Home Forums General Karting Discussion Why do drivers sit so tall in sprint karts?

This topic contains 55 replies, has 19 voices, and was last updated by  Scot Smith 11 months, 2 weeks ago.

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  • #14409

    Paul Kish
    Participant

    I don’t see what advantage there is for a driver to sit up so high in the seat.

    Are there rules requiring it?

    The obvious is if there was something faster sprint karts would not be designed that way.  But there must be some reason it’s done.

    I’d bet this has been asked before.  If someone can point me to a previous discussion of it on here, it would be good enough and I’ll go there to read.

     

    thank you

     

    #14414

    Stewart Willis
    Participant

    weight transfer

    #14415

    russ Jolly
    Participant

    Isnt there a rule in some classes about the seat being so far back or the back being so close to the axle? Some I would imagine like it because of the control you get over the steering wheel.

    #14418

    Walt Gifford
    Participant

    Seat has to be in front of the back edge of the rear axle and 14″ from the ground min.

    Gif

     

     

     

    #14422

    Matt Dixon
    Participant

    It’s all about kart set up, lighter drivers tend to set the CG a little higher. Even more so in low grip situations. But that’s just this wet behind the ears, pre teen’s opinion… and Stewart’s.

     

    #14425

    TJ Koyen
    Participant

    Because that’s how sprint karts work. You need to transfer weight efficiently so you need a higher CG to get the kart to rotate.

    #14489

    Timothy Strawkas
    Participant

    I used to think same as most but, In the last two years its been proven that ether setup can win at the highest level. The only class I have not seen it(lay-down seat) win (yet) is in TAG. I’ve seen “sit-up” karts with lay down seats run identical lap times as a regular “4cycle chassis” and vice versa.

    The true question is, which seat compliments your physical size, and you driving preference I think. period.

    #14494

    Paul Kish
    Participant

    Thank you all for the replies.  I’ve wondered why so many situp high drivers.

    The lay down seat should in all sprint karting classes be faster.  It’s because the lay down seat allows for increased use of the inside rear tire.  And it is fact the same grip distributed across two rear tires will go around the track more efficiently or ‘freer’, then with increased unloading of the inside tire and more use of the outside tire.  Thank you for the input to my question.  I was wondering why so many sprint kart drivers still sit up so tall.  In addition a seat more laid down also gives an aero advantage.

     

    paul

    #14500

    TJ Koyen
    Participant

    Paul wrote:Thank you all for the replies. I’ve wondered why so many situp high drivers.

    The lay down seat should in all sprint karting classes be faster. It’s because the lay down seat allows for increased use of the inside rear tire. And it is fact the same grip distributed across two rear tires will go around the track more efficiently or ‘freer’, then with increased unloading of the inside tire and more use of the outside tire. Thank you for the input to my question. I was wondering why so many sprint kart drivers still sit up so tall. In addition a seat more laid down also gives an aero advantage.

    paul

    Here we go…

    Care to explain why using the inside rear tire is faster Paul? You’re pretty set on that idea, you brought it up quite a bit in the driving topic. And the fact that it goes against every basic principle of sprint kart tuning makes me interested in what you have to say.

    Aero advantage is pretty minimal in sprint karting as well.

    #14501

    Paul Kish
    Participant

    I shouldn’t have to explain but because you do not have a differential you “MUST” unload or slip the inside rear.

     

    … before I go on, do we agree with that one point?

     

    I can’t go on if that is not understood.

     

    ___________________

    I guess there is one other thing we have to agree on before I can convince you I’m correct.

     

    If you take a tire, any tire and roll it do you agree it will want to roll straight?  (I know you can throw in a bunch of stuff that can make it want to not roll straight, but for all practical purposes, roll a tire and it will want to roll straight.

     

    Can we agree on that?

     

    ___________________

     

    This next one may be a bit tougher for you to want to agree with.  But from what I read so far of your words you will not try to dodge it.

    The tire which is rolling straight, don’t you have to add input to make it roll in a direction other then straight?

    I think you will say yes.

    And what if you added weight to it, won’t it take more input to make it roll in a direction other then straight?

    I think you will… maybe reluctantly but I do think you will say yes.

