A well-greased bearing gathers no rust… OK that is a lame version of the “rolling stone” truism, but it is true nonetheless. Another area that often gets neglected on bikes are the bearings. Granted, it is no fun taking the linkages apart and dealing with those little rollers. But once you let bearings get dry and start corroding, you are going to spend a good chunk of money and time replacing them. Better to spend some time a few times a year to clean and grease the bearings, and you’ll get longer life out of them, not to mention better wheel/steering/suspension performance.
There are three sets of bearings to maintain on a typical dirtbike: Wheel bearings, steering head bearings, and swingarm/linkage/shock bearings. I’ll deal with them separately, with some info on maintenance, then replacement. This article will show you how to inspect, clean, and replace the bearings if necessary.
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Wheel Bearings
Wheel bearings come in two types: Sealed, and non-sealed. If you bike has sealed wheel bearings, your in luck in that you don’t need to do any maintenance on them, just replace them when they get sticky/clunky. You can tell if they are sealed by popping off the dust seal, and you will see the inner and outer race, and some type of plastic material in between. The bearings are greased during assembly, and the plastic seal keeps the grease in, and keeps dirt and water out. Smart.
If your bike has non-sealed bearings (you will see the round bearings in between the races) then you need to keep them clean, and well greased. I recommend inspecting wheel bearings often, maybe every ten hours, as the wheels are subject to a lot of dirt and dust, and also water from pressure washing spray. In addition, any time a wheel is off, inspect the bearings.
What you will need:
- Wrenches and sockets
- Long 3/8” extension
- Hammer
- Torque Wrench
- Waterproof grease
- Nitrile gloves
- 5 gallon bucket of trash can to set the wheel on.
Inspection
- Remove the wheel, axle, the spacers, and put all the parts in a bowl. Note if the spacers are different sizes, which one goes where.
- Set the wheel on a 5 gallon bucket, or trash can, take a large, flat, screwdriver, and pry out the dust seal. (its not good to set the wheel flat on a surface, as you risk bending the brake rotor. Not good.)
- Set the dust seals into your parts container.
- Inspect the bearings: hopefully it hasn’t been a year since you looked at them, and they aren’t all rusty and dry. If they are, go ahead and go online and order new bearings for both wheels, and skip down to the “bearing replacement” section!
- Bearings that are still in good shape should turn smoothly, and not have any corrosion on them. I will take a paper towel and run it through the axle hole, cleaning out any old grease and dirt.
- Now wipe off any old grease on the bearing faces. I don’t recommend using any solvent, as it can run into the wheel hub, and later work its way back into the bearings to thin out the grease you are about to pack into them.
- Now take some waterproof grease, and work it into the bearings, pushing it into the races and giving the entire bearing compartment a good packing. You can’t put too much in, any excess will squish out when you re-assemble the wheel.
- Also, don’t use regular grease. I use Belray Waterproof grease, it’s only about $4 at the local cycle store.
- Before I re-assemble, I will take the dust seals, spacers, axle blocks, axle, bolts, etc, and wash them off with mineral spirits, then dry them off.
- Coat the dust seals with a thin layer of grease on the outer edge, and push them gently back into place. If you need to tap them in, get a large socket that fits over the seal, and tap it into place.
- Put the spacers back onto the wheel.
- Give the axle a thin coating of grease, set the wheel in place, and insert the axle (for the rear axle, remember to slide on the axle block first, then insert the axle.
- You may have to work the axle a little to get it lined up – DON’T BANG IT WITH A HAMMER. If it needs a little love-tap, I will use a rubber mallet.
- Install the wheel parts in the reverse order as you took them apart. Check your manual in order to tighten everything to the correct torque settings.
- Set the wheel on the 5 gallon bucket, and then take the socket/extension and insert it into the axle tube, and position it so that it rests on the inside bearing race of the bottom bearing (facing down). The axle tube moves around some, and it allows you to sit the socket on the inside edge of the bearing.
- Give the bearing a good solid pop with a hammer, then move your tool to the other edge of the bearing, and repeat the process. The bearing should be moving out of the race, just keep tapping into it pops out.
- The axle tube will also fall out, turn the wheel over and tap out the other bearing from the inside out.
- Now that you have the bearings out, give the inside of the hub a good cleaning, as well as the axle tube.
- Remove your new bearings from the freezer, if they are not the sealed type, pack them full of waterproof grease, and rub a thin coat of grease on the outside of the bearing, and the inside of the hub where the bearing will sit.
- Take one with the numbers facing out, and set it on the wheel level on the race.
- Take a socket that is large enough to sit on the outer race of the bearing (NEVER put pressure on the inner race), but not large enough to contact the wheel hub, and use your hammer to gently tap the bearing into place, keeping it level as you go. It should slide in tight, but you should not have to beat it in.
- Flip the wheel over, insert the axle tube into the hub, and then install the second bearing just like the first. The axle tube should be able to move around a little between the bearings.
- That’s it, you can re-assemble the wheel with your now clean parts (see “Re-assembly”)
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