Grumbling is a pretty sure sign of a bad bearing. The bearing is a one-peice "unit bearing" and yes, sometimes they go bad prematurely. <img src="/forums/images/graemlins/rolleyes.gif" alt="" /> They are not servicable. It's happened to me, and it was on a vehicle with around 60K miles on it.
CJ


'98 TJ, 4 cyl., auto
31" AT KO's on rockcrawlers,
custom bumpers, Hellas
2" Teraflex lift, no top,
no doors, no problem.