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  1. #1
    Join Date
    Jul 2011
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    137

    Default Digressive stack vs. barrel spring

    Would a Digressive stack on the Lr help keep the car on the bars on corner entry more so than a linear barrel spring? Iím thinking since a Digressive stack would be riding on the bottom stiffer spring at full drop (say a 175-200) it would help keep the car from sitting down on entry as much as it would with a 16inch 100 pound linear spring? Am I thinking right?

  2. #2
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    Jul 2011
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    Default

    For comparison purposes letís say both set ups maintain the same drop out load.

  3. #3
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    May 2007
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    Default

    For clarification: a digressive stack has the lock out nut under the floater plate, so it's never on just the lower spring. it's using the combined rate of both springs.

    That being said if the stack is a softer rate, to get the open load the same as the stiffer single spring the lock out nut is reducing the open load at a pin to pin just short of the extended length. So at a distance short of the full extended load it will have more load and thus hold the car up better.

    Example: 19" ride pin and 23" full extended pin

    Single 100# spring (making up numbers here)

    23" 150#
    22" 250#
    21" 350#
    20" 450#
    19" 550#

    Stack spring (175/200 = 93#) this spring is so close to the 100# spring it's not worth comparing as the loads are gonna be so similar you probably can't tell a difference. So I'm gonna use a 66# combined rate to show this 100/200 combo

    23" 150#
    Hits lock up to cut the load down
    22" 357#
    21" 423#
    20" 489#
    19" 550#

  4. #4
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    Jul 2011
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    Default

    Doesnít the lock out nut capture the top spring at a certain point in travel (close to full extension) so that spring is no longer active, leaving the car riding on the bottom spring rate? Not at all trying to argue, billet, just trying to ask questions to better understand because Iíve never ran a Digressive stack before.

  5. #5
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    Sorry, I could have said better

    Yes it does, but it's the load you need to be looking at not the rate of spring persay.

    Basically since those to spring set ups are basically the same rate, the lock up should hardly be taking out any load to end up the same ride and extended loads. But if set up with the exact same loads, yes the stack should have slightly more pounds at the 22" (it's gonna be small).

    Assuming your likely in a 650 range load at least for ride load that means a 93# spring is gonna be compressed around 7" so at 7# difference between a 100# and 93# your talking 50 pounds more extended load if you didn't use a lock out nut.

    Long story short which ever has more extended load at any of the 23 thru 20" pins is gonna stay up better.

  6. #6
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    Default

    If I do the actual 175/200

    23" 150#
    Hits lock up to cut the load down
    22" 271#
    21" 364#
    20" 457#
    19" 550#

    The stack is a little better then the 100#

    The difference will be more if your ride is higher then the 550# I started at

  7. #7
    Join Date
    Jul 2011
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    Default

    Thank you for the explanation. And just to clarify, I wasnít meaning a 175/200 stack. I was just picking a random range as in a 175 or a 200 to be used on the bottom. I was figuring a 100 or 125 on top. While Iím picking your brain, would an 8Ē 100 on top of a 12Ē 225 be something I could try to experiment with? Only asking because I have these springs on hand and could try them to see if itís something I like before I go buy new springs just to test?

  8. #8
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    20" of total spring is about all you can typically use depending on your shock brand. More then that and your top nut will be all the way up and can't get ride hieght low enough unless your really really soft on total rate. Typically your gonna use a 10" max tall spring on bottom (can use an 8" but need a divider that won't let spring come off shock body at full extension and get hung up under shock body).

  9. #9
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    Default

    However if you use an 8" lower you have no threads to put the lock nut because the floater is off the shock body. How far your shock is threaded down the body also comes into play.

    A 10" lower is the safest bet and then vary the upper length so have enough travel out of it so it doesn't coil bind and not so long you can't get ride hieght down to where you need it.

    10" lower and 8" upper is the most common but if super soft you can sometimes use a 10" upper
    Last edited by billetbirdcage; 05-16-2022 at 05:26 PM.

  10. #10
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    Default

    What rates would you start with?

  11. #11
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    That's a loaded question, lol

    Not knowing anything about the car, track and etc or what issues your having. I would alter the extended load 50#, that's enough of a change you should notice it but not so much to completely change the car. Then go another 50# if that helped and fine tune from there.

    Or alter your 22" number up 50/75# or so and try with same full extended load, then you can adjust the lock nut and lower or increase the full extended load.

    Sorry just realized you probably meant rates not loads. Again a loaded question. Something in the 125/200 or 100/200 or 175/175 is gonna lower you overall rate under the 100# you been using and will increase the between pin number loads and allow you to have more full extended load if you want it or run what you been running.

  12. #12
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    You can pick about anything that just ends up with something around 90# or less. I would go 85# or less so you see a change more easily and have a better idea where to go next if that helps

  13. #13
    Join Date
    Jul 2011
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    Default

    Yes rate is what I was meaning. Basically Iím wanting to take some compression out of the LRF shock because I feel it is really hurting my overall grip. But Iím concerned the car wonít stay up if I do that. (Iím working on my trail breaking) but I was thinking a Digressive stack may help the car stay up and allow me to take compression out of my front shock.

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