The oshkosh manual i have, indicated that the front hubs are just grease lubricated. No reason to think otherwise. After A comment from a member here, i rushed out to find my hubs to be in fact an oil bath type. Oil and seals ok. What lubricant, just hypoid gear oil? Smells like hypoid. Plastic covers are crazed and need replaced. Are the green rubber plugs somehow different than the red ones?
Yup, gear oil. Viscosity depends a little on manufacturer's recommendation and a lot on ambient temperatures you run in.
I'm just guessing here...the red plugs are probably a "brand" feature of the STEMCO hub covers. STEMCO seems to be a popular brand in this market. Other color plugs might be used by other cover and/or plug manufacturers, but are
probably functionally equivalent. On our coach, one front hub cover plug is red, and the other one is black. (?)
Found the photo (below) online showing different type/color plugs:
Not sure if this is a Hi Jack but a interesting find. My '81 had dry rear hubs. It had an axle seal to keep the oil from getting to the axle bearings and they had to be serviced with wheel bearing grease. I bought a kit and converted it to a regular wet bearing system. I have no idea why Hendrickson Motor Coaches set it up the way it was.
Since our U280 is my first ever "large" vehicle, I found the front hubs interesting. Being used to seeing "dry" greased wheel bearings on cars and pickup trucks all my life, I wondered about "Why" the difference. Is it because of the weight of large vehicles? Do "wet" lubricated bearings have a higher load bearing capacity? I would
not think it has to do with number of miles driven, because many cars run successfully for decades, and hundreds of thousands of miles, without
ever having the bearings serviced.
If I were to guess it would be that the oil bath bearings remove heat from the hub better than grease.
Duh red for port, green for starboard maybe?
Phed. Get back to work!! :)) :))
There are some Stemco videos out there on the sight glasses,think they do reccommend changing oil once a year,it does get
dirty.
Have not located a part number on the casting but a 5918 on the plastic. Mine have drain plugs, but look pretty corroded. Really dirty so i may have to pull tire and wheel and wire brush well prior to removal of cap assembly. I don't have a jack yet. Dremel might work, along with a custom modified Allen wrench. Since I'm a weekend warrior, i hate starting projects without the parts in hand.
Is a 20 ton jack really necessary, or just so much easier to pump, search showed it to be quite popular choice?
Do most big rig parts stores stock these or are there a hundred different variations?
I'm a gasket guy, enuf said.
Thanks in advance
You do not need to remove the wheels to replace the stemco hub cover. Just take it off and catch the oil, take the old one to NAPA and match up, come back and install new with new gaskets and refill to the line marked. If the oil is real dirty then maybe remove the wheel and hub or if there is water in the oil which would make the oil milky colored.
No milky oil/water, just evething around it is gritty dirty. Used to be a dozen or more Napa stores in a town of 400k. Nearest naps now is 40-50 miles away unfortunately.
I started buying the windows and seals online once I had the numbers.
If it is just dirty on the outside cleanb it up. No need to replace hubcap. Look on the cast aluminum in between the bolt holes. There usually is a number cast into the forging.
I use a 12 ton bottle jack to lift my coach.
A little trick if you only need to replace hubcap or gasket is drive whatever wheel onto some leveling pads and let it sit so the oil has time to go into the hub. You can also just ibnb acknit up.You will have less to catch!
If you look on your front axle in the center front there it s a tag. Post a picture if it and I will look up your inner seal and hubcap etc part numbers. They are/should be also in your 3 ring binders. In t big e front axle book.It shows the merritor/Rockwell numbers which are easily crossed to national brands.etc
It's just easier to pump.