One of the keywords that often appear in maintenance articles is "chain tensioning". I've heard that the chain needs to be tensioned, and if it's not, it can make strange noises and wobble, so even if I don't like it, I have to adjust the chain tension!
Looking at the article, it looks like the adjustment is kind of hard, and I'm worried about failing to adjust it and over-tensioning it, and it takes a lot of courage to loosen the shaft that holds the tire in place. Many of you may be hesitant to make adjustments on your own.
WebiQ is here to bring you a little tips and motorcycle knowledge. In this issue, let's talk about what would happen if you failed to adjust the chain tension and over-tensioned it?
If you get frightened after reading this, adjust your chain! If you don't have the confidence to do it yourself, get a motorcycle shop to adjust your chain!
What happens when the chain is stretched?
Make the adjustments before this happens!
A chain that is used without tensioning can become stretched to the point of being unmanageable.
It can be extremely rare, but it is a very special case and a terminal condition. In case you are wondering, it is when the links of the chain are stuck and bent and not fully extended that the chain becomes taut. The reason for this is that the commas are not straight with each other, so the overall circumference of the chain becomes shorter. This means that the condition is so bad that the oil for lubrication is gone and it is sticking, so it is very dangerous condition that it may break at any time. Please replace it immediately regardless of the extension.
Now, let's go back to a normal example. When the chain is stretched in normal use, the first thing you will notice is the large driving shock that occurs when you turn the gas pedal on and off. When you open the throttle to accelerate from a situation where the engine brake is being applied for deceleration, you will feel a big shock like a "thud" or "crack" and it will be difficult to ride.
The chain gradually stretches, so it's hard to feel the change when you ride every day, and by the time you notice it, it's stretched to the point of being worn out, so be careful.
Why does the drive shock increase?
This is because when the tension of a slack chain is reversed during deceleration and acceleration, the difference between "loose and tight" becomes large. It's hard to tell.
To be more specific, during deceleration, the lower side of the chain is taut because of the (negative) driving force, and the upper side is slack because of the lack of driving force, but as soon as the throttle is opened, this driving force is reversed, so the upper side is taut and the lower side is slack. At this time, the shock of the pinch! When the throttle is opened, the driving force is reversed, so the upper side tenses and the lower side slackens. The shock of this tensing is so great that it can be felt as a thump.
If it's just hard to ride, you can live with it, but if there is a shock, it means that the drivetrain is being shocked every time. The shocks are absorbed by the hub dampers and clutch dampers, and the unabsorbed shocks are transmitted to the transmission, swingarm pivot, and finally to the crankshaft, which is the heart of the engine, shortening the life of your motorcycle little by little.
If you continue to ride with the chain stretched in this way, it will not only damage the chain and sprockets in the long term, so for the sake of your beloved motorcycle, be sure to adjust the chain tension.
- When the chain is stretched, the shock when the accelerator is turned on and off increases.
- Eventually, the chain and sprockets won't just be damaged.
Why is it necessary to have some play in tension adjustment?
The amount of play in the chain is specified by the manufacturer for each motorcycle. It is not just a matter of stretching it so that it does not slacken.
Although there are some differences between vehicles, the amount of play in a chain is always specified as about 20mm, and there is no such thing as a vehicle with "no play = 0mm". (Strictly speaking, there are a very small number of them, but they are very special cases, so I'll ignore them for now.)
But if stretching and loosening the chain increases the shock, why bother to loosen it when it would be best if there was no loosening at all, that is, if the chain was taut from the start?
It's the front sprocket shaft, swing arm pivot shaft, and rear sprocket shaft (axle shaft). Because the three points aren't always at a fixed distance.
If the three points are always equidistant, it is most efficient to keep the chain taut without loosening it, but unfortunately, motorcycles are not built that way. The position where the distance between the axes, which changes with the movement of the suspension, is the longest (generally when the suspension is 3/If you adjust the chain tension to the optimum position (about 4 shortened positions), the chain will be slack under normal conditions, which is what chain play is all about.
How much the distance between the shafts varies from model to model and is dependent on the length and angle of the swingarm and the position and distance of the swingarm pivot. This is why each motorcycle model has a different chain play value.
By the way, the three axis positions are set for a super important body component called "anti-squat".
- Due to the design of the vehicle, the distance between the sprocket and the chain varies depending on the movement of the suspension.
- The reason why the chain tension is a little loose from the beginning is to absorb the change in sprocket distance with the chain tension.
What happens if you overstretch it?
If the chain is too loose, it will cause shock and damage to various parts of the body, but due to the structure of the body, it is necessary to leave some play (slack).
So, the main question this time is, what happens if you mess up the adjustment and over tension the chain? Let's take a look.
