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Roll resistance calculations error?

  1. Dec 24, 2011 #1
    Hi,

    I am trying to calculate weight transfer from the front to rear of a vehicle and have already calculated the total sprung weight to be transfered.

    I now need to calculate the Roll resistance generated by the springs using the following forumula and this is where the error occurs.

    (SF/(WmF/SmF)^2) x TF^2 [ x ] 2 x ∏ / 180 = ArF

    In laymens terms

    SF = Front Spring Rate
    WmF=Front Wheel Movement
    SmF=Relative Front Spring Movement
    TF = Front Track
    ArF = Roll Resistance of Front Springs

    Now i can't figure out if the x i placed in brackets [ ] is supposed to be / (x or /)?

    The example is as follows;

    (175/(1.00/0.75)^2)xTF^2x2xPi/180 = 2889.77 in.lbs per degree (roll resistance of front springs)

    you will notice that the formula does not equate to the answer and to obtain the answer i must devide.... which present me with a problem as my understanding of this particular aspect is clouded by my understanding of the units...

    I realise this is probably a 'suck eggs' moment but can somebody explain in practical terms what is meant by in.lbs per degree... the amount of in.lbs per degree of roll but in.lbs is both a distance and a weight...

    Any help with either or both of the above problems will be much appreciated.

    Regards
    Jason
     
    Last edited: Dec 24, 2011
  2. jcsd
  3. Dec 25, 2011 #2

    Ranger Mike

    User Avatar
    Science Advisor

    hello and Welcome
    suggest you read Race car suspension Class
    on t his mech eng forum posted Jul29-09

    page two has calc for spring rates


    merry Christmas
    rm
     
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