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Spring arithmetic

Discussion in 'Technical Q&A' started by ferrarilou, Apr 2, 2005.

  1. ferrarilou

    ferrarilou Formula Junior

    Apr 13, 2004
    512
    US
    Full Name:
    Lou Menditto
    #1 ferrarilou, Apr 2, 2005
    Last edited by a moderator: Sep 7, 2017
    The 348 Workshop Manual provides the rear coil suspension spring information from the photo below. From this information, I'm trying to derive the spring rate in US/SAE terms. I can't seem to find the right conversion to get to anything that matches typical rates for either street or tuned cars. I expect that the numbers to use are the ones at the bottom that are differentiated by the three spring offerings (yellow, red, and no color), but I don't know how to interpret them. Anyone on this forum know how? Thanks.
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  2. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,428
    The twilight zone
    Full Name:
    The Butcher
    I'm sure I can convert it for you, but I can't read anything in the pic. Can you repost just the english numbers or email a high res version to me at
    markeberhardt@comcast.net
     
  3. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,381
    Texas
    Full Name:
    Steve Magnusson
    (Static Load)/(Free Length - Length with Static Load) will give you the spring rate in N/mm -- you can then convert to lb/in if necessary.

    The "colour" table at the bottom is used to indicate what measured static load is necessary to compress a particular spring to the nominal "length with static load".
     
  4. ferrarilou

    ferrarilou Formula Junior

    Apr 13, 2004
    512
    US
    Full Name:
    Lou Menditto
    Sorry for the lowres pic. I had reduced it to keep the download time short, but I suppose I overdid it. Here's the text from the tables:

    LI - Free length (mm) ...................... 305
    Cs - Static load (N) ........................ 4517 +/- 135
    Ls - Len w/Static load (mm) ............. 220
    Cd - Dynamic load (N) ..................... 7751 +/- 224
    Ld - Len w/Dynamic load (mm) .......... 159
    df - Wire diameter (mm) .................. 13.5
    de - Spring outer diameter (mm) ....... 108.5 +/- 1.1
    qm - Flexibility mm/da (N) ................ 1.181

    Color categories
    Yellow ........... 4400 : 4468
    No color ........ 4468 : 4566
    Red .............. 4566 : 4635

    Note that for the last three items above, the separator is actually a traditional US arithmetic division sign rather than a colon, but my keyboard doesn't have that :)

    Thanks very much for your help.


    Lou
     
  5. ferrarilou

    ferrarilou Formula Junior

    Apr 13, 2004
    512
    US
    Full Name:
    Lou Menditto
    Steve,

    Thanks! That result makes sense (303 lb/in).


    Lou
     
  6. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,428
    The twilight zone
    Full Name:
    The Butcher
    It looks like I woke up too late to help....I now understand why Lou was having touble with the conversion. That seems like a bizarre why to specify spring info and I'm not sure how long it would have taken me to realize what they were doing.
     

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