Tension springs determine in your scooter when the clutch engages. With the right tension springs, your scooter will pull away more smoothly, pick up speed a little faster and limit slip and heat. In this article you can read what exactly tension springs do, how color and strength work, which set suits your setup and how to replace and adjust them safely.
What are extension springs in your scooter and what do they do?
In a CVT transmission, the variator, variator rollers, compression spring and clutch work together. The clutch contains clutch segments that want to move out due to centrifugal force. Tension springs do the opposite: they pull the segments inwards.
From a practical point of view, tension springs determine at what speed your scooter will “pick up” from a standstill. Stronger springs keep the clutch closed for longer, causing it to engage later. Weaker springs actually allow it to catch on sooner.
How exactly do tension springs work?
If you accelerate, the speed increases. As soon as the centrifugal force exceeds the spring force, the segments press against the clutch bell and the scooter starts moving.
What you notice on the road:
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Too light tension springs: it picks up very early, but can feel a bit lazy or hold back with a sports exhaust, for example.
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Tension springs that are too heavy: revs a lot before starting, more noise, and if you overdo it, it can start to slip and become extra hot.
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Well-chosen tension springs: smooth and predictable starting, without jerking and without prolonged slipping.
Color codes and strength of tension springs
Many brands use color codes to indicate strengths. Only: those colors do not transcend the brand. Red for brand A can therefore be approximately equal to blue for brand B. Therefore, always look at the specification on the packaging; often there is a percentage or hardness level.
|
Type designation |
Relative strength |
Typical application |
|---|---|---|
|
Soft or standard |
Light |
Original setup, quiet driving, low engagement speeds |
|
Medium |
Average |
Lightly tuned, sports exhaust, slightly higher revs |
|
Loud |
Heavy |
More tuning, higher revs needed for powerband, quick response |
Which tension springs do I need for my scooter?
Bring you first setup mapped out. Consider cylinder capacity, exhaust and whether your variator is still original. Use the guidelines below as a starting point and then refine with testing.
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Standard 50cc with original exhaust: soft or standard is usually the most pleasant.
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50cc with sports exhaust or light variator tuning: medium is often better, because the engine is allowed to rev slightly higher before it engages.
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70cc or clear performance setup: more often hard, but only if your setup really delivers its power at higher revs.
|
Complaint |
Probable cause |
Towards solution |
|---|---|---|
|
Driving away lazily, the speed drops |
Clutch engages too early |
Try slightly stronger tension springs |
|
Screams long before he drives |
Clutch engages too late |
Try slightly lighter tension springs |
|
Irregular gripping or slipping sensation |
Springs tired, dirty or wrong adjustment |
Inspect, clean, replace springs and readjust |
Adjust tension springs with compression spring and variator rollers
Adjustment works best if you look at it as a whole. Variator rollers mainly determine how quickly the variator shifts up and at what speed you drive during acceleration. The compression spring is about counter pressure and downshifting. Tension springs are mainly located at the moment of action when driving away.
A sequence that often works out useful in practice:
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Adjust rollers to a stable speed during acceleration.
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Adjust the compression spring if it shifts up too quickly or downshifts poorly.
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Adjust the tension springs until the starting point and feel are correct.
Replacing tension springs: step-by-step plan
Work safely: there is spring tension in the coupling. Preferably use a clutch compressor, or have it done if you are unsure.
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Place the scooter in a stable position and remove the CVT cover.
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Disassemble variator and clutch using the correct method for your block.
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Clean the coupling and check coupling segments and bell for wear or glazing.
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Replace the tension springs one by one, so that you do not twist or force anything.
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Reinstall everything with the correct torque and install the hood.
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Take a short test drive and pay attention to engagement torque, shocks and possible slippage.