Trailer Maintenance: Bearings.

Posted By: KeithD
Date: 11/1/99 6:28p.m.

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Trailer maintenance: Bearings Wheel bearings are nifty little things, they are simple, quiet and very rarely give any trouble (when kept properly maintained). Here I propose to discuss what to look for when you are doing a bearing inspection, and what those things can tell you about what is going on under your boat. A lot of this is stuff I learned from the board, not just my own experience. As always feel free to disagree and, if necessary, correct. Please forgive any facetiousness, as when I do this for work, they won't let me cut loose. Tools: Jack, jack-stands, hammer (either plastic or steel), either a large adjustable wrench or a large pair of waterpump pliers (Channelocks) , needle-nose pliers, medium-size standard screwdriver, bearing grease (heavy duty-marine grease preferred), Solvent (paint thinner, lacquer thinner or acetone, paint thinner is best) a shallow tray for the solvent (pie tins work great but don't get caught sneaking it out of the kitchen) spare cotter pins, rags, brass drift, or a punch with a flat end on it, patience, latex gloves (If you are squeamish about icky grease on your hands), enough time to do the job right. Bearing Buddy Removal: These come off the same way that the little dust caps on your old Dart did, they are a press fit into the end of the hub, and unless the hub gets very warm, shouldn't fall off. To remove them, either jack up the trailer and spin the wheel around as you tap on the side of the Buddy with a plastic hammer or a wood block and a steel hammer, or if you don't want to use the jack just yet, tap it on the 4 major points of the compass, alternating E,W,N,S or in whatever order you choose. Just don't hit it too many times on one side. If it gets cockeyed in the hub it could damage one of the surfaces that hold the Buddy in place. If you are going to take the wheel off the hub or drum, loosen the lug bolts or nuts. Jack the trailer up, put the stands under it, and let the trailer down onto the stands. remove the wheel. Place a clean rag flat on the ground close by so that you can easily reach it to place parts on it. Put another rag close to wipe your hands. Remove either the dust cap or Bearing Buddy. First look under the cap: What color is the grease? Is it pretty close to the new grease you have handy? If it started out black, brown or green, and is now a lighter shade of that color, kind of milky, you probably have sucked water into the bearings at some point. Time to repack and figure out how it got there. If you have Bearing Buddies, you may just not have put enough grease in them to keep the water out. If you don't have them, you may have a bad seal, or you just may be dunking a too-warm hub into the water where you sail. When you get to the ramp, give the hubs a chance to cool off before putting the trailer under the water. This will keep the grease inside from rapidly cooling and drawing water in past the hub and dust cap or bearing buddy as it cools. (An aside on bearing buddies) Bearing buddies are kind of neat. The way they work is this: The grease and air inside the hub get warm and expand, pushing the outer cup out against the spring. When they cool down, either by a quick dunk in cool water or by normal cooling down after a trip, the grease and air contract, allowing the cup to move in towards the hub again. When greasing this type of hub, you should make sure that you put enough grease into it that the cup is pushed up off of its bottom resting position. This way, there is a little "cushion" when the bearings cool, so that a vacuum is not created inside the hub which will draw water into it. Too much grease on the other hand, will compress the spring and hold the cup out against the clip-ring, and not allow any expansion to push it out any farther. This will result in grease leaks, and it could even squish enough grease out that when it cools, it pulls water in. If you have bearing buddies or a similar contraption, check with the manufacturer for the proper greasing procedure. There are many different ways of securing the nut to the spindle to keep it from rotating. If these methods didn't exist, the nut on the right spindle will keep getting tighter and tighter, and the nut on the left one would just spin off. (this is why your old Dart had left-hand lug nuts on the left wheels. At least til they discovered it wasn't really necessary) Either one will make a mess. Some spindle/ hub combos have a simple nut with notches in it called castellations. A cotter pin fits into one of the notches and through a hole in the spindle to keep the nut locked in place. Another type has a special washer that goes over the outside of the nut, and has the castellations in it for the cotter pin to lock through. Another kind has a thin washer as well as a thick one behind the nut. The thin washer has arms that bend up around he nut to secure it in place. None of these locking methods will