Home Forums Chassis & Handling Snap Over Steer

This topic contains 7 replies, has 4 voices, and was last updated by  Chris Hatch 3 years, 7 months ago.

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  • #50996

    Walt Gifford
    Participant

    How would you fix a snap over steer if you have too much rear weight and are top heavy plus you can’t move weight forward or down.

    Back of the kart is stuck. When I dial in more jacking it breaks away suddenly mid corner. Dial in less jacking and I need lots of steering input and the karts front bound for the whole turn.

    Gif

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

  • #51017

    TJ Koyen
    Moderator

    So you need more lift, but you still need it to be very progressive because of your height.

    What I would do is dial in more jacking, with the adjustment of your choice, and then put a little bit of negative camber in. For us, that’s always slowed down the lift a little bit.

    That, and making sure to be super smooth and progressive on the wheel and pedals.

    Driver/Coach/Wrench : Innovative Performance/Exprit
    Owner : Oktane Visual - www.oktanevisual.com
    www.facebook.com/oktanevisual
    www.instagram.com/oktanevisual

  • #51043

    Walt Gifford
    Participant

    Thanks TJ that’s the exact thing I’m doing already. I guess the trick is to get good at catching it before you over rotate. If only karts were a little bigger like 45″ wheel base 60″ rear track.

    Gif

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

  • #51053

    TJ Koyen
    Moderator

    Walt, what seat are you using? If you aren’t already, take a look at a Tillett T9 or T11, both are leaned back a bit more and the T11 has that flat bottom for mounting lower in the rails.

    Driver/Coach/Wrench : Innovative Performance/Exprit
    Owner : Oktane Visual - www.oktanevisual.com
    www.facebook.com/oktanevisual
    www.instagram.com/oktanevisual

  • #51055

    Walt Gifford
    Participant

    Thanks for the advise. Ribtec XLT. I’ve got the flat on the seat tilting up in the front and my nuts on the gas tank. I’m trying to get Margay to send me the parts to weld on an extended front porch. That’s something I haven’t tried yet. More total weight uhg. Although, I knew a guy who was at max weight but put more weight on the front. kart cornered better and got lower lap times with more weight.

    Gif

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

  • #51122

    Chris Hatch
    Participant

    In my experience working with drivers complaining of a snap loose condition, it is almost always a result of an under-steer condition first.   The driver believes the kart is turning in, but there is not enough weight being moved to truly initiate a smooth turn.  What happens is that the kart begins its initial turn in, but is sliding the front a small amount.  When the kart gets to apex, the kart has lost enough speed to allow the front tires to stop slipping and gain the traction they needed to not only initiate the turn in but the full rotation needed for the turn.

    Now the hard part:  What is not working?

    I look to weight placement and seat mounting.    As a tall and heavy driver, 57-59% rear weight has worked best for me on the Margay.  I would have the seat tilted back at about a 45-50 degree angle.

    I also used long front hubs on the Margay to stiffen the spindle arms.

     

     

  • #51149

    Paul Kish
    Participant

    Only one reason to snap loose.  No grip at the inside rear and the outside rear is being worked beyond what it can give and the front has grip.

     

    When you drop down weight jacking your causing the inside rear to help hold you in by not allowing it unload as much and the hard steering is because you still have grip up front.  At that time your wanting to accelerate but your killing it because your still turning and fighting the back to go where you want to go, with an engaged inside rear.

     

    Or in other words push in loose out and in your case it’s a whole ton of loose out.  Your telling us you can’t fix it with adjustments because the  adjustment your trying to fix it with, puts or keeps the inside rear engaged too much.

     

    If you cannot truly fix it with adjustments you have to fix it with your driving.  Your either driving in too far or cutting off the corner.  If your driving in too far, then it’s the thing won’t turn and when you slow to make it turn, you have too much turning left to do and you break the back loose.  But I don’t see that as your driving problem.

     

    I see your driving problem to be your chopping off the corners.  That means your pretty much driving a straight line down at and by the corner, and then trying to make it turn.  It can’t because you did not get enough of your turning done prior to that point on the track.  But since you have grip up front the front holds and your outside rear lets loose.  Your driving fix is one of two things.  One, you can try entering higher to give you room to complete more turning through the corner, before you get to your apex an on out.  The second way to fix it if you can’t manage to change your line, is to brake and then roll a little in an arc to complete more of your turning, before you consider an apex point.  Either way you have to get more initial turning done,  before choosing an apex.  If you don’t and have too much turning left, your either going to be a pig grinding off speed with the fronts fighting the somewhat engaged inside rear or you will snap loose.

     

    maybe?  … :)

     

     

     

     

    Brake, Insert 'arc', Turn, Accelerate

  • #51221

    Chris Hatch
    Participant

    One other thing that contributes to this problem more with 4-cycles than 2 cycles is that a 4-cycle has a great deal of torque at lower RPM’s.  As a result, when returning to the accelerator, that torque causes weight transfer to return to the left rear and a loss of grip at the RR.

    You might be surprised to see the effects of putting a hard axle.

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