This is not from factory specs, just from experience. I am assuming you have four wheel drum brakes, and tapered roller bearings. You have to remove the grease cup from the drum(center), behind the cup is a castellated nut held with a cotter pin. Remove the cotter pin, loosen the nut, and pull the drum off. If you are servicing the bearings, pull the inner seal to get the inner bearing out. On reinstallation, put the drum and bearings, plus any washer on the spindle, thread the nut on snug. While rotating the drum to seat the bearings, tighten on the nut until resistance to rotation is felt, back off on the nut, tighten again until slight resistance is felt. Line up the nut with the hole in the spindle and install a new pin. The trick is not to get the bearings so tight, that they get hot, nor too loose to have play in the drum. Of course you have to consider that the grease is going to thin, and bearings are going to seat further, you are trying to preload them some to accomodate this. It works the same if vehicle has discs.