Trailer bearing temps

pescador

Well-Known Member
So I check the temps on each trailer bearing on my tandem axle trailer when I stop during any long haul trips with my boat using one of those infra red temp devices. Normally on a day when the ambient temp is around 20 degrees, the bearings are about 85-87C. When ambient temps go to 25 degrees, the bearings can get up to 90-97C range. One bearing is always 5 degrees hotter than the other three. Are these normal temps and should I be concerned about a minor variance in temp with that one bearing?
 
That’s where bearings on my boat trailer run, sometimes even cool to the touch. And wheels running on the sunny side run warmer but not by much. If you get every bearing running the exact same temp, that’s pure coincidence. Small variations are not an issue.
 
Mine run up to 102-104, oil bath and seem fine. I would prefer 85-90 but it’s within load range
 
You sound well within acceptable range. I too check my bearing temps regularly paying close attention that all four wheels are running close to the same temp. Mine run cooler when traveling highway speed vs conditions that require lots of braking (heat transfer from the disc brakes). Check the temps on your truck hubs sometime or even the asphalt temp on a hot sunny day and you'll actually be impressed at how relatively cool your trailer bearings are running.
 
Thanks guys. Ya my SUV wheels run about 80-90C. So close the trailer. I wonder what the “I’m about to blow a bearing up temp” is?
 
Thanks guys. Ya my SUV wheels run about 80-90C. So close the trailer. I wonder what the “I’m about to blow a bearing up temp” is?
EZ Loader once told me that you "cross a line" at 180 F on oil bath hubs. That's outside hub temp so I believe that the actual bearings would be running warmer than that.
 
That seems hot to me. I have a tandem with 520o lbs axles. Total boat and trailer weight is around 9000 lbs. I tow it between Calgary and Vancouver and back every year. EOH disk brakes on both axles.
I generally see about 20 to 25 degrees above ambient temperature.
the only time it is higher is if I need to use a lot of brakes before I stop.
 
5 degrees temperature difference would not overly concern me. It may just be a little bit tighter than the others.
 
''What temperature should wheel bearings run at?
Good question, Bearing are to hot at 177deg C or 350 deg F that's when the special purpose grease fails designed by Timken. Timken say bearing should not exceed 300 Deg F or 150 Deg F for precision bearings. Don't seem to be much info on it, but double the ambient temp for the bearings seems to be the sweet spot.
The rule of thumb for temperatures is if it hurts to keep your hand on it for 7 seconds or less, it's 150 degrees or above. If you have disk brakes they will run that hot or hotter. You need "high temperature" grease made for disk brake systems."
 
I have a heat gun and mine typically run 85 to 95 F depending on outside temp and braking. Since I bought the temp gun I have been much better at letting the tranny brake on the downhills and also planning the downhills so I use minimum braking possible.
 
''What temperature should wheel bearings run at?
Good question, Bearing are to hot at 177deg C or 350 deg F that's when the special purpose grease fails designed by Timken. Timken say bearing should not exceed 300 Deg F or 150 Deg F for precision bearings. Don't seem to be much info on it, but double the ambient temp for the bearings seems to be the sweet spot.
The rule of thumb for temperatures is if it hurts to keep your hand on it for 7 seconds or less, it's 150 degrees or above. If you have disk brakes they will run that hot or hotter. You need "high temperature" grease made for disk brake systems."

Most people can’t tolerate more than 120 degrees F to touch for more than a few seconds. At 150F every normal person would have to immediately let go. Hubs of all types should be below 120F at all times unless you are towing through a desert that is 120F. With a normal hub you should be able to lay your hand on any type hub for several seconds without recoiling in pain, if you can’t something is wrong and needs attention.
 
Some of you guys must be mixing up Celsius and Fahrenheit as most bearings running sustained in the high 80 to 90 C or 200F range would be cooked and into failure in no time at highway speeds.
 
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