Wheel Bearing Failure
 

Recently had an SKF Wheel Bearing fail after only 36,000 miles on the bearing. The cause was not obvious until I pressed the wheel hub out of the old bearing intending to reuse it.

Symptoms: while driving down a dirt road, not particularly bumpy but not hard surface, got a brake warning light, then an ABS Warning, later got a 4WD warning. Progressively over the next few days I started getting various 4WD disabled & then 4WD locked lights.

Inspected the tone rings expecting one to be bad. All were good. Jacked up the car and pulled wheels. My right front wheel wobbled while taking out the wheel nuts. Hm-m-m...

On inspection the tone ring had eaten into the wheel speed sensor. This was the cause of the symptoms above while on the road. So decided to remove the hub nut and inspect the bearing. With the hub nut removed the bearing outer race fell off in my hand. Clearly the bearing failed, but why after only 36K?

Only after pressing out the wheel hub in anticipation of reusing it did the answer become clear: the hub had a step in the shaft. See picture attached and note the step in the middle of the shaft. This is a reduction in diameter of a few thousandths. However it is enough to put the lions share of the wheel loading onto the outer bearing race. Thus one race carried little load and the other carried nearly all of the load.
Hence the shortened lifetime.

Bottom line: When replacing wheel bearings hang onto the OEM Hubs and don't use a hub that has such a step in it, even if otherwise "New."