By Jim Kerr
Legend has it that love makes the world go round, but when it comes to vehicles, it is small bearings that keep things turning. With summer soon here, there will be many drivers towing trailers again. It may be a small utility trailer to get landscaping supplies, a boat trailer for some fun at the lake or a travel trailer for some adventure across the country. Unfortunately, I have often seen many trailers stranded on the side of the road because of failed wheel bearings. Some maintenance now can save a lot of grief later.
First of all, it is seldom that a bearing itself actually fails. Bearings are precision manufactured devices and when installed properly, they can easily have a life span of over 300,000 miles. When a bearing does fail, it is usually because of either impact damage or rusting of the bearing components.
Impact damage can occur a few ways. When a trailer or vehicle is shipped, if it is tied down too tight to the vehicle carrying it, this places a high load on the bearings. The rhythmic vibrations set up by the moving vehicle cause a slight impact wear on the bearings called brinelling. If you visually inspected these bearings, they would have slight wear bars across the face of the bearing races from the impact. When you tow the trailer, the wear on the bearings gets worse and the bearing surfaces start to fail.
Impacts can also damage a bearing. Sliding a tire into a curb or hitting a deep pothole at speed, especially with the brakes locked, can damage a bearing. The best way to find impact damage is to remove the wheel hub, clean the bearings of all lubricant and rotate the parts together by hand. If you can feel any roughness, then look for damage. If you can feel roughness, the bearing should be replaced.
Rust can destroy bearings quickly. Older, high mileage vehicles may have worn wheel bearing seals that will allow moisture into the bearings, but boat trailers are particularly prone to rust damage. When a bearing rotates, it creates heat in the bearing hub. When you back the boat trailer into the water to unload the boat, the water cools the hub and air inside the hub contracts, pulling water past the wheel seals. Avoid backing axles into water, and if you have to such as with a boat trailer, let the trailer hubs cool for a short while first and then repack the bearings often to help remove water that has entered.