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Often forgotten: Roller bearings
Things that have to turn… And we’re not going to make jokes about the wheels! Although… A lot of people don’t even know that they’re driving around with raw wheel bearings. After all, we don’t drive that many kilometers on our classics. And you don’t always have to notice it. But wheel bearings – and other bearings – are simply wearing parts.
The wheel bearings. Make sure that your wheels are off the ground, one by one. Give the wheel a spin. If you hear noise, rumbling or rattling, a bearing is broken. Always replace wheel bearings in pairs. They are twin brothers. So if one has had its day… Bearing pullers come in all shapes and sizes. But in an emergency, you can make do with a wedge bolt and some targeted force. Be careful not to damage anything.
With the front wheel off the ground, you can also check the headset bearing. Move the handlebars from one side to the other. There should be no 'heavy' point in that movement. With both wheels on the ground again, roll the bike back and forth a bit. While you operate the front brake, feel with your other hand - or have an assistant feel - whether there is a tilting movement in the headset stem. If so, the headset bearings have play. There is often an adjustment option, but replacing them with conical, adjustable bearings is always a good idea.
You can check the rear fork bearing by trying to move the fork horizontally back and forth with the rear wheel off the ground – you can buy paddock stands for this from our advertisers for a reasonable price. With ZGAN classics with mono-suspension and lever systems, there is a bit more to it, but we will not concern ourselves with that modern stuff for now. Motorcycles are supposed to have two suspension elements on the rear.
Between the wheels is a bearing that often has (had) a hard time: the bearing of the output shaft of the gearbox. If the chain is (has been) too tight, that is often fatal for that bearing. With a bit of luck, it can be dismantled 'from the outside'. But think carefully before you do anything, otherwise you will be left with a ruined crankcase half.
Bearings are wearing parts, but also amazing technical feats. And of course they come in all sizes, from many brands and in many qualities. The established names are:
SKF (Sweden), FAG (Germany), TIMKEN (US), NSK, NTN, NACHI, KOYO, NMB en I O (all Japan).
And then of course there are the Chinese who copy all those brands, including all the stampings, inscriptions and neat boxes with the 'suggested' brand on them. The real brands are of course not happy about that, but those products keep popping up.
A nice example of Chinese economic thinking: The Chang Jiangs are Chinese BMW clones. A lot BMW Originalteile can be transferred one-to-one. And vice versa. The Chang that stayed here had wheel bearings with six balls per bearing. European replacement bearings have seven. Just imagine how many ball bearing balls you save if you make 50.000 Chang Jiangs that all have four wheel bearings with one less ball each.
So don't just buy bearings online, but from a specialist with good, credible reviews. Then things will run smoothly again.
How?
Make sure the new bearing and its mounting surface are clean. Use a lubricant (oil or grease) in the bore and on the axle. Apply a suitable amount of bearing grease to the inner race of the new wheel bearing. Align the new bearing with the hub and press it into place. Make sure it is seated properly and according to the manufacturer's instructions.
The most important thing: the bearing must not be "skewed" (sitting crooked). Press or tap it into its housing with a pipe or socket wrench that fits the outer bearing race. If the bearing sounds "dull", it has not yet reached its seat.
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The Chinese are smart guys and they might save a bullet but I have seen that from other bearing manufacturers too. The world of roller bearings is a shady one. Rumor has it that the Mercedes F1 team once lost a GP because a 'counterfeed' bearing had been fitted to their gearboxes and that bearing went to the eternal hunting grounds.
Also at my boss we had received in a box from a renowned Swedish roller bearing manufacturer a ball bearing that already had a heavy running point in it, brand new out of the box. That would never have passed the final inspection there and so that must also have been a counterfeed and perhaps even ground on the beaches of Bangladesh. Also the finish was not in accordance with the applicable standards.
In terms of tools, bearing pullers, the former Dutch State Mines had a special bearing puller for each of the most common ball bearings that gripped between the bearing balls with 'fingers' in the ball groove of the inner ring. You tightened it like a collet or like a self-tightening drill chuck with the fingers gripping the ball groove. Then you tightened the central push bolt and the bearing came off the shaft. And the nice thing was that the bearing could simply be reused if it wasn't broken before. Great tools!!