What it Does
Many wheel bearings and wheel hubs require press operations for removal and replacement. This commonly involves thousands of pounds of force so hydraulic presses are commonly used. Components with good design and condition will fit together very tightly, but not so tightly that they cannot be pressed together. A typical replacement sequence could look like the following:
- After removal of the wheel knuckle (or “spindle”), the wheel hub is pressed out of, or knocked out of the knuckle and wheel bearing assembly.
CAUTION: Many knuckles give limited clearance for press adapters prior to removal of the hub. Creative thinking is often required for a safe, secure, and level setup (safe both for the press operator and for the knuckle itself.) - The hub will commonly press out with one of the bearing races still attached to it. If the hub will be re-used, this race must be removed from the hub.
CAUTION: These races are commonly cut for quick removal, but these service methods can risk nicking or gouging the hub shaft. Proper usage of a bearing splitter avoids this risk, but successful race extraction can be time-consuming. The concern here is that we don’t want any damage to the hub shaft that can impact bearing race uniformity (said race needs to be as perfectly round as possible to maintain proper bearing clearance, and we want to see it fully supported by the hub shaft.) - At this point, removal of the knuckle’s dust shield (often but not always equipped) may be a good idea. The bearing snap ring should be removed.
CAUTION: Some dust shields use an interference fit and may have to be replaced rather than re-used for a secure fit. Snap rings can require unseizing and extraction due to rust seizure. - The wheel bearing is pressed out.
- The new wheel bearing is pressed in.
CAUTION: Care must be taken to properly support the wheel knuckle in this step. It should be firmly supported and level. There is also risk of the bearing not starting straight in the bore and then binding up and gouging the bore under press force. This can happen even if the knuckle is level. It is critical to ensure that the bearing starts straight and to catch the problem early if it doesn’t. Damage at this point can require replacement of the steering knuckle. - At this point, the snap ring should be reinstalled or replaced (as appropriate), and the dust shield (if equipped) reinstalled or replaced (as appropriate.)
- The wheel hub should be pressed in.
CAUTION: This is another step where it’s critical to make sure that things push straight together. Otherwise, damage to the wheel hub and wheel bearing may result. It’s also important to make sure that the inner race of the wheel bearing is supported so that it does not push out as the hub pushes in.
Possible Problems
The majority of possible problems here relate to workmanship (provided that parts are the correct parts and of good quality.) Parts that are being pressed should be properly supported, clean, and pressed straight. If this is not achieved, component damage can result, repair longevity can be compromised,and vehicle safety can be affected.