[Rob Doe]

You may know all of this, but just in case:

Your hub may be fretting on the axle.

The axle key is in the axle, correct???

You had to use a wheel puller to get the rear wheel off originally, correct?

You washed until clean and dry, the tapered section of the hub and the tapered portion of the axle, cleaned and repacked the roller bearing, reinstalled with a new seal and the bearing retaining clip, then torqued to a least a minimum of 75 - 95 foot pounds, the axle nut, with the heavy, thick washer and its gasket, correct?

Some drive around the block and remove the wheel and tire to recheck that the nut is still tight.

The hub and the axle tapers are supposed to be smooth, clean and dry, no grease, oil or anti-sieze when assembled. When properly torqued at the nut, they act as a single unit to carry the torque of the axle to the wheel. If the axle nut is not adequately tightened, the key will wear and the key way will become loose. If the key carries too much load, the axle will eventually crack. If not discovered soon enough, the axle sometimes fails in such a way that the wheel, hub and drum leaves the car. Not good.