If you even SUSPECT your front wheel bearings are going bad, REPLACE them, and save yourself mucho $$$. If the bearing binds up and spins the race inside the hub, it's VERY likely the hub is trashed. You could be looking at $590 (Mazda dealership) to replace that hub, unless you can find a good one used (good luck!) I got REALLY lucky and found a good used one, but I spent half a day on the phone finding it, and it was still a gamble. Damn thing must be made of space ship alloy!

 

If you re-pack them often and make sure you tighten the hub nut to proper torque, they will last a long time. If you clean them up good, you can inspect them closely. You want to took for de-lamination of the metal, flat spots and make sure the bearing spins smoothly. You also want to check the condition of the race, make sure its not scored up. If both the beaing and race and in good condition, re-pack the wheel bearings with a liberal amount of grease, replace the grease seal and your good.