As you can easily imagine from the previous explanation, a big problem will occur when the suspension is retracted. Since the change in the distance between the shafts, which should be absorbed by the chain play, cannot be absorbed, a tremendous force will be applied to the drive system involving the chain.
The chain itself will also be subjected to tremendous force to stretch, which will dramatically increase the wear of pins and rollers. The worst that can happen is that the chain will break, and God knows what it will destroy as the broken chain goes on a rampage. It might smash the crankcase, and if there is a pedestrian on the other side of the road, it will be the same as hitting them with the chain with all your might. I don't even want to imagine what would happen to the person who was hit.
If the chain doesn't break, it's a big problem, and the sprocket will be subjected to tremendous force. The teeth of the sprocket are not easily bent in the vertical direction, so it won't be destroyed instantaneously (at least I've never heard of it), but it will certainly be reduced to a mess.
Plus! If you use an offset sprocket, the sprocket will be subjected to a tremendous amount of twisting force at the point where it connects to the shaft, and at best, the sprocket will break (because the force is applied horizontally instead of vertically), and the joint between the shaft and sprocket (where the spline groove is dug) will be worn to a mess. The shaft where the sprocket fits will wear out. The shaft that the sprocket fits on is very expensive, and replacing it requires disassembling the engine, which costs a lot of labor. Engine overhaul for a mere overstretched chain! It's horrible!
Bearing damage can also occur in areas that are difficult to see. The bearings that support the sprocket and swingarm shafts are subjected to a great deal of force, which can result in severe bruising and scratching, or worse, damage to the internal balls and needles, causing them to disintegrate. In the worst case, the internal balls and needles are damaged and disintegrate into pieces. Replacement and repair require extensive disassembly and maintenance, which costs a lot of money.
It doesn't matter if you say, "I don't weigh enough for the suspension to shrink," or "I can't jump". A motorcycle is a vehicle that is designed to shrink its suspension just by riding and turning normally. It is important to remember that the tires can only grip when the suspension is working well.
- Too much tension and you're in trouble!
I've tried to make the chain too tight on purpose.
If you set the play to 0mm with the swingarm fully extended...
When I was young, I wondered about the need for play in the chain and was lucky enough to learn from various experienced riders.
However, although I understood the chain play in my brain after listening to them, I was not convinced. But I wasn't convinced. I mean, does a small amount of chain pull really make that much difference? Don't you think? I thought, you're exaggerating, but in reality, it doesn't make that much difference.
Besides, if the chain tension increases as the suspension shrinks, wouldn't the suspension shrink if the motorcycle was binned from the start? I thought. It's just a matter of tensioning the chain, and I'm not sure how much that would happen.
So I did a quick experiment. I tried to see what would happen if I tightened the chain while the suspension was fully extended.
The results were shocking. First of all, when I put the motorcycle on the ground after adjusting the chain tension, the suspension did not sink at all. I thought, "Well, the weight of the motorcycle is light, so it should sink a little ......", but it didn't budge at all. It is clear that the rear suspension has not been retracted, as evidenced by the fact that the footing has deteriorated.
I thought this was a bad idea and tried to ride around the neighborhood for a bit, but I felt so many bad feelings that I made a U-turn within 10 meters and went home right away! I hurriedly readjusted the tension to the correct level. If I had gone for a lap around the neighborhood like that, something would have definitely broken.
Symptoms of being overstretched
Too much tension can put a lot of strain on the rest of the chain, so watch out for the noise and the metal dust! Of course, visual inspection is best, and if it's too taut, readjust!
It is rare to see a motorcycle with a chain that is stretched to the limit, but I have seen a few motorcycles with chains that are clearly stretched too tight. How would you know that on someone else's motorcycle and without touching the chain? This is because the following symptoms occur from a vehicle with an over-tensioned chain. If you see or hear traces of it, you can determine that the chain on that vehicle is too taut.
- A thumping sound is coming from the chain and sprockets, which are rubbing against each other with strong pressure.
- The underside of the chain does not shake at all while riding and is always in good shape.
- The underside of the chain is taut when the motorcycle is stopped.
- Metal powder adhering to the wheel.
- Squeaking noise from wheel bearing.
- Chain shakes from side to side while riding.
Squeaking from the bearings and metal dust on the wheels are two things that any owner should be able to notice immediately. For example, if you wipe the wheel when you wash it and find metal dust that is not black brake dust, there is a good chance that the chain is over-tensioned. Either the sprocket or the chain, or both, are shaved, and you have already done a lot of damage! Go to a motorcycle shop immediately and tell them the symptoms.
The chain tension may be uneven in some places, but this is almost always due to a part of the chain link sticking. In rare cases, the sprocket may be shaking due to poor roundness, but by far the most common cause is a sticking chain link. Replace the chain immediately!
In this article, we will talk about what happens if the chain is over-tensioned, so we will not describe how to adjust the chain tension.
