Track Tac

Does stagger always have to cause drag on the straights ?

mikey56 said:
really? laughing at me? I think this thread needs to end because it's going no where fast. mr south, I never implied or said that you were wrong. I simply asked a question. ....I race, I have fun and I have NOT said one word about being a national champion or having multiple wins or even implied that I was laughing at you, about what you said or that your own opinion is wrong. before I say anything ungentlemanly or show my butt, I won't comment further because obviously in a contest of minds, the smartest thing is for me sit quietly in the cheap seats and watch those that have determined no one else can ever best a legend in their own mind.........

nuff said.....laugh all you want...doesn't mean a hill of beans to me........nothing I say will change your mind and nothing you say is anything that I care to listen to after what you wrote....
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Mr South 59 said:
It all good. Just having a little fun while im up late watching some of my teammates race, on the net.
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Dang Mikey. You post something that just cracked me up. It was freakin funny as all to me. And you get your panties all in a wad. Like I said in that post, "It's all good. Just having a little fun". Good thing I was just funnin. Do you get this way every time somebody laughs at what you said??? You wouldn't last long with my crowed LOL that's for sure.

So suck it up!!! I did really want to here your theory on racing on a continually loaded RR and I guess loading the LR some how to rotate the kart? And why you feel that front stagger is important? We all might learn something.
 
Ted Hamilton said:
Mr. South thinks he knows more than us, but he still can't escape the laws of physics...

I highly encourage anyone who wants to know what's going on to do a free body diagram of the forces and vectors involved and study the results. I agree that front stagger on a kart is pointless, unless you're trying to use it as a band-aid to change corner weights instead of raising or lowering the spindle heights.

That said, the difference in rollout in the rear will create a moment about the LR if both sides are weighted enough to generate grip. This moment is trying to "lever" the kart to rotate left, but this action is resisted by the contact patches of the front tires. When the front tires are brought into closer alignment with the forces of this levering action, the effect is noticed as an easier turn-in instead of being wasted energy in slip/heat/friction. Because this levering moment doesn't occur right at the yaw moment of the kart, there will always be some resistance / loss.

As to whether the LR or RR is dominating the picture, that depends on which one is weighted more. On the straights, with today's typical setups, the LR dominates, in the corners it's probably closer to equal (unless you're on asphalt, and then it's DEFINITELY the OUTSIDE TIRE) and the stagger is helping turn-in until enough power is applied to create slip on both tires requiring countersteering or steering angle is released allowing the straight-line config/weights to act as the primary forces.

Physics is physics -- analysis of the forces is complex, but can be approximated fairly closely. Taking the time to do so can reveal some errors in thinking and some new insights for tuning.

Here's a question that's relevant -- what's the relationship between cross and stagger? How have both changed in the past decade of kart design?
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Ted. You have read enough post over the years to know that I don't think that I know more than all of you on every subject. If I thought that I would jump on every post like I knew what I was talking about. Even if I never had any experiance with it. There is another guy on Bobs that takes care of that just fine. I got better things to do with my time.

You know that when I reply it is when I know something is posted blatantly wrong. Like this stagger thread. I only reply on things that are in my field of expertise and that I know from past experiance and results that it is correct. Like where you posted above your theory on stagger. You are "not sure" which tire is dominate, the LR or the RR. You "think"'that "probably" in the corner they are equal. And you "think" it's the heaviest tire that dominates. That's a lot of speculation.

Ted. It's info like this that is the exact reason why I reply to topics like this. It is in my field of expertise. The info that is being passed along is sketchy at best.

So Ted. You know a lot of things that I know absolutely nothing about. You will not see me correcting something that you have more experiance in that field than I. But I can tell you this. On this topic you are a little out of your field of expertise and you should be glad the people like me that have more experiance and, yes, know more than you do about the subject, reply without ridicule.

So to reply to your first sentance. Yes, if I reply to a topic than I do feel that I know more about it than the previous posts on that subject. If I didn't know more about that subject than it would just be a waste of my time to reply. Like I said earlier, Bobs already has a guy that does that just fine and waste everybody's time.
 
