Spring Rates for Coilovers

Discussion in 'E9 General Discussion' started by Rek, Dec 4, 2018.

  1. Rek

    Rek Active Member

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    By trial and error, I am establishing the spring raters I need for my front coilovers. As the springs once fitted, are sold, then I an trying to limit the error element of this by getting some feedback.

    For anyone with adjustable coilovers on their E9, then I would presume that the length and width of these are different from stock. Can you give me some feedback on diameter, length and rating and whether you are happy with the set up.

    Mine are Gaz Gold coilovers which utilise a 2.5" internal diameter. They are 9 inches long, but are currently too weak and coilbound over more extreme bumps in the road. As I live in a city known for its more extreme bumps in the road this is not acceptable in the long run.

    Any help is very gratefully received.
     
  2. Rek

    Rek Active Member

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    Anyone?
     
  3. BarryG

    BarryG solo e9 Site Donor

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    Rek
    Coil overs, what to do with them is a individual choice.
    My front spring are 440 lbs Rears 600 lbs. Length is a non factor being most housing are different. Shock absorbers a big parts of your ride quality I’m using Koni double adjustables.

    I have had a few members ride in my car and they say “ hey I thought it was going to be more ruff ride”.

    Very happy with my setup.

    What spring rate are you using?

    Good luck , Barry
     
  4. Belgiumbarry

    Belgiumbarry Well-Known Member

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    Intrax in Holland designed and mounted my coilovers ( all 4 corners) …. but i should look if i have still the data.... ???
     
  5. shanon

    shanon Well-Known Member

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    Been running this set up for a long time.
    Ireland Engineering coilovers up front with 550lbs springs and rear Bilstiens, 500lbs springs.

    hth
     
  6. Rek

    Rek Active Member

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    Thanks - thats useful info'.

    I have a selection of springs from 400 to 250ibs.

    Next week I am off to Demon Tweaks in North wales for them to play around with the car. They have helped me in the past and waived their fees. Good people I think.
     
  7. BarryG

    BarryG solo e9 Site Donor

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    We need to swap cars and go for a run
     
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  8. shanon

    shanon Well-Known Member

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    Barry, meet us soon in Buttonwillow for a proper test
     
  9. bfeng

    bfeng Well-Known Member Site Donor

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    FWIW, I would start with the the stock spring rate and add 15%.
    Or perhaps you could start with the spring rate of the Carl Nelson spring set (shorter, slightly stiffer).

    As a data point, I have a car that weights just about 1000lbs with about 55/45% weight distribution. The front spring rate is about 350lbs/inch. But you have to consider that there is very little suspension travel in this car (a bit less than 3"). Given that an E9 is nearly 3x heavier, but has more suspension travel, I would be surprised if anything under 500lbs/in would be sufficient for sporty driving at a lower than original ride height.
     
  10. Rek

    Rek Active Member

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    550 lbs would make my car rock solid. My springs are 7 or 8" long and 2.5" internal diameter. Perhaps the size of your springs differ.
     
  11. bfeng

    bfeng Well-Known Member Site Donor

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    I thought the diameter and length of the spring was only relevant in regards to suspension travel. Spring rate already takes into account the stiffness of the steel and the diameter of the coil
     
  12. Rek

    Rek Active Member

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    I am no expert on this so you’re probably right.

    Experimentation seems to be the way forward.
     

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