Wheel bearings may be the single biggest source of anguish for trailer boaters. Trust me when I tell you, there is absolutely nothing like the shock of watching one of your trailer’s wheels pass your tow vehicle while cruising down the highway. With the proper preventive maintenance, this will never happen to you.
Preventing Rust Trailer Axels
The main problem with trailer bearings is that any air pocket in the hub cavity will contract when a hot hub is submersed in cool water. This forms a vacuum, which invites saltwater through the rear seals. By assuring there are little or no air pockets in the hub, trailer users can prevent this sort of destructive contamination. To avoid a potentially disastrous situation, your trailer wheel hubs should be repacked no less than once a year, and rebuilt whenever bearing damage is suspected.
Clean both bearings and hub with a cleaning fluid – acetone or mineral spirits work well.
To inspect and repack the hub, the trailer should be jacked up on a level surface – be sure to use jack stands. Remove the lug nuts and wheel, then remove the dust cap with a dust cap puller or a flathead screwdriver.
Now, remove the cotter pin or other locking device and take off the axle nut. The hub should slide off, but be careful not to allow the outer bearing to fall out Image 1. Turn the hub over and remove the inner seal with a seal puller Image 2.
You can also drive it out with a punch from the front side. Don’t worry about damaging the seal, as they should always be replaced. Clean both bearings and hub with a cleaning fluid – acetone or mineral spirits work well. Once the parts are clean and dry, inspect for any scoring, pitting, or discoloration. Check the races that are still in the hub as well and if there is any sign of damage, the entire hub should be rebuilt. Image 3 (Removing Races), Image 4 (Installing Races)
If all the parts appear in good condition, proceed with the repacking process. First repack the bearings with marine-grade grease. If you do not having a bearing packer, you can use the old method of putting a glob of grease on your palm and scraping the edge of the bearing across the grease Image 5. Make sure you do a final wipe of the hubs’ inner surface to remove any dust and grime.
Start with the hub lying bottom up on a bench. Apply a glob of grease to the inner race and hub cavity. Now insert the inner bearing into its race while turning the bearings’ taper to match the races’ taper. Take the new seal and drive it flush with a block of wood and hammer. Turn the hub over to the front and repeat the process with the outer bearing. You want the hub to be full of grease. Before you install the hub make sure the spindle is clean and free of damage. Any slight imperfections may be sanded with an 80-grit emery cloth Image 6. Grasp the hub with both hands and use your thumbs to prevent the outer bearing from falling out Image 7. Gently slide the hub onto the spindle until it is fully seated. The spindle may push out excess grease, but it can be used later when remounting the dust cap. Install the axle washer and the axle nut. Tighten the nut while turning the hub, then stop and back off to the next castellation; install the cotter pin. You never want to over-torque a hub, but you don’t want any noticeable endplay. Pack the dust cap with the extra grease and install it with a dust cap driver. While the entire process may sound difficult, with the right tools it is actually quite easy. If you don’t feel comfortable doing the job yourself, it is best left to a professional.
Posi-Lube or Accu-Lube axles have grease fittings drilled into the end of the spindle. The grease enters the hub from just behind the rear seal and will force the old grease and dirty seawater out of the hub.
An easy way to check your bearings before any trip is to jack up your trailer and give the wheels a spin. The tire should spin smoothly and silently. Now check the endplay. There should be no more than 1/16” at the end of the wheel.
Bearing Protectors are handy for keeping the dust cap full of grease but do little to expel any water or contaminated grease. Bearing Buddy (www.BearingBuddy.com) is an effective protector but care must also be used, as too much grease can blow out the inner seal.