"you should be glad the people like me that have more experience" ... "Bobs already has a guy that does that just fine and waste everybody's time" .... yep just read his post and have to agree that he wastes everyone's time... I don't get my panties in a wad unless someone tries to act like everyone is beneath them and claims to know everything...... sound familiar? please don't reply to me....treating people right is not your forte.....as you so eloquently put it...."on this topic you are a little out of your field of expertise"....
 
I'm not putting a lot of conditions on it, just push it on the driver way and let it roll the direction it wants to roll.

Does anyone think most all of us agree a LTO kart can roll to the left with very little drag?

?
 
I'm just going to answer.

If nobody's sitting in the kart 1 human power can push it easily, so there is very little drag. We are calling it very little drag because it's easy to push. If it's on a driveway with a hill and we let it go and it rolls, we probably will say again it has very little drag because 1 unit of gravity is enough to roll it down the driveway.

So far were relating drag to a unit of energy enough to make it roll and we call it rolling easy.

Well if I pile a ton of lead on it, put a motor on it and it rolls wouldn't it be fare to say, it again has very little drag because one unit of engine is enough to roll it ? And it was easy, I only had to start the motor.

yeah... butt, but but but ... you say ? common now, quit stumbling over yer lip, ain't it ? ... :)

... and what does it mean ?


tell ya tomorrow after I sleep on it ... :)


But but but, I going to sleep in tomorrow, so let's here what ya'll think first.
 
Mr South -- the "uncertainty" in my post isn't "guessing." The uncertainty is required because in my example there were no constraints mentioned -- track type, track composition, turn radius, straight length, etc. etc..... The ratio of which tire is loaded (LR or RR) is determined by the current moment of observation, and changes based on driver inputs and track position. I'm sure you'd agree that when an input is made by the driver, there's a certain "lag time" caused by inertia between when he/she inputs and how the vehicle responds....the more firm the suspension, the quicker and more directly that input tends to appear in the vehicle dynamics, assuming the contact patches and suspension compliance allow it. That's why Indycars have knife-edge handling and sedans are slower and more sedate in feel.

I'm glad that you're chiming in with your expertise. I've also seen people who can correctly tell you what to do to make a car handle and have no real idea --or worse, a wrong idea -- of what's happening, and why. The "what to do" is whatever makes for the lowest lap times, and is experimentally arrived at by lots of racers.... Experiments take time, however, and a good engineer can reduce that time by making good assumptions and getting a close baseline so that the precious little testing time can be maximized making the right changes.

Good car chiefs are paid because they have the knowledge to tell a team what to do for a given situation because they've seen a lot of situations..... GREAT car chiefs are paid even more because they know what do to when the situation is less than clear -- they can reason it out clearly even if they've not encountered it before. The proof is in NASCAR's grizzled veterans being replaced by younger engineers and DAQ personnel... I'm not making any implications here, as I really don't know much about you....or indeed anyone, here on Bob's. All I can confidently comment about is myself, and I am confident with my understanding of collegiate honors level Physics. I suspect our understandings are more similar, but our plane of reference may be different. I'd be happy to chat further about the forces involved as you see them if you'd care to post what you know instead of merely enjoying what you think we don't know...

As Carroll Smith quipped, "The racecar is an inanimate object, and must, therefore, eventually respond to reason." Anyone wishing to read other outside views on stagger may wish to read his books, as well as Mark Donohue's "Unfair Advantage" that has a little tidbit about his preference for a solid welded-diff axle in his sportscars instead of the other diffs in popular use at the time. As a primarily lefty-righty racer he didn't have much use for stagger as LTO cars do, but he had fair success on the few ovals he did too.

