Originally Posted by Lou Braun

Since this is a repeat failure, I'd recommend checking a few things before just replacing the bearing.

The bearing inner and outer races need to be replaced as a unit. Just replacing the bearing and not the race can cause the problem you are seeing. Make sure that the new cup is fully seated in the hub - very important.

The bearing is installed, followed by a flat washer that is smaller than the OD of the bearing. You want the washer to push against the bearing cup and not touch the rollers.

A hub nut goes on next. Tighten to seat the bearing, back off and retighten to about 1 fl-lb to remove play. Install the nut retainer. Install a cotter pin. The hub nut may be a castle nut with the nut retainer as part of the nut. In that case a nut retainer is not used.

With the correct parts and with a properly seated bearing race and bearing, your truck should go for thousands of miles without any problems.

Lou Braun

Originally Posted by 2006lariat

Are your axle shafts wore? My brother has a chevy, and the "stub" shaft, (the one that goes through the unit bearing was wore) and he was eating bearing's till a mechanic told him to replace the half shaft with the unit bearing. been 2 yrs with no problem's.

I don't know if it would matter on a super duty, but the mechanic said the axle shaft on the chevy supported the bearing's.
(I have never had the front of my Super Duty apart)

Originally Posted by Frankenbiker

Any strange tire wear? I'm thinking anything that's bent enough to start chewing up wheel bearings would chew up tires even faster. If there's no funny or fast tire wear, you can probably rule out bent suspension or steering parts.

Sounds like a stupid question, but are you sure you're getting the right bearings? I'd take a stab in the dark and say that since the OEM bearings from Ford (presumably based on your VIN when in the shop) lasted the longest, there's an issue with someone's parts computer/book elsewhere, that's listing the wrong bearings. Heaven help us if they're listing ball bearings versus tapered roller?

What brand of bearings? I think Timken may be the only US-made brand left...

As far as I remember, bearings don't fail unless they're either the wrong size, or are not lubricated. You're using HIGH TEMP wheel bearing grease, right?

I'm covering the basics here in order to clarify everyone's thought process.

Normal bearing operating conditions are such that failures show up FAST; properly lubed and assembled bearings last for hundreds of thousands of miles before failure.

HOW do the bearings fail? Does the cage come apart? Do the bearing rollers shatter? Do the races pit, gouge, groove, or otherwise degenerate? Note that the bearings on the 4x4's have plastic(!) cages.

I'm thinking here that you're getting the wrong bearings, which are listed incorrectly in the parts book or computer. The inner and outer race diameters are such that they fit the hub and spindle, but the bearing rollers are the wrong size, probably too small. This makes the bearing too narrow, and so the "proper" torque on the spindle nut doesn't properly pre-load the bearings. The "excess" weight (since the bearing is too small) quickly overloads the strength of the rollers, and the whole thing shatters.

-blaine