Dual Stage Spring Setup ?

[HuckleberryB4]

I see that Afco suggests starting off with their 400 lb secondary and 700 lb primary spring. It works out to being a 254 lb sping on entry and a 700 on exit for the right front setup.

I have a 600lb secondary spring and was going to run it with a 10" 450 lb primary. The math works out to being a 250 lb spring on entry, but would this mean that it would only be a 450 lb spring on exit? This is also on a full cast motor car.

[AmickRacing]

You're correct. I'm currently running the 400 top / 600 bottom spring on my car.

I think you'll be lacking a lot of drive coming off with that soft of a primary spring, of course it depends on the car and driver also. Might be able to play around and make it work if you have the track time to make plenty of adjustments, but I think I'd try for a stiffer spring as the primary.

FWIW, I'm running an all steel motor as well, and running around 1" gap.

[jrkracing54]

What length springs are you running? I run Hypercoil springs and have been told the 4" spring on top could coil bind so was thing of using a 7" primary and a 6" top spring. Any thought on that or are you just running the 4" with an 8"? John 1*

[11jcr51]

What length springs are you running? I run Hypercoil springs and have been told the 4" spring on top could coil bind so was thing of using a 7" primary and a 6" top spring. Any thought on that or are you just running the 4" with an 8"? John 1*

Speaking of spring length for Stack Springs. I find it really hard to believe that length of springs doesn't also play into the equation. How can't it? your putting more spring pressure on a shorter spring trying to reach ride heights verses a taller spring. or am I completely out of the ball park here?

[7uptruckracer]

Your out of the ball park......Spring height only have the potential to store more energy that doesn't mean it does. It will take the same weight on the spring to achieve that same ride height if the rate is the same no matter what the height is. Thats why its pounds per inch. unless its coil bound the spring doesn't know the difference. A 12" 200lbs/1" spring and a 10" 200lbs/1" will both take the same weight to reach the same height and release weight the same way as well your adjuster just has to screw 2" more before it begins to contact the spring. Don't get stack and dual stage mixed up one has lockout nuts and and hardware the other is just that a stack.

[11jcr51]

thanks that helps. Well then I better start calling ours Dual Stage Springs didn't realize there was a difference. thanks!

[dualdj1]

thanks that helps. Well then I better start calling ours Dual Stage Springs didn't realize there was a difference. thanks!

yep dual stage uses a stack to achieve the lower rate, but also has the lock nuts to utilized the heavy spring.

[let-r-eat]

Understanding what is happening with dual stage or stacked setups is not cut and dry. Anyone saying there is equations for this and that is foolish. Springs often become dynamically related when you pair them. Look at the progressive 5 th coil springs and other progressives. Stacking/dual stage requires a measured determination of wheel rate for a given suspension movement.

[MasterSbilt_Racer]

Understanding what is happening with dual stage or stacked setups is not cut and dry. Anyone saying there is equations for this and that is foolish. Springs often become dynamically related when you pair them. Look at the progressive 5 th coil springs and other progressives. Stacking/dual stage requires a measured determination of wheel rate for a given suspension movement.

Progressive springs have different coil spacing throughout the spring so that some coils bind early. Figuring a dual rate spring is just math up until the point coils start to bind on one of them. If I know the total travel I achieve with a linear spring, I can tell you what travel I will achieve with a dual rate setup if I know the spring rates and divider gap and the springs don't coil bind.

[Matt49]

Understanding what is happening with dual stage or stacked setups is not cut and dry. Anyone saying there is equations for this and that is foolish. Springs often become dynamically related when you pair them. Look at the progressive 5 th coil springs and other progressives. Stacking/dual stage requires a measured determination of wheel rate for a given suspension movement.

Physics is quite real and the mathematics that explain it are quite accurate. Just because you can't do the math or don't know the variables does not make it foolish.

