I have a chassis question for the chassis gurus on here.

The only things the same between Sprint Karts and LTO karts when turning left, is the right side or outside tires are being pushed at the track and the left side or inside tires are being pulled on the track.

There difference is as follows. With a Sprint Kart the front end in addition to making the front move to the left, also mechanically assists in controlling weight on the inside rear for purposes of unloading and loading the inside rear tire, to >allow< the solid axle to rotate. With a LTO Kart the front end in addition to making the front move to the left, also mechanically assists in controlling weight on the inside rear for purposes of >causing< the staggered solid axle to rotate.

A Sprint Karts ability to turn and carry speed through a corner is deficient if the inside rear tire is not >unloaded< properly. A LTO Karts ability to turn and carry speed through a corner is deficient, if the inside or LR tire is not >loaded< properly.

It's the unloading of the inside rear which aids speed through a corner with a Sprint Kart and it's the loading of the LR which aids speed through a corner with a LTO Kart.
 
With the following I am not trying to say or even suggest you are wrong about anything with your theoretical exercises, I'm trying to add to it per my theoretical exercises.


"Obviously the waist and front end geometry determine the behavior of the interaction between the legs of the triangle between LF, RF, and LR."

Sprint Karts operate per the triangle and removing weight from the inside rear, LTO Karts operate based on cross weights and retaining weight on the LR.

_____________________

An additional thought I think relates to the idea I'm trying to convey.

The reason LTO karts require so little weight jacking is the weight jacking is only needed to control the load on the LR. As opposed to Sprint karts where weight jacking is needed to both unload and control the load on the inside rear.

Ideally with a LTO kart you never unload the LR only control the load on it. With a Sprint kart it's mandatory to unload the inside rear.
 
Yep....your about 8 years behind

Not really, 10+ years ago I theorized the reason for the softening of the LR chassis area, beyond trial and error. I did not then personally relate the theory to specifically softening the LR area. It's the reason why the softening can gain speed, which sped up the process of change. The engineering mechanics and mathematics were in place for ever, what I added was new understanding of the total process involved.

The net of it and the understanding I have given to the big picture is stagger functions because the two rear tires on a staggered solid axle, have different surface speeds.
 
Here's a little more on it. This is a copy of a letter I sent after a one on two conversation I had with a couple of fairly know people in the racing world. There response to my general line of BS and theory, after kindly and intently listening to me, was by one and I'm almost quoting, "What you said is a refreshing new way of looking at things and you are 100% right, I'm an engineer and I can follow you the average person would have trouble with it.".

I hope you enjoy the reading, I don't remember if I posted this before.

HOW A STAGGERED SOLID AXLE WORKS
by Paul Kish SR


edit up front: This started out as an essay and ended up as a letter.

I've written this and preached this so many times now, the story just flows out of my fingers.

When ever I hear someone explain stagger in terms of how a Styrofoam cup rolls I cringe.

Yes more stagger in general will create more turning effort from the axle and yes if there's a general trade off for balancing stagger; it's about do you use less stagger supporting forward acceleration or more stagger enhancing turning ability. I'm not about or into any specific stagger, for any specific situation. I'm about and my theory’s are about, choosing the the correct stagger for the situation, your racing needs and the ability of the vehicle your racing to use stagger. But when I'm asked the question, “How does stagger work and what happens when you adjust stagger?”, this is my reply.

Assuming you already have a staggered solid axle, there are 'only' three things which can be altered when stagger is changed:

First a change in stagger will adjust ride height at one or both rear corners of the car.

Second when the axle is rotating, stagger creates a difference in tire surface speeds between the right and left rear tires. When a change in stagger is made, the difference in tire surface speed between the left and right tires is changed.

And third speaking only in terms of the LR(left rear) tire, changing stagger changes the 'potential' for the LR tire to either slip or grip, depending on your ability to apply weight to the LR tire.

The key word in the previous sentence is 'potential'. To understand what I mean by 'potential', requires being able to see there is relationship between the slower surface speed of the LR, the faster surface speed of the RR and the track surface. Explaining 'potential' further what follows assumes your already slowing down and turning into a corner. Under those conditions you have x surface speed at the LR tire and your pushing the LR tire into the track with 100 pounds of force, creating y amount of friction or braking action with the LR. The braking action at the LR will allow the RR with it's faster surface speed to rotate around the LR. If you put more force to the LR more friction will be created and you will receive more braking action from the LR.

