What is bearing preload – is it the same as play? Can a bad alignment cause a wheel bearing to wear out prematurely?

Well, actually the answer comes down to the word “preload.” Preload is not the same as end play. Preload is actually aligning the inner and outer races together and loading the bearings. So the rolling elements make proper contact with the two surfaces. This usually involves a nut and an axle that clamp the two together and set the load pass. When properly torqued down the axle nut will set the ball-bearings or other rolling elements in relationship to the inner and outer races. This is where the loads are carried.

So if this is not properly set, you’re going to have issues with the bearings wearing out too soon or having the wrong angular contact pattern. So how does this apply to our second question? How can a bad alignment angle cause a bearing to fail prematurely?

Well, we’re looking at the load path through the bearing. Just imagine a bearing has too much camber. Well, the load path changes on the bearing and where the bearings make contact and where the loads are carried. If you have too much toe and the vehicle is going down the road. Well, that changes the loads inside the bearing too. So keep this in mind. If you’re replacing a wheel bearing, you might also want to check the alignment.

This video is sponsored by GMB.