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dj2motorsports

Importance of Taking Tire Temps - Part 2

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dj2motorsports

In the previous post, I discussed how the tire temps will look if the tire is over, or under, inflated. Now let’s look at what the tire temps would look like if we do not have enough initial negative camber set. (Remember that negative camber is the top of the tire tilting toward the center line of the vehicle.)

If the temperature on the outside of the tire is significantly hotter than the inside, this indicates that the tire is riding too much on the outside edge, and more initial negative camber needs to be set to lean the top of the tire toward the centerline of the vehicle.

If the inside of the tire is too hot, then you need less initial negative camber and to tilt the top of the tire away from the centerline of the vehicle a bit more.

What does it mean when the inside temp on both of the front tires is warmer than the outside of each tire? You either have too much initial camber set on both wheels, or it could mean that you have too much toe-in set, or maybe a little of both.

If the outside of both tires read hotter than the insides, then you either do not have enough initial camber, or too much “toe out” set, or a combination of the two.

As you can see, your tire temperatures can tell you quite a bit about your set-up, so pay attention to them to get faster. To get the maximum traction from any type of tire, you need to maximize the tire's contact patch in the corners by having the correct pressures set, and have the suspension components set so that they position the wheel/tire at the most efficient angle while cornering.

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beerkat

Again thanks for the post.

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rwhitinger

This is great information for a Rookie! Thanks for the post.

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Trevor57

This is all true, but ham-fisted driving can play a big role too.

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dj2motorsports
This is great information for a Rookie! Thanks for the post.

 

Thanks!

Rookie I'm not though.

I actually have 20+ years in design and engineering background with a CAD degree, and purposely focused most of my research on race chassis and suspension design. I have two books written and am working on my 3rd and 4th book currently.

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SNAKBITN

I think he was referring to him being the rookie.

 

Robert

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dj2motorsports
I think he was referring to him being the rookie.

 

Robert

 

Ahh...yes, that makes sense too! I should have had more coffee before that one.

That's who it is geared towards. Trying to help cut the learning curve a bit for the rookies/novices which will also hopefully help to keep them in racing longer and keep moving them forward and/or make it more fun.

I try to gear my articles, and books, toward the novice, or slightly experienced, person to help teach them the basics behind the chassis dynamics and break them down into basic, easy to understand language, without making it overwhelming so that they can understand the car handling better. It's not meant to be a super technical guide to train a crew chief to the elite ranks. Just a help to those starting out who also might be doing things on their own without a large, or experienced crew.

 

I understand that a large group of people on this forum may be beyond that, however everybody has to start somewhere, and they are here too.

 

It definitely won't make up for seat time, but it will give them the tools to help evaluate what is happening. I have had very positive feed back from people so far.

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beerkat

You might want to post these articles in the HPDE section so the DE1&2 people will read them.

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dj2motorsports
You might want to post these articles in the HPDE section so the DE1&2 people will read them.

 

I will definately do that.

Thanks!

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OHIO4DRTEG

Can you sent me in the Titles of your books I always love reading material on how to setup cars and tech stuff.

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retlaw

post the titles here ?

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dj2motorsports

The titles are:

- Control the Roll Part 1 - Independent Front Suspension

- Roll Cage Design and Construction Basics

 

I'll occasionally post some excerpts from the books (currrent and future) as time goes on.

 

You can find the above books for download in PDF format at:

 

http://shop.dj2motorsports.com/

 

Thanks!

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Karl
What does it mean when the inside temp on both of the front tires is warmer than the outside of each tire? You either have too much initial camber set on both wheels, or it could mean that you have too much toe-in set, or maybe a little of both.

If the outside of both tires read hotter than the insides, then you either do not have enough initial camber, or too much “toe out” set, or a combination of the two.

 

How does toe-out increase outside tire temp? It would seem to me that if you had the correct camber and excessive toe out that the inside tire temp would still be higher due to straight line scrub. This scrub is the reason I try to get the toe set as straight as possible and adjust the balance and handling characteristics through other means.

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dj2motorsports

You are correct. I did type that in backwards. Your thought process is correct.

Excessive toe-out would show higher temps on the inside of the tire.

Excessive toe-in would show higher temps on the outside.

 

And toe settings definitely do not need to be played with, or monitored, like the camber and tire pressures unless you get off track or hit something.

Recommended toe-out is 0 to no more than 1/8 inch depending on what feels better to the driver.

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speedengineer

With the amount of camber most race cars run, wouldn't either toe-out or toe-in both cause the inside of the tire to be hotter? I mean, with my car just sitting there, the outer third of the tire hardly even touches the ground.

 

Personal preference of mine, I like to run a tiny bit of static toe-in, rather the the toe-out most people use.

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dj2motorsports
With the amount of camber most race cars run, wouldn't either toe-out or toe-in both cause the inside of the tire to be hotter? I mean, with my car just sitting there, the outer third of the tire hardly even touches the ground.

 

Personal preference of mine, I like to run a tiny bit of static toe-in, rather the the toe-out most people use.

