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Old 02-14-2008, 05:53 PM   #1
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Default why no dual rate springs?

how come with touring car shock springs their just a single rate?
wouldn it make sense to have dual or even tripple rate springs?
wouldnt this allow more gipp in bumpy section while still preventing exxcessive roll in harrd corners?
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Old 02-14-2008, 06:14 PM   #2
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HPI makes progressive springs.
Some oval parts makes make progressive springs for the center shock. The center shock is most likely a touring shock body with a longer shaft.
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Old 02-15-2008, 12:26 AM   #3
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Hara Ver.1 springs are progressive rate.

And certain XRay springs are progressive rate as well.
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Old 02-15-2008, 11:56 AM   #4
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Just like in real on-road race cars, progressive rates are rarely used. Linear rate springs provide you with much more predictable handling response. The fact that progressive springs start soft, and suddenly become stiff cam make turn-in response slow, and can suddenly loose traction at the transition point. You can always make your own progressive rate suspension by running dual springs on each shock. Of course you will have to find springs short enough (or have them made). You also have to understand what happens to spring rate when springs are used in series...

A really cool use of multiple springs can be found in certain DTM cars. They install a secondary spring that's been shackled into a pre-compressed state. This causes the secondary spring to start compressing only after the corner load exceeds the secondary springs pre-compressed rate. This means the main spring's rate is the only one in action before this point. Then since the springs are stacked in series, the rate suddenly becomes softer after the transition point. This "digressive" spring rate allows the cars to hop curbs without destroying the suspension. And as long as the car never reaches the digressive transition point during normal cornering, the driver will always have a predictable vehicle.

Here's a terrible pic of the shackled secondary spring installed:
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Old 02-15-2008, 01:50 PM   #5
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well depending on how the different rates are achieved there doesn't have to be a transition points between the two rates...If 2 springs are used sure, but if one spring with a varying diameter is used you wont get that problem...

But why? Its much more for comfort, or to allow a vehichle to carry a large load with out having rediculous spring rates when its unloaded.

It doesn't help as much with body roll because at the point where the body is starting to roll the spring is weak, its not until after you have a good bit of body roll that you get the roll resistance you want.

My RC doesn't even have sway bars so a progressive or helper spring is even worse here...

Second it can be hard to tune. You only have one shock setting trying to work for a whole range of spring rates, so you could only set it to optimal at a given point during compression (I.E. not tuned as well as it could be until the car is at the exact speed in the exact radius of turn)

The same problem is even worse if you are trying to tune sway bars in conjunction to spring rate...

Progressive springs, in general are more of a comfort then performance thing...

Edit: that picture/concept is very cool as much as I have seen that, I never really though about it used to lower spring rate.
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