Holding the handlebars of any off-road machine gives you some immediate feedback about the state of the front wheel bearings, as you can easily detect wear in the bearings. Gently turn the handlebars from left to right and this wear will be identified, as the wheel falls slightly to the side. If you spin the wheel you may also hear a ‘rough’ noise. Feeling good and in control inspires confidence in your riding and we suggest the wheel bearings are checked on a regular basis, whenever you maintain your machine. Here we show you how to change them and keep the feel-good factor of being in control, from the comfort of the Birkett Motosport workshop.
Article: Classic Trial Magazine
1: It’s always recommended that you start work on a clean machine and feel competent that you can carry out the task you are undertaking. If you are not sure or happy about this we suggest you take the machine straight to your nearest dealer to carry out the work by qualified people. If you are carrying out the work yourself, a read through the workshop manual will give you an insight to your machine; it’s always good to talk to your local dealer to see if any special tools are required and to make sure that the replacement parts are available. If you are carrying out the work we suggest wearing the appropriate safety clothing and eye protection and using a good set of quality tools. Remember that a good clean workshop and the use of quality tools also help to provide a safe working environment.
2: The inspection of the wheel bearings on your machine is a very important part of everyday machine maintenance; not just for mechanical reasons but for safety ones as well. If you place the machine on a centre stand and rock the wheel vertically, placing one hand at the top and one on the fork leg as demonstrated, you should be able to detect any ‘play’ in the bearings.
3: To start the process of removing the wheel it’s always easier to remove the disc protector and the brake calliper first.
4: The fork bottoms will have a clamping system to hold the wheel axle firmly in place; these will need undoing before the axle can be removed.
5: The axle head will vary in size and shape but it’s essential that the correct spanner or tool is used and to maintain a good firm purchase when undoing.
6: Holding the wheel with one hand, remove the axle and the wheel.
7: Many machines have a front wheel speedometer drive which the axle passes through. Take your time removing the wheel from this to avoid damaging the drive method.
8: Remove any rubber sealing or protection bushes and then proceed to gently apply some heat to the bearing housing on the side you want to remove first. It’s always worth checking your owner’s manual to see if they recommend moving a particular side, left or right, first.
9: With the bearing now exposed and some gentle heat applied it’s time to knock out the first bearing. We were advised on the Mono-shock Yamaha to take out the bearing opposite the brake disc first.
10: The access afforded from the other side by using a ‘drift’ allows more room to work on the bearing. A variety of tools can be used for removing the bearings, and experienced mechanics have their own tools they have usually made themselves. Ask around amongst other riders what they use, if they have a similar model to yours. Although shown here being hit with a steel hammer for maximum effect, a plastic-type mallet will do the same job. To remove the old bearings use a ‘drift’ to knock them out. Make sure you take your time to ease out the bearing evenly to avoid damaging its housing.
11: There’s no rush to get the bearing out. It’s better to take your time and ease out the old bearing as evenly as possible to avoid damaging the bearing housing, especially on older machines. Once the bearing on the hub side is removed you can take out the bearing spacer.
12: Now, with much more room in the hub to work, gently ease out the disc brake side bearing, once again taking your time to protect the purchase area of the bearing housing.
13: Give the housing a very good clean before replacing the bearings. Then gently using a heat gun once again slowly apply some heat to the bearing housing in a sweeping motion to heat the hub evenly, as demonstrated earlier.
14: Gently rest the new bearing on the housing and gently tap it until it starts to take purchase on the hub. It’s worth stopping during the process and checking with your fingers that it’s going in evenly. Then proceed to follow it all the way home until it’s up against the stop.
15: Before replacing the bearing spacer it’s worth covering it with grease as sometimes they are made from steel and not aluminium, which will corrode and then damage your new bearings.
16: Once again, give the brake side of the hub a good clean before fitting the new bearing. Use the same fitting procedure as before but make sure that the bearing will ‘mate up’ to the bearing spacer okay, once again taking your time.
17: You should now have both new front wheel bearings in place. Once you have done this, before you replace the wheel put the axle/spindle through to make sure the bearings are lined up and then replace the wheel, fitting the spacers etc in a reverse procedure to how they were removed.
18: Before re-fitting the brake calliper check the disc brake pads for wear and replace if necessary, before gently putting the assembly back over the disc rotor.
19: Make sure that the wheel spins free and easy now that it’s fitted back into the front forks.
20: When fitted always remember to pump the disc brake pads out onto the rotor with a gentle action on the front brake lever.
If you encounter any other problems concerning this ‘changing wheel bearing’ procedure contact your local dealer for advice.
Classic Trial Magazine would like to thank the staff at Birkett Motosport Web: www.birkettmotosportltd.co.uk for their kind co-operation in producing this article.
This article is taken from Classic Trial Magazine Issue No: 11 available to order at: www.trialmaguk.com