Paul -- I suspect half the reason these conversations are dying on Bob's is that nobody bothers chassis tuning anymore -- they just pull out a set of tires with different prep... ;) And no, if you plop me in a LTO kart with heavy stagger and I hold the wheel so the front wheels are straight ahead, it will NOT roll easily down the driveway. Just like if you plop me in a sprint kart and it starts coasting down the driveway there will be LOTS of scrubbing if I try to turn the wheel. I encourage you to try to push a sprint kart through a crowded asphalt pit area sometime. Even a LTO kart can be a bear to push on a tarmac grid unless you're trying to go slightly left...... ;)
 
Ted Hamilton said:
And no, if you plop me in a LTO kart with heavy stagger and I hold the wheel so the front wheels are straight ahead, it will NOT roll easily down the driveway. Just like if you plop me in a sprint kart and it starts coasting down the driveway there will be LOTS of scrubbing if I try to turn the wheel. I encourage you to try to push a sprint kart through a crowded asphalt pit area sometime. Even a LTO kart can be a bear to push on a tarmac grid unless you're trying to go slightly left...... ;)
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We have a track we run a few times a season and they have a paved "ribbon" that goes around the track from the pits areas to the grid. From where we generally pit, there are two left turns in the 75 or so yard trek to the grid. I am usually pushing the kart by the steering wheel with my 80+ pound son in it and I can say with great accuracy, that the ONLY time the kart pushes with little resistance is for maybe a kart length or so through the turns. There is definitely rolling resistance that you can feel in the remainder of the arc(s) in the turns and the straights.

At that track, we are running 1" of rear stagger. I agree with Ted that if at that same track, we ran zero stagger, that the kart would push with less resistance for the straight sections of the ribbon only and the opposite in the turns.
 
I think through out I have been consistent with pointing out a sprint kart and a LTO kart are different and except for parts looking alike, operate differently.

For the sprint kart straight is straight as the crow flies and for the LTO straight is a curved path. If you reference each to it's own definition of straight, yes I invented the definition of straight for the LTO, but if you use it drag is not an issue in the comparison. When I think about the straight of an oval track for purposes of trying to make what's racing fast, the word 'straight' does not describe the track, it is only a name placed on a portion of the track.

The title of this thread is "Does stagger always have to cause drag on the straights ?".

The title says nothing about going in a straight direction or how a kart or car which is designed to turn both left and right go's in straight direction. The title and this thread is about how a LTO can travel on the 'straight' portion of an oval track with little drag. It is because of how it's staggered tires are loaded, per the speed it is going. We all need references to compare things. References when comparing different things can be either similarities or differences. If you compare similar things, to understand you need to look at how they are the same. If you compare differences, you need to look at how they are different.

A difference between a sprint kart and a LTO kart is how they roll with low drag. The sprint kart rolls on a straight line with low drag and a LTO kart rolls on a curved line with low drag. If your going to look at how each is going to get involved with drag, when the line is changed from something other then a low drag line, you need to start with each in a low drag situation. Placing either in a situation other then a low drag situation to start comparing, only will lead to confusion. This thread is about a LTO and trying to understand how it operates on the portion of the track called the 'straight'. Bringing in a sprint kart, which operates different on the portion of the track called the 'straight', causes confusion. This is not about how a sprint kart works on the 'straight' portion of the track, it's about how a LTO works on the 'straight' portion of the track.

LTO and sprint karts are different. But an LTO kart with it's staggered solid axle can be operated out on the track like a sprint kart, unloading the inside rear tire and turning it with the front tires. And I agree and always have agreed if you match the radius of the tires to the turn, it will turn left better unloading the inside rear tire. I have also always said if the track is a perfect circle and you match the stagger to the circle you don't have to even lift the inside rear tire to be fast. I am in total agreement you that you can unload the inside rear tire when using stagger and get around the corner. I am also in total agreement that when using the axle that way the closer you match your stagger to the radius, the faster and better you will get around the track.

But I also have been saying for awhile now, unloading the inside tire and matching the stagger closely to the radius of the track is not the best way to use a staggered solid axle. The best way to use it for oval racing is the 'ideal' way I describe in my general BS. And I have been saying all along, not every LTO has the same ability to get to the 'ideal'. I think a big difference in mind set is when I think about fixing on track problems, I first look to see how the problem can be fixed by moving over all setup closer to what I describe as 'ideal'. And many if not most others look to fix on track problems by moving over all setup, closer to how a sprint kart works when it has stagger. That is a big difference.

