Wheel bearings are a consumable item on your camper or your caravan. They’re not meant to last forever. They simply don’t. The service interval for replacing your bearings is 10,000 kilometres. Now, to some of you, that may seem a bit excessive, but bear in mind, service intervals with car manufacturers, trailer manufacturers, are designed to minimise the risk of failure to as close to zero percent as possible. If you’re going to replace every 10,000 Ks, it’s likely you will never have a problem. There’s also the service interval in between that. You should be opening up your bearings, having a look, re-greasing them every 5,000 kilometres. If you’re doing a lot of harsh outback rough road conditions, you should be checking them every 2,500 kilometres. If you do that, you’ll minimise your risk. It’ll be virtually zero percent chance of failure.
The expense of changing them every 10,000 kilometres and servicing them at the correct interval, is a great alternative to a $2,000 or more tow fee being picked up in the middle of nowhere, and have your trailer transported back to a city so you can get it fixed. It’s going to cost a fortune, so not worth the risk. Every 10,000 km, it is recommended to put in new ones. They’re not that expensive and easily found.
A bearing consists of a cone and bearing race, the cone fitting to the inside of the hub and the bearing race seating against it.
The other part you have that is attached to the back is a seal. What this does is it stops the grease when it gets hot from getting out around the stub axle and ending up all over your wheel. It keeps the grease in there. Then on the other side, we have a bearing cap. This keeps the grease in on the nut side of the hub, and you don’t end up with a mess.
So we’ve got our new bearings ready to go. First of all, to get the bearings out, use a small screwdriver and a small hammer and gently tap them out of the hub. Tap around the rim of the cone. Just gently tapping it out around the perimeter until the whole thing comes out, being careful not to damage it or damage the inside of the hub. Now, when you replace them, always use new cones, seals and bearings. Don’t try and reuse the parts. Just have a whole kit ready to go, and it will make putting it together a lot easier.
Because you’re out on the road and don’t have a press to press the bearings in, what you’re using is a socket of almost exactly the same size as the cone. You can place the cone in its seat, place the socket over the top, and using a mallet or a hammer, gently tap that into place, working it down around the seat to get it in. Now that you’ve got your cone seated, flip the hub over and do the other side exactly the same.
Older model MDC campers and caravans will have a tapered bearing. All the new models come with a parallel bearing. Same bearing number both sides of the hub. So one size fits all. You don’t have two different bearing kits to go in it.
Gently tap … don’t thump too hard on these as you may damage them. Be very gentle. Use the right size sockets so you’re forcing it in around the end of the cone, not against the working surface where the bearing runs. That’s the area where the bearings sit up against it.
Now they’re in. What you need to do is fit the seal and bearing on the other side. Don’t be shy to grab a lot of grease here. If the grease fits in, then keep going. When you do this, try and force grease into every crevice, every opening, and try and push out as much of the air as possible. I’ll let you in on a little secret. At the MDC factory, we actually have a machine that greases the bearings, and you would be amazed at how well it works. It was actually designed and built specifically for MDC to do our bearings, so there’s no mistakes. The machine doesn’t make mistakes. It pumps enormous amount of grease in there.
Now you’ve got your bearing in there, put the rubber seal in. Inside the lip, there’s a spring which helps keep a bit of pressure on the inner side of the seal. Make sure you’ve got plenty of lubricant in there. Pack in a lot of grease getting as much as you can into those bearings.
Now to get our seal in. When you’re doing this, try and avoid getting any grease and lubricants on the inside of the drum. You want that dry. So, if you’re doing this out on the track, and you’re taking spare bearings and grease, take a can of brake cleaner with you, as you will need to clean up afterwards and make sure you don’t have any lubricants, grease, et cetera on the brake shoes or the brake linings or on the inside of the drum. This is a very important step. Normally, if you were doing this in a workshop, there would be a press, so everything would get pressed in perfectly with an axial load on top, and you’d have no worries at all.
Once the seal is in, clean up and get any of the excess grease off. Flip your drum over and keep packing. You’ll be amazed how much grease you can actually get to stay inside these hubs. Grease up your second set, again, forcing it into all the openings, getting out any air that might be in there. As air heats up, it expands, and there’s the opportunity to push grease out. Drop our second bearing in, and then fill the cavity between each sets of bearings in there. Remember when doing this, use a high temperature bearing grease so it doesn’t turn into liquid as soon as the brakes get a bit hot.
Once you put your hub back on and do up the nut, put the split pin in, put your bearing cap on. When you place this back on the stub axle, the idea is you do the stub axle up, and you may actually hear the bearings click into place as everything sits, because it’s the side of the track, you’re belting things with rubber mallets and what not, not exactly what I’d call precision operation and often, you’ll hear the bearing click. What you want to do is spin the hub. If the hub is difficult to turn after you’ve tightened it all down, start to back off the large nut until the hub spins freely, and then make sure there’s no excessive play or anything in it. Put on your grease cap. Put your wheel back on, and you’re on your way.
Remember, after you’ve done this on the side of the track, you’ve removed the wheel and everything, you need to pull up and check everything at 50 kilometres. Check there’s no play in the wheel, in the bearings, and retighten your wheel nuts. Then again at 100, then again at 500, then again at 1,000. If you do these checks, you’ll catch anything going wrong very quickly, and it will save you more heartache. You’ve just spent four hours on the side of the road changing your bearings in your trailer. You don’t want to spend another four hours, or because you’ve got no spare bearings left, waiting for a tow truck.
So that’s it. That’s changing your wheel bearings. Remember, if you’re putting your trailer or camper through tough conditions, such as a lot of water crossings, a lot of corrugations, really rough roads, every 2,500 kilometres, take a look at them. Make sure there’s plenty of grease. Make sure everything fits nicely, there’s no play. Absolutely get your mechanic to re-grease them and check them every 5,000, and every 10,000 kilometres, keep the old set as your spares so you’re not throwing them away, that’s fine, but if you adhere to those maintenance schedules outlined in our log books and owner manuals, you’ll have no trouble at all.
There you go. It’s that easy. Don’t forget, clean everything up with some brake clean before you put it all back together. Make sure there’s no grease on the brake linings or on the drum, and you’ll be fine to get away.
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