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355 Fiorano Handling Package Vs Challenge Suspension ECU.

Discussion in '348/355' started by ShineKen, Aug 17, 2021.

  1. ShineKen

    ShineKen F1 Veteran
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    @601

    Btw, for coil diameter I am plugging in 12 or 12.5mm.

    For spring diameter, I’ve tried 103 or 103.5mm.
     
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  3. OCKlasse

    OCKlasse Formula Junior
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    Just cut one coil people and you, too, can have Fiorano springs :)
     
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  4. 601

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    This photo shows more clearly where the coils start and end. I count just under 9 coils on the Fiorano spring (top) and just over 9.5 coils on the standard spring (bottom). So you're right, the difference is probably closer to one than 1/2.

    The first and last coil of each spring is inactive, so keep that in mind if you use a calculator that asks for active coils rather than total coils.
     
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  5. ShineKen

    ShineKen F1 Veteran
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    #79 ShineKen, Sep 15, 2021
    Last edited: Sep 15, 2021
    Using 7 & 8 active coils respectively, with Fiorano coil diameter of 12.5mm and spring diameter of 103.5 mm , I’m getting 54% stiffer, which brings it to 285 lbs/in.

    If I use a spring diameter of 103mm , I get 57% stiffer. That’s 290 lbs/inch.


    Watchu got?
     
  6. 601

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    You need to use calipers on the coil to get more precise. Your spring diameter range is fine, just pay attention to whether your calculator calls for inner or outer diameter.
     
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  8. ShineKen

    ShineKen F1 Veteran
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    Just visually comparing the two, spring coil diameter is 1mm more than standard. Since standard is spec’d at 11.5mm, I use 12.5mm.

    Spring diameter has got to be either 103 or 103.5mm

    I plugged in 104mm just in case and got 52% stiffer. That brings it to 280 lbs/in.

    This is all under the assumption the standard spring is 185 lbs/inch.
     
  9. ShineKen

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    The calculator I’m using only asks for outer diameter.
     
  10. ShineKen

    ShineKen F1 Veteran
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    Using the same ruler to measure coil diameter on both springs, I’m pretty confident it is right at 1mm thicker for Fiorano. You can sort of see that 1mm thickness in the pics.

    This has got to be a 280-290 lb spring.
     
  11. 601

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    Unlikely. It would sit too high even with the perches turned all the way down.
     
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  13. ShineKen

    ShineKen F1 Veteran
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    Ok. I found two pretty accurate mm gauges.

    I measured standard front springs, standard rear springs, and Fiorano front springs. They all checked out close to WSM specs.

    Standard front - 11.7 mm

    Standard rear - 12.2 mm

    Fiorano front - 12.7 mm


    .2 mm difference from WSM must be the thickness of the powdercoat coating.


    Fiorano front coil spring is indeed 1 mm thicker than standard front. 12.5 mm. This is actually the same thickness as the Fiorano rear springs (150415).
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  14. ShineKen

    ShineKen F1 Veteran
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    Only other thing I can think of is we have # of active coils wrong. That’s the only number that would make a big difference.
     
  15. ShineKen

    ShineKen F1 Veteran
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    BTW. My other spring is already at Swift. I’m just calculating to see how close my guess is :).
     
  16. 601

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    The calculation for the spring rate in N/mm is as follows. Units omitted for simplicity.

    78,500 x 12.5^4 / (8 x 7 x (103.5 - 12.5)^3)

    This converts to roughly 260 lb/in.

    You’ll recognize your measurements in the formula and 7 is my visual estimate of the number of active coils. It's not a whole number in reality and that imprecision potentially causes significant error.

    As you’re aware, the testing will give more accurate results.
     
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  17. ShineKen

    ShineKen F1 Veteran
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    This formula doesn’t factor in free length height?
     
  18. 601

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    No, I requested free length for other reasons. Such as, we can use it to estimate spring rate based on the assumption that installed length would be similar as with the standard spring.
     
  19. ShineKen

    ShineKen F1 Veteran
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    Ok. I am using a general online calculator and free length was requested for calculations.
     

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