Wheel Bearing Temps & Test Drive

[aluminum_flyer]

I have a 2010 KZ RV CL164 and repacked the bearings this spring (single 3500# axle). I have done bearings before (on a small pop-up) but never took the temp with and IR temperature gun.

Here is what I found. I don't have time to take it for a longer trip before my big vacation trip. Otherwise I would.

About a 40 mile round trip broke up into there and back segments with an hour in between. I dragged it along to an appointment. Trying to kill 2 birds with one stone.

After coming back the bearings were 85 degrees F. I sparingly used the brakes (manual transmission helps out with that) to get a more accurate reading as well. The latest Good Sam magazine said 165-185F was typical bearing temps. I would think that if they were too tight they would have gotten hotter than 85F in that time. Correct thinking?

I did check after the repack and there was a small amount of 'wiggle' in the rim (bearings)... grabbing the rim and rocking back and forth.

The rubber temperature of the tire (sidewalls and tread) was also 85F as a side note.

Any suggestions, comments or concerns?

[campigloo]

I'm in the low tech camp. If the wheel near the hub is ambient temp or slightly warm everything is aok. If I can't hold my test probe (finger) on it for a few seconds comfortably I know I may have a problem and pay extra attention to that wheel. Same goes for the tire tread.

[hddecker]

Passin Thru wrote:
Quit worrying. If they are all the same temp they are normal. Pull the heck out of it. Trouble with technology is it causes more problems that it ever relieves. I am against computers.

Help stamp out help stamp out causes!

I'm with you there, people are relying too much on technology and not enough on good old common sense.

[myredracer]

We stopped at a rest stop yesterday after about a 300 mile run with our KZ. Maybe around 85 ambient temp. I checked the tire air pressure all around and then thought I'd give my IR gun a try which I've hardly used so far.

On one side aiming as close to the center of the drums as I could, I got 80-85F on one side and 130 - 135F on the other. I got a little panicky at first and then realized that the sun was bearing down on one side the whole time while the other was in the shade. We were steadily climbing in elevation for 200+ miles so any braking had little effect on the temp.

Interesting to see the difference the sun can make. If we had only one hotter wheel on the sunny side, then I would have been worried.

[aluminum_flyer]

Just an update... After a 1600 mile trip. 800 miles each way done in two days down and one day coming back. Outside temp in the 80's. Wheel bearing hubs (with the IR gun) where 119 degrees (sunny side) and 99 degrees on the shade side. Hope that helps anyone. I know the IR is a guess but it would show a big value and a big discrepancy between the sides. Glad they worked, made me nervous. I've done bearings before but not on this trailer.

[aluminum_flyer]

With the IR temp gun I try to get as close to as possible to the axle bearing locations. I don't measure the rim or beauty cap but the hub... thru the rim holes. I know that it is a guesstimate. I was looking at big differences from side to side. They were virtually the same temps.

When I say wiggle in the bearing; I mean about a ~1/16 inch of play. Not much but a little. Too loose if I back it off one notch and too tight if you go one more. Rotating the wheel by hand (jacked up) has it spin freely and make a half dozen rotations with a hand spin.

I've done bearings before but not on a larger TT.

[Turtle_n_Peeps]

westend wrote:
IMO, shooting temps of bearings with an IR device to assess the alignment of wheel bearings is chancy at best. Shooting them through a rim and beauty cap is indicative of nothing. The problem I see is that the aluminum rim and cover will dissipate a lot of heat between he actual bearings and the point of measurement. I don't know how , with all the hub configurations and wheel choices, that a range of temps can be established to indicate bearing "wellness". The temp gun may turn up a failing bearing set, though.

The other part of this is that someone new to bearing service reads that there should be some "wiggle" in the rim after assembly. How much that runout is can mean the difference between failure and acceptable. It may also result in excessive tire wear. Myself, if I service axle bearings, I tend to go towards the tighter end of procedures, i.e. no "wiggle" at all from the hub/wheel. There is a fine line between over-tightening and acceptable load but I do not have any bearing failures or tire wear by using my methods.

Hopefully, this doesn't add to the OP's anxiety. Maybe an additional check of the bearings and the load of the axle nut would allay all fears and get the bearings loaded perfectly.

Really good post. ^^^^^^^^^^

[westend]

IMO, shooting temps of bearings with an IR device to assess the alignment of wheel bearings is chancy at best. Shooting them through a rim and beauty cap is indicative of nothing. The problem I see is that the aluminum rim and cover will dissipate a lot of heat between he actual bearings and the point of measurement. I don't know how , with all the hub configurations and wheel choices, that a range of temps can be established to indicate bearing "wellness". The temp gun may turn up a failing bearing set, though.

The other part of this is that someone new to bearing service reads that there should be some "wiggle" in the rim after assembly. How much that runout is can mean the difference between failure and acceptable. It may also result in excessive tire wear. Myself, if I service axle bearings, I tend to go towards the tighter end of procedures, i.e. no "wiggle" at all from the hub/wheel. There is a fine line between over-tightening and acceptable load but I do not have any bearing failures or tire wear by using my methods.

Hopefully, this doesn't add to the OP's anxiety. Maybe an additional check of the bearings and the load of the axle nut would allay all fears and get the bearings loaded perfectly.

[aluminum_flyer]

As a side note... I can't put my hand on these hubs due to the alloy wheels and center caps (covering them. That is why I got the IR temp gun so I can get the backside and thru the rim.

[aluminum_flyer]

I thought the average was 120F myself. Trailer Life stated 165-185F. I too thought that it was somewhat high (maybe not in Death Valley). I was always taught, warm to the touch. The steel and grease have a much higher tolerance than that though. I think the grease I used has a drip point of 500+ degrees. The steel bearings should run all day at much higher temps but I know that is not a real life temps for axle bearings.

One of the reasons too for the paranoia is that I have a serious health concern and roadside repairs are not what I am looking for and I try to de-stress my life. I know that I am stressing about it but I am at home with all the tools and supplies handy. I know that nobody likes roadside breakdowns. Just trying to rest my mind.

I do think that it will be fine (95%) but I have an 800 mile trip coming soon.

[ScottG]

I read the TL thing about 165~185 myself and was shocked. The only time I've ever seen anything near that high was when there was areal problem with one wheel. Otherwise I have seen about 100~115 avg.
Kind of have to take everything they say with a grain of salt after that.

[Passin_Thru]

Quit worrying. If they are all the same temp they are normal. Pull the heck out of it. Trouble with technology is it causes more problems that it ever relieves. I am against computers.

Help stamp out help stamp out causes!

[aluminum_flyer]

It was at highway speed (~60 MPH). I know that it was a shorter distance than ideal. I guess what I am looking for is some reassurance that after 40 miles something would have 'blown up' if repacked improperly. Just like when I rebuilt the truck differential... if you make it 10 miles then your good. Otherwise it would eat itself up and spit out metal chunks.

[BurbMan]

Depends on how fast you were going. If you were at 65 mph for a few hours on the road, they would be hotter.

On our trip last weekend, it was in the 90's outside, and the tire temps on my TPMS were 117-123 depending on wheel, so the bearing was probably hotter. I was running at 70 mph.

I don't think bearings get "up to temp" like an engine does, since there is nothing regulating temp except grease and airflow. Overall bearing temp is a function of speed, duration and ambient temps. Assuming all is working weel, the bearings shouldn't get hotter than 165 or so.

[aluminum_flyer]

I know I only went 20 miles, stop for an hour, then 20 miles home. How long do you think bearings take to warm to temp?