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Automotive Roll stiffness affecting Steering Effort .

  1. Jul 9, 2012 #1
    I am currently working for a Touring Car Team . I have modified the front suspension geometry . Made the roll moment lesser and increased the Roll stiffness . Driver complained that the steering effort has increased considerably in the corners .

    1.How does increased roll stiffness increase steering effort ? Does it have anything to do with the lateral load due to diff geometries pushing the tire down or giving it a more of a tire wall deformation effect ?

    2.What are the methods to reduce steering effort other than
    a.Reducing the scrub radius .
    b.Increasing the knuckle moment (very difficult as it changes the steering geometry) .
    c. Simply giving him a bigger steering wheel .
     
    Last edited: Jul 9, 2012
  2. jcsd
  3. Jul 10, 2012 #2

    Ranger Mike

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    what exactly did you do? what is the car doing at turn entry, middle and turn exit?
     
  4. Jul 10, 2012 #3
    I am working to change the stock suspension of a touring car (Mc Pherson Strut)
    The front suspension geometry is being changed (the question above is about the new front geometry) . I have brought the front roll center of the car closer to the front Center of Mass(or mass centroid as referred to as in many books) . This has decreased the effective roll moment and thus increased my roll stiffness of the front without having to stiffen my springs .
    Now as I have kept the new control arm ball joint in the same position of the old one , the KPI and scrub radius shouldn't have changed . As the driver complains that steering needs more effort now , what could have caused it .
    The car trail brakes at the entry (dive-wt transfer to the front and roll-wt transfer to the outer ) . It kisses the apex (ideal condition) and then accelerates out of the corner . Pl. tell me if I am wrong .
     
  5. Jul 10, 2012 #4

    Ranger Mike

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    i sure dfo believe the driver now has a handful driving..when you rasie the roll center it shortens the lever arm and you have a lot less weight being planted on the front tire in a turn. Plus you increase camber build
    i am not a big fan of high RC..the lower, the better
     
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