How do you diagnose a front wheel bearing / hub assembly ?

You may have seen my post asking about that sound. I think this is different in that others searching for bearing advice might find this and get some help.

I've seen the videos of wheels that will rattle all over or free-spin. My question is, on a 4x4 XJ, what is the best way to check if the front bearings are good? My u-joint and axle seem to spin with hub even with 4wd disengaged. That seems like it might be influencing my perception of the hub.

Do I have to remove the thing to really feel it?

I've done the jiggle from 3 to 9 and 12 to 6 with no movement. Also, there is no noticeable grittiness or anything but smooth rotation. I also still have that noise.

I think I know the answer to this question, but:

If a wheel doesn't appear bad in a wobble/spin test, and otherwise seems ok- can it still have a bad bearing?

You have done the usual testing and since the bearing is not obviously noisey; the bearing can be just starting to go bad and has reached the loose or gritty phase yet.
When you decide to replace them; DONOT go on the cheap and purchase some chinese knock offs...
Do yourself a favor and purchase a Timken hub assembly 513084 which fits a 90-98 Cherokee.


http://www.amazon.com/Timken-513084-Axle-Bearing-Assembly/dp/B000BZ4ZZU/ref=au_pf_pfg_s?ie=UTF8&Model=Cherokee%7C347&n=15684181&s=automotive&Make=Jeep%7C42&Year=1998%7C1998&newCar=1&carId=001