     

    I think you already know what happens if you make a tire roll in a direction other then straight.  Because there is no need to play 20 questions I’ll answer.  A slip angle will be created.  … not think about it…

    To conserve energy and put the hp you have into going forward, would you want to turn one tire with a big slip angle or two with smaller slip angles?  It’s tough to say two ain’t it?  But you know you do feel two smaller slip angle will be easier to turn.  In fact they are.  Next I’m sure your going to want me to quote verse, rime and reason why two small slip angles will be easier to create then one large one.  … I can’t do that.  All I can do is say from all that I’ve ever seen LTO racing, unless you have gobs of hp able to take advantage of dumping weight on the outside rear, it’s faster to split the split angles.  If what your racing does have all the hp you need to put the hp to the outside rear and go, assuming the outside rear has all the grip you need, you will not agree with me.  But if you are at the limit of your hp, it’s faster to split the slip angles.  In LTO racing when you have the outside rear so heavily weighted it just wants to roll straight too much, we call it right rear tight or … Outside rear tight.

     

    If your on a shifter you may not be able to see it.  But if your on a lower hp can or brigs, it will show itself to you.

     

    … what follows is what’s left and what’s left is all about forces out on the track.  It’s how lowering the seat changes how you use forces to be able to free up the tires and split the slip angle.

    I think I did ok explaining it, but time will tell.

     

    ______________________

     

    edit:  If your wondering why laydown seats can even be competitive, what I just explained above or at least tried to explain IS why.  Yes I understand the higher CG and how it helps leverage the chassis, but…  think about it… doesn’t the higher CG also create a longer lever and don’t longer levers work slower?  And then to make that longer lever work as needed, don’t you have to then round up extra effort to make the long lever work as FAST as needed?  Now… shorten the lever by dropping down the driver.  All of a sudden you also have a shorter lever to operate.  … hummmm… it’s a win win situation, ain’t it?

     

    —————-

     

    thanks for the reply, been fun writing, I’ll look back in tomorrow am unless I head off to a track out east.

    #14502

    Mike Clark
    Participant

    #14503

    Mike Clark
    Participant

    Paul,

    Already it seems you are saying use the inside but lift or slip the inside. That sounds like a contradiction.

     

    #14504

    Jimmy McNeil
    Participant

    “The lay down seat should in all sprint karting classes be faster”

    Its just the opposite. Go to a road race and watch the laydown karts crawl through the corners compared to the “sit up high” drivers.

    “I shouldn’t have to explain but because you do not have a differential you “MUST” unload or slip the inside rear.”

    “And it is fact the same grip distributed across two rear tires will go around the track more efficiently or ‘freer’, then with increased unloading of the inside tire and more use of the outside tire.”

    You kind of answered your own question. You are correct, you must unload/slip the inside rear tire. If you ran a laydown style seat that increased the weight on the inside rear, the kart wouldn’t rotate as well. Plus, with the laydown seat you would decrease the weight transferred to the outside tires through the corner resulting in less grip/slower corner speed.

    #14505

    Paul Kish
    Participant

    <div class=”d4p-bbp-quote-title”>Mike Clark wrote:</div>
    Paul, Already it seems you are saying use the inside but lift or slip the inside. That sounds like a contradiction.

    I expected not your specific reply but something similar.  And while I was writing I anticipated it.  It’s not about not needing to lift, unload or slip the inside rear, that is needed, a must and just the way it is and is not going to go away.  It’s about how you use the unloaded inside rear and changing the requirements of how much you unload the inside rear.  Sure, you got to unload it enough but how much is enough will change, when you drop down the seat.

    You will be taking some of the forces available to you to leverage the chassis to unload the inside rear and use them to shove the inside rear outward.  The combined shoving and leveraging will require less effort to free the inside rear then just leveraging it up, using the outside rear as the fulcrum point.

    You absolutely do NOT have a need to unload or lift the inside rear tire.  You have the need to free up or slip the inside rear, in fact if you can cause it to slip as needed it never even needs to leave the track.  There is a big difference.

    It’s also going to make a difference when you need to load the inside rear to accelerate.  You already know load it too soon and your pig out of the corner.  If  you slip it and then ease it back into the track, you will have more control for using it again then if you lift it and bang it back down.  … yeah I exaggerated to make a point, but the idea is there and sound.

     

    edit:  I know sometimes you see karts in turns where the inside rear never leaves the track.  Is it always bad when the inside rear does not leave the track?

    I think not.  If your slowing down anyway or on the power maintaining your speed and you have the power to do it, there’s may be no advantage to completely unloading the inside rear.  I don’t know but I suspect someone may get on here and say … so and so is fast and his inside rear never seems to leave the track… or not because it’s just something I suspect.

    #14506

    Paul Kish
    Participant

    Jimmy, been there done that as far as watching and seeing the difference in the corners and you are 100% correct.