do any good sitting in the tool box. If you forget to put it on, it probably won't be OK, fix it. Remove the cotter pin with the needle nose pliers. You will probably have to bend the little arms on one end back at least close to straight, then pull it out by the rounded end. If you have the kind with the washer that has the arms bent up around the nut, use the screwdriver to pry the arms away from the nut enough to unscrew the nut. Check the cotter pin. If it looks like it has been bent more than a few times, or is just plain ugly and you don't like it, toss it. You have spares, right? Put the cotter pin on the rag along with the dust cap. The nut may be tight enough that you need to break it loose with the adjustable wrench or pliers. Loosen and remove the nut. Watch to see whether the washer comes along with the nut or if it stays on the bearing as you remove the nut. Put these pieces on the rag with the cotter pin and dust cap. Usually, the hub falls down just about as you get to the rag with the nut, and you think it is going to fall off. It probably won't but you are almost guaranteed to turn your head and look. Don't worry, be happy. If the hub has fallen forward a little, push it back on and remove the outer bearing, if not give the hub a little tug out, and the bearing will slide forward, then push the hub back on, and remove the bearing. Place it in the pie tin. The hub is a bit heavy, especially if you have drum brakes. (All this is the same for disc brakes BTW, except that you have to remove the wheel and caliper before you start on the hub) Pull the hub towards you (drum brakes may have a bit of grab to them and if needed, adjust the shoes away from the drum a little) and slip the hub off the spindle. Place the hub on the rag with the outside face up. With the Brass drift or flat punch, reach in through the hole in the center of the hub and place the punch against the outer cage of the inner bearing. Don't know what I am talking about? Look at the outer bearing. It has a center race, the rollers, and the outer cage. The outer cage holds the rollers in place when it is not in a race (remember the wheel bearings in your skates? Gosh what a pain putting THOSE back in was eh?) With the outer bearing in your hand the smaller diameter facing up, you can see that the outer cage sort of goes up over the top of the rollers. This is the place you are reaching for on the inner bearing when you are reaching with the drift or punch. Anyhow, place the punch through the hub onto the outer cage of the inner bearing, and hold it firmly in place. Then, take the hammer, and strike a sharp blow to the punch. If the bearing and seal don't fall out the bottom, move the punch to the opposite side 180 degrees from the first position, reset the punch and hit it again. It usually won't take more than 2 blows to knock the bearing and seal out. Pick up the hub, and the bearing will be laying there, on top of the grease seal. Put the bearing into the pie tin, and unless you are using acetone or lacquer thinner, put the seal in too, then pour in some of the solvent. Just use enough to cover the top of the bearings. Swish the bearings around in the solvent, and go get a soda. Soaking is good for them, really. If you are impatient like me, you can put on your safety glasses and gloves, and wipe the bearings and seals off with a rag really good before you pour in the solvent, and there will be less for the solvent to have to clean. A small bristle brush or toothbrush works pretty well for getting the grease off the outsides of the bearings. If you place a couple of fingers through the bearings and spin them in the solvent, it helps to get the grease out of the insides as well. If you have compressed air handy, you can blow more of the grease out of the bearings, but for gosh sakes, DON'T let the bearing spin on the race when you are blowing compressed air on it. I know it makes a really neat noise and all, but DON'T DO IT. The cage could break from the centrifugal force, allowing the bearing rollers to become shrapnel INSTANTLY. And you thought I got this dent in my forehead in 'Nam. An alternative to compressed air is aerosol brake cleaner available at any auto parts store. Wipe the seals with a rag and inspect them for any cracking or splitting. There is a tiny spring that encircles the part of the seal that goes on the hub. Make sure this spring is still good too, not kinked or broken, as it is what keeps the rubber against the metal, keeping the seal...... sealed. Clean the races in the hub. I use Easy-Off. Just spray it on, and go watch some TV, then come back and spray it off, the grease comes right off. This works better the warmer your neighborhood, so if it is chilly where you are, just watch two shows instead of one before getting out the hose. Follow that with some spray brake cleaner and you are styled out. Once the races in the hub are cleaned, you can inspect them. Optimally, they should be satiny and silver. Any discoloration such as a yellow, brown or blue color