How to Repack Boat Trailer Wheel Bearings
Repacking boat trailer wheel bearings is a messy process, but a necessary part of trailer maintenance. You’ll want to have plenty of gloves and a whole box of rags to deal with the greasy mess.
Your boat’s trailer wheel is likely to have one of three different types of caps on the end of it. One is just the standard cap. The second type is the Bearing Buddy setup, and the third one is a cap with a rubber insert and a zerk fitting. For the purposes of this project, we’re focusing on the Bearing Buddy setup found on our boat trailer. Watch the video above or read on below to learn how to repack trailer wheel bearings.
Tools and Supplies - Repacking Trailer Wheel Bearings
- Ratchet and extensions
- Dead blow hammer
- Soft blow hammer
- Bearing packer
- Shop rags
- Side cutters
On this particular setup, if you only fill the grease from the outside, the grease that’s the oldest is what's still running and getting abused on the bearings inside.
So just by adding more grease to it, you're not really flushing the old grease out. And that's the reason you need to repack the bearing so often. The wheel hub grease only has so long of a lifespan. And after a while it breaks down, starts to get contaminants in it from the natural wear of the bearings, and then it fails. If that happens, it’s possible to lose the entire trailer wheel.
On our trailer, there wasn’t enough grease to get the job done, and eventually the outer bearing failed, and ate away the locking nut and cotter pin until the entire wheel came off. This is why we recommend you repack trailer wheel bearings at least once a year.
As for what grease to use, the manufacturer doesn't really matter, but you want to choose a grease with the best rating for a high temperature application. We’re going with a grease that has a high NLGI rating of GC-LB.
How to Repack Boat Trailer Wheel Bearings - Bearing Buddy Setup
Step 1. Remove the wheel from the trailer, followed by the Bearing Buddy, using a soft blow hammer to hit it at an angle to knock it off.
PRO TIP: Clean each area with rags and contact cleaner as you’re taking everything apart to reduce the mess you’ll have to deal with as you go along.
Step 2. Use side cutters to straighten out and remove the cotter pin from the axle’s castle nut.
Step 3. Remove the axle nut, followed by the washer behind it.
Step 4. Remove the wheel hub from the trailer and wipe the axle clean.
Step 5. Pry out the seal and the inner wheel bearing from the hub.
Step 6. Clean out the old grease from inside the wheel hub.
Step 7. Inspect the outer and inner bearing race surfaces to make sure there’s no pitting, imperfections or damage of any kind, and replace them if necessary.
NOTE: Our bearing races were recently replaced and in good shape, so there was no need to replace them again.
Step 8. Replace the wheel bearing seals.
Step 9. Use a bearing packer with fresh grease inside it, then place each bearing (one at a time) inside, tighten it down and hold it in place. Next, apply a fair amount of pressure on it to force the new grease up into it and force out the old grease.
NOTE: You can buy a bearing grease packer at just about any automotive store.
Constant pressure will start pushing out the old grease. Check to make sure the old grease has been pushed out and the new grease has been applied.
NOTE: Grease is pretty viscous, so if it's cold where you are, you may want to consider bringing in your grease up to room temperature. Otherwise you're going to have a tough time forcing out the old grease and getting the new grease in there.
As mentioned, GC-LB grade is a good choice for grease, since it’s super sticky and lasts a long time.
Step 10. Load up the bearing race in the inner part of the hub with some fresh grease, then drop in the inner bearing.
Step 11. Tap in the new bearing seal flush with the hub.
Step 12. Pack in the area in between the bearing and the seal with grease, making sure you get it all the way around the seal itself.
Step 13. Inspect the axle for pitting and other damage. Use an emery cloth and some contact cleaner to clean up the axle.
NOTE: If the axle on your boat’s trailer has pitting like ours does, it will eventually need to be replaced because it's going to eat through the seal faster than it should.
Step 14. Grease the axle, then reinstall the wheel hub. Turn the hub while you're placing it over the end of the axle so it doesn't grab one of the edges of the seal and pull it in the wrong direction.
Step 15. Install the outer bearing, washer and castle nut onto the axle, then hand-tighten the castle nut just enough to snug it up, and rotate the hub a couple of times.
Step 16. Rotate the hub as you’re tightening the castle nut with a socket and wrench to force out a little bit more grease and seat it against the race. Next, back it off about an eighth to a quarter of a turn to where it has just a little bit of play but spins easily.
Step 17. Install a new cotter pin onto the castle nut.
Step 18. Install the Bearing Buddy by gently tapping it in first with a dead blow hammer, then wiping off the excess grease with a rag, and using a soft blow hammer to get it seated properly.
Step 19. Use a grease gun to fill up the cavity of the Bearing Buddy just for good measure, then install the Bearing Buddy cover and you’re done.