    But while reading your reply, this came to mind.  I’ll bet if you can give me a very short driver in a short laydown kart, we will keep up just fine in the corners.

    paul

    #14507

    Jimmy McNeil
    Participant

    Paul, if your theory was accurate, when it rains, people would lower their seats for additional grip. It’s just the opposite. When it rains, people raise their seats for a higher center of gravity. This does two thing, on corner entry it transferes weight to the outside front, lifting the inside rear allowing the chassis to rotate. It also transferes weight to the outside tires through the corner for additional grip/speed.

    Hope I’m explaining this ok.

    When your over stuck, lower the seat to take out grip

    #14508

    Paul Kish
    Participant

    <div class=”d4p-bbp-quote-title”>Jimmy McNeil wrote:</div>
    Paul, if your theory was accurate, when it rains, people would lower their seats for additional grip. It’s just the opposite. When it rains, people raise their seats for a higher center of gravity. This does two thing, on corner entry it transferes weight to the outside front, lifting the inside rear allowing the chassis to rotate. It also transferes weight to the outside tires through the corner for additional grip/speed. Hope I’m explaining this ok. When your over stuck, lower the seat to take out grip

    :)  I agree with everything you said except: the if your theory was accurate part. … :)

    What works when and what you do when, depends on available grip, available hp and I usually will say the need to maintain momentum.  But with the rain scenario I’ll change the last to “the need to deal with momentum and the ability to brake”.

    I’m assuming there is enough grip to handle either a sit up kart or a seat laid back seat kart.   I’m seeing the sit up kart in the corner with the inside rear off the track and all rear load on the outside rear.  And the alternative I’m seeing is the laid back seat kart with the inside rear not completely off the track and all of the rear load not completely on the outside rear, with some load on the slipping inside rear.

    I’m tired and I’ll read this in the morning.  I may see my folly in it or I may say brilliant explanation… nawww that won’t happen

    #14513

    Tim Pappas
    Participant

    I think there is a great opportunity for you Paul.  Throw a laydown seat in a chassis and head to the Supernats.  The track is a great test….no grip to start and decent grip by the end of the weekend.  After your laydown seated kart smokes all those silly sit up drivers you can go into business selling laydown seats to all the Euro chassis guys or pimp yourself as a set up guru.

    P.S.  The track turns right and left…stagger won’t help you.

    #14518

    Rodney Ebersole
    Participant

    Paul, With either seat the top point of the pyramid of traction control is the seat/driver. The bottom is the tires contact points. The taller the pyramid is will increase the amount of  vertical force upon the contact points when trying to change direction.

    A lay down seat set up would need  narrower and shorter contact points in order to try and equal the vertical force that a sit up seat would have.  At some point in width and length decreases it would not be able to produce as much vertical force upon the tires.

    Horizontal forces and dirt reduce grip .

    #14520

    Paul Kish
    Participant

    <div class=”d4p-bbp-quote-title”>Tim Pappas wrote:</div>
    I think there is a great opportunity for you Paul. Throw a laydown seat in a chassis and head to the Supernats. The track is a great test….no grip to start and decent grip by the end of the weekend. After your laydown seated kart smokes all those silly sit up drivers you can go into business selling laydown seats to all the Euro chassis guys or pimp yourself as a set up guru. P.S. The track turns right and left…stagger won’t help you.

    I expected and anticipated someone to bring stagger into this thread.

    If you will notice I related what I’m introducing here to LTO racing only for the reason of bringing in the thought of splitting slip angles between rear tires and how it may be an advantage over not splitting them.  I started the thread to try to get into a discussion of why do most all sprint racers sit in such an up right position.  I’m open to what may flow from it so long as the direction does not include throwing barbs and arrows and new directions it may take.  I did not bring in stagger.  I did not bring it in because it does not apply.  I don’t think using something which does not apply to the parameters the thread is so far addressing, is meaningful in any way.  I don’t race.  I tried it and found out I was no good at it.  I’m going to try to address your kind input and try to answer in a way it will keep this thread on a path I want to take.

    Repeating myself, stagger has nothing at all to do with the possible benefit I see from increasing the splitting of slip angles between the rear tires.  Though it helps when you turn in only one direction, stagger is not a way to match up the rear tires to the radius of a turn.  It is something when used as needed can provide additional control of direction for whole kart, in addition to the directional control you get from the front tires.  Stagger can also be the primary thing which controls the direction of travel of what your racing.  Produced slip angles at the rear, weather you are using stagger or not, will allow for more efficient travel through a corner if split between rear tires.  I said nothing about the ability to meet the ideal or not.  You may not, but I see it as obvious how varying the situation and circumstances will either enhance your ability to get close to ideal or not.  I also see how if you have an abundance of one of the things I have mentioned or a lack of another, you may not have the ability to even try to get close.   Again those things you have to use and blend are available grip, available hp and the need to maintain momentum.