But since the LR is rotating while moving across the surface of the track, a change in LR tire surface speed by putting on a smaller LR tire, will increase the difference between the surface speed of the LR tire and how fast the LR tire is moving across the track. If the same weight of 100 pounds remains constant, by increasing stagger you have just increased the 'potential' for the LR tire to slip on the track, because you increased the difference in surface speed between the tire and the track. In fact it will slip more and not provide as much braking action at the left rear. That means to maintain equal braking action from the LR tire if you increase stagger by putting a smaller tire on the LR, you must also do something to increase weight applied to the LR. If you do not you will not get equal results and you will loose rotation.

The above paragraph explains what I mean by increasing 'potential'. It is explained using a potential for increased slip, but the reverse is true when decreasing stagger by putting on a larger LR tire. Expanding on the thought process and my theory, the same applies to the RR but to gain initial understanding it's much easier to see it using the LR for an example. In addition there are similar relationships that have 'potentials' for change. They are how the right and left rear tires work together and how the axle assembly in total works with the track.

Expanding a little more words like slip, braking action and grip, fit in easily when trying to pass on a general idea. In actuality what alters in each rear tire are slip angles, slip ratios and lateral slip ratio. But there is no need to go into slip angles and slip ratios when trying to pass on my unique theory on how stagger works.

Before going on it must be understood that I do understand different view points when thinking about how tires interact with the track. From discussing this with many people over the years I have come to the conclusion there are two general ways racers look at setup. Dirt oriented racers who come from a winged background will in general think about setup from the back first. And asphalt oriented racers and even dirt racers who normally do not get very deep into stagger think about setup from the front first. There is no right or wrong way but the end results of their considerations will always end up the same. If there is one thing that transcends all high hp LTO(left turn only) race vehicles, it is you can dump all the weight an hp you want onto the right side tires and go faster until you exceed the capability of a right side tire or run out of hp. Once the capability of a right side tire is exceeded your only option to go faster is to better use the left side tires. I only noted the above because I know you are involved with racing higher hp race cars.

Continuing on with that thought, once it's realized the only way to go faster is to better use the inside tires, the only debate becomes how your going to use the left side tires. I'm probably boring you already and I'm not going to now start explaining theories on why and how the inside tires need to be used. Those ideas get into the need to split slip angles, why you might want to load one rear tire over the other. I already partially explained and started to get into a why you would want to load a particular rear tire when I met you two and you both were kind enough to listen to me.

In closing if you read books on how race cars work and study the math on how race cars work, though it's meaningful to how “real” race cars work and cars in general work, we do not race “real” race cars we race LTO race vehicles. And all that is written does not necessarily apply. I'm into theory and have tried to explain a few of my thoughts. When ever I write something I always try to end with a question. My question to you ending this letter is the toughest question of all. Does grip follow dynamic weight transfer or does dynamic weight transfer follow grip.

Sorry to be so long winded and thanks for reading

paul

Paul Kish SR
 
My question which prompted this thread was "Can you get enough exclusively from the LF to operate the RF.

My reason for asking if not significant to others, seem significant to me. If you cannot then there is a limit to what can be done with the LR area in terms of maintaining and controling weight on the LR. And if you can't it defines the reason to be, because some LR weight will be needed to operate the RF. That's all just wondering about something I thought might limit chassis design.
 
I think you're wrong on lto vs. sprint, but I guess I would consider "asphalt racing in the rain" more equivalent to LTO dirt. I'll agree that available grip determines maximum speed and until you're using all the available grip you're leaving speed on the table. You are right to consider grip available on all 3 (or 4) tires. If there's enough grip to bicycle, LTO's work EXACTLY like sprint karts. And plenty of LTO's have been rescaled to work on sprint tracks... Hope you find what you're looking for...
 
