If wheel bearings are sealed, why do they need to be repacked every year?

By Dave Solberg
Dear Dave,
If the wheel bearings have been serviced and are sealed, why do some people say they need to be serviced very regularly? I have been pulling trailers of all kinds for years, and as long as there are no seals leaking, you’re good to go. Obviously, if there’s an issue or if you’re doing brakes, then I would, especially if the trailer sits a lot. What’s your take? Thank you. —Chris

Dear Chris,
Most axle manufacturers recommend repacking the wheel bearings once a year or every 12,000 miles, and some as early as 10,000 miles. I personally think that there are so many variables that can affect the performance of bearings—such as extreme heat, temperature changes that can create interior condensation, and weight—that the axle manufacturers are erring on the side of caution.

For ten years I ran a company that had three trucks and trailers that installed commercial pressure washers in fast food restaurants around the country. Each truck would log more than 100,000 miles each year in some very extreme conditions, and we learned a lot about bearings, axles, and maintenance.

Cheap bearings aren’t worth it

What we found is quite a range in quality of bearing, axles, grease, and even the workmanship of repacking the bearings. The “discount” trailers we started with had cheap bearings that we had issues with from the very beginning. We had bearing issues before 5,000 miles, and most of the time it was a repair on the side of the road.

We then used an infrared thermometer to measure the temperature at the hub and brake drum to verify what was happening inside the spindle. If the ambient temperature was 80 degrees, it was not uncommon to see 100 degrees at the hub. However, when the temperature spiked to 180 degrees or more, it meant the bearings were getting dry or were compromised and needed to be addressed.

I can tell you it’s much less expensive repacking wheel bearings in a service center than it is replacing an axle on the side of the road!

We also would pull the cap after each trip and inspect the grease and verify the nut and spacer were in place, and we often found condensation and rust due to temperature changes. We also found there was quite a difference in the quality of grease. However, it typically applied more to the heavy-duty use we put our equipment through.

More expensive equipment is worth it

More expensive axle spindles and bearings, such as the Dexter E-Z Lube, have superior performance since you can periodically apply grease through the zerk. That pushed the grease through the middle of the spindle and forced it through the back bearing out to the front, which helped lubricate and displace moisture. However, even Dexter recommends cleaning and repacking the bearings every year or 15,000 miles.

So, to answer your question, I feel the variables of heat and condensation combined with the quality of the bearing, grease, and workmanship warrant repacking once a year or 15,000 miles. I feel that running longer than that would be pushing the limit. Could you go longer? Yes. Have I gone longer? Yes. But I have also had to replace bearings on the side of the road.

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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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