Tire temps

When taking tire temps and doing the math by hand how do calculate the cross number such as the +0.2 or -0.2. I ha e watch the videos that harril Wiggins did on the top secrect videos club I understand how he got all the other numbers but I can't figure out how you get the cross number.
about a year ago there was a big discussion on this here on Bob's. I put all the numbers people recommended into an Excel spreadsheet. You put in the tire temps, left, middle and right, for all 4 tires and all the various combinations show up next to that. LF + RR RF + LR, etc. etc. I think there is something like 9 or 10 weight combinations, including the average for each tire. You're welcome to it.
anunley@austin.rr.com
 
A few years back now I took rear tire temps of every car coming off of qualifying, when they went onto the scales at a couple of Allstar(Winged 410 Sprint) races.

I was then able to compare qualifying times to accurate knowledge of exactly how the rear tires were heated. I was then able to look at who was fast and who was slow, in terms of how rear tires over all heated up. And I could compare exactly how each cars rear tires, heated across each tires surface.

What it told me is only valid in terms of how I interpreted the results, someone else might see the results differently. What I did not get because I could not do two things at once is a video of the line and how each car performed on the track during qualifying. Without having video of on track performance of each car to look at and after being able to compare rear tire temps to qualifying times, I'm going to say total heat or how hot you can get tires out on the track is not an indicator of fast. If anything it appears to me to be an indicator of on track problems. In general the fastest cars came in with over all average or lower rear tire temps, not higher.

It would really have been great to also have video of each car out on the track qualifying to compare. Because after qualifying I also went out on the track and took readings of exactly how the track surface was heated. I could actually see the grove or the area/line on the track, which was heated and might be called the racing line. But though I could see the exact heat line around the turns, sadly without video of cars qualifying, I did not know if the heat line entering and through the turn was caused by LR's or RR's. I did observe and make this comparison for myself, as far as who is fast or not. When I looked at the line on the track RR tire presentation to the track seemed to dictate where most put their RR at entry. But where most put their RR at entry, did not co-inside to who was fast. Those who were fast, generally presented their RR's for turn entry, beyond where the norm was established by how the track was heated.

Another thing I was able to observe while at the track was to get a look at cars which were over all slower prior to the feature. When I got to watch some of the slower cars and then compare to qualifying times and rear tire heating, it became obvious the added heat and lower times was due to pretty much a lack of skill and quality equipment. I also tried to look at faster cars and as I do every race I get to, try to look for common thing across the board which relate to fast. What I've learned over the years watching is it's a lot easier to see on track problems and common on track problems, then it is to see common traits which make up quality and fast.

Just a few observation from a couple of days at the track looking at tire temperatures. I don't have the experience Mike, Andrew or others have taking and using tire temps to be fast, I'm only passing on what I think may be some unique observations I have made. If they fit in fine, if not I hope it was at least interesting reading.
 
Paul. I wanted to share this with you. You know that I take tire temps almost every weekend on all kinds of different race vehicals. Not so much kart, but about anything from street stock, super late models to the cars we crew on that run the Rolex 24. On the oval track cars we try to get the front averages to equal the rear averages. And you try to get the LF/RR averages to equal the RF/LR averages. And we would like to get the right side tires to be the same as the left side tires. The last one is the hardest one to interpret because you would like to have them equal each other but with LTO it is almost impossible to get the rights equal to the lefts.

This is where my story is going. I have been crew chief on a Pro Truck team for over the last year. We have been working really hard with our setup package to get the right sides to equal the lefts. Well, a few weeks ago, in victory lane, I probed the tires and "it was a first". It was the first time in my many years of probing that after a 50 lap feature my left side tire average was 4* hotter than my right side tires and our truck is on rails!!! People say that it can't be done with 57% left side weight in that class but I have proved them wrong. After that feature I had 3 tires at exactilly 205* and the LF at 209*. And that was after a 50 lap run. That is about as balanced of a setup as you will ever see.
 
Thank you. I added your reply to my saved good stuff. I went to a few asphalt oval races this past year and what you have previously posted about tire temps and again kindly explained, made watching asphalt a LOT more fun.

