Bearing inspection: Cant believe this!

[PiarFam]

24 SLX 260bh
Bought a few weeks ago(pre-owned)
Tires weren't even worn in and plastic still on everything inside. Basically "new".
Went from KY to MI and back. 750mi.+/-

On the way back I noticed one hub getting warmer than the others. Almost hot. I forgot to bring my IR thermometer. Made a note to keep a close eye on it and inspect.
Had some time today to start getting ready for our trip to OBX.
There is barely any grease in these bearings. I am amazed they didnt destroy themselves. Actually not bad for china bearings. I cleaned the outer and it doesnt look like it got very hot. A very faint barely noticeable goldish color on the rollers. Races look good with no discoloration at all. The caps had never been removed so it came from the factory like this. I opened up another hub and it had slightly more grease. So these are all getting packed. I'm also getting spares to take with. Maybe just a spare drum set.
Does anyone know what is up with the weird wear pattern on the brake drum? Does that look like excessive wear for so few miles?

 

[norty1]

Great pictures! I am eager to hear what those with more knowledge on this subject have to add.

 

[JFlightRisk]

The crosshatch pattern on your drum is from the carbide tip on the lathe that machined it. Very unusual for a factory surface. In a previous life I've turned many hundreds of drums and rotors and that pattern is caused by the feed speed being set too fast, but doesn't explain the inward cut. The machines I used only cut outward. It doesn't cause a problem and will eventually wear down the longer you own it. You can always have it re-machined if you wish. .003 or ,004 of an inch will smooth it out if the drum is perfectly true.

 

[Travln2]

Great photos. I'm just here for the info, too. I get some reddish-brown staining on the inner surface of the bearings, like you do. Curious to find out what is considered "normal" staining.
I just replaced our outer bearings and cups (races) due to staining like that, with Timken purchased from Rock Auto. Reasonable price, I thought, about $13 a bearing/race set.

 

[JFlightRisk]

That discoloration is a hot spot caused by a seized/stuck bearing spinning on the axle shaft. A new bearing properly greased would be a good idea, along with a new seal. I bet the hub temperature would return to normal.

 

[435-fht]

That discoloration is a hot spot caused by a seized/stuck bearing spinning on the axle shaft. A new bearing properly greased would be a good idea, along with a new seal. I bet the hub temperature would return to normal.

I agree. The goldish color is from heat. The question to answer was there too much heat? Here's a chart I found on-line. I'm a belt and suspenders kind of guy, and would replace them for peace of mind.

The relationship between the tempering color and temperature of carbon steel.

Tempered color	Temperature ℃
Light yellow	200
Yellow-white	220
Golden yellow	240
Yellow-purple	260
Dark purple	280
Blue	300
Dark blue	320
Blue-gray	340
Blue-gray light white	370
Black-red	400
Black	460
Dark black	500

 

[JFlightRisk]

I don't know what the actual temperature of the bearing might be inside the hub, but checking the hubs on our TT rarely get above 125 or so on a hot day. The grease is good for considerably more than that. If it was mine, I wouldn't worry about the discolored axle. I'd just replace the bearings and seal and repack them.

That reminds me, it's time I check ours again.

 

[TowPro]

I was going to say those lines in the inner race might be from the rv sitting, but without having the bearings and race in my hand i cant say. Can you fell those lines with a fingernail? How abut that shadow in outer race? How does the bearing feel when turned with your fingers dry inside the outer race dry? Bearings installed now are much cheaper than bearings installed sunday night on the side of highway, let alone finding someone who can cut the inner race of a spun bearing off to save the spindle.

 

[PiarFam]

The bearings and races do not have any indications of excessive heat or any wear. The dark spots of the inner race seem come off with a bit of elbow grease. I do not believe there is any reason to replace them at this time. Waiting on new seals before I tear into them. I believe a proper grease job is all that's needed here. Thankfully.

Being a former heavy haul trucker I stop the first 50mi and every 150mi or 3 hours. I do thorough walk arounds and won't continue on questionable equipment. I won't forget my temp gun this time. It takes a much longer interval for bearings to burn up.

What bothers me is I had a notion to check the bearings ever since I bought this camper but have not had the time. I could have added some grease through the ez lube spindle and it most likely would have been fine. I think I will be doing that routinely on trips just as an easy countermeasure to continually keep fresh grease in there. I got to see how far you can go with just a bit of grease.

Thanks all for the input and advice. Much appreciated.

Lesson learned: Don't trust the manufacturer's competence.

 

[PiarFam]

Any thoughts on the break drum?

 

[norty1]

Just don't over grease because that cause more problems.

 

[ccorbett1]

As a newbie RV owner I was unaware of the attention that bearings require, since regular auto wheel bearings generally are such a long-interval maintenance item. I've put 300K miles on cars with sealed bearings and never had an issue. My question is, is there a standard mileage interval for bearing inspection or do you just look periodically for higher than normal temperature? Thanks in advance for any sage advice.

 

[JFlightRisk]

I believe once a year is sufficient unless you tow a bazillion miles. I check the hub temps when we stop for gas, or a break. The infrared thermometers are handy for that.

 

[PiarFam]

As a newbie RV owner I was unaware of the attention that bearings require, since regular auto wheel bearings generally are such a long-interval maintenance item. I've put 300K miles on cars with sealed bearings and never had an issue. My question is, is there a standard mileage interval for bearing inspection or do you just look periodically for higher than normal temperature? Thanks in advance for any sage advice.

Supposed to be 12,000 miles or once a year. But that is starting with good serviced besrings

 

[ccorbett1]

Thanks. Would have been easy to overlook.