It's the unloading of the inside rear which aids speed through a corner with a Sprint Kart and it's the loading of the LR which aids speed through a corner with a LTO Kart.
Only partially right. On a sprint kart, if you don’t unload the inside rear tire, when starting a turn, the kart will not turn. This is why karts have so much caster. And yes this unloading of the inside rear tire does help the speed through the turn, but that’s not its sole purpose. I have a theory that says; the kart that holds the inside tire off the ground the longest, through a turn, will be the fastest kart through the turn. With a sprint kart, in a turn, if that inside tire touches the ground, it’s going to slow you down. So in that part Paul, you’re right.
You should read up on caster and kingpin inclination in Wikipedea and get a better understanding of what they do for handling. You’ll find that in a car, their use is completely different from a kart. When I built my karts, I decided that kingpin inclination was not needed in a kart. I later found that the Bug kart, at that time, didn’t have kingpin inclination either. It’s a well-known fact, that in its day, a Bug Stinger was the kart to beat. My karts handle really well, so well in fact Emerson Dismore asked me if I wanted to build karts for him after the 1975 IKF Nationals. Not having the money for such a venture I declined. It turns out he did build a copy of my kart. Maybe not exactly, but close. I’ve seen a picture of it here on Bob’s.
Now my thoughts on stagger. Now I may be wrong, but I thought the whole purpose of the LTO was to get more weight on the LR in the turns. I thought the purpose of stagger was to get both rear tires turning the correct revolutions for the radius of the turn they were traveling. If the stagger is wrong for the turn radius, one tire, most likely the inside rear, will be sliding. A sliding tire will not have the traction of a rolling tire. (For proof, look at what happens when a sprint kart locks the rear wheels when going into a turn. The kart spins because the weight is being transferred forward, and while the front tires are rolling and have good grip, the rear tires are sliding and have lost their grip.) This can only slow you down. On the other hand, stagger, down the straights, can only slow you down. I would think you would have to find a balance between the turn and the straight. Let’s think about a track that is 1/8 mile long. If it has a tight turn radius, meaning long straights, I would think you would have to balance the stagger for both. This means, maybe not the best stagger for the turns, but maybe better for the top end down the long straight. On the other hand, if this 8th mile track has a big turn radius, you will spend less time on the straights and stagger will affect you less. And of course, with a bigger radius, you need less stagger.
What I always wonder about is people asking for setup information and only giving the overall length of the track. No turn information or straight information. Without the track configuration, I have no idea where someone could come up with setup information. How do they do that? Now maybe they have been to that track and know what a good setup is, but they don’t always say that, so how could we know?
Comments, compliments, criticisms and questions always welcome.
 
It would be interesting to set a kart to its' racing configuration, and take some hi-resolution photos of what each tire "bulge" looked like when loaded to a known weight -- ie. load each tire in increments of 10# and take a photo, so each tire would have a library of images. Then film a race with a videocamera in the same position as the still camera was and see how much, when, and how long each tire loaded up. It would be different than simply taking tire temps, though that's an indicator of load/work on the tire too.... Maybe I'll try it this spring....I gotta' test a lot anyhow. :)
 
The gist of what I'm trying for so many years now to explain says, the pictures would be interesting when looking at an individual tire and would relate to the amount of weight on a tire because of loading, loading forces and transfer. But looking at an individual tire would tell you nothing about the performance of the rear, because performance is the result of the interaction between the two rear tires. Now if your thinking about capturing both rear tires and somehow super imposing one on the other to see them working together or maybe even relating them somehow via spread sheet... you really got my interest. ... :)

paul
 
Quoting me:

"Second when the axle is rotating, stagger creates a difference in tire surface speeds between the right and left rear tires. When a change in stagger is made, the difference in tire surface speed between the left and right tires is changed."

Bryan, there's no need to injure yourself physically abusing your head. Read what follows on here. It will make everything become so clear you will no longer have need to bang the cob webs out. ... :)

There's another consideration I did not cover in the letter. The consideration is what is changed when you alter tire size, going to larger or smaller tires on both sides in the back and the difference in tire surface speeds across the back remains the same. What happens is it alters ride height in the back. How you will look at and deal with it depends on what your racing. Though the principals remain the same and my theories still fit the change, how the change is looked at generally depends on what your racing. If your racing a sprint car the change because your measuring ride height from the ground might be considered a significant change. If your racing a latemodel measuring ride height from the axle, it might not even be considered. But I have even seed latemodel drivers crawl under their car and measure ride height from both the axle and the ground. When the change is made to a kart, I don't think most even consider the ride height change in the back.