would indicate overheating of the bearings. A slight yellow shows that they got warm, brown would be quite warm, and blue would be glowing hot. If there is no visible scoring or scratching of the surface, and the races are shiny silver (they don't need to be mirror smooth, that would be too smooth and not allow the rollers to roll) then you are OK to use them. If they are discolored, then they got hot, and heat tends to remove the hardness of the metal leaving you open to little pieces of the race coming off and turning the bearing into a grinding with all the possible consequences of that. To remove the races, you need a punch with a flat end, a hammer and a good sturdy surface (such as a driveway) to place the drum on. Inside the hub where the lip that keeps the race from going too far into the hub is, you will find usually two cutouts in the lip. This is where you place the punch to drive out the races. Hammer them evenly back and forth until they fall out. The outer race comes out the outer end of the hub, ad the inner comes out the inner end. For installing races, you should have either a bearing race installing tool or a lot of patience and a brass drift. I use an aluminum block 1" thick and about 4 inches long that is just wide enough on one end to fit inside the hub to start it, and follow that with a brass drift. I also feel better when I put the races in the freezer for a while before I put them in. I doubt 30 degrees is enough to really make the race smaller, but it makes me feel better. When driving the races in, make sure that you start the race square to the hub. That is where I use the aluminum block. On its flat side, it is big enough to cover the whole race. I hit it dead-on in the center over the race until I can't go any further. The block has a notch in it on one end to fit inside the hub. I hit, then turn it 45 degrees and hit it again until the race is seated against the lip in the hub. Then I follow with the brass drift all the way around. You can tell when the race is all the way down because the hub will make a nice ringing sound like you are just hitting on the hub. Be careful to not ding up the seal seating area around the inner bearing, or the cap seating area around the outer bearing. After the races are installed, wipe them down with solvent to get rid of any junk that may have come off the rag or block. Bearing Packing: This is the fun part if you like to get your hands dirty. Take two fingers and scoop a generous amount of grease out of the container. Place it into the palm of your other hand, smearing it around to cover the palm. Take your bearing and hold it so that the larger end of it is facing towards the greas in your other hand and starting from the heel of your hand, scrape the grease off your hand into the bearing When grease comes out the top of the bearing like in the Pla-Doh extruding set you had when you were a kid, turn the bearing and repeat this process, turning the bearing and scraping, until the bearing is completely filled with grease. Alternatively, there are automatic dealies, air powered grease-gun or hand powered that you can buy to automatically pack the bearings. I prefer to get my hands all greasy so I do it by hand, it really isn't too icky. Put a thick coating of grease all around the bearing after you are done, and set the bearing aside on a clean rag. After all the bearings are packed, it is time to install them. Inner bearings first. Place the hub outer side down on a clean rag (no, I don't own a rag factory) Place the bearing into the hub and place the seal over it. Make sure that the seal is facing the proper way with the flat metal part up, cover the seal with another clean rag and gently hammer it down into the hub. I use the same aluminum block as an installing tool for the seals as I used for the races. The seal needs to go down square with the hub, and should not be dented or kinked after it is all the way in. Most hubs only require the seal to be driven flush with the hub surface, so you don't need to use a drift to pound it down into the hub. Usually the seal will have a green or red paint around the outer diameter which will be scraped off as the seal goes in. This flaky mess can be wiped off after the seal is in and is no big deal. Once the seal is in, I usually add some grease behind the bearings. I just take a scoop of grease with my fingers and squish it around the bearing inside the hub and try to force it all around the bearing. Installing the hubs: Now is a good time to lube up the pivot points of your brakes since, hopefully, you won't see them for a while. White lithium grease is a good lube for this because it is heat resistant, and won't run off the brake backing plates onto the shoes when they get warm from use. Anti sieze compound like Nev'r Seez is also good because it helps resist corrosion too. Just a little dab will do on each of the points where the brake shoes slide, the threads of the adjusters, and any points where the actuating mechanism moves. Put some grease on the