[let-r-eat]

I'm very familiar with the math. I should for I've designed many springs. Math don't solve all the problems in the spring world. Sorry.You tell me why a spring is linear in rate and I'll tell you why different rates working dynamically won't be explained using a mathematical equation of any type.I'm not trying to be harsh here. I'm just pointing out information. Take it for what its worth. I'm merely pointing out the grey areas for with springs there are many...........heat/material/pitch fade just to name a few. Have you cycled a shock on the dyno and then cycled the same shock with spring installed? Shock dyno programmed to counteract unsprung weight? You done this with single rate/dual rate?

[Matt49]

I'm very familiar with the math. I should for I've designed many springs. Math don't solve all the problems in the spring world. Sorry.You tell me why a spring is linear in rate and I'll tell you why different rates working dynamically won't be explained using a mathematical equation of any type.

I shouldn't have to tell you why a spring rate is linear. Hooke's Law does it for us and as a spring expert surely you are familiar with it. Certainly you know that Hooke's law has its limitations. But with the materials used for coil over springs and the forces they are under, I believe we are are well within those limitations. Do you think otherwise? If so I'm interested to get your take on that.
Unless there is irreversible deformation of the material, there is nothing that should change the linear rate of a spring (or two springs stacked together) other than coil bind or some other interference with the movement of the material being deformed. Coil bind is removing "active" coils from the deformation process thereby changing the characteristics of the spring (making it stiffer).
A spring is simply a coil of wire of an elastic material. If you know the diameter of the wire, the diameter of the coils, the number of coils active, and the shear modulus of the material, you can calculate the spring rate with a formula. But surely you already knew that.

So now explain to me how two springs stacked will not demonstrate a linear spring rate without coil bind. I'm certainly interested in hearing this since it violates widely accepted scientific data to the contrary.

[Matt49]

I'm very familiar with the math. I should for I've designed many springs. Math don't solve all the problems in the spring world. Sorry.You tell me why a spring is linear in rate and I'll tell you why different rates working dynamically won't be explained using a mathematical equation of any type.I'm not trying to be harsh here. I'm just pointing out information. Take it for what its worth. I'm merely pointing out the grey areas for with springs there are many...........heat/material/pitch fade just to name a few. Have you cycled a shock on the dyno and then cycled the same shock with spring installed? Shock dyno programmed to counteract unsprung weight? You done this with single rate/dual rate?

Yes material and heat can change the rate but that changes the shear modulus which is part of the...wait for it...EQUATION. But obviously that math is not a problem for you.
What the heck does cycling a shock on a dyno with or without a spring have anything to do with the spring rate?
You say you're "just pointing out information" but I have yet to see any information.
All of these variables that you are talking about are a part of the equation when dealing with spring rate. Changing the material will not make a spring non-linear. Changing the heat will not make a spring non-linear (Edited: unless you heat the material to the point of losing elasticity in which case you have much larger problems on your hand if you spring is that hot). Changing the pitch of spring will not make it non-linear.
So I guess I'm completely missing your point which was (correct me if I'm wrong) that it is foolish to use an equation for any of this. I'm looking for you to provide me with an example of spring setup that does not follow accepted laws of physics and the mathematics associated with them.

[let-r-eat]

Yes material and heat can change the rate but that changes the shear modulus which is part of the...wait for it...EQUATION. But obviously that math is not a problem for you.What the heck does cycling a shock on a dyno with or without a spring have anything to do with the spring rate?You say you're "just pointing out information" but I have yet to see any information. All of these variables that you are talking about are a part of the equation when dealing with spring rate. Changing the material will not make a spring non-linear. Changing the heat will not make a spring non-linear (Edited: unless you heat the material to the point of losing elasticity in which case you have much larger problems on your hand if you spring is that hot). Changing the pitch of spring will not make it non-linear. So I guess I'm completely missing your point which was (correct me if I'm wrong) that it is foolish to use an equation for any of this. I'm looking for you to provide me with an example of spring setup that does not follow accepted laws of physics and the mathematics associated with them.

