froggy47

This season I am doing all my own alignment & will be taking tire temps (probe) and making changes.

Autox has some differences from road race and so I am looking for a link/reference to information specific to autox.

I don't want to just post temps, too many variables & opinions, would rather get a book or link to some good "how to do it" source.

Any suggestions? Thanks! I already googled it, overwhelmed.

ipuig

You can run a little more toe-out in the front for autocross to help with turn in. I've played around with my alignment for several years and have decided that you do not need to go very aggressive to achieve very good handling characteristics on these cars.
I'm running -1.4 front camber, -.7 rear camber, 0 rear toe, 1/16" toe-out in the front; lowered about 3/4" below OEM on stock bolts, the car seems to be very neutral and predictable.
Were you at Qualcