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Discussion Starter #1
From what I’ve always read and gathered through the billavista guide when setting up springs on a coil over with dual springs you’re supposed to run the longer and heavier spring on the bottom and the softer shorter spring up top, giving you the dual rate and allowing you to then set up the dual rate adjuster.

What draw back does it have to run the longer spring in the bottom at a lower rate than the top one?

I’m asking because whilst setting up the coil overs in my Jk I threw in a set of springs I had laying around to mock everything up and to my surprise it gives me the ride height I’m looking for.

I’m on Fox 2.0 emulsion, 12” with a 14” 150 on the bottom and 12” 200 on top for reference.
 

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I would be interested in seeing the responses on this as well. On trail rigs, I tend to use the longer, softer rate on the bottom, that way when the shock hits the cross over it is a smooth transition from the soft dual rate to the firm linier rate.
 

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NERD
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Depending on the vehicle weight and size of C/O's you have, the longer lower rate springs tend to bend and hit the C/O body or the shaft.
Yes, that can happen.

Aside from obviously being backwards, you will not have the dual rate effect. No matter which spring is on top or bottom, the total combined spring rate is the same. 200/150 or 150/200 has the same spring rate of 85.7. This is calculated the same way resistors in parallel are calculated. Multiply the two spring rates together then divide that by the sum of the two spring rates. (150 x 200) / (150 + 200).

If your springs aren't setup correctly, you will have problems. Even if the lighter spring is longer, it needs to be on top. If it's not setup correctly on the slider and shock body due to length, you need to find correct springs.

PAC just stopped making springs for COs, so now is a good time to buy them cheap. There's also a CO spring thread in Misc for sale forum so I'd look there too. Get these springs right and you'll enjoy the awesome benefits of dual rate springs and adjusting your thresholds. Good luck.
 

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Discussion Starter #5
Yes, that can happen.

Aside from obviously being backwards, you will not have the dual rate effect. No matter which spring is on top or bottom, the total combined spring rate is the same. 200/150 or 150/200 has the same spring rate of 85.7. This is calculated the same way resistors in parallel are calculated. Multiply the two spring rates together then divide that by the sum of the two spring rates. (150 x 200) / (150 + 200).

If your springs aren't setup correctly, you will have problems. Even if the lighter spring is longer, it needs to be on top. If it's not setup correctly on the slider and shock body due to length, you need to find correct springs.

PAC just stopped making springs for COs, so now is a good time to buy them cheap. There's also a CO spring thread in Misc for sale forum so I'd look there too. Get these springs right and you'll enjoy the awesome benefits of dual rate springs and adjusting your thresholds. Good luck.
Thanks for the info. I assume I need to factor in the length when calculating the rate, correct? Being that I have 1 12" 200 and 1 14" 150 what would the overall rate be? Would it still be 85.7?

Once its all done I think ill need to add a little more spring to accommodate for the spare which hasn't arrived and the tools in the back.
 

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GIJEEPN
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Thanks for the info. I assume I need to factor in the length when calculating the rate, correct? Being that I have 1 12" 200 and 1 14" 150 what would the overall rate be? Would it still be 85.7?

Once its all done I think ill need to add a little more spring to accommodate for the spare which hasn't arrived and the tools in the back.
The Length of the springs makes no difference in the calculation.

(Main Spring * Tender Spring ) / (Main Spring + Tender Spring)
200 * 150 / 200 + 150
30000 / 350 = 85.7 lbs/in

The only reason to factor in Length of the springs is to see if you have enough room for preload. for example if you need a 200lb spring and a 150lb spring but only need 1" of preload then you might want one or two shorter springs to give you more adjustability.

As for more load in the rear. depending on the set up ( eg. Angle of installation, distance from the springs to the load etc.) you might be able to adjust with preload.

Hope that made sense, I've been watching star wars movies and hitting the Jack for May the 4th. lol.

Joel.
 

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NERD
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The Length of the springs makes no difference in the calculation.

(Main Spring * Tender Spring ) / (Main Spring + Tender Spring)
200 * 150 / 200 + 150
30000 / 350 = 85.7 lbs/in

The only reason to factor in Length of the springs is to see if you have enough room for preload. for example if you need a 200lb spring and a 150lb spring but only need 1" of preload then you might want one or two shorter springs to give you more adjustability.

As for more load in the rear. depending on the set up ( eg. Angle of installation, distance from the springs to the load etc.) you might be able to adjust with preload.

Hope that made sense, I've been watching star wars movies and hitting the Jack for May the 4th. lol.

Joel.
x2

I thought you said you read The Billavista bible, motorsports3?? :flipoff2:
 

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Aside from obviously being backwards, you will not have the dual rate effect. No matter which spring is on top or bottom, the total combined spring rate is the same. 200/150 or 150/200 has the same spring rate of 85.7.
I disagree. If the lighter rate spring is on the bottom you will still have a dual rate effect, it will just be a smaller transition.

200 over 150 has an initial rate of 85.7, and a final rate of 150
150 over 200 has an initial rate of 85.7, and a final rate of 200

I agree this is not how it's typically done, but that doesn't make it wrong. There have been discussions on here recently about how minimizing the rate jump may be a good thing.

The major downside is depending on where you crossover from the combined rate to the final rate, you might need a lot of travel from a low rate spring, which leads to a long spring. The Eibach catalog lists spring travel for standard springs.
 

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NERD
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I disagree. If the lighter rate spring is on the bottom you will still have a dual rate effect, it will just be a smaller transition.

200 over 150 has an initial rate of 85.7, and a final rate of 150
150 over 200 has an initial rate of 85.7, and a final rate of 200

I agree this is not how it's typically done, but that doesn't make it wrong. There have been discussions on here recently about how minimizing the rate jump may be a good thing.

The major downside is depending on where you crossover from the combined rate to the final rate, you might need a lot of travel from a low rate spring, which leads to a long spring. The Eibach catalog lists spring travel for standard springs.
There’s always one guy that wants to find an idiotic way to still be right :flipoff2: you contradicted yourself, by the way. It’s a sharper transition from 85 to 200 and is not the intended rate you’d want. If you want to bend your lighter spring and run it on the lower, go for it. You’ll be buying springs, shock bodies, and sliders pretty soon so I hope it’s worth it to still “technically be dual rate”. Good luck. We warned you. :):homer:
 

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There’s always one guy that wants to find an idiotic way to still be right :flipoff2: you contradicted yourself, by the way. It’s a sharper transition from 85 to 200 and is not the intended rate you’d want.
Yes, 86 to 200 is a sharper transition. Or as I said, 86 to 150 is a smaller transition. :flipoff2:

Are you saying 85 to 200 is too big or too small of a rate jump, or are you saying that his rates are just way off based on the fact that it's the rear of a JK?

motorsports3, how much preload do you need to get to the ride height you want?

Wayne's first post here explains preload pretty well:
https://www.pirate4x4.com/forum/general-4x4-discussion/1074029-spring-tech-thread.html
 

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NERD
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Yes, 86 to 200 is a sharper transition. Or as I said, 86 to 150 is a smaller transition. :flipoff2:

Are you saying 85 to 200 is too big or too small of a rate jump, or are you saying that his rates are just way off based on the fact that it's the rear of a JK?

motorsports3, how much preload do you need to get to the ride height you want?

Wayne's first post here explains preload pretty well:
https://www.pirate4x4.com/forum/general-4x4-discussion/1074029-spring-tech-thread.html
I’m saying this is a waste of time and it should be done right. If you want to lead him and others astray to satisfy your need to be an internet sensation, go for it - he’ll be pissed when he comes back and his springs are bowed, his shock body is worn, and the end cap is nearly gone from the slider shaving it off.
 

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I agree and would want a higher rate when hitting the secondary nuts. Both ways would be a dual rate as long as you can get the secondary nuts screwed down low enough so they engaged before you hit the bump stops. You do need to make sure the lower spring is equal to or longer than the travel in the shocks or the slider can bind on the shock body when you fully extend and rebound. 200/150 sounds too light for a JK but I don't know your set up. I typically see 300/200 300/250 on the LCOG builds out there due to the limited amount of up travel.
 

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hmm.. a pissing match. Might I piss as well....

Do WTF you want OP, you still have a step up ratio, you still have the ability to get on the primary spring from your lower length. It is true that lighter springs bow more.. but whatever man. I'm running 150/150 front and 125/125 rear... it bows a little, and its fine. It will never touch the shaft.

From my experience, you'll be changing springs again anyways before you find your magic place. Just run em for a bit and learn some more about what affects what and change them out when the time comes.

-Nick
 
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