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Thread: Advice on spring rates and ride height

  1. #1
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    Advice on spring rates and ride height

    After putting some miles on the car, I’d like to soften up the ride a bit. Our set up is the newer IRS with 500# springs in front and 400# in the rear (8” height), along with the red Koni shocks. We also have front and rear sway bars. Our tire pressure is 23lbs with the 17” Hallibrand style rims.

    Secondly, our ride height is 3 7/8” despite our best attempts to raise it as much as possible by tightening the collars against the spring using a spanner wrench. I’ve read that others have had similar issues…

    So I thought I would kill 2 birds with 1 stone by getting softer and longer springs. My plan is to go with 9” height and 450# front, 300# rear. I calculate that this would raise the ride height by about ½ inch which would be perfect. And by reducing the spring rate in both front and back, we would hopefully maintain the balance of the car.

    Does this sound like a reasonable plan?
    MK4 Roadster #9138
    Blueprint 427 with Sniper EFI, TKO600, IRS, complete kit
    https://thefactoryfiveforum.com/show...8-Build-Thread

  2. #2
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    After several years of use, I too went with softer springs 100 lbs. off the front and rear. I had no ride height issues which is at 4 inches all around with an extra 1/8 inch left rear (for driver weight). I have a set 50 lbs off which was not enough for sale. PM if interested .

  3. #3
    Senior Member CraigS's Avatar
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    Your plan will work out just fine.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

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  5. #4
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    Thank you, I appreciate the confirmation. I'm no suspension expert so wanted to run it by the group. Thanks!
    MK4 Roadster #9138
    Blueprint 427 with Sniper EFI, TKO600, IRS, complete kit
    https://thefactoryfiveforum.com/show...8-Build-Thread

  6. #5
    Senior Member CraigS's Avatar
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    I just had an additional thought. Did you verify that the Konis are on full soft adjustment before you installed them?
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  7. #6
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    Yes, I adjusted the Konis to full soft before installing
    MK4 Roadster #9138
    Blueprint 427 with Sniper EFI, TKO600, IRS, complete kit
    https://thefactoryfiveforum.com/show...8-Build-Thread

  8. #7
    Senior Member GTBradley's Avatar
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    I would suggest disconnecting the anti-sway bars and see how it feels first. I haven't installed any and like the way it rides with the IRS rear.
    Bradley

    Build thread - Mk4, Coyote, IRS, Wilwood brakes, old-style soft top and accessories.

    The distance between "finished" and finished is literally infinite.

  9. #8
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    That’s an easy experiment to do, I can try that first before ordering the shocks to see if it helps with the ride. Won’t help with my ride height issue but I’m all for getting more data.
    MK4 Roadster #9138
    Blueprint 427 with Sniper EFI, TKO600, IRS, complete kit
    https://thefactoryfiveforum.com/show...8-Build-Thread

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