Thank you very much and I think I'm close to being able to see your thought process, which I'm able to fit very easily in my picture of how stuff works.

paul
 
Paul. I have been wanting to talk to you on the phone about your thoughts you brought about loading the LR to soon or to late. And how the RF dominates turn in. You are looking at it completely different than me and may be why you have a little struggle with it. I think if you could see it the way that I do it may give you a whole different view of what makes the kart rotate. When you look at it like me you will not even concider the loading and unloading of the LR.

As you can see. I am not the best one for putting my thoughts into print. But I can verbally explain to you in such a way that it will click.

PM me if you would like to talk.
 
I would love to hear that conversation, especially if successful!

Good luck Andrew!

After quit a few PM's about me telling Paul to not worring about unloading the LR ever again I think the reply I had the other day explains it the best. Like I said. I am not the best at putting my thoughts into words but here is a copy and paste of me trying.

Paul and myself have talked chassis dynamics for years but Paul's philosophy tends to lean towards loading and unloading the LR for rotation. That is not how it works. I really needed to talk to him on the phone to make it click. Let me try to give you the short version.

If you were unloading the LR to rotate the kart that would mean you were rotating the LR. In order to rotate the LR it would have to rotate rearward in LTO racing. If the LR rotated forward you couldn't turn left and it can not rotate rearward because it is in a forward motion. So, your rotation really comes from the RR rotating forward. If that makes sense?

Here's the deal. Today's karts run high cross and low VCG's so. The LR is load all of the time. Period. It does not have to unload. This is why. The surface speed of the RR tire is faster than the surface speed of the LR tire. So the RR is always slipping. As the kart loads the RR, the surface speed of the RR tire loads and rotates the RR forward because the RR is spinning faster than the LR. If that makes sense?

If you load the RR to fast and hard you will push. If you load it to slow and soft you will be loose. If you get it right you are on rails.

So, that is the short version of why you shouldn't worry about load and unloading the LR. It is always loaded. Period. The RR rotates around the LR. Not vise versa.
 
Also. The above is also why stagger does not hurt you down the straights. The RR is always slipping. On the straights the RR's surface speed is faster than the surface speed of the LR tire that is driving you down the straight. So the RR's added stagger/surface speed is helping you down the straights, not hurting you at all.
 
I understood Andrew and you said it perfectly.

I see the confusion. I am not preaching unloading the LR.

The only unloading of the LR I ever think about is in terms of providing weight to the RR so the RR can out accelerate the LR. I now know the confusion comes from my NOT ever considering the over all increase in weight because of an increase in g's. Thank you.

If I include grabbing additional weight via an increase in g's, I can see where the additional weight from an increase in g's >alone<, could be sufficient to cause the RR to rotate 'forward' around the LR.

thanks

paul

Thank you, you fixed a major flaw in how I see it and presented it, because I did not ever consider weight gain because of g's.
 
I see a little flicker of the light coming on!!!

yeah and just as fast as it came on ... I told myself to be very careful, I don't start using the free weight as a crutch to solve on track problems. I would like to keep problem solving in terms of what can be done, to move the total process towards the ideal.

Throwing weight at an on track problem is much like throwing prep at an on track problem. ... :)

I like thinking in terms of function and how to shift the process. ... what ever that means. ... :(
 
That weight you speak of is always there and in motion. How you use it will determine weather or not you are fast or slow. The guys using it the wrong way(to unload something) are the lappers. The ones using it the right way(to direct weight where needed) are the winners. Just because you can't see it or measure it does not mean it is not there. It is and you have to know how to use it to your advantage.
 
I don't start using the free weight as a crutch to solve on track problems. I would like to keep problem solving in terms of what can be done, to move the total process towards the ideal.

Paul. I don't understand "free weight". Like I said this weight is always there and always in motion. If you can't understand and manage this weight you will never be consistently sucessful with chassis setup in any type of race vehical.

