Hub Temperature Differential

tacchino · 01-14-2022, 12:58 PM

Serviced my wheel bearings last week and noticed when I towed after that I have one hub that is measuring around 10-15 degrees hotter than the other three. I pulled the wheel back off and took a look. Couldn't see any problem but went ahead and pushed some more grease into the outer bearing and spread some more around the inner bearing. I didn't pull the inner bearing yet since I don't have a replacement seal with me. I plan to do that next since a second tow showed the same difference as the first.

Anyone have any thoughts on that degree of difference? The others three are quite consistent so it seems to be to be a problem but curious to hear from others with more experience. Any advice on next steps?

Thanks!

Iowa Dave · 01-14-2022, 01:33 PM

Are all of your king nuts tightened down the same torque. The standard is only 5-8 lbs. I usually put about 40 lbs on them to make sure everything is seated ( thrust washer). Then back off till they “break loose” and snug up lightly with a socket. I’m assuming you inspected the bearings when you greased them and your bearing cups for being smooth and not pitted or nicked up.
In addition, are your tire pressures all the same and your side to side loading fairly even. My first guess is that your nut is a little tight.
How did the wheels spin after assembly? Should all
Turn for about the same amount of time with no play or rumble. Are your brakes adjusted the same also. They can heat up the whole assy. If one is hanging up. You should hear or feel that when you spin the wheel. Listen for a slight high spot “Ching” but not a prolonged scrape as you spin the wheel. These are the “free” things you can check yourself.
Just spitballing here.
Iowa Davw

tacchino · 01-14-2022, 01:40 PM

Yeah, I wondered about the nut as well. Of course, did that tightening process again when I pulled the wheel back off. My technique was to hand tighten with a wrench and then back it off and finger tighten. Wheels all spun fine, all make some rubbing noise, before and after I serviced them. Something in the brakes I assumed. I did inspect the bearings and cups when I did the first service and didn't see any problems.

All tires are filled the same. I *think* my loading is reasonably close but haven't had the opportunity to measure side to side. That said, the other passenger side hub (rear) measures the same as the two drivers side. It's the front passenger side that is different.

Iowa Dave · 01-14-2022, 01:57 PM

Sounds like you did things right to me. Maybe back the brake adjuster on that wheel off a
Couple notches and try it again. Can’t hurt and yo can readjust it if it doesn’t help.

tacchino · 01-14-2022, 02:02 PM

Quote:

Originally Posted by Iowa Dave

Sounds like you did things right to me. Maybe back the brake adjuster on that wheel off a
Couple notches and try it again. Can’t hurt and yo can readjust it if it doesn’t help.

Good idea on the brakes, will try that. All the wheels make a sustained rubbing noise, no ching that i noticed but will go through them again.

Any thoughts on what my level of concern should be? I'm on the road so servicing as i can in campgrounds

HABBERDABBER · 01-14-2022, 02:45 PM

Quote:

Originally Posted by tacchino

Any thoughts on what my level of concern should be? I'm on the road so servicing as i can in campgrounds

Forget about it.

Measurement error, very slight temperature difference which does not suggest anything grossly out of order. Variation in all things, and the slight differences detected are of no concern. You're tightening by feel, not instrumented tools.

tacchino · 01-14-2022, 03:39 PM

Quote:

Originally Posted by HABBERDABBER

Forget about it.

Measurement error, very slight temperature difference which does not suggest anything grossly out of order. Variation in all things, and the slight differences detected are of no concern. You're tightening by feel, not instrumented tools.

I wondered about that as well but since 3 of the 4 are all the same or no more than a degree off the other seems like quite the outlier.

Of course I never checked them before servicing so it's possible it's always been this way.

elongest · 01-14-2022, 05:55 PM

FWIW when traveling, the sunny side of the trailer the hubs can run 10-15 deg. F. hotter than the shady side of the trailer. Like others said, the spindle nut may be too tight or dragging brakes. Did you pull, wash and inspect the bearings before repacking? I just found a pitted bearing and did not notice it until I cleaned the bearing.
Eddie
I just bought some parts from a local RV shop. Their axle repack special was posted, $350. to pack 2 axle trailers. $230 for single axle trailers.
(USD)

tacchino · 01-14-2022, 06:09 PM

Quote:

Originally Posted by elongest

FWIW when traveling, the sunny side of the trailer the hubs can run 10-15 deg. F. hotter than the shady side of the trailer. Like others said, the spindle nut may be too tight or dragging brakes. Did you pull, wash and inspect the bearings before repacking? I just found a pitted bearing and did not notice it until I cleaned the bearing.

Yeah but the rear on the same side is running the same temp as the other side so it's not sun. And yeah, cleaned the bearings before repacking them. Will be trying the brakes to see if it helps

Iowa Dave · 01-14-2022, 06:11 PM

$350 for a bearing repack only brings one thing to mind.
https://www.google.com/search?q=i+wi...ile-gws-wiz-hp
Iowa Dave

HABBERDABBER · 01-14-2022, 07:25 PM

Quote:

Originally Posted by tacchino

Yeah but the rear on the same side is running the same temp as the other side so it's not sun. And yeah, cleaned the bearings before repacking them. Will be trying the brakes to see if it helps

I'd suggest that there are many, many more things in the world and life to fret about than a 10-15F temperature differential in your rim/bearing temps.
If you want a more definitive answer, do the work, and get a calibrated torque wrench and snug the castle nut properly, using Iowa Dave's technique, which is the manufacture's standard. And mark identical and measured spots to take your temp readings.
Otherwise, I feel you're chasing shadows in the dark. You may have a slight and inconsequential difference in some axle geometry to create the added friction/heat. Or just a different feel and effort when you "tighten by hand".
Who knows? Not me.
Unless you see 'em smokin', there ain't much to fret about with your bearings, in my estimation.

$350 for a bearing repack? $.62 of grease cost, $349.38 of labor cost, excluding shop towel surcharge. Glad I do my own bearings. There may be some perceived mental comfort in having the "expert" do the work, but it sure ain't rocket science. My comfort is gained by my fatter wallet.

Is your "hot" bearing the first one you measure? Last one? It may matter.
YMMV

Ron in BC · 01-14-2022, 09:58 PM

I was tracking my hub temperatures last summer because I had an axle with a problem. I was surprised with the inconsistency of the readings. There was a pattern and the sun side hubs were higher but the variation of the readings did surprise me. I did have my hubcaps off and tried each time to put the laser in the same spot but there were some unexplained differences. I did have one that was about 10* higher than others but then other times it wasn't.

Ron

cpaharley2008 · 01-15-2022, 06:00 AM

Thanks for the memories Dave.....

azjack · 01-15-2022, 10:25 AM

Last april we picked up our new 5.0 about 100 miles away and checked temps within 50 miles and had one wheel temp higher than the other 3. We checked again before arriving home and the same wheel temp was higher so we just raised that side and our son got down and checked and adjusted the brakes, problem solved.
AZjack

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