I don't think Andrew has come around to my way of thinking and I don't think I have come around to Andrews way of thinking. I think each of us has come to understand LTO's and 'real race cars' are totally different on our own. I don't think he is supporting my thoughts and I am not supporting his thoughts. From my past experience I think what we are both experiencing is ... it's just nice, comforting, a relief and reassuring to see your not the only one who thinks of LTO's in that way. It's like you've been talking to a wall and all of a sudden there a crack in the wall and a whisper is coming out of it saying... yeah I see it ...

In this thread Andrew in lower portion of post #63 explained it and what I have been preaching not very well over the years, very well.

I have never spoken to Andrew and we may never speak to each other, but I think through here we have come to understand some of each others thoughts are very 'similar'. Understanding has nothing at all to do with who knows more or who is right, it's just a nice little piece of the puzzle that comes along once in awhile.

If you read this far, thanks for reading and I don't know if any of what I wrote is right or wrong because it is just IMHO and ain't necessairly right anyway. ... :)


edit: Yes I agree if you push a sprint kart straight as the crow flies, it's easier then if you push a LTO kart straight as the crow flies. Interesting observation, but when only talking about LTO's, it's a useless and miss leading comparison. We don't race "real race cars", we race LTO's.

edit again: I sure hope I didn't offend or make anyone mad with what I just wrote, I was just trying to explain ideas. If they make you mad because I still don't get it and it's frustrating you, I understand and can relate to your feelings. ... :)
 
Paul -- the problem lies in you "BS" explanation. A kart, ANY kart, LTO or Sprint, will work best when it's not fighting itself via competing contact patches -- for the longest amount of time possible around the track. I will grant you that a LTO spend little time with the wheels pointed straight ahead going truly straight -- the longer the track, the more time it DOES. However, the stagger defines what arc is the most natural for the kart to travel. The closer that is to the preferred line on the track, the better the kart will handle and the faster it will be. Unless you're three wheeling as a result of weight transfer and grip.

You're right that LTO's and sprints don't handle the same, but IMO you're wrong about WHY. They conceptually operated EXACTLY the same, but on DIRT, with a LTO, there is rarely enough grip to allow total weight transfer to the right side of the kart. As a consequence, the "band aid" of stagger is used. This "band aid" makes up for the portion of the LR that can't be unweighted because there's not enough grip available to do so. The more stagger that's introduced, the more weight you can place on the LR without undo scrub while turning.

Taken to an extreme, in my friends USAC Silver Crown car, solid rear, the car had to be literally steered RIGHT down the straightaways to keep going straight and to turn be basically just released the wheel slowly and let the car settle into it's preferred natural line. You've taken the LTO's "preferred natural line" and called it "straight for LTO karts", which is confusing and less clear terminology, IMO. The "natural line" of LTO's is a leftward arc, the "natural line" of most sprint karts is neutral or true "straight".

The fact that sprint and lto karts work the same in large degree is confirmed by the fact that their front end geometry is largely the same. If LTO's didn't rely on weighting and unweighting, there'd be no need for caster angles like sprints.

I can't make sense of whatever your self-named "BS" theory is..... the nearest I can figure is that you're saying that while in mild left turns the RR is slipping, and then on dynamic turn entry the RR takes over and somehow helps turn in... I presume you're considering cross (LR/RF) as a teeter-totter? In other threads you've mentioned that you and Andrew have talked several times on the phone over several years, so I don't know why you say you haven't talked?

I seem to have made the mistake of assuming that this thread was about increasing our understanding of whether a staggered-rear setup kart HAS to create drag down the straights. I've given several examples of why the answer is determined by several variables. Setup is all a compromise. The basic question is whether you want to be fast in the corner or down the straight. With higher powered karts, one may elect to use less stagger to get more forward bite off the turn, at the expense of harder turn-in. It's all a balancing act.