I'm glad you responded, even though condescendingly. You are taking my remarks out of context. I made the remark simply because of a simple concept. Understanding one is much easier than understanding two. Hooke's is reliant and is only a 1st order operation. A very generic way of looking at things. Why do we check springs to see if they have maintained their dimension? I will suggest that we test them because during dynamic operation the first order operation variables may change. For how long? When? How?Your spring lasts forever, but my spring doesn't. Whose right?Let's now get away from the simple Hooke's and move to the second order operations:Newtons second law: mx" + cx' +kx = F(t)forced, unforced, damped, or undamped.Do these two different spring rate springs have different frequencies? Different dynamic forces upon them?Here is an important question for you:I build a coil spring suspension for a highway pickup. I use a 800 pound 8" spring and a 700 pound 4" spring stacked on the right rear. Which one will wear out first? The short or the long? Now an 800pound against a 200 pound? Which one is doing more work or risks moving outside the 1st order?That question will never be answered by a first order operation. My point is that formulas that relate springs of different rates in the 1st order often don't tell the whole story. But since you already knew that it doesn't really matter in this conversation does it?

[let-r-eat]

Here is some reading if you like to delve into this kind of stuff. This is the general concept.http://uccpbank.k12hsn.org/courses/A...studysheet.pdf

[Matt49]

I'm glad you responded, even though condescendingly. You are taking my remarks out of context. I made the remark simply because of a simple concept. Understanding one is much easier than understanding two. Hooke's is reliant and is only a 1st order operation. A very generic way of looking at things. Why do we check springs to see if they have maintained their dimension? I will suggest that we test them because during dynamic operation the first order operation variables may change. For how long? When? How?Your spring lasts forever, but my spring doesn't. Whose right?Let's now get away from the simple Hooke's and move to the second order operations:Newtons second law: mx" + cx' +kx = F(t)forced, unforced, damped, or undamped.Do these two different spring rate springs have different frequencies? Different dynamic forces upon them?Here is an important question for you:I build a coil spring suspension for a highway pickup. I use a 800 pound 8" spring and a 700 pound 4" spring stacked on the right rear. Which one will wear out first? The short or the long? Now an 800pound against a 200 pound? Which one is doing more work or risks moving outside the 1st order?That question will never be answered by a first order operation. My point is that formulas that relate springs of different rates in the 1st order often don't tell the whole story. But since you already knew that it doesn't really matter in this conversation does it?

I think the condescension started when you said that anyone who thinks there is an equation for this or that is foolish. Now here you are trying to lecture me on second order linear equations (or operations as you like to call them). I took a little math in engineering school but thanks for the refresher on Newton's second law.
If it happens in physics, it can be explained with math. Your original post seemed to imply that wasn't the case and anybody that thought it was the case was foolish. I obviously misread or misunderstood something. I'm moving on.

If you agree that all thing in physics can be explained using math, then I think we're on the same page albeit not necessarily speaking the same language.

[let-r-eat]

I apologize if my remarks were out of context. If equations were the rule of the world we wouldn't have tests.........We would already know the result. There would be no reason for trial and error.

[Ghopper]

I apologize if my remarks were out of context. If equations were the rule of the world we wouldn't have tests.........We would already know the result. There would be no reason for trial and error.

I am a simulation guy, but -

We are looking at low frequency applications, with low velocities........so heat and fatigue in the life of a dirt springs is not that big of a deal. Also this is a passive system! So I think we can keep it simple.

I suggest using a spring rate machine that tests the whole spring/damper system and take good notes in your testing.



Ghopper

[Matt49]

I apologize if my remarks were out of context. If equations were the rule of the world we wouldn't have tests.........We would already know the result. There would be no reason for trial and error.

I agree...there is no reason for trial and error. That is a completely unscientific problem solving methodology. The only reason to test anything is to verify or nullify a hypothesis. We try/test things on race cars not because we don't know the result of one change but because we don't know if that one change will improve an overall situation (i.e. a larger more complex system with external variables (e.g. track conditions and driver input)).
I guess I would still like for you to provide me with an example of when a spring (or combination of springs) would provide a non-linear rate without some type of coil bind or other external forces being introduced.
You said that stacked spring was not cut and dry. I'm simply saying that it is. Provide me with an example of when it isn't and I'm all ears. Otherwise, I think we're going in circles here.

[drtrkr244]

Hmmmmm! I wondered why alot of the super dlm drivers have a Gale Force in their hauler!