How it worked for me
My spacer ring measurement before. Note [original factory] seal lip wear line
The anti-skid gear reluctor wheel measurement from bearing edge. It's important to note that I'm measuring from the bearing edge because the backing plate and carrier are not tight on the bearing, that is that the bearing floats in the carrier until it is located by the axle tube.
I did this job back in January and I've put a few thousand miles on it since then. A huge thank you to BigFishAllDay for this write up and for all those who contributed to it.
Some pointers to anyone doing this themselves: the depth of the sensor wheel can be checked by removing the sensors from each side of the axle as seen in previous pictures; it should be basically centered. Also, there is no need to reverse the orientation of the seal ring provided two things:
first, the seal must be installed with something that doesn't distort it during installation; and
second, the seal ring should be installed farther away from the sensor wheel. I used a plastic cap I had lying around for the seal which happened to be the right diameter--if you use anything made of ferrous metal and don't remove the sensor, the magnet will pull it off center and the seal will get distorted/warped/damaged. Obviously, using a socket will almost certainly damage the seal by pressing the center farther in than the outside, but even a seal/bearing driver can do this because the outside edge will bottom inside the axle tube and one extra smack with the hammer can bend the center in just a little farther. Order three seals because unless you do this all the time you will ruin the first one.
As shown in my picture above (and others) the seal ring is pressed about 5mm past the edge of the polished machined section of the axle shaft which allows the old-style seal to mate about 2mm in from the bevel and installing the new ring to this depth will cause the seal lip to mate somewhere around the bevel instead of on the flat and it will leak (but this is made worse if the seal is damaged as mentioned above). The bevel is designed to guide the seal to slip on the ring easier, so instead of installing it backwards, just set it a few millimeters closer to the machined edge of the axle. I set mine at 2-3mm and it has not leaked. This means that there will be a space between the sensor gear and the seal ring, but that is inconsequential.
The ID past the inside of the seal where the axle tube starts to neck down is not so small or close that the ring can contact it (within reason), so as long as the seal is not pressed in so far that the surface is deflected inward, the seal lip should line up. Best thing to do is the 'grease test'.
Side note, in an effort to save money I purchased a set of Nachi 6308-2NSL bearings for about half of what one single bearing would have cost from the stealership. I matched the number from what came on the truck originally and they have performed flawlessly. Time will tell if I really benefited from the cost savings.
