When installing new hubs or new bearings into an old hub, it is necessary to pre-load the bearings. This prevents potential swerving from a wobbly hub. You want to be sure that the races in the hubs are 100% in place against their machined stop points.
First, install the spindle washer and spindle nut onto the spindle with the hub and bearings in place. Tighten the spindle nut finger tight, then tighten it another quarter turn with channel lock pliers or a crescent wrench. This will fully seat the races. Next, loosen the spindle nut until it is very loose, then re-tighten to finger tight to engage the nut retaining device. Some reverse lubricating spindles use a tab washer for the retaining device. It is very important to not run your spindle nut too tight nor too loose. A nut that is too tight will cause your bearings to overheat, while a nut that is too loose can cause individual rollers to come apart in the bearing and then cause the hub to fracture.
After 20 to 40 miles of highway travel, check to see if the hub is loose on the spindle. Pull the tire in and out a few times. If the hub is loose, you will need to re-tighten the spindle nut and re-engage the nut retaining cotter pin or tab washer. Never reuse the same tab on the tab washer. They are designed to be used only once.
You are now ready to install your dustcap and complete the hub installation.