Hot Hubs & Trailer Bearing Grease

When you check the temperature of your trailer hubs, how hot is too hot?

In the past I'd touch a lug nut. If I could hold my finger on it I was happy. Then I started using a non-contact thermometer and could get an instant digital reading. I always stop about 50 miles into a trip for the first bearing/tire check. And I stop about 50 miles later for another check. If both times the readings are under 100° I don't plan any more regular stops, but do check them at any rest area or gas stop.

If the readings are between 100 and 200°F I'll check every hundred miles or so. Temps can easily get this high during hot summer months in traffic with a lot of braking or during downhill compression braking with surge brakes. If your hubs don't ever get hot, your brakes aren't working. I've seen 300° on a drum brake that ran thousands of miles without attention after it was 'unadjusted'.

When any check shows a hub temp over 250F it's time to be concerned (like in the dragging 300° brake above) but if you've done a yearly bearing re-pack, it's usually a dragging brake. Surge discs were a nightmare for me. They were constantly overheating due to brake drag from sticky calipers that aggravated a "tight" spindle nut.  We see smoke in the rear view mirror, or worse yet experience the wheel coming off the trailer. We quickly pull over to the side of the road. No wonder I've got a problem...all the grease ran out -- there's grease all over the place.

In my experience that's the thinking that allows this to happen again and again. More grease. More grease. Pump grease in before, during and after every outing to fix the problem. I've got news, the grease doesn't just decide to leave the hub on it's own. It's heat that that makes it fluid enough to escape.

Sure, the heat can come from a bearing that rusted from being waterlogged, but you'd catch that on your annual repack, likely before it became a real problem - unless of course you give your Bearing Buddies a few pumps and drag the boat off the lot after it's been sitting for a couple years.

Today there's even a better method to keep tabs on your trailer tires/hubs. It's a TPMS which allows you to see the tire pressure in your trailer tires and the temperature at the valve stem while you drive. It alarms if the pressure drops more than a few pounds in a few minute or immediately if there's a blowout.
Click here for TPMS info.

Then I discovered the Posi-Lube / EZ-Lube systems I thought they were the perfect companion to my TPMS.
Posi-Lube
EZ-Lube

Now I could repack my bearings without any dis-assembly. I could tell if the grease coming out was contaminated, and only if it was would I need to dis-assemble the hub. What a blessing!

Turned out that I bought a boat/trailer that didn't have the Posi or EZ Lube convenience. My first thought was, "I'm getting new modern axles - I'm not going to dis-assemble four hubs every year."

I towed many thousand miles during which I upgraded the springs and tires on the trailer but there was never a good time to replace the axles. In preparation for our second trip of 2,000 miles towing to Lake Powell from SC I pulled the dust caps to see if there was any water getting into the bearings that I had replaced only a few hundred miles ago. One of the dust caps had a ruptured rubber plug and the grease in that hub was a slightly lighter color.

I'd seen this before and it never amounted to more that a little water getting to some grease  in the outer part of the hub. And if I'd had an EZ-Lube hub I would have just 'repacked' the bearing. But because I was planning a 2,000 mile road trip I decided to pull things apart and make sure everything was all right.

This is what I found:

If I'd had EZ-Lube axles and conveniently repacked this bearing, I never would have found this problem but who knows, maybe it could have endured until I inspected things a year later?

This find bothered me, so I decided to visually inspect the components of the other three hubs...and lo and behold I was glad I did.

There was galling on another bearing. I replaced the Chinese bearings in all 4 hubs with American made Timkins. The 4,000 miles out and back to Lake Powell was uneventful.

The moral of the story is, that even if you have the most sophisticated hubs, there's no substitute for visual inspection.