Dave911

I just pulled off all of the hubs off my M51 dump and found a variety of issues.

I found the left front dual had it's locknut loose and the hub was full of gear oil. There was virtually no signs of any grease in the bearings. The hub had 2-3 cups of gear lube in it. On the other duals, the bearings had some grease in them along with a cup or so of gear lube. I have no idea how long it has been since this truck has had the bearings greased but I am guessing 10 years or so.

I think the manual says they should be re-greased every 6000 miles or so.

What I am curious about is what do you guys find is normal?

Do the rear outer seals eventually leak gear lube into the greased bearings?

If the inner seals are good, is it possible to forget about using grease in the rear hubs and just remove the outer seal and fill the hub with gear lube and go?

The hubs seems to naturally fill with gear lube anyway. I have some other trucks with oil lube hubs and they are very low maintenance.

Once I figured out how, it was easier to remove the duals than the front wheels and hubs. I used a pallet jack under the dual wheel set and hub to ease it up and pull it off the spindle. Replacement was just as easy. I cleaned out all of the gear lube and packed the bearings as well as I could since I didn't have any seals on hand.