Running temp for wheel bearings on a modern 4wd/etc with 'wet' bearings - is there an acceptable spec range ? (1 Viewer)

[sunrk]

Curious about this. In Aug I fully replaced the front end so the front bearing hubs were done then, and just recently have done the rear wheel bearings plus the rear brakes. On christmas day I drove about a 300 km round trip and noticed the rear hubs running quite a bit hotter than I'd noticed them previously (I usually walk around and feel each hub at a stop on any long trip).

I don't really understand what temp spec range wheel bearings are supposed to run at but I understand there is a large range of factors that affect it. Correct setup/adjustment of the bearings, grease condition/packing/quality/etc. setup of brakes, and more.

What got me thinking was doing the rear wheel bearings and replacing the rear brake rotors/pads (and HB adjustment) in the last week, and on the tub of Castrol HTB-2 grease is printed wording that it's intended for use with automotive wheel bearings runnings at very high temps.

What is 'very high' in this context?

I've had 'very high' temp bearing experiences a few times in my career as a freight train driver but they're much bigger bearings (6 x 11 or 6 x 12 inch package bearings, or similar) and carry much bigger loads.

 

[Malleus]

I measured mine when I replaced the seals recently. One side was very hot (140°F), compared to the other (80°F), after a ten minute test drive, with heavy braking. The ambient temperature was 80°F. I eventually found a sticking caliper on the hot side; they're both running the same temp now.

According to Castrol, your grease is rated between -20°C/-4°F and 160°C/320°F

 

[Rusty Marlin]

On a multi hour trip, running 60-70+ MPH I monitored the hub bearings and pumpkins with a non-contact radiant thermometer.
At every fuel stop the hubs where a constant 124F and the pumpkins ran 140-ish.
No idea if this is normal, but it's what my truck runs.

 

[DivByZero]

You know, I've never measured this. I'm curious, so I think I'll take the infra-red thermometer out on a trip soon, see what my temps come back as.

 

[Rusty Marlin]

I was concerned/curious because I just changed gears and bearings in the thirds and all new wheel bearings/spindles up front.
I'd been monitoring temps for the first 1000 miles in my 11 mile commute and didn't see anything out of the ordinary.
The long haul temps were the same as the break in temps, so I considered them normal.

 

[mudgudgeon]

On a multi hour trip, running 60-70+ MPH I monitored the hub bearings and pumpkins with a non-contact radiant thermometer.
At every fuel stop the hubs where a constant 124F and the pumpkins ran 140-ish.
No idea if this is normal, but it's what my truck runs.

More specifically, what part of the hub are you pointing the infrared gun at?

I've tried to check this and compare hub to hub and found it hard to get a consistent reading.
I was trying to avoid braking so I was reading bearing heat, not brake heat

 

[Rusty Marlin]

I checked around the drive flanges, the grease caps & the lug nuts, they were all pretty well the same temp.

More specifically, what part of the hub are you pointing the infrared gun at?

 

[Malleus]

When I checked mine, I was pointing the IR beam at the center of the outer bearing width. The outer edge of the discs were much warmer than the hub, by maybe 25°, which is what lead me to the stuck brake caliper piston. I figured if the temperature rise was due to the bearings being too tight, the outer edge would be cooler, since it's farther away.

I didn't mention it earlier, but my 1/2-hour in-town (stop-and-go) trips resulted in the same temperatures as the 5-10 minute heavy braking exercises. This lead me to believe that I had reached a steady state operating temperature very quickly, so I didn't take it out on the interstate as I had originally planned. I did not check the differential temperatures. I need to do that for posterity.

FWIW.