Pop-up Wheel Bearings

The pop-up trailer was making some noise when rolling slowly. It could have been the brakes, but it could also have been the wheel bearings. As this used pop-up was new to us, and I had no evidence that anyone had checked the wheel bearings recently, I thought it would be a good idea to undertake the task. It is not overly complex, but it is dirty. I highly recommend wearing disposable gloves for this project. The amount of grease that gets on the gloves is substantial, and without the gloves you'd probably have to belt sand your hands to get them sanitized.

1. Chock the wheel that you are not working on.

2. For the wheel you are working on, loosen the lug nuts a bit while the weight of the trailer can keep the tire from rolling.

3. Jack up the trailer. The nice thing about a trailer is its mostly frame underneath, so finding a place to place the jack is pretty easy. I would generally recommend putting jack stands in as well, as they offer a bit more security should the jack itself fail.

4. Take off the lug nuts completely, and remove the wheel to expose the hub. On my camper, the hub includes an electric braking system, so what I saw was a brake drum.

5. At the front of the hub is the dust cap, this is what you see outside the wheel, unless you've got really cool wheels on your camper. This dust cap needs to be removed so that you can get all the pieces off of the hub. Use a flat blade screwdriver or chisel and gently tap the seam where the dust cap rests against the hub. Rock the blade back and forth a little bit to separate the dust cap from the hub; a little bit of work should loosen it enough to pop off with your hands.

6. With the dust cap off, you can see a large nut that holds everything on the hub. This nut is a hex nut, but it has some grooves built into it. The purpose of the grooves is so that a cotter pin can be inserted through the hub and in one of the grooves. The cotter pin prevents the nut from rotating. The cotter pin needs to be removed, and then the nut can be backed off. It shouldn't be too tight, but it is a big nut, so you may need a channel lock or a pipe wrench.

7. With the nut off, the brake drum should slide off. From inside out, the parts should be: washer, outside bearing/race, inside bearing/race, grease seal. The first two are actually right under the nut, so they can fall out when you start pulling the drum off the hub.

8. Getting the outside bearing/race out is easy, it just comes out. The inside bearing/race is something different. The grease seal on the back can be seen on the back side of the drum, but it's pressed into the cylinder, so it's hard to get out. I had an extra piece of 1x2 wood, so I cut that down so that it would fit into the cylinder (the bore in the drum into which the hub slides) and push up against the inside bearing. I sprayed a bit of WD40 on the grease seal seam, where it mates with the bore, and then I got a hammer and started tapping/hitting the wood block. The bearing pushes against the grease seal, and pops it out.

9. With both bearings removed, it's time to clean the grease. Use a rag that you don't mind disposing of to wipe off the grease in the bore and on the parts. This will get some, but by no means all of the grease off. Use brake parts cleaner to do most of the work. While the drum is off, there's no reason not to clean the inside surface. You can also soak the parts in some sort of mineral spirits or some other non-polar solvent (alcohol won't work well here) to try to loosen things up.

10. With everything clean, it's time to re-grease everything. Greasing the bore is easy, it's like buttering bread, but with a non-appetizing, red butter. Clean the hub also, and grease it up too. The bearings, though, need to be "packed."

11. I didn't have a bearing packer tool, so I had to do it the old-fashioned way. Grab a dollop of grease, and put it in your hand, and then force it into the bearing. You don't just want to coat the outside of the bearing, you need to get the grease into the bearing. I rolled the bearing, twisted it, grabbed more grease, and generally just made a mess of the bearing with grease in order to get it well greased up. Fortunately, grease is cheap, so even if you leave some on your gloves, rags, newspaper, or garage floor, you're not out much money.

12. Reassemble the inside bearing/race assembly; this amounts to dropping it in place. Make sure there is grease in the bore (and its race).

13. Re-install the grease seal. I used a wooden block and a hammer to press/pound the grease seal back into place.

14. Flip the drum over and put the outside bearing back in the bore, and then re-install the drum over the hub.

15. Put the last washer on, and then the locking nut.

16. Tighten the locking nut a few times with actual force, I used a pipe wrench. You'll feel the bearings squish down and you may hear some grease squeezing around. Do this a couple of times, and then back the nut off and tighten it lightly against the washer.

17. Install the cotter pin.

18. Re-install the dust cap. Your drum should be back on now with newly packed bearings.

19. Put the wheel back on, tighten the lug nuts, remove the jack stands, and lower the trailer back down onto the ground. Make sure the lug nuts are tight.

20. You've done one wheel, the other side is identical. If you're a little tired from any exertion, then wash your hands and grab a proper drink. Then attack the other side.