As an avid Motorcycle Mojo reader, you used the advice in the last issue to replace the oil in your forks. While you were at it, you checked the wheel bearings and discovered that they needed servicing. In this issue, we’ll cover replacing them.
To check the bearings, remove the wheel from the bike, insert your finger into the inner race of each bearing and rotate it back and forth. The inner races of both bearings must turn smoothly. If either bearing feels like it’s grinding in sand, feels like it has flat spots, or is spewing some rust-coloured gunk (meaning it has been contaminated with water and is corroding), then it’s time to replace both bearings.
You’ll first need to fashion a punch to drive out the old bearings. I use a long, 3/8-inch bolt, slightly bent at the threaded end and with its tip filed down to provide a flatter edge to push against the bearing.
Some wheels have dust seals outboard of the bearing, and these will have to be removed carefully with a flat-blade screwdriver so as not to scratch the seal bore. These seals protect the bearings from outside elements, so you should replace these seals with new ones.
Before attempting to push the bearings out, clean the exposed portion of their bores thoroughly. Any dirt here will lodge itself between the bearings and the wheel as you push them out and either jam the bearings in their bores, damage the wheel, or both.
Once clean, use a propane torch to heat the centre of the wheel. A propane torch isn’t hot enough to damage the wheel, but the heat will cause the bearing bores to expand and make it easier to push out the bearings. After about four or five minutes of applying heat evenly, when the hub is too hot to touch, use a squirt gun to apply a thin layer of oil around the exposed part of the bearing bores – this will help the bearings slide out.
Insert the bearing punch you fashioned earlier through the bearing on one side of the wheel and butt its tip against the inner race of the opposite bearing. Use a hammer to drive out the old bearing, but be sure to push it out evenly – don’t just hammer on one spot. With the wheel properly heated and lubed, it will take only moderate pressure to remove the bearing.
Once one bearing is removed, carefully reach into the centre of the wheel, so as not to burn yourself, and remove the bearing spacer tube. This is an important component and must not be forgotten when reassembling the wheel. Now remove the remaining wheel bearing and thoroughly clean the wheel hub.
Replacement bearings can be obtained through a bike shop, but you can also buy good-quality replacements at your local bearing shop. There is a number located either on the bearing’s outer race or on the bearing seal; use this number to source new bearings. If you are uncertain, just bring the old bearings to the bearing shop and they’ll find the proper replacement. Also, some OEM bearings lack seals, which you will notice because the ball bearings are exposed. We recommend replacing these with sealed bearings, as they add an extra measure of protection.
After the hub is clean, reheat it and lubricate the bearing bores liberally with oil. Place the new bearing squarely over the bore and use a ratchet socket and a brass or copper hammer to drive the bearing in – this prevents damage to the socket. The socket must have a large enough outer diameter to push on the bearing’s outer race, but must also fit loosely into the bearing’s bore, allowing you to push the bearing all the way onto its seat without jamming the socket in the wheel.
Make sure you drive the bearing in squarely and you don’t cock it to one side, as it will jam in the bore and damage the wheel. Again, proper heat and lube is the trick to make this easy. Never push on the bearing’s inner race to drive it into the wheel, as this will destroy the bearing. You’ll know when the bearing is properly seated when the sound of the hammering changes tone: it will sound like a much more solid hit.
With one bearing installed, put the spacer tube back into the wheel and drive the other bearing in as carefully as you did the first. With both bearings in place, using light pressure with a screwdriver, align the spacer tube so the wheel axle slides into the wheel without any problems. If your wheel has dust seals, now’s the time to drive them in using the same method used to drive in the bearings, though you won’t need heat and you will put much less tension on them – just make sure they are installed squarely.
If you ride an older Harley-Davidson, you’ll want to get the bearings checked by a dealer, as they use taper roller bearings that must be adjusted for free play using spacer tubes of different lengths. Getting this wrong can cause the wheel to seize.
Technical articles are written purely as reference only and your motorcycle may require different procedures. You should be mechanically inclined to carry out your own maintenance and we recommend you contact your mechanic prior to performing any type of work on your bike.
