Vibration can be really annoying, and can also cause damage to motorcycle components. The good news is that there are plenty of ways to combat vibration.
Note: The videos are in German.
Give your motorbike a real gazzini makeover!
Some degree of vibration is a fact of life with virtually all motorbikes. When motorbike magazines report on their road tests, they often talk about the bike having “character”, or giving you a gentle massage. But depending on its frequency and strength, the vibration you feel through the handlebar can soon get on your nerves. Certainly, when your fingers and feet start to go numb after a couple of hours on the road, you’re going to want to do something about it. Vibration is even more annoying if it starts to cause cracks or makes nuts and bolts work loose or even fall off. Then it really is time to take steps to cut out the vibration.
Handlebar and mirrors
We’ll begin at the place where vibration affects the rider worst, namely the handlebar. Here it’s mainly the high-frequency, tingly sort of vibration that spoils your enjoyment the most. Specifically with this in mind, some motorcycle manufacturers fit rubber mounts to their handlebar risers at the factory. That works, but has the disadvantage that steering precision and feedback from the front wheel suffer a little.
The tried and trusted alternative is heavy handlebar ends, which dampen vibration simply by virtue of their weight, effectively utilising the principle of mass inertia. The only problem is that not every mass is suitable for every sort of vibration. To solve this problem, gazzini has developed variable vibration dampers, whose weight can be varied by using different weight discs, rather like a weightlifter’s barbell.
Once you’ve stopped your bar ends from vibrating, there will be less tendency for the rearview mirrors to give you a blurry picture. But if you find that vibration is still a problem, there are vibration dampers specially designed for mirrors. They function like rubber mounts to isolate the mirror additionally from the rest of your bike.
License plate and fairing
The thin metal from which license plates are made is particularly susceptible to vibration - a problem that riders of single- and twin-cylinder machines know all too well. The most elegant solution is small O-rings and matching washers. They decouple the license plate from its bracket to eliminate vibration, which has the added benefit of saving you unnecessary problems next time your bike is due for its safety inspection. To make sure that the bracket itself has a long life, you should use self-locking nuts. Liquid threadlocker also protects against nuts and bolts working loose due to vibration.
You can also use O-rings for fairing bolts. This will decouple the fairing elements from engine vibrations, helping to protect them against cracks and chafing.
As a welcome added benefit, the noise that occurs with fairings which are rigid or under tension is also minimised. What we perceive as noise is in fact vibrating air. This trick with the O-rings also works well on fairing windshields.
While we’re on the subject of noise, multi-part fairings, which produce a droning sound when you ride at certain speeds or engine revs, can be silenced with a bead of sealant applied to the connection and contact points. But the sealant should be allowed to set before you install the fairing.
Tank, battery and headlight
Motorcycle tanks are normally decoupled from the bike frame by means of rubber pads, which are, of course, also subject to vibration themselves. Over a period of years, they become brittle, like anything else made of rubber. So if you’ve been riding your machine for a good number of seasons already, it’s time to take a look under the tank and check that the vibration damping is still doing its job.
And while you’re doing that, also check the inside of the battery compartment for good measure. Because vibration is not good for any type of battery. It’s a good idea to line the compartment with foam rubber – especially if your bike is equipped with a smaller, lightweight lithium-ion battery.
Some motorbikes (mainly older models) are known for eating up headlight bulbs. If your bulbs never seem to last as long as the manufacturer claims, the reason could be inadequate vibration damping. It may be possible to solve the problem by installing a headlight bracket with rubber mounts.
Other parts and screw connections
A good way to prevent sudden loosening of screw connections and vibration cracks, or even additional instruments falling off, is to install rubber vibration dampers, also known as rubber-metal dampers or silent blocks. These ingenious screw fittings cut out the vibration that affects lamps, side covers, smaller oil tanks, battery trays and mudguards – thereby prolonging their life.
Another useful way to prevent screw connections working loose is to use liquid threadlocker. Apply a drop of liquid to the thread of the screw or bolt before you insert it. The liquid sets hard and prevents the screw working loose. Liquid threadlock comes in various strengths, e.g. medium- and high-strength. This determines how much force will be required to undo the screw again. With high-strength threadlocker, it’s even necessary to apply heat in addition.
Self-locking nuts are also a good idea for some screw connections. They use a plastic ring to prevent the nut working loose.
For large screw connections, a split pin pushed through a hole in the threaded bolt is often used to prevent loosening. There are two types of split pin. For safety reasons, standard split pins are intended for single use only, but there are also special reusable split pins.
The root of the problem: engine and wheels
Most vibration is produced by your motorbike’s moving parts, i.e. the engine and wheels. (The one exception is the effect of the airstream). To tackle this problem at the root, it’s advisable to first make sure your engine is running smoothly. The extent to which this is possible naturally depends greatly on the type of engine you have. A single-cylinder bike is never going to give as smooth a ride as one with an in-line four engine. Nevertheless, the vibration in any engine can be improved by correct valve clearance, a clean air filter, new spark plugs and, in the case of older bikes, accurately synchronised carburettors (see DIY tip Carburettor Synchronisation).
If your wheels are out of balance, it can be a very significant vibration factor. Tyre tread wears down unevenly when you ride your bike. This alters the weight distribution, and the wheel no longer runs smoothly. That causes vibration. It’s particularly unwelcome on the front wheel because you feel the vibration through the handlebar, and your hands will soon start to ache. The best way to check your wheel balance is to remove the front wheel, put it on a wheel balancer and use weights to correct the balance. In any event, you should not allow your tyres to wear right down to the permitted minimum tread depth. A new set of well balanced tyres will not only cut down vibration, but also make riding your bike that much more enjoyable.
The Louis Technical Centre
If you have a technical question about your motorbike, please contact our Technical Centre, where they have endless experience, reference books and contacts.
These tips for DIY mechanics contain general recommendations that may not apply to all vehicles or all individual components. As local conditions may vary considerably, we are unable to guarantee the correctness of information in these tips for DIY mechanics.
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