Wheel hub temps & why does my back axle run hotter?

[SilentSeven]

So I remembered I have one of those laser temp guns...you know...the kind you can point at something and it will report the surface temperature. Figured that would be a great way to actually monitor my axle hub temps to see what they are are and if any particular hub is running hot - a early warning sign of problems to come.

So coming back from a 90 mile tow this weekend I pulled in, grabbed the gun and shot each hub. My front hubs on both sides are about 100 degrees and my rear hubs are both just over 115 degrees. Now not thinking this is really any issue but this is the second or third time I done a temp check like this every time the rear axle is running a little warmer.

Any ideas on why? Only theory I have is that the rear wheels scrub more on turns and maybe that puts more load on the hub...outside of that, no real idea.

Some details on the setup. DHM brand. Same axles and hubs on all 4 corners. Disc brakes on all 4 corners. Same brand of tires. All hubs have been rebuilt and are in good condition. Spring loaded grease caps on all 4 corners (however not the same brand).

BTW...I've now made the laser temp gun a permanent fixture in the side pocket of the drivers door right next to the air pressure gauge. Decided it's a super easy way to keep tabs on hub health.

[SatherG230]

Is your trailer riding level? I haven't checked mine with a laser temp gun yet, but will in the future, thanks to your suggestion... My front hubs were running hotter this trip but I was thinking that it is because my trailer was riding a slight bit lower in the front since we were loaded down.

[srock]

Is your trailer riding level? I haven't checked mine with a laser temp gun yet, but will in the future, thanks to your suggestion... My front hubs were running hotter this trip but I was thinking that it is because my trailer was riding a slight bit lower in the front since we were loaded down.

This is more prevalent in torsion axles where its more important to be level for an even loading.

[shag]

Maybe the different brand spring loaded grease caps have a different compression spring rate. At any rate, 10-15 degrees isn't much.. I doubt I would notice it using my hand..

[SilentSeven]

Is your trailer riding level? I haven't checked mine with a laser temp gun yet, but will in the future, thanks to your suggestion... My front hubs were running hotter this trip but I was thinking that it is because my trailer was riding a slight bit lower in the front since we were loaded down.

Interesting question. Trailer is mostly level, maybe just bit down in the nose. I would suspect that would increase the load on the front axle.

Maybe the different brand spring loaded grease caps have a different compression spring rate. At any rate, 10-15 degrees isn't much.. I doubt I would notice it using my hand..

Right. I can't rule this out. I do have new caps to update the rear axles to match the fronts; I just haven't put them on yet. The fronts are quality Bearing Buddies...the rears are some sort of no-name brand that came via the PO. The temp diff is notifiable with a finger check but it's not much. That's when I got the inspiration to use the laser temp gun to see if my my finger was lying or not.

[philb]

it might be that the front hubs are seeing cleaner air where as the rears are getting a little less as they have something in front of them.

[SilentSeven]

That's a pretty reasonable hypothesis!

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