sjmarcy

I've wondered about these and had the chance to compare when a non-ABS car ran into front hub trouble due to inner bearing failure. The ABS hubs obviously include the toothed, aluminum ring for the sensor to use to gage wheel speed. The steel hub itself is a bit larger and heavier to provide something for the ABS ring to press onto. You can pop off the ring to use on a wind chime or something. If you place it over the non-ABS hub there is a bunch of extra space due to less steel being used. I should have weighed the two parts, the non-ABS hub is a bit lighter. Often the ABS hub is available cheaper than the non-ABS version.

https://www.miataturbo.net/attachmen...1&d=1311809691

The hub that failed exhibited trouble most easily seen at the innermost race. See the missing metal (circled) at 6:00? The grease was dark on that side of the double row bearing. That is, the outer bearing was still fine. I think the failure was due to inadequate sealing at the back of the hub. Grease darkens with dirt and water infiltration. This was on the LF of that Miata and when driven it was silent on turns to the Left, and whiney to the Right. This hub used the earlier seal style which apparently Mazda found to be inadequate. The later style seal can be seen in the side by side hub photo, on the left.
https://www.miataturbo.net/attachmen...1&d=1311809691

sjmarcy

I've done some measuring. Particularly on the beefier ABS hubs, there appears to be sufficient "beef" to open up the hub. To one smooth bore. Of the right size to allow a larger cartridge bearing insert.

Upon examining the wear on the OE hub, the ***** were still pretty mint but the hub outer bearing races had the most concern. They are integral to the hub. I'd want to see more failed samples. However this could mean that this part of the bearing is a compromise. It is locally hardened, since heat discoloration on the hub OD is visible.

It may be possible to make a much stronger hub/bearing assembly from a stock ABS hub core. Has anyone done so?

hustler

iTrader: (6)

I started using "better than Redline" Amsoil grease and all my bearing failures went away.

sjmarcy

When you were having failure…was there a "degree of fail" difference between the innermost and outermost bearings? A number of fronts I've seen went bad at the innermost first.

hustler

iTrader: (6)

Outboard.

sjmarcy

Makes sense, closer to the brake disc's heat. Whereas street Miata bearings seem to die inboard which is rear seal related. The one I just change out was on a pure street Miata. Inner grease was black and dirty. Outer bearing grease still looked newish.

hustler

iTrader: (6)

The grease on both sides of my dead bearings was also black. With the same brakes the AMsoil grease survived. Now that I have "really big" brakes I think they will last forever.

sjmarcy

Clocking your wheel bearings.

If you think about it…the inner bearing races never move as they are clamped to the spindle by the big nut. This means that the bottom surface of the inner races always see the load from the weight of the car. All the shock loads from bumps.

It wouldn't hurt a thing to loosen the nut and then reset the bearing with the inner races in a new position. The bearing I examined had failed at the bottom of the innermost inner race.

Newer design wheel bearings like on the NC cars have a no-spindle design. In that case the outer races are stationary. This helps a bit due to the larger diameter over which to spread the load. And the smaller inner races move so that load gets spread out too. Those can be clocked by rotating the four bolt mount flange to one of the remaining three positions.

Just a thought. On the car that I just load an de-ringed ABS hub, I just may reclock the other side for the heck of it.