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Thread: What spring rates do I have?

  1. #1
    Join Date
    May 2019
    Posts
    61

    Default What spring rates do I have?

    Dumb question, I know. But none of the springs currently on the car have any information on them. Fronts are red, rears are yellow. Dampers are gold. Other than that, I have no idea without putting them on a spring or shock dyno.

    Any way to tell or do I just need to go back to stock and start there?



    This is a 1992 S3 with a 1.4 k-series


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    Last edited by Andy69; 06-28-2019 at 05:27 PM.

  2. #2
    Join Date
    May 2019
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    61

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    I think I can get a good first kick at the cat by using an online spring rate calculator and taking a few measurements. That should tell me if I'm somewhere close to stock. I think the suspension is virtually stock which I think should put them in the 150-175 range
    Last edited by Andy69; 06-29-2019 at 09:38 AM.

  3. #3
    Join Date
    Nov 2010
    Location
    Gresham, Oregon
    Posts
    129

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    I'm not sure about all springs, but the ones on my QA1 shocks have the poundage stamped on the base of the spring.
    Mike
    2005 WCM Ultralite S2K

  4. #4
    Join Date
    May 2019
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    61

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    Quote Originally Posted by m wirth View Post
    I'm not sure about all springs, but the ones on my QA1 shocks have the poundage stamped on the base of the spring.
    I think all major manufacturers do that. Perhaps these have been refinished at some point.


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  5. #5
    Join Date
    Dec 2014
    Location
    Los Angeles
    Posts
    228

    Default

    My Birkin came with 175/F, 200/R for what it is worth (QA-1 shocks set full soft). From what I have heard, this is a fairly standard starting point. The cars are so light that they don't respond well to much heavier spring rates.

  6. #6
    Join Date
    May 2019
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    Quote Originally Posted by papak View Post
    My Birkin came with 175/F, 200/R for what it is worth (QA-1 shocks set full soft). From what I have heard, this is a fairly standard starting point. The cars are so light that they don't respond well to much heavier spring rates.
    At some point you end up with a spring that is essentially an infinite spring rate, in that there isn't enough weight in the car for it to compress against. Still, people run upwards of 1000# springs in CRXs and Miatas, so even though the Caterham is significantly lighter, there is some room there.

    Depending on what the car has now, I may not even change them out. The car has no ARBs, so I can change roll resistance by adding them. I'm hoping still to model the suspension though. The thing is, you can reduce understeer by reducing roll stiffness at the front or increasing it at the rear, but my approach is to make sure the fronts are at their "happy place" first - optimal roll stiffness - and adjust the back to match. That way you are sure you are getting the most out of the car. A car can be neutral handling and still not be as fast as it could be.
    Last edited by Andy69; 06-29-2019 at 01:24 PM.

  7. #7
    Join Date
    Sep 2005
    Location
    St. Louis, MO
    Posts
    436

    Default

    Andy- it sure looks to me like you have both a front and rear ARB.

    My ‘98 did not have a rear ARB, and I installed what I see in your picture. The bar in front of your upper wishbone is the front ARB.

    Steve

  8. #8
    Join Date
    Apr 2007
    Location
    Bozeman MT
    Posts
    495

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    You can use an online spring rate calculator and get really close on your spring rate. It will ask for the diameter of the wire, the number of coils and the diameter of the coils - all of which can be determined with the springs in place.

    dave

  9. #9
    Join Date
    May 2019
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    61

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    Quote Originally Posted by bball7754 View Post
    Andy- it sure looks to me like you have both a front and rear ARB.

    My Ď98 did not have a rear ARB, and I installed what I see in your picture. The bar in front of your upper wishbone is the front ARB.

    Steve
    Iíll take another look at that. I had seen some online but didnít recognize them on the car


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