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/APPhysicsCI/course%20files/readings/lesson18studysheet.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!

[let-r-eat]

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. The problem is not determining when a bind may occur. The problem is in determining when the next one will, or the next one, or the next one, or the next one, along with what direction the forces are moving. The problem is this often creates a strain beyond the modulus of elasticity of the material. Here is a short explanation: Lets take a sudden jounce:Using this formula shown here:http://mathworld.wolfram.com/QuarticEquation.htmlYou One can take the modulus of the material and calculate the first, second, and third orders and find that many times during a suspension event the modulus of the material may be exceeded when bind occurs using the wrong combination of parts. Such as placing too much burden on the first stage. I could do some of the math for you but that's what we have computer programs for. The modulus of elasticity depends on how much of the grain structure of the material suggests an isotropic or anisotropic structure. Young's is dependent on this and determines a materials response in Hooke's The more one can understand the directions, the more one can use the dampening to control them or understand when you are "out of bounds" with a particular application. Such as a 50# spring stacked on a 2000# spring, not that you would or anything but using as an example. Placing 2 springs on top of each other can make it a two-fold problem in determining when these events that strain the modulus the most occur. The linear portion of the stress or strain curve, although linear in slope, will depend on the isotropic structure of the material.The bottom line:The quality of the material matters and a basic assumption about the material is all a man has with the spring, a rater or calculator. The average Joe, experimenting as they do, may create a combination that is *out of bounds* Just like a valve spring or any other spring. That reason is what I was trying to explain. A person must know when they are putting themselves in a position that places their arrangement "out of bounds." Much easier to get out of bounds with 2 than with 1................................................. .................................................. ........................................Ghopper,An ything that has a frequency is doing work. Work creates heat. What happens when you warm something you are measuring 10 degrees? It expands < modulus of elasticity on carbon steels. Although may seems trivial but really matters more than one may think. ***********************************Summation****** ***************************** There is also strains that are not along the major movements. We control this buy understanding what we are working with and the dampening of those forces. Let's go back to the, 150# spring against a 2000# spring................= 193# spring. Anyone see a problem if the dampening isn't controlled precisely or the crossover point isn't controlled appropriately?That is the reason why you need trial and error.

[let-r-eat]

Gale Force is a nice piece of equipment for its purpose.

[Matt49]

You might want to check your math on what the resultant spring rate is when combining a 150 pound spring with a 2000 pound spring. Based on what you typed and what it actually is I'll give you the benefit of the doubt and assume it was a typo.
You think trial and error has its place and I call it guessing. Let's agree to disagree.

[Ghopper]

Ghopper,Anything that has a frequency is doing work. Work creates heat. What happens when you warm something you are measuring 10 degrees? It expands < modulus of elasticity on carbon steels. Although may seems trivial but really matters more than one may think.

Really. How much? I think your sensitivities are off. You are focusing on details that pertain to .01% usage in our dirt car application.

Question - Did you ever change your springs at the track because of the grain structure or operational spring temperature was not within your tolerance?



Damping:
These folk are combining 200-800lb/in springs with a 0.5-1" gap. We are not really concerned with the damping for the travel range that is outside of 95% usage. Example is that we spend 95% of the time within 3-4" of damper travel. Look at the spring rate at this point and set your damping (or overdamping) for this state.....which is most likely on the primary spring.


The question that we all are trying to master is having the right dynamic wedge for our combination. That is a much more simple quest than writing a Matlab program to study temperature/friction/noise/vibration/impacts of the spring on the damper. We can figure this out without textbooks on Mechanics of Materials or Mechanics of Vibrations.

The spring and damping combinations discussed is just not at any component extremes.



Ghopper

[let-r-eat]

You might want to check your math on what the resultant spring rate is when combining a 150 pound spring with a 2000 pound spring. Based on what you typed and what it actually is I'll give you the benefit of the doubt and assume it was a typo. You think trial and error has its place and I call it guessing. Let's agree to disagree.You would be kind enough to check it for me and show your work so I might be able to understand it?

[let-r-eat]

Really. How much? I think your sensitivities are off. You are focusing on details that pertain to .01% usage in our dirt car application.Question - Did you ever change your springs at the track because of the grain structure or operational spring temperature was not within your tolerance? Damping:These folk are combining 200-800lb/in springs with a 0.5-1" gap. We are not really concerned with the damping for the travel range that is outside of 95% usage. Example is that we spend 95% of the time within 3-4" of damper travel. Look at the spring rate at this point and set your damping (or overdamping) for this state.....which is most likely on the primary spring.The question that we all are trying to master is having the right dynamic wedge for our combination. That is a much more simple quest than writing a Matlab program to study temperature/friction/noise/vibration/impacts of the spring on the damper. We can figure this out without textbooks on Mechanics of Materials or Mechanics of Vibrations. The spring and damping combinations discussed is just not at any component extremes. GhopperI agree its a little deep. But you have to know where the bottom of the hole is if your going to jump.

