I just replaced a rear bearing today and found the problem of short bearing life. The bearing's rollers are ridiculously undersized for the weight of the car and the offset of the wheel. I have replaced many hub bearings in the past and I can't recall ever seeing a wheel or hub bearing with such small rollers. The bearing housing (outer race) is normal to large, as hub bearings go, but the actual rollers are tiny, barely 3/8" long and maybe a 1/4" diameter (roughly half the length of a more common bearing.) This bearing would probably have worked reasonably well on the rear of a Loyale.
The outer race had one medium-sized pit and a few very small pits, barely perceptible. However, from 15-20 mph and up it sounded like I was dragging the rear bumper - to me that shows that there is a lot of pressure on each individual roller.
I think I've mentioned this before, but knowing how some mechanics do things, I'd bet that the under-spec'd bearings coupled with sloppy installation habits are the problem (Boy, watch that statement bite me in the butt...
) In other words, what a lot of mechs get away with when installing bearings in most cars just isn't going to fly with these.
To be honest, there is one area of the installation that normally isn't a problem, but can be because of this particular bearing. Even if the complete bearing is installed into the knuckle correctly, the pressing of the hub into the bearing can be tricky. I have the correct press, it only pushes the hub and the inner races together, no pressure is exerted against the rollers. However, as it is an interference fit, the amount of pressure required to fully seat the hub into the bearings could overwhelm the spacer ever so slightly and create a wee bit too much pre-load on the bearings. This shouldn't be able to happen, the spacer exists solely to determine and maintain the pre-load, but I can't help think that maybe the bearing engineers were using specs for a bearing with much larger rollers that could tolerate the extra pre-load without disintegrating (small rollers = small lube film surface & higher loading/roller = higher operating temperature = higher rate of disaster.)
The notes from the factory that we've seen elswhere on this site are as stated "common sense" items for a mechanic. One would have to get pretty vigorous with an impact wrench to warp the knuckle/housing. The big nut in the center of the wheel should only be tightened by hand, with a torque wrench and while in the air, not on the ground. That should help to not exceed the pre-load setting on the bearing.
Sorry for the long post, I just wanted to be clear about what I saw today.