But where is the movement? It can be at the trunnion bearings where the spindle unit meets the center housing, or it can be in the wheel bearings and show up between the hub and spindle. Movement in the trunions won't directly affect the seal performance. The wheel bearings are a different matter.
With this style package, there is no bearing "adjustment". It's all predetermined by the engineers based on bearing dimensions, and the distance between the bearing races in the hub. Whatever preload the engineers decided on (and accuracy of the machine work involved) is what you have to work with. The only true variable is the condition of the bearings.
That said, what I have found in some cases is problems with the dowel spacers, bolts, and the internal threads they screw into. (Items 9 and 10 on this diagram) If those bolts and/or spacers ever get loose, getting them to tighten back down (and STAY tight) can be difficult. The spacers are a tight fit. They come apart hard, and they go together hard. If they don't, they will often work loose in a short while.