 

True, the more initial negative camber that you have set, the higher the temps on the inside.

I should clarify that the toe settings will have the most identifiable effect on the tire temperatures if your camber is set at 0 (which is very rare) and I just wanted to mention it earlier in the posts to just note that it could be a contributing factor to increased temps. And the more toe in, or out, that you have, because of the increased slip angle created by the toe setting, it will increase the resistance (heat), and amplify the temperatures on the contact patch of the tire. For example, with your vehicle, if you adjust your toe setting from the slight bit of toe-in that you normally run, to a 0 toe, and leave all other settings the same (camber etc.), you should theoretically see a slight decrease in temps on the inside of your tire because you have decreased your straight line slip angle slightly. Now if you moved the toe setting from 0, to a slight toe-out, you would see the temp start to increase again on the inside of the tire.

 

Camber should be adjusted well before adjusting the toe. Toe should be checked at the track just to ensure nothing has changed and is within your initial set up parameters. The biggest factors to concentrate on are the camber and tire pressures out of these three items. You just have to love all of the factors that affect the handling and how they all work with, or against, each other!

Just out of curiosity, is the preference of having a bit of toe-in a feel item for you? If so, what is it about the feel do you prefer? (Quicker or more forgiving turn it etc.)

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speedengineer

On this car, the steering feels better to me at turn in with a little bit of static toe in. It is sharp and responsive. With a small amount of toe out, it doesn't feel very nimble. If I go to a lot of toe out (like greater than 3/16"), I get that darty feeling that some people claim to like. I don't like it.

 

I also have a theory that running a little bit of toe in increases my steady state front cornering grip by better using each tire to its full potential. It is just a theory, I don't have any data to back it up. When normal force on a tire increases, so does the slip angle at which maximum lateral grip is achieved. During cornering, significant load transfers off the inside tire onto the outside tire, suggesting that 'optimally' you want your outside tire to be at a slightly larger slip angle than your inside tire. By running toe in, maybe you are closer to achieving this. If you run toe out, then you sort of cause the opposite to be true, since the angle of the tires relative to the car are geometrically fixed. I am making a lot of generalizations here about how slip angles are developed, so maybe in real life this isn't exactly how it works out, but it is my theory. And if nothing else, the car at least does feel better to me with a bit of toe in.

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Varkwso

I like all my competitors to run Toe-In on their C5/6 Corvettes.

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Kubs
On this car, the steering feels better to me at turn in with a little bit of static toe in. It is sharp and responsive. With a small amount of toe out, it doesn't feel very nimble. If I go to a lot of toe out (like greater than 3/16"), I get that darty feeling that some people claim to like. I don't like it.

 

I also have a theory that running a little bit of toe in increases my steady state front cornering grip by better using each tire to its full potential. It is just a theory, I don't have any data to back it up. When normal force on a tire increases, so does the slip angle at which maximum lateral grip is achieved. During cornering, significant load transfers off the inside tire onto the outside tire, suggesting that 'optimally' you want your outside tire to be at a slightly larger slip angle than your inside tire. By running toe in, maybe you are closer to achieving this. If you run toe out, then you sort of cause the opposite to be true, since the angle of the tires relative to the car are geometrically fixed. I am making a lot of generalizations here about how slip angles are developed, so maybe in real life this isn't exactly how it works out, but it is my theory. And if nothing else, the car at least does feel better to me with a bit of toe in.

 

This could be the case on an S2000. Slip angle generation is very dependent on the suspension geometry, including king pin angle, scrub radius, etc. If toe in works for your car thats great, way to be a thinker!

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dj2motorsports
On this car, the steering feels better to me at turn in with a little bit of static toe in. It is sharp and responsive. With a small amount of toe out, it doesn't feel very nimble. If I go to a lot of toe out (like greater than 3/16"), I get that darty feeling that some people claim to like. I don't like it.

 

I also have a theory that running a little bit of toe in increases my steady state front cornering grip by better using each tire to its full potential. It is just a theory, I don't have any data to back it up. When normal force on a tire increases, so does the slip angle at which maximum lateral grip is achieved. During cornering, significant load transfers off the inside tire onto the outside tire, suggesting that 'optimally' you want your outside tire to be at a slightly larger slip angle than your inside tire. By running toe in, maybe you are closer to achieving this. If you run toe out, then you sort of cause the opposite to be true, since the angle of the tires relative to the car are geometrically fixed. I am making a lot of generalizations here about how slip angles are developed, so maybe in real life this isn't exactly how it works out, but it is my theory. And if nothing else, the car at least does feel better to me with a bit of toe in.

 

I totally agree, way to think outside of the box and try something different! And if it makes it more comfortable to you, then you will usually be faster because you'll typically drive harder.

 

Good information!!

Have you ever measured your bump steer? I'm interested to know the effect when that front outside corner is loaded to see what happens to the inside wheel on your car, and if it maintains the toe-in, goes to 0 toe, or slight toe-out etc.

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