The quick and simple answer is YES, a kart is always scrubbing some speed off unless it's following it's "natural line". LTO karts' "natural line" is determined by stagger amount. In actuality, you'll find that the kart is going on the same arc radius very seldom unless the track is short with wide turns (almost circular ideal line.) So the effective "straightaway" we're talking about may be very short. If so, the drag is hard to measure, but it's still there.... Since I can't make you understand, and don't have any more illustrations for you, I'm done.

Good luck with your setup theories. If you can explain to me how the rear axle is doing something other than generating an overhead CCW yaw moment along its' axis anytime there's stagger, I welcome the explanation. The only time a kart isn't scrubbing speed with 4-wheel-contact is when it's on its' natural line.
 
paulkish said:
In this thread Andrew in lower portion of post #63 explained it and what I have been preaching not very well over the years, very well.

I have never spoken to Andrew and we may never speak to each other
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Paul. I let this thread progress until post number 63 when I realized that nobody who had posted before it (and after) really understands how stagger works on LTO dirt kart. They all got some good theories, but none of the will make speed . So I had to chime in. It only took till post number 64 for someone to take a jab at my response. That's pretty much why don't post on here much anymore.

In that post I explained how stagger is supposed to work on an LTO dirt kart. You do not unload or unweight the left rear tire. If that were the case we would have a much larger scrub radius on the LF, less KPI and way more Ackerman to enhance that affect. We don't. The left rear is not what causes rotation. We dont drag the LR to cause a "lever" affect either.

While reading through the post I see where it says "99% of the karters searching for speed to catch the guy in front of them....". If you use stagger the way I listed above you will be in the other 1%. The guy they are trying to catch.

If you use stagger the way it's explained it in the post above you will always be in that 99%. Chasing that other 1%. I will choose to keep being that 1% guy.

LTO and Sprint karts do not work conceptually in the same way. Not even close. The frontend geometry between the two are worlds apart. The only thing in common are the names of the parts. You can not use a steering shaft from a Sprint kart in an LTO kart. You can not use the spindles from a sprint kart on an LTO. And you can't use the tie rods from a Sprint on an LTO kart either. Only the names are the same. Thats it. Sprint karts use frontend geometry, a large scrub radius, really large amounts of Ackerman, and castor jacking affect to unload the inside tire for rotation. An LTO kart rotates the way I explained it in post number 63. YLTO and Sprint karts do not handle or conceptually work the same way whatsoever. Not even close.

In Sprint kart racing when was the last time you saw the guy in fromt of you inside rear tire come off the ground. Probably almost every corner that you followed behind him. Now. In LTO racing when was the last time you saw the guy in front of you have the left rear tire come off the ground. Probably the only time you ever see that is when you're coming up to lap the guy, again. In Sprint karts you have to lift the left rear to rotate because they do not run stagger. In LTO karting you have to load the right rear to rotate because we used stagger. If unloading the left rear is what will cause rotation in an LTO kart nobody would be running 60 to 70% cross. Everybody would run 50% or less. Just like in sprint kart racing. But we don't???? Things that make you go Hummmmm. Maybe Ted would like to explain that one.

And you definitely can't compare a kart to a USAC Silver Crown car. I also explained that in post #63. Well, they do both have 4 tires a motor and LTO, but that is about it. You definatilly can not compare stagger.


And this is for Ted. Ted. I don't believe Paul ever said that he had talk to me on the phone in any post. Why would he. We have never spoken. I mentioned in one post that I wanted to talk to him on the phone because it was hard to explain things in type. But we never got a chance to speak.
 
Ted, I replied to your post with "Thank you for your thoughts". I read your post and I was overwhelmed by it. In one post you have recited almost by verbatim, every miss conception of how LTO karts work which has ever been discussed on here from the beginning of time. After some thought I have to ask if you are just pulling our chains with your post ? It's so wrong and brings so many things to the table incorrectly, it's brilliant. I don't have the words needed to reply to your post, I did start but deleted what I started and replaced it with, "Thank you for your thoughts".