Here's a story from observation of how I think similar stagger with different tire sizes across the back, effected outcome. I don't remember the years, it was over ten years ago but not 15, Rod George and Ed Lynch would compete Friday at Lernerville and Sunday at TriCity. Lernerville a banked 4/10 mile that slicked up for the feature and TriCity a big 1/2 mile that slicked up for the feature. Long story short Ed pretty much had Rod covered at Lernerville and Rod pretty much had Ed covered at TriCity. So much so that Ed would win the points at Lernerville and Rod would win the points at TriCity.

We also raced both tracks every Friday and Sunday, we were new and especially Rod and his crew cheif Ron, and Ed would answer anything we asked helping us greatly. During that time frame my son and I were in the stage, which we still are, of grabbing and trying to grasp everything we could about setup and who was setup how. Long story short if there was a difference in equipment that allowed one to win at TriCity and the other to win at Lernerville, I felt it was Rod ran American Racers and Ed ran Hoosiers. Sure it's easy to just say it's the tires that made the difference. But both tracks slicked up to the point of real slick come feature time. Yes one was bigger but in general though higher speeds were involved at TriCity, proportionally I think the cars entered the corners the same at both tracks. Notice the word 'proportionally' in the last sentence. Back to stagger and ride height. My observations told me both Rod and Ed ran about the same stagger, at both tracks. The only real difference between equipment I saw was tire size in the back. Rods American Racers were over all smaller then Ed's Hoosiers. When I realized that one difference, I made drawings of both cars with proportional measurement to see how and if over all tire size might be a factor. I also projected the cars in terms of my observations of any differences in track banking and configuration. Sure my observations could have been flawed or biased incorrectly one way or another, but I did my best to be objective. The whole point was to see how to make our car faster not there's, so I tried my best to be objective.

Long story short as I like to say, when I looked at how weight projected and knowing they usually used the same rim inset, over all tire size from my observation gave Rod an advantage at TriCity and Ed an advantage at Lernerville. All that to say a stagger change in the back might not alter the difference in surface speed between the two rear tires, but it can effect other things. What I've presented again on here is not about a lot of other things, it's only about how a staggered solid axle needs to be made to interact with the track, in the ideal way to be fast. The sole reason behind how it needs to be made to work with the track is because there is a difference in tire surface speed between the two rear tires. Everything you do to get the back to rotate when using a staggered solid axle, boils down to your ability to push each tire into the track at the right time. Because there is a difference in surface speed, each tire can independently be made to give you either negative, neutral or positive acceleration. You cannot get the same negative, neutral or positive acceleration, independently our of a solid axle, unless there is a difference in surface speed between the two rear tires.

What follows next should be familiar to you if you've been reading on here for years. You set up what you race with its staggered solid axle, so when decelerating and turning you are able to push the LR with it's slower surface speed, into the track well enough for it to out brake the RR and allow the RR to roll around the LR. Next comes transition from deceleration to acceleration. The transition is simply rolling as needed until the start of acceleration. At that time your LR smaller tire will ideally be loaded and allow for the start of acceleration to come from the smaller 'low gear' LR tire. Ideally then it's on to accelerating and exiting onto the straight, during which time you control the amount of weight transferred over to the RR. Again ideally, you only need to transfer to the RR the amount of weight needed to allow it, with it's faster surface speed, to out accelerate the LR. How much you make it out accelerate the LR and how quickly it does so, will depend on how soon the turn ends and an actual straight begins, if any. And if Al's reading on here; Al, follow the sequence of events. It's the LR mainly carrying the load even on to the straight, which is >ideally< and it's just that the ideal IMHO situation. Here's the key Al, even on the straight or so called straight, with a staggered solid axle you only need to transfer enough weight to the RR so it can out accelerate the LR, as needed. The only reason it can be done that way and the weight can be mainly carried on the LR, is because there is a difference in surface speed between the left and right rear tires. Al you have often asked about the concern of speed being scuffed off on the straight and I'm sure others have the same concern. I think it's best to simply consider it a non issue. I can say that because unless your traveling a radius where the difference in size of the rear tires exactly matches your travel, one or the other or both rear tires are slipping anyway. It then becomes a matter of which rear tire can you slip, in a way which will give you the best advantage. The answer again turns out to be carry the load on the LR because it's smaller and offers less resistance carrying the load down the track. Slip the bigger RR if at all possible because slipping it will eliminate the biggest threat of resistance to forward travel. What I have just written describes the ideal of using a staggered solid axle. Circumstances and the ability of what your racing to use a staggered solid axle in the ideal way, be it a Winged Sprint Car, a Late Model or a kart, will determine how close you can come to the ideal, which my theories describe.