[Matt49]

You would be kind enough to check it for me and show your work so I might be able to understand it?

The combined spring rate of two stacked springs is the product of the two spring rates divided by the sum of the two spring rates. Or (A*B)/(A+B)
(2000*150)/(2000+150) =
300000/2150 =
139.5

Now...would you be kind enough to check your math again and show me your math along with the work and you figured 193 so I might be able to understand how you could possibly combine two springs and end up with a rate that is greater than the lesser of the two originals. Because I'm pretty sure it's physically impossible.

[let-r-eat]

I transposed the numbers. Sorry about that. I didn't double check. Of course there is no math that will reach a higher rate than the lowest rate of the stack. Our problem is determining the work on that 4" spring with the 150# rate.Now that we have a 4" 150# spring.atop a 8" 2000# spring. How much weight to reach coil bind on that 150# spring? 139/150 = .926 Assuming below parameters for 4" spring we have 398 is .926 of 427# as the rate at which coil bind of 150# spring occurs. So now we need to consider the ratio of rates when doing the calculations. Assume spring parameters are .341 wire, 4" free length, and 3.5 outside diameter..........The answer is the point I'm trying to make. The ratio of rates matter and coil binding the spring often without control the dampening properly can make the handling erratic. Why? What happens after the spring binds. What does the rate go to then?

[Matt49]

Yeah...I know you didn't double check...that's why I suggested that you do so. And even suggested that you may have made a typo. But you ignored that suggestion and instead asked me to "show my work" as if I'm your student here or something. ha ha ha.

I KNOW that the rate will change when coil bind starts to occur. I've been saying that since LITERALLY three days ago on this thread. Coil bind is not occurring on any stack spring setup I have seen on a late model which is why I refuted your comment that "equations for this or that is foolish" in the first place. The equations work. Period.

The first time I see a 150 pound spring stacked with a 2000 pound spring on any type of race car I will let you know.
In fact when I see a 300 with a 1000 I'll let you know.

[let-r-eat]

Yeah...I know you didn't double check...that's why I suggested that you do so. And even suggested that you may have made a typo. But you ignored that suggestion and instead asked me to "show my work" as if I'm your student here or something. ha ha ha.I KNOW that the rate will change when coil bind starts to occur. I've been saying that since LITERALLY three days ago on this thread. Coil bind is not occurring on any stack spring setup I have seen on a late model which is why I refuted your comment that "equations for this or that is foolish" in the first place. The equations work. Period.The first time I see a 150 pound spring stacked with a 2000 pound spring on any type of race car I will let you know.In fact when I see a 300 with a 1000 I'll let you know.I was being sarcastic of course because you knew that I knew that you knew..............lolBut back to the topic:Now, Why was the stacked spring created for left rear applications? Could it be because the desired rate/dimension would bow? Bowing doesn't occur with a traditional spring within traditional parameters? What is the bow's effect on rate?You are still dealing with trivial elements that I assume we both know about. How does your equation predict bowing or I assume you think it doesn't matter?The rub marks created from coil springs just happen......?? That pitch I talked about earlier doesn't have a thing to do with bowing?I'm waiting on your equation for that?Could this be another reason for testing?HMMMMMMMM>

[let-r-eat]

The standard practice is length > 4x D is when buckling becomes a big problem. Giving that information for the record.

[let-r-eat]

Another thing I would like to state for the record is that springs are designed to work between 20% and 80% of their length.10" 400 pound spring should have 800 pounds of static weight to start with on it? What happens when we stack? Are we outside of those parameters?I'm sure you know when we check springs we compress them beyond and then back off to take readings. Yes, I'm taking you into the reason now for me saying that formulas don't solve all problems. They will when you are inside the box.............but how do we know we are inside that box?That is another point I'm making here.

[let-r-eat]

I would rather be helping people here determine what the proper combination may be and how they might find it. But to do that we must start by getting some things the books and magazines, chassis builders, etc don't teach into the limelight. You don't get faster on the racetrack without understanding what is really going on nor will you get faster without testing.That is the reason I'm conversing in this manner.