And this is from someone so insecure with his reasoning, I so often end with saying this is all just IMHO and ain't necessairly right. You've got to be kidding us Ted.
 
Yeah you and me both. WOW!!! It is beyond me that somebody who claims to be a mechanical engineer and thinks they have a full grasp on physics can come up with this stuff. I thought the same thing Paul. He must be pulling our chain. If not I really feel sorry for his professors. I'm sure he is in the 99% of racers.


But on a side note. Again I appreciate the PMs. I think I have replied to the all. I know some of you are a little upset with me for letting the cat out of the bag on how stagger really works. I really don't mind helping the racers out. I am really tired of just racing with 1% of them. If a few more people catch onto this we might be able to have 2 or 3% running out front and the other 97% chasing us. It gets kind of boring up here all by ourselves. It's lonely at the top. LOL

Just sayin!!!
 
I don't claim to be a MechE, just that I underwent most of the education toward that degree. I have completed honors Physics, and statics and dynamics, kinematics, etc, and thermo. I later finished with a different degree, but remained a student of racecar design and engineering, and read Van Valkenburgh, et al. Out of the 8 years I've raced kart-type vehicles, I've acquired 4 State Championships, 1 perfect season, 6 points championships, and hold a win percentage above 50%, including qualifying races. I don't know if that qualifies as your 1% or not.

If I understand your explanation of the operation of stagger correctly --
1 - On turn in, the cross between LR and RF acts like a teeter-totter, and centripetal force shifts the weight right and aft, gradually transferring weight from L to R and from LF to RR, enabling the RR to overpower the LR and rotate the kart while the LR scrubs...
2 - This tapers off as the RR is dynamically un-weighted as cornering force and steering angle diminish on turn exit and the LR takes back over, driving the kart down the "straight" while the RR scrubs??

Is this what you're saying?
I still don't see how you're avoiding the "scrub" condition originally asked about?
 
I don't think your asking me but I'm going to take a stab at helping before Andrew gets to explain things correctly. ... :)

The best help I can give you to see it through my eyes, if you even want to or think it may serve a good purpose, is to remove from your process a lot of what the mechanics do, and shift more toward what needs to be accomplished.

I'll try to recite about stagger and if it makes any sense at all for you, it's what all the mechanics is going to act upon.

Changing stagger does three things. One it adjusts ride height, two it sets the difference in surface speed between the left and right rear tires. The third thing is a little harder to see. It alters how easy or hard it is to slip either the left, right or both rear tires. Stagger effects both tires the same way as far as altering their ability to slip. More stagger creates more potential to slip a tire, less reduces the potential.

That is what stagger does. The rest is how you use what it does.
 
Ted Hamilton said:
...and Paul, glad I could be of service.... ;) lol
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I understand. I can never repay the patience others have given me on here over the years. If I did those who were so patient with me would have need for locked rubber rooms. I really do not like a good debate, I like a good exchange of ideas and to have others over come my stubborn ability to not see any view but my own. ... :)
 
paulkish said:
Changing stagger does three things. One it adjusts ride height, two it sets the difference in surface speed between the left and right rear tires. The third thing is a little harder to see. It alters how easy or hard it is to slip either the left, right or both rear tires. Stagger effects both tires the same way as far as altering their ability to slip. More stagger creates more potential to slip a tire, less reduces the potential. That is what stagger does. The rest is how you use what it does.
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Well, I have no real disagreement so far, and would simply point out that ride height is more easily changed elsewhere, and "slip potential" is also more easily changed via tire width, compound, or treatment... But we're keeping this about stagger, so...... what next?
 
Also, not sure how stagger affects the slip potential other than that the perpendicularity of the tire to the rim limits compliance to the footprint the ground's trying to force on it....wider tires must deform more, especially on the "outside" edges, unless we're also stretching tires asymetrically in addition to our rollout stretching.
 
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