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  1. Servicing Utility Trailer Hubs

    I initially wrote this up in 2009. Click on the small pictures in the post for a full sized view.)


    Since I got a set of new load range C tires to put on my utility trailer, I figured it might be prudent to pull the hubs apart and service them while I had the old tires off since I had not done so yet and the trailer is rather old. I have monitored the temperature of the hubs and tires whenever we stop and they have always been just warm - the passenger side a little warmer than the driver's side, but not more than what I'd consider normal. Still, it sat for years and years in a garage without moving before I got it, and grease doesn't last forever.
    I had already done the driver's side before I took these pictures while doing the passenger's side.

    First, assemble your tools and supplies. You'll need some basic hand tools, a lug wrench and jack, plus grease, paper towels, a set of bearings and outer races (if you're going to replace the bearings), and a set of grease seals. The old seals will be destroyed when they are removed, so you'll need the seals for sure.
    [attachment=85459:image.jpg]

    Next, loosen the lug bolts while the trailer is on the ground, jack it up, and remove the bolts and wheel. I gave the hub a spin and while it rotated easily, it was pretty noisy, much more so than the other hub. Not a good sign:
    [attachment=85457:image.jpg]

    Use a hammer and cold chisel or screwdriver to pop off the bearing cap. I was somewhat dismayed to find water. You don't want to see that. The other hub I already did had very little grease but no water:

    [attachment=85458:image.jpg]

    Use a pair of pliers to straighten out and remove the cotter pin then unscrew the castellated nut. There may or may not be a washer under the nut; if so, remove it as well. This trailer didn't have a washer. Wiggle the hub to dislodge the outer bearing then remove it. Note the presence of more water. I was beginning to be thankful that I got a new set of bearings:

    [attachment=85460:image.jpg]

    Use the paper towels to clean off all traces of the old grease from the axle and inspect it. I found some signs of previous damage that had been cleaned up:

    [attachment=85461:image.jpg][attachment=85462:image.jpg]

    Pop out the old grease seal then remove the inner bearing. Clean all of the old grease out of the inside of the hub. If you will be replacing the bearings, use a punch to drive out the old outer races, if not leave them in place. If you will be reusing the bearings, make sure you keep track of which one was the outer and which one was the inner, so you can put them back where they came from. You can wipe as much of the old grease off then clean them up in a solvent tank if one is available. Here's what the inside of the hub looks like:

    [attachment=85463:image.jpg]

    I was not surprised to find signs of damage to the races, more so on the inner than the outer:

    [attachment=85464:image.jpg][attachment=85465:image.jpg]

    All that material had to go somewhere - closer inspection of the "good" parts of the inside bearing's outer race showed a pattern of dimples, caused by the flakes of metal being pounded into the bearing surface by the rollers:

    [attachment=85466:image.jpg]
    Using a soft steel punch, drive the new outer races into the hub after lightly greasing the OD of them. Make sure to drive them down evenly and verify that whatever you use for a punch is not hardened or you could damage the races. An arbor press and a piece of rod just smaller than the bearing OD works best, if you have one - I don't. The races MUST be driven down until they seat against the shoulder or stops; if you don't, they will work their way in until they do, and your bearings will loosen up.
    This hub was different than the one on the other side - it was stamped steel and had a series of dimples pressed into the hub to act as stops for the outer races. Kind of cheesy, I thought. The other hub was a casting with a machined shoulder for the race to seat against. The bearings were of different brands, as well - Timken on the driver's side, SKF on this side.
    With the different hub designs, different bearings, and signs of damage to the axle on one side, I am guessing that at some point they lost a bearing on the passenger's side and had to clean up the axle and replace the hub.

    Here's a look down the hub at the new outer race up against the stops:

    [attachment=85467:image.jpg]

    Next, it's time to pack the bearings with grease. Make sure your hands are clean, then scoop out a gob of grease about half the size of a golf ball and place it in the palm of your left hand, if you are right-handed:

    [attachment=85468:image.jpg]

    Grasp the bearing in your right hand so that the larger part is facing your left palm, then use it to begin nibbling away at the grease with a scooping motion. Continue to scrape the bearing against your palm toward the heel of your hand, so that the grease is forced up into the space between the inner race and the cage. If you are doing it right, you should begin to see grease oozing up between the rollers and into the gap between the cage and inner race that is facing you:

    [attachment=85469:image.jpg]

    Rotate the bearing and continue to pack it with fresh grease until the entire bearing is filled. When it is, you can set the first one aside then pack the second one and drop it into the inner side of the hub:

    [attachment=85470:image.jpg]

    Set the new seal over the inner bearing,:

    [attachment=85471:image.jpg]

    Then carefully seat the seal into the hub. Be sure not to cock it in the bore, and don't drive it in too far or it will contact the bearing. Using a large socket and a press works best, but if you are very careful you can use a hammer:

    [attachment=85473:image.jpg]

    Scoop up some grease and smear it into the space in the center of the hub between the inner and outer bearings. Don't be stingy. Grease up the axle shaft where the seal rides and the seal lip, then carefully slide the hub onto the axle. Push and turn to get the seal lip up onto the area where it rides, then slide on the outer bearing, washer (if used), and start the castellated nut:

    [attachment=85475:image.jpg]

    Tighten up the nut while rotating the hub to help squeeze most of the grease out of the bearings. Continue tightening it with a moderate amount of force to ensure that the outer races are securely seated, then back it off to the next opening in the castellated nut lines up with the hole in the axle for the cotter pin. You want to make sure that there is not excessive play in the bearing, but also that it is not too tight. With the tire attached, you should just barely be able to feel some movement when you rock it from side to side. Once the bearing preload is set, install the cotter pin and bend the end over so that it does not contact the hub or bearing cover. Make sure the bearing cover is clean then put a gob of grease inside and using the hammer, tap it onto the hub. Install the tire, and you're all set:

    [attachment=85476:image.jpg]

    Don't forget to tighten the lug bolts securely once you get it on the ground. After using the trailer it's a good idea to torque down the lug bolts again and also to jack it up and check the bearing preload by rocking the tire as if you were trying to make it steer. If it loosened up, you'll need to remove the bearing cap and cotter pin then tighten up the castellated nut and reassemble.

    Easy!

    • Dec 23, 2014 07:39 PM
    • by Oo-v-oO
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