    In the case of the track you mentioned which goes from slick to grip.  Just in case your not already aware of the obvious, I’ll point out the obvious to you.  Maybe the next time you race there it will help you play a way to attack the track, which goes from slick to grip.  The two obvious things you have to deal with are the changing available grip and what is most always over looked and usually not even considered, the reduction of forces available to you when the track grip is reduced.  I assume you know what you can and cannot do to physically increase grip when the track is fresh and slick.  Actually you are limited to doing things directly to the tires.  The tires are the only thing which you can change that will directly and physically change grip.  Everything else you do is because of changing the levels of forces available to you.  Simply put all the other setup things you can do, are to make the chassis react quicker to move the force of the CG to tires or slower.  When the track slicks it assumes it’s easier to exceed the limit of grip at the tires.  Even with a slick track your only option may be to bang weight quickly into a tire and hope it holds.  Other times you need to bang or move weight quickly over to where it is going to operate a tire and then ease it into the tire as best you can, trying again not to exceed it’s limit.  It just depends on need at the tire and the tires ability to grip, how you move weight and the speed you move weight.

    I’m going to stop.  I think I addressed that I am not even considering stagger when writing on here.  And that if stagger is introduced as an argument in this thread, how it is meaningless to the direction of this thread.  And I hope I showed that I do see how setup needs to be shifted in the way it will deal with available force, when a track goes from slick to grip or vice versa.

    If you would when thinking about if it’s really a benefit to split slip angles between the rear tires, just pick one scenario of available grip and available hp and stick with it in your mind.  I think if you can keep the scenario you relate to for the time being constant, if what I’m proposing is valid it will fit in.  If you do fit it into just one scenario, I think you will then be able to fit it into other situations of available hp and available grip.  I don’t mean to keep harping on available grip and available hp, but I have to because the hp you relate to when thinking about on track situations is just as important to define the situation as available grip.  I’ll assume every driver is driving perfectly and there are no things a driver can do to fix a problem.  By the way, there is no need to think about or understand any of this, unless you can use it to fix on track problems.  Without the ability to relate theory to fixing on track problems, it’s all meaningless.  When I’m at a track, unless approached with a specific problem by a driver or a crew member or unless I see an obvious mechanical issue needing addressed, I never comment on things without first knowing the driver or crew or I have the same understanding of an on track problem.  I don’t care if your the best driver in the world and never loose, your a racer and your out there to win and win in such a way second place wonders why there even racing.  But if I happen along and correctly bring up a specific on track problem your having your going to want to talk about it.  Well, most all will want to talk about it because there are three phases in learning to drive.  The first your starting out and your open for anything and most anything suggested to you will help.  Then there’s the I’m fast stage and  no matter what anyone suggests it won’t help you because your fast and know your fast.  Then if you make it through the ‘I’m fast’ stage without terrible injury or running out of money, you start to become a journeyman and you concentrate on refining your race craft.  But the funny thing I’ve noticed is along the way you first started out wanting to and hoping to talk to every and anyone about racing, then you clammed up knowing it all and finally as a journeyman your open again looking for any and all input to refine your race craft.  I’ve seen many racers grow and become skilled in their craft.  I don’t know you  Tim or who ever may be reading on here, you can fit yourself in where ever you like and you can fit me in where ever you like.  But in the end were all just feeding our addiction and love of racing in all it’s aspects.  Let’s talk about stuff and not about each other.  Tell me where I’m wrong so I can learn if I can change my hard set head, but lets not just look to show who’s the most ignorant.  If there needs to be a winner on ignorance to move on, I’ll take first place and then lets get on to the next race.

    #14521

    Paul Kish
    Participant

    <div class=”d4p-bbp-quote-title”>Rodney Ebersole wrote:</div>
    Paul, With either seat the top point of the pyramid of traction control is the seat/driver. The bottom is the tires contact points. The taller the pyramid is will increase the amount of vertical force upon the contact points when trying to change direction. A lay down seat set up would need narrower and shorter contact points in order to try and equal the vertical force that a sit up seat would have. At some point in width and length decreases it would not be able to produce as much vertical force upon the tires. Horizontal forces and dirt reduce grip .

    I think I see exactly what your explaining.  I’m not disagreeing with any of it.  I’m going to try to include what you explained and bring it into my way of seeing its application.  I’m trying to look at thing by shaping the triangle to how I choose to use the tires.  … it’s tough to explain…  If my goal is to make sure I get enough grip out of the outside leg of the triangle to use it’s contact point to hold me in, then I’m mainly interested in the height of the triangle.  And I’m only concerned in how the height alters my ability to use the outside leg.  The inside leg will do what it will do when addressing the use of the outside leg.  All I expect and need to get out of the inside leg is minimal interference with the functioning outside leg.  When we need to use the other leg, it will then be acting the same as the outside leg does now.  We will just be shifting and dealing with it in reverse.  Simple cut and dry and I agree it works.