thanks for reading,

paul
 
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This thread allowed me to think out and write again since the crash, my theory about a staggered solid axle.

I think I was pretty complete with it and as usual, hope their close to being accurate but I don't know because it is all just IMHO and ain't necessarily right anyway. ... :)
 
If anyone thinks what I brought up in this thread has any validity to it, you ought to copy it because if it disappears again I probably won't be able to re-construct it again. ya know that old age thing. ... :)
 
I just read though the last long post I made and when I do it I always seem to have a yeah what if or see another connection fitting things together. I'm biased about it being correct, but my nature still finds the yeah but what if's. From my perspective and just for my own good feelings, years ago when I first used the forbidden word of 'slip' in reference to tires working out on the track, I was totally beat up by everyone on here. Back then it was impossible to control how much a tire slipped. If you dared to speak of how a tire worked in any other way then how it gripped, you were on a path to the underworld and would spend an eternity condemned. It was only after a post made one day by Chris Gabeheart saying he now saw how on a straight one tire must be slipping, that others began to include tire slip in their though process. I think until that time nobody in the karting world except me or possibly in the racing world considered tire slip as a controlling factor to being fast, the same as grip controls how you can be fast. Sure there were always slip angles and slip ratios and there still are today, but until then they were only looked at in terms of being able to do something. I think today there also looked at in terms of yes slip angles and slip ratios happen because of grip, but how and when you release them because of slip is where your find fast. Grip determines your ability to apply hp, slip determines your ability to balance applied hp. Being fast is not simply about the application of hp, it's about your ability to balance the application of the hp. Adding flexibility to the LR area of kart chassis is not about being able to put more weight on or hold more weight longer on the LR, it's about enhancing your ability to control weight across the rear axle so it can be operated closer to the ideal I described.

Quoting me: "unless your traveling a radius where the difference in size of the rear tires exactly matches your travel, one or the other or both rear tires are slipping"
___________________________
just felt like writing more for my own enjoyment... assuming everything coming out of my fingers is bull, don't read on it's just for my own enjoyment


There are different situations which make what ever your racing fast for specific conditions.

In the past the primary condition to be fast was to grab hp dump it on the RR(or outside rear) and go. If you have grip you can dump more weight on the RR and go faster. The mind set was no matter what you races be it high hp or low, "you can't beat cubic inches". Even karts originated from that mind set, which suited sprint and road racing perfectly, because of there needing to unload the inside tire. You don't hear old timers talking about how they engaged their tires smoothly, you hear them talking about how they applied hp. If smooth or tire application is talked about referring to years ago, it's only in terms of how hp was able to be applied. And the only place it could be applied was the outside rear tire. And then there were and are the books, which from day one deal with and assume everything that is raced turns both left and right, "Real Race Cars". We don't race "Real Race Cars", we race LTO's. The sentence, "We don't race Real Race Cars." was given to me years ago by Ted at Goodhope. This may be the first time I've given credit to him for it. If there's anyone to blame for building my confidence and spewing this garbage continually on here it's Ted. Thanks Ted ... I'd better stop I think I just got into trouble. ... :(

if you read this far, thanks for reading and don't forget it's just IMHO and ain't necessarly right anyway. ... :)

___________________________

edit: Low hp boxstock karting did more for gaining speed in LTO racing world in the last 10+ years, then anything else. I say that because fine tuning limited hp to race at the limit of grip is no different then fine tuning having excessive hp to run at the limit of grip.

LTO kart racers learned to run their LTO karts at the limit of grip and what they did and are still doing; is being directly translated to high hp racers.

