As you can imagine, lubrication around the spindle is critical to keep the bearings spinning and to prevent the hub from making contact with the spindle's surface. Grease caps normally do a fine job of keeping grease in place in typical towing conditions. However, on a trailer that's towed through sand or a regularly submerged boat trailer, for example, the grease -- even with properly installed grease caps -- can become contaminated or even washed away completely. That's why you must frequently inspect your spindles for signs of wear.
There are several reasons that you may need to install new spindles on your trailer. For instance, you might have to replace the spindles if your wheel bearings failed, or if your trailer was involved in an accident where the spindles were bent or cracked. Another situation where you may find yourself pondering new spindles is if you decided to build your own trailer axle or even your own complete trailer. After all, you simply can't pull a trailer down the road without spindles -- not very far, anyway.
There are very few bolt-on spindles available; in fact, most spindles are welded to the axle tube. Replacing a spindle requires breaking the existing weld and then welding the new spindle in place. Since welding axle components together probably falls outside of the comfort range of a lot of weekend mechanics, the installation of spindles in the typical homeowner's garage or driveway isn't very likely -- but it is possible.
By no means are we trying to discourage you from attempting a do-it-yourself installation of trailer axle spindles, but unless you're a skilled welder, this may be one of those jobs that are better left to the professionals. It's critical that spindles are properly aligned and secured to the axle. A licensed trailer repair facility should easily be able to install a new spindle or two. Remember, sometimes it may be worth the extra cost to save the time and frustration that can sometimes accompany a difficult (and unfamiliar) repair.
To read more about towing, spindles and other related topics, follow the links on the next page.