    Does that sound ok?

    All I’m suggesting is instead of looking at the inside leg as functioning to give us minimal interference with the operation of the outside leg, lets look at what else the minimal interference is maybe doing for us and enhance it.  I’m suggesting to look at the minimal interference of the inside leg of the triangle and having a function.  If your slowing down anyway isn’t the inside leg also helping to hold the back end in.  I’m suggesting to enhance the use of the inside leg while slowing down and cause the load to be split, as much as possible, between the two rear tires.  And then when you apply hp again, you can better control the introduction of the hp, because you previously have included being able to control slip at the inside leg.   It’s the outward direction of force you can use to give you more control over slip at the inside leg.

    On a side note controlling slip at the inside rear is not all about gaining an additional tool to control slip.  It’s also about recognizing your also moving along the track while all this control is taking place.  Sometimes to fix a problem or gain a need, it’s simply a matter of preventing something from happening for an instant and your at a new place on the track where the problem no longer can occur.

    I’d better stop for now and see what comes back.

    Sometimes when things come back up it leaves a sour taste in your mouth. … :)   just more dry humor for my own benefit and fun

    #14525

    TJ Koyen
    Participant

    Let me try and understand this in a more simplified way:

    You absolutely do NOT have a need to unload or lift the inside rear tire.  You have the need to free up or slip the inside rear, in fact if you can cause it to slip as needed it never even needs to leave the track.  There is a big difference.

    So I think, correct me if I’m wrong, Paul is stating that you can have a laydown seat, induce a fraction of amount of oversteer and slide the rear ever so slightly to unload the inside tire, and end up with slightly more grip from two rear tires rather than relying on just the outside tire to plant and use all of it’s grip. Therefore having more grip and being able to corner faster. Yes?

    If this is indeed correct, I can tell you from experience that this might be somewhat of a valid theory on a slick track or on hard tires, but completely goes out the window when any form of grip goes down.

    In club racing with hard tires and slick tracks, it’s pretty common (or at least this is what we did when we raced club stuff) to go for a slide oversteer condition to free the rear up and get the inside rear to slip, rather than trying to force the kart to lift and rotate. It was just much easier to get the kart to consistently oversteer slightly. And it worked, we were quick and won championships locally.

    Slap on any other tire that is remotely softer and race on any track that has a bit more grip and it becomes next to impossible to apply that same theory. The kart actually has to work like it was designed at this point, and lift the inside rear and dig in on the outside rear and rotate.

    I don’t think it’s possible to compare the tuning characteristics and theories of LTO racing with sprint racing. Every possible variable is different; tires, chassis design, seats, wheels, driving style, track style, grip levels… We never have a condition of “outside rear tight” as you’ve said. That doesn’t happen in sprint karting. If you’re lifting the inside rear, then your kart is turning. Do you have any experience with regional or national level sprint racing Paul?

    #14527

    Paul Kish
    Participant

    .

    #14529

    Paul Kish
    Participant

    Do you have any experience with regional or national level sprint racing Paul?

     

    Only regional level and very little.  And at that time I also know I had very little knowledge of anything about how stuff works.  I then not even knowing, relied only on driver skill and seat time, monkey see monkey do and having and engine as good as if not better then anyone else.

    And our results were only mediocre too.

    On a side note, I strongly feel except for the top of the ladder, how far you get up the ladder is a matter of attendance as much as it is skill and knowledge. … :)

     

    Thank you for the courteous reply and I hope my reply was the same.

     

    paul

    #14532

    Rob Kozakowski
    Participant

    I agree with TJ that in very limited situations, Paul’s theory might work.  With real hard tires that don’t provide any “side-bite”, making the rear rotate by sliding, rather than unloading the inside tire can work.

    The trouble is that with the tires we run in 99% of the applications, and with the design of “Euro” sprint karts, we have to unload the inside rear to make a kart work as designed.

    We could probably work around the design of karts by moving the weight bias so far forward and bumping tire pressures so high that the rear might slide again, rather than needing to unload the inside rear.  Trouble is by doing this, you’re creating all kinds of other handling problems that you’ll end up slower than setting the kart up the way it is designed to work.

    While you want to ignore stagger, you can’t ignore its impact on LTO karts.  It’s like ignoring the tires and the kart design we use in sprint karts.  It’s all part of the complete package.

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