A trailer hub cap keeps dirt, water and other debris from getting to the wheel nut. These simple, inexpensive caps are easy to fit and can save a lot of headaches. They're available at most hardware stores, automotive parts retailers and big box stores that sell trailer parts.
Whether you're buying trailer hubcaps to replace worn ones or just looking for some new trailer wheel accessories, it's important to know a few things about them. The type of hubcap, for example, should match the style of the axle. Also, the type of bearing is important. Some are oil-filled while others use grease. If you're unsure what your trailer uses, ask the parts counter person, or read the trailer owner's manual to find out.
It's important to know whether the hub has a parallel or narrow spindle design. Narrow hubs have a smaller diameter than a parallel design. They require a thinner bearing and are only suitable for a limited number of applications. Parallel spindle hubs are the more common on semi trucks and utility trailers.
Many experts recommend buying dust caps to protect the bearings from excessive heat. When these caps are damaged, however, they're a sign of bad adjustment inside the hub or of contaminated grease. Dust caps often come off when removed to check or service the hub or when put back on afterward. They should be replaced whenever they're damaged, even if only a portion of the hub is exposed.
If you're removing a dust cap to check or repair the hub, it helps to jack up the tire first. Then you can tap the dust cap with a wood-and-hammer technique, or with a screwdriver that has a flat tip. It's recommended that you use a non-marring mallet. You can visit this helpful article to learn more about hub caps.
Once the dust cap is removed, the hub and axle nut should be cleaned and lubricated. A light coat of grease is OK, but a heavy coat will make it harder to remove the wheel. It's also a good idea to scrub the axle with a ScotchBrite pad or kitchen sponge with a scrubbing pad to help keep it clean and prevent corrosion.
Then you should install a new dust cap and cotter pin. After that, the wheel should be remounted and the castle nut retightened. The cotter pin should be tightened to the manufacturer's recommended torque setting. It's a good idea to repack the wheel bearings with grease at least twice per year, particularly on trailers that are used in saltwater.
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