HOW TO – KEEP THEM TURNING
The wheels on any off-road machine come in for horrendous abuse. Trials riding may be slow but the abuse is just as bad. The wheel bearings located in the hub assembly in the middle of the wheel do not escape this punishment. The rear wheel provides the drive for your machine and it’s vital that the bearings are checked on a regular basis. Here we show you how to change them and keep them turning in the comfort of the Birkett Motosport workshop.
Article: Classic Trial Magazine
Copyright: Words and Pictures – Classic Trial Magazine
1: First things first and that means you should only ever carry out maintenance on a clean machine. General workshop knowledge is required to change the rear wheel bearings. In this article we have changed the rear but as it’s such an essential part of the safety of the machine, if you are in any doubt of your capabilities we suggest you take the machine to your nearest dealer, who will advise you on what is required to do the task and carry out the work if you require it. It’s always good to have a look at and read the machine manual or ask your local dealer first what suitable replacement parts are available before starting work. 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.
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 at the bottom, you should be able to detect any ‘play’ in the bearings. If there is any then the bearings need replacing.
3: With the machine supported on a centre stand that allows the rear wheel to turn, follow the normal procedure to remove it.
4: It’s always best to use a ring spanner as opposed to an open ended one as the ring type has more contact points on the nut. It’s also worth noting where the chain adjusters are for re-assembly.
5: Always be careful when you have your fingers near the drive chain. The chains split link does not have to be moved to take out the rear wheel. You just need to knock the spindle slightly out and let the axle go up to the forward position in the location slot and the chain will slip off as it will be very loose.
6: Once the wheel is away from the swinging arm you can remove the brake assembly.
7: The first job is to flick out the rubber seal which protects the bearing with a tool as demonstrated or a large flat head screw driver will do the same job.
8: The bearing is now exposed. On the Yamaha Mono-Shock model it’s advised to first remove the bearing on the brake side. The access afforded from the other side for ‘drift’ you will be using has more room to work on the bearing. It’s always worth checking your owner’s manual to see if this is applicable on the model of machine you are working on.
9: Many tools can be used for removing the bearings and experienced mechanics have their own tools they have usually made themselves. Ask around 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. Some mechanics recommend heating up the hub gently to allow the bearing to come out easier, a procedure which can also be applied when fitting the new ones as you will see later.
10: There’s no rush to get the bearing out. It’s better to take your time and ease out the old bearing as ‘even’ as possible to avoid damaging the bearing housing, especially on older machines.
11: 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 drive side bearing.
13: Give the housing a very good clean before replacing the bearings. Then gently using a heat gun slowly apply some heat to the bearing housing in a sweeping motion to heat the hub evenly.
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 and checking with your fingers that it’s going in evenly.
15: Then proceed to follow it all the way home until it’s up against the stop. Its good practise to use a ‘drift’ made from either aluminium or brass to avoid damage to the new bearing.
16: 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.
17: Once again give the brake side of the hub a good clean before fitting the new bearing.
18: Use the same fitting procedure as before but make sure that the bearing will ‘mate up’ to the bearing spacer okay.
19: You should now have both new rear 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.
Whilst the wheel is out remember to check the brake linings for excessive wear and replace if necessary.
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: 10 available to order at: www.trialmaguk.com