IMHO, every record you will ever see broken by a car on an oval track, is directly related to LTO boxstock and now clone kart racing.

And the only reason it happened and I can say it happened is because of Bob and his 4cycle.com karting site.
 
922 views and so few comments?

Common now give a kid a Christmas present. ... :)

All yer setup stuff, mechanics, mathematics, tire prep etc., to help your driver do what's needed to win is all done so you can make your staggered solid axle work as close as possible to my theory, of the ideal.

Until my unified theory on everything there was all this knowledge about stuff regarding a staggered solid axle, then I went and told ya how to use the thing. ... :)

Cross, critch, cratch, cretch, who cares ! In the end it's about how it rolls and how you make it roll... that's all.
 
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i need more popcorn...

More popcorn Wesley, with it's heart blown up into a big white puff is not what you need. What you need is more of the meat and potatoes I gave you to eat. The popcorn you've been force fed up front on here, gets small and easily runs through you when consumed. Meat and potatoes will put fat and muscle on your frame.




... :)

Happy New Year


"life is good, enjoy it"
 
Indeed - split screen four camera angles at once! and from just below the frame rails, have a drag and drop feature so you can have side by side comparison of each. Man this would be so help full for explaining weight transfer, and roll rate, and Stagger, and checking out different tire Manufactures.
 
Indeed - split screen four camera angles at once! and from just below the frame rails, have a drag and drop feature so you can have side by side comparison of each. Man this would be so help full for explaining weight transfer, and roll rate, and Stagger, and checking out different tire Manufactures.

Yes a picture is worth a thousand words or twenty thousand of my words. Is it possible to read lateral and vertical acceleration at each corner? I think the lateral is already done.

Can vertical acceleration be measured, at each corner while on the track? Could it be computed from lateral and forward acceleration and deceleration? Another thought on a possibility is could GPS tracking measure height? Then the first thing that comes to mind is how do you separate out bumps in the track from vertical acceleration due to weight transfer? Let's say you could read vertical acceleration at all four corners, yes it's all about results, but to understand the why of the results you'd also have to put sensors on all mechanical movements. And thinking about it with today's electronics, it would be possible and probably not that difficult.

... This is all getting too complicated. The whole point of my BS theory on here is to see it simple. What you can or cannot do to make the simple happen is what's difficult. The point is when you have a staggered solid axle, you will have two different tire surface speeds. I'm saying the true ability to be able to make your axle rotate or turn out on the track is because of how you are able to push each rear tire into the track, while decelerating, rolling the corner and accelerating. Having a larger tire on the outside with a faster surface speed then the inside tire is what allows for all the things you do setting up to work. The larger or smaller tire sizes to fit a particular radius is nice and makes the difference easier to use, but in the end it's your ability to apply weight to each rear tire that rotates the back end. It's so simple and fits so well to everything you do setting up, it's beautiful.

To rotate a staggered solid axle when decelerating, apply enough weight to the LR so it's slower tire surface speed can out brake the RR. Then start your acceleration on the loaded, low gear LR tire and transfer weight as necessary to the RR and cause the RR to out accelerate the LR as needed.

That's it and what needs done to be fast is that simple.

It's circumstances and the ability of your LTO equipment to operate in an ideal manner, that is difficult to make happen. What's faster and what's fastest depends on comparing apples to apples. If your racing something LTO which has a staggered solid axle and the rules dictate you will have minimal stagger, to be fast you may very well rely on dumping weight on the RR, throw power to it and go. If that's what you have to work with then that's what you have. But it does not change why and how a staggered solid axle works, it only means your using your solid axle with minimal stagger in a way other then ideal.

It just so happens that today with a kart you can get the stagger needed to use your solid axle in the ideal way. Your not going to calculate to the ideal. The only way your going to get to the ideal is to put the thing on the track, identify on track problems preventing your staggered solid axle from being used in the ideal way and adjust towards it's ideal use. I think if you look at on track problems, they can all be defined in terms of how the difference in rear tire surface speed is being applied to the track. Maybe because this is all just IMHO and ain't necessarily right anyway. ... :)

but it's fun to think about, at least it's fun for me !
 
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