[Matt49]

We all have our own way of doing things, clearly yours is different from mine. I believe math gives us a very accurate model as long as we take as many variables into account as possible.
To dispute that, you have increased the number of variables thereby making the math more complex. Still doesn't mean it can't be "solved" with math but I have not the time nor the inclination to sit here and figure CoF constants for an Eibach spring rubbing against an Ohlins shock to see how that plays into my racing program just to prove a point. I'm done discussing whether or not math and physics are real things. And I’m not going to spend a bunch of time and energy figuring out how springs rubbing shocks are changing my spring rate when I could just avoid that situation altogether.
Springs bow for reasons that are well within our control.
1) Spring already bent or worn unevenly
2) Spring not flat on both ends (either ground that way or worn that way)
3) Spring damaged or deformed
4) Improperly installed coil-over hardware
5) Etc.
I don’t worry a lot about these things since checking all of this is on our weekly maintenance list for all springs that were raced any given weekend. So is checking our shocks for signs of shock interference from rubbing springs. It (interference) simply doesn't happen that much on our stuff but maybe I'm just getting lucky...or maybe it's because we configure and maintain our equipment to avoid it. Who knows.
Obviously spring interference is going to have an effect on spring rate (increasing it) but rather than spend a bunch of time figuring out how much, why not just do what can be done to avoid and potentially even eliminate it altogether. Works for me anyway and it's what I suggest to anybody that is willing to listen.
Softer springs are also more susceptible to bowing if they suffer from any of the ailments listed above which is why we combine two heavier springs to make a softer rate (stack) in the first place. You can also use shock savers to minimize the friction of a rubbing spring that might come unseated as is often the case on the LR. Or you can use a helper spring with a slider to do much the same. That's what we prefer on the LF.
To each their own.

[ALF401]

The guy just wanted to know if a 4' top spring would work or should he go to a 6" spring. I have read thru 20 BS statements by you "Engineers" and not one comment even close to answering the guys question. Can someone answer the guy's question??? I really believe you guys should give up racing and get into politic's, you would fit nicely there!!!!!

[let-r-eat]

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.I would not run that light on the primary spring. What type of track? Big banking or flat? Smooth or rough?

[7uptruckracer]

To answer your question NO DO NOT RUN a 4" spring it will coil bind. I recommend the 700/400 Combo just don't run that 4" spring and run a sleeve on the shock so it can't hang up on the bottom of the shock body

[jrkracing54]

After reading all that I feel like I just gave birth. To a Physicist. Thanks for the input. My question is how does a 4" spring coil bind when both springs are active and the stop nut is only 1 1/4" from the slider? John 1*

[7uptruckracer]

Your 4" Tall spring has a 4" Free Height. Compress it to Ride Height, then see how much you have left to travel in racing conditions. Until you hit the lock out nut your one both springs which is the point, but you just simply run outta room because of how they have to design the coil and space the coils to get it to be 4" tall. I know this is cloudy but one day try on a corner of your care different spring heights but the same rate and you will see your coil spacing is different.

[MasterSbilt_Racer]

Depending on your wheel weights and setup, you MAY get away with a 600# 4 inch, but no way with a 400#

[7uptruckracer]

You don't wanna spend all that money to find out if it will work like I did just give yourself the extra room and you will have more gap to work with. When I talked to Josh when we were at Rocket he gave me the impression they run a 375 RF and NEVER change it, and he scales twice a year on some old grain scales. Take it for what its worth I guess they just play the shock game.

[let-r-eat]

Reading my information closely you will find why the 4" spring may bind. This is why I stated that keeping a system from being "out of bounds" was the reason for my comments. If you got a (not a nice word)(not a nice word)(not a nice word)(not a nice word) binding combination on there to start with, formulas and math ain't gonna do a (not a nice word)(not a nice word)(not a nice word)(not a nice word) thing especially if your running springs outside of their windows.A 4" 400# spring was in my comments. Is this a Rocket I assume? Blue front? I don't want to give out any secrets here but if you pm me I'll help you with what I know.

[jrkracing54]

Reading my information closely you will find why the 4" spring may bind. This is why I stated that keeping a system from being "out of bounds" was the reason for my comments. If you got a (not a nice word)(not a nice word)(not a nice word)(not a nice word) binding combination on there to start with, formulas and math ain't gonna do a (not a nice word)(not a nice word)(not a nice word)(not a nice word) thing especially if your running springs outside of their windows.A 4" 400# spring was in my comments. Is this a Rocket I assume? Blue front? I don't want to give out any secrets here but if you pm me I'll help you with what I know.

Says your box is full.

[let-r-eat]

Says your box is full.Sorry about that..........I cleaned it up.