off my phone at the moment

 

[SlammedRanger]

And loctite is your friend on that btw. I usually coat the whole threaded sleeve in blue loctite. Or it will come loose all the time.

 

[SlammedRanger]

So should the rounded part of the bigger nut be against the rotor and the jam nut against the hex side closer to the wheel?

No. Your picture shows it the right way. All but one part. There should be more threads showing toward the brake rotor hub. So the nut wasnt tightened before they tightened the jam nut. Loosen the jam nut and turn the hex part of the other nut until it tightens the threaded sleeve to the brake rotor. Then tighten the jam nut. Remember loctite or it will loosen up on you all the time.

 

[SlammedRanger]

That nut is what tightens against the brake rotor hub and carrier bearings. It pulls tight the sprocket hub on the other side. With that nut loose like it appears in the picture it is the whole axle wouldnt be tight against the bearings in the carrier which would directly explain your axle slop side to side.