what temp should hub be with infared thermometer

I have used infrared temp sensor from Harbor Freight for about 5 years. I have a 36' DP and always check the tire temps and the toad tire temps and have developed a range that is "normal" for both the RV and the toad. I also check the radiator/CAC and tranny cooler temps since I don't trust the dashboard instruments. It is interesting to see the temperature difference in various parts of the radiator. I have consistently found that the drivers side tires have a few degree higher reading due to the road crown on most 2 lane highways, but not on most interstates. However, one note of caution when using the Harbor Freight device...it is very sensitive to the condition of the batteries. Even though you will get a reading from the device when the device batteries are not fresh it will give you false readings. you need to keep fresh batteries handy for it.

Searching this topic and found this thread. Not too old so I will bump it back up with my findings.

Last year I lost a wheel bearing about 1.5 hours from home south of Kalamazoo Michigan on a Sunday evening. Could not find both bearings in a small town, so had to drop trailer, drive home, pull bearings off boat trailer, drive back up and fix it and then pull it home. Bearing just fell apart, still had grease in it. For a few dollars, I now carry two sets of bearings pre packed and stored in individual baggies and two seals with cotter pins!

I now carry a cen tech infrared thermometer from harbor freight for $20. It may not be accurate, but it is repeatable. My trailer rides almost at 10,000 lbs and has 4 wheel brakes with standard white steel rims. When cooler in the 50's, I get temps 70 to 90 depending on braking. Once warmer, they run 90 to 110. All temps are measured on the rim surface between the lug nuts since I have plastic covers over the hubs.

Last trip at the end, I had one bearing read at 135 while one behind it was 108 and other side was 98 and 102. So that one was pulled apart and repacked. If it acts up again, it will be replaced.

All four tire temps usually run around 130 depending on road temps. I have also come into rest areas and turned off the trailer brakes. That way no brake heat in them and the exit ramp gives me time to coast down and use truck brakes. Let's you also see if one is getting hot due to harder breaking.

Brian

For easy lube and standard lube the hub is the place to monitor temps.

For Nev-R-Lube Dexter hubs with disc brakes I have found the place to monitor for temps is the rotor braking surface. The hub seems to stay quite cool vs the rotor when in the early stages of bearing failure.

Because the inner & outer races are quite close together the angle of the disc from vertical is more extreme for a similar amount of bearing wear. This causes the disc to cant within the pad area and generate heat.

Any hub temperature increase will most likely come as a result of propagation from the rotor with metal to metal contact between the disc and caliper flange coming in the later stages of failure. I have seen temps in the 375° range once this commences.

I've seen mine get up to the same 135F range. I more use it to compare front and back, each side (sun side will be warmer). I also use them to monitor tire temp. TPM monitors pressure while I drive. Only takes about a minute to walk around TT and TV to check all 8 tires and wheels when I stop for fuel, stretch, or restroom break....

skipnchar wrote:
I use my hand. If it's not comfortable to place my hand on the hub it's time to investigate further. Keep in mine WHEN you check temps will make a HUGE difference in temperature. Checking right after pulling off of the highway and using brakes to stop and you'll get higher readings than waiting a bit longer. If you're wanting to just test BEARINGS then coast to a stop with little or no brake use THEN check hub temps (by any means you like)
Good luck / Skip

this is right and the only true way to test/check you wheel bearing temp
coast to a stop with little or no brake use THEN check hub temps (by any means you like)

Mine always run between 95 and 115 depending on if they're in the sun or not.
I agree with Phil, the biggest thing to look for is inconsistency. I had one that was 185 while the others were 95 - I knew I had a problem.

I've seen them go up to 140 on a hot day. But what you should be looking for is consistency. If three are 120 and one is 160, that would indicate a potential problem for the higher one.

I use my hand. If it's not comfortable to place my hand on the hub it's time to investigate further. Keep in mine WHEN you check temps will make a HUGE difference in temperature. Checking right after pulling off of the highway and using brakes to stop and you'll get higher readings than waiting a bit longer. If you're wanting to just test BEARINGS then coast to a stop with little or no brake use THEN check hub temps (by any means you like)
Good luck / Skip

I checked mine last week on the way up to Orlando on the 5th wheel. All 4 trailer wheel hubs were in the 120°F range, plus or minus 3°F. My front truck hubs, after pulling into the rest area on the turnpike, were both in the 145°F range, probably from using the brakes on the truck to get off the 4 lane. Outside air temp was in the mid 80s and I was running about 62 mph for about an hour the first time I checked them. Then checked them again after about another hour and they were holding the same temperature as the first check.

And the sunny side always read a slight higher degree. Otherwise I always looked for a different in temperatures as mentioned above.