Adjusting the static weight, frontend geometry, and tire selection is the only way to manage this free weight and is the only reason we make these adjustments. We are either trying to overcome their effects or enhance their effects. But that is what chassis setup is all about. Trying to get a balance on these "free weight".

Static weight is simple. Dynamic(free) weight is the hard one.
 
Andrew I think your a much better reader then I am a writer. ... :) Instead of trying to explain the error of my writing and why I wrote as I did, I'm going to instead just try to say it differently.

With the exception of including in my thought process the amount of dynamic weight increasing as g's increase, I think about how things operate out on the track and how weight effects the operation, in terms of the movement of dynamic weight.

I can talk about or alter my picture of a corner of what's being raced by mentally altering height or mechanically pivoting a corner, side or end. But the significant s of the mechanical movement is pretty much only to direct dynamic weight. In my mind I put pretty close to zero, the actually effects of mechanically moving chassis weight. In my mind and in my thought process, I see the change in the physical location of parts on the chassis through how it effects dynamic weight transfer. Though I see in my mind physical movement and if you scale you will see weight changes on the scales, the movement and changes on the scale are only an indicator of how dynamic weight will be directed.

Even with the finger puppets I introduced, thought I can open and close what springs allow done and I can raise, lower and change the physical relationship between sides, all that ends up only being physical changes made with the real thing of importance being how it effects weight I see shooting or traveling from one side to another. Tough to describe finger puppets and harder yet to describe the imaginary transfer of weight I see moving across from one side to the other. ... :( I think you were able to add to the puppets an imaginary sway bar and you were also able to relate to how movement at one end of the sway bar, could be transferred via the sway bar to the other side. If so I think the puppets may become a new 'handy' tool for you to use. ... :)

If I expressed things better, then the next thing is I have to have some sort of reference for how dynamic weight needs to be applied or moved.

The 'ideal' process if you have a staggered solid axle is my general BS, as I like to call it. Simply put, you can control via weight applied to each rear tire at the appropriate time, the direction a staggered axle will roll. The reason you can do it is because there is a difference in surface speeds, between the right and left rear tires. With a staggered solid axle you can carry all of the rear load all the time on the left rear tire, with the exception of the weight needed on the right rear tire to cause it with it's faster surface speed, to rotate as needed around the left rear tire.

The paragraph above is a description of what is ideal and it does not mean what your racing can use it's staggered solid axle in the 'ideal' way. I accept most all the time the 'ideal' way of using a staggered solid axle will not be obtained. I consider as fact that any short comings to using a staggered axle in the ideal way, will have to be over come by the front tires. In my general thinking I also consider any need to turn the solid staggered axle with the front tires, will create a conflict for control of direction and in turn eat hp. My thought process is; base line what ever your racing as best you can and put it on the track to see how it preforms. Then if there is an on track problem, fix it. My first thoughts of how to fix the on track problem are always to think of things that will fix the problem, by moving the function of what your racing which has a solid staggered axle, more towards the 'ideal'.

After all that I have to repeat what your giving us numbers on your balanced tire heating, did for me.

It allowed me to logically bring back a thought I have had for years, about the benefits of storing weight at the LF corner. Here's where I see the good of storing weight at the LF comes from. Simply put I think it's easier to roll carried weight out on the track at the LF corner then locating weight anywhere else. What that says to me is if you can get needed function(balanced function if you like) out of the other three tires, then over all rolling resistance and most importantly your ability to maintain momentum, will be maximized.

Time to go get my second cup of coffee and also time to stop writing and read through what I'm posting to see if it was what was on my mind.

Andrew, the point I think I was trying to make in the other post, was that it's the process which is used to decide how to cause dynamic weight to be applied that is important.

I don't care what amount of weight is moved, so long as it achieves the results I want, via my now established process. And I think that may include your input of how dynamic weight is what's tough to work with accurately. It's tough because you not only don't have anything exact to tell you how it will be directed, even if you did you would not know how much was directed. Thinking about the last sentence, makes scales the only thing you have, to even try to come close accuracy. But even scales are only a tool, to hopefully help your thought process to be brought into reality out on the track. It's an art form, with the performance of your thoughts played out on the track. And your applause is being able to end your performance before anyone else.

later... gota go get that coffee NOW !
 
