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Oversteer snap-back

Discussion in 'Roadster: Performance' started by nick, Jun 26, 2017.

  1. nick

    nick Member

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    I did the REFUEL track day at Laguna Seca Speedway last weekend - 1.5 Roadster. Good fun.

    Oversteer out of turn 11 onto the straight, corrected...the tail started coming back as expected then suddenly snapped-back straight. Wasn't pretty - figure that left a mark on the track.

    What is going on there?
     
  2. nick

    nick Member

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    Thinking this through...

    Tail is skating sideways smoothly. Off the throttle - regen slows the wheels. Tires grip when the wheels have slowed sufficiency causing the sideways movement to jerk to a stop (only forward movement remains).

    Should I have stayed on the throttle a bit?

    It doesn't seem like there is much margin between full grip and losing the tail.
    (running AD08R tires on the rear)
     
  3. dhrivnak

    dhrivnak Active Member

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    You may be onto something as I found the line between having full grip and sliding is quite thin.
     
  4. wiztecy

    wiztecy Active Member

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    #4 wiztecy, Jun 28, 2017
    Last edited: Jun 28, 2017
    I feel Its just nature of the beast and more with layout of the car such as rear favored weight distribution and a very short wheel base. Anytime you have a pendulum style car, and our Roadsters mimic that, you're going to have a violent swing of the weight. Shorten the stick or wheelbase, and its very hard to get control. Energy (oversteer) + Weight + Direction = Momentum. More weight focused in the rear or in one direction, forces get multiplied and so does momentum with the combined energy. The Roadster is not all that long of a car, rear wheels relatively close to the driver, which also adds to quick violent responses from the car in those conditions. I actually think regen would keep your back stuck in the road and to straighten out the car honestly where it wants to drag and balance the rear out once traction has been lost. Rolling wheels give traction and control, stopped and locking one's don't.

    And oversteer is 95% of the time not pretty in the Elise, Exige and our Roadsters as well as 911's and other rear weighted favored cars hence why they don't make the best drifting cars and why the factory dials in so much understeer :)
     
  5. slcasner

    slcasner Member

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    Traction control on or off?
     
  6. nick

    nick Member

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    Off.

    There is something wrong with the traction control so I turn if off every time I get in the car (normal road driving). In a perfectly straight line the traction control doesn't interfere but if there is the slightest hint of a curve my wife's Leaf will out-accelerate the Roadster.

    On my todo list is to swap the front wheels with my other set with AD07 tires to see if that changes the traction control. Running AD48 tires on the front at the moment.
     
  7. Doug_G

    Doug_G Lead Moderator

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    When you get the tail out on a RWD car, you should give it a little throttle to put some more weight on the rear tires. That will get you more traction on the rear tires.

    Not too much of course, or you'll power oversteer and make it worse.
     
    • Like x 1
  8. supersnoop

    supersnoop Tesla Roadster #334

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    Which tires do you have on the rear? The 1.5 traction control is very picky about the tires, but the A048s should work on the front, as long as they're the 195/50 size. The AD07's should be 175/55.
     
  9. nick

    nick Member

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    Front = A048 195/50R16 84W
    Rear = AD08R 225/45R17 91W
     
  10. nick

    nick Member

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    Another track day coming up... wondering if I should try a set of R888's
     
  11. nick

    nick Member

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    Ordered Toyo R888R tires for front and rear... will try them out at Laguna Seca later this month.
     
  12. nick

    nick Member

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    The Toyo R888R tires were fantastic on the track - world of difference.
     
  13. n2mb_racing

    n2mb_racing Member

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    What sizes did you get?
     
  14. nick

    nick Member

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    195/50R16 and 225/45R17

    I could power out of a corner, car straight, with a gentle 4 wheel track out.
     
  15. n2mb_racing

    n2mb_racing Member

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    Nice! Stock forged rims?
     
  16. n2mb_racing

    n2mb_racing Member

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    • Informative x 1
  17. nick

    nick Member

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    Stock forged rims (2nd set).

    Tirerack is fantastic - good prices and you can ship direct to your favorite installer.
     

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