have had ishues with aftermarket axle nuts having to big of outside diamiter and not tightening up proper theese nuts are about 5\16 bigger and look like some kind of mazda or honda junk they fit but do not titen up properly on hub after about 2000kms the axle works loose and damages the inside of the hub as it gets loose in berring [warnig do not install theese nuts if its not the same as what came off dont use it will save some big problems] have had 4 or more thiss year mostly rebiuld axles

I just use the old axle nuts. The crimped part never ends up in the same place. Re-crimp it and it's just like new.

I could see a larger 'washer'/shoulder area affecting actual clamping force I suppose.

 

Make certain you are not torqueing with the cars weight on the wheel. I put a very large screwdriver in the rotor vent and let the caliper 'buck up' the assembly while torqueing the axle nut. (I'm sure Ivan knows what he's doing, but others reading here might need that info.)

the larger nut actually tightens up to the center hub and not to the axle which is tappered and eventually works loose and ruins the hub where the bearing sits

Yeah, I always jam something in the rotor. Screwdriver, small prybar, large punch, etc.

 

While we're talking about these, what's the torque spec for Subaru axle nuts? I found 137 +/- 14 ft lbs in the MY 95 FSM.

I think the spec for my wife's 03 H6 OBW was 159 ft/lbs.

 

But my wrench maxes out at 150 so I used that. - hope it's close enough.

1/2 inch snapon inpact as tight as you can get theese nuts can not be overtightend by desigin the tighter the better