In the above post I wrote: " In my mind and in my thought process, I see the change in the physical location of parts on the chassis through how it effects dynamic weight transfer."

I think most will say if the location of physical weight doesn't mean much, then why do we bother placing weight in any particular place when scaling?

My reply is you scale to obtain a baseline and some numbers to represent what is going on out on the track. Out on the track though the actual weight of movement of chassis parts, IMHO even on a suspended chassis is not a big factor. If you have an on track problem, come in and physically move a lot of weight to a different location on the chassis, it's how the weight moved to the new location dynamically transfers out on the track which makes the difference. It's a tough thing for me to try to distinguish between with words, but I am trying to separate out results from what happens dynamically and what happens mechanically. And when separated I'm trying to show it's the dynamic weight transfer which is the major factor.


maybe ?
 
The actual weight of the movement of the chassis part doesn't mean all that much but, the direction and the speed of that movement is critical. And even more so on a suspended vehical. If you have an on track problem you "don't" come in and physically move a lot of weight around on the chassis. You come in and adjust things that change the effect of the dynamic weight that is causing the on track problem.

Honestly Paul. In my last 10 years of crew chiefing on suspended vehicals I can say I have physically moved ballast at the track maybe 2-3 times to solve a track problem. It is very rare. We max out what the rules will allow and adjust the chassis from there. We change everything else on the car to rectify the effects of dynamic weight transfer. Some vehicals are built lite enough to where we have ballast to be able to move lead foward in the left frame rail to have some front to rear adjustment but most of us are looking for as much rear weight as we can get. And we always max out the left side to what the rules will allow.

To me Paul. Doing chassis adjustments to use the free weight to your advantage to solve the on track problems is key. Physically moving ballast around a chassis would be a crutch. In karting, yah you might move ballast around a little but, taking the 25# of weight from the seat and moving it out in the nose because the kart was pushing would be a crutch. There are a ton of other things to throw at it before I would go there.

With your finger puppets can you see how more bite in the tires or track will change the dynamic weight transfer? And how frontend geometry can change that effect? Or even how adding cross will effect dynamic weight transfer? Now can you see how adding a little more static weight to one of them effects that free weight? it's not very much. Kind of like how this post started. "The actual weight of the....".
 
Good for me to be on the same page as you, but it's suspect for you if your even in the same chapter as me. ... :)

When we started with suspended cars in 2000 what you just wrote, sunk in quickly for us. The tracks we raced weekly Lernerville 4/10's on Friday, Mercer 3/8's on Saturday and Tricity bigger half mile on Sunday, all went from grip to very slick come feature. Lernerville and Tricity would especially go from grip to skating rink. Mercer was no matter how good it looked, treat the thing like the grip is gone come feature time.

That is what quickly made us realize, you could not just throw the kitchen sink at it maximizing out adjustments, to physically put weight to the LR and back end. You needed to not quite throw the kitchen sink at it, leaving room to move weight to the LR and back end, across the 'other' cross. We learned when the slick came, cross and wedge were meaningless, without the ability to actually cause weight to move from the front to the back.

Actually we already had experienced the need to cause weight to move and get eased on the back, from karting, when we ran UAS.

We often discussed on the way home the question of, do you just dump weight to the back or do you do things to >throw weight to the back. That and the discussions about how to ease weight into a tire instead of 'banging' it at the tire on a slick track, seemed to prove very productive. The net of it though I don't talk about it much, is I'm not only interested in putting weight to the tires when needed, I'm also interested in how the weight put to the tires is applied.

Thank you again I appreciate the conversation.


paul
 
What do you mean? Al didn't answer either question that was asked. Does anybody take tire temps? And. What temps are we looking for? But, "Not believing there is a correct answer" is not the correct answer to either question.

The first answer would be, yes.

And the second one would be, balanced temps.

That is what the memory pyrometer is all about. Getting as balanced tire temp as you can achieve.
 
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