spindle where the seal rides, and on the bearing surfaces. The seal has a sharp edge of rubber that keeps the grease in. This sharp edge works a little bit like a windshield wiper to keep the grease from escaping out onto the boat. If you don't lube the sealing area at least a little, the seal could "grab" on the spindle, and wear out prematurely. Slip the hub onto the spindle, and hold it centered as you position the outer bearing onto the spindle. Now, take your washer and place it over the spindle followed by the nut. Run the nut down snug with your fingers and spin the hub a few times to squish out the grease trapped between the rollers and the races. This is the tough part because everyone has a different way to do this. The way I will describe here is the way that has worked for me for the last 10 or so years on things from my little trailer to a 36 foot enclosed car trailer that I built to carry 2 race cars and serve as living and pit headquarters when at races. This has also been the method I used on all the racecars I built over the years too. You may have a different way that works for you. If you have a wrench big enough to fit the nut, then by all means, use it because pliers on a nut isn't a really good thing. You could round the nut, make shavings from the nut that end up in the bearings, or worse, they could slip and make you bust a knuckle. Snug the nut down as you spin the hub. Then back the nut off and tighten the nut until it is snug. Then take a small screwdriver and try to move the washer back and forth behind the nut. I tighten the nut and move the washer until it won't move, then loosen the nut just until I am able to move the washer again. Others have said that one should tighten the nut to XX inch/lbs, or just til it is snug or whatever, but the above is the way I do it. Occasionally, you will get the bearing set to just the exact tightness that you want, and you can't see the hole in the spindle for the cotter pin. In this case, the first thing I try is the nut from the other side. Sometimes variations in the machining cause the nuts to be just enough different that this approach works. Other times I have been known to sand the washer down to make it thinner, or if the nut looks like it has some bow to it from the stamping process used to make it, I will hammer it to try to make it flatter. On other occasions, the races may not be seated all the way. This is when I reef down on the nut with the pliers to see if the races can be forced in a little bit, or even finish putting it together and drive it around the block with the nut TIGHT. The rule of smashed thumbs for me is that if the slot for the cotter pin just barely covers the hole in the spindle, thus making the nut just a tiny bit loose, I will run it and then go back when I check it after a few miles and see if I can get it right. If the hole is just about to peek out into the slot in the nut, I will run it just a little tight, figuring the races and bearings will "run in" a little bit. And if the hole is right in the middle of the castellation of the nut, I will switch nuts, start hammering or filing or whatever on the washer. Once you have the hubs back on, put the wheels back on, and adjust the brakes. Use the method suggested by the manufacturer of the brakes on your trailer. Most drum brakes should be adjusted to have just a slight bit of drag when the brakes are not applied. This means that the tire should go around maybe 2 or 3 times when you give it a good, healthy shove around and you should hear the brake shoes scrape on the drum as the tire goes around. Disc brakes don't usually need adjusting and will self-adjust when they are used. After all that, get that sucker down off the stands, and onto the wheels again so you can go out and drive it around a little bit. Don't forget to torque the lug-nuts or bolts. If you don't know the torque spec, there are several places on the web, usually wheel manufacturers that can tell you what torque to use. I started with mine at 75 ft/lbs, and after about 50 miles checked them. They were a little loose, so I went up to 85 ft/lbs, and after that, only two on one wheel and one on the other were loose at the next gas stop. I stayed with 85 on those, and none were loose again after 3000 miles. Your wheels and hubs may be different, so that is just a sugestion for a starting point. Aluminum wheels will need a little less, and wheels with nuts or bolts bigger than half-inch will need more, and smaller will need less. Be sure to road test your trailer after you have done this sort of thing on it, because it will be much easier to fix something you left off or didn't do right on a Saturday when you have time than on Friday night on the way to a weekend sailing trip with all your gear in the boat and the truck loaded with food and guests, and your heart loaded with excitement. Comments, corrections and suggestions, but not hate mail can be emailed to me at the above address. And a special thanks to joe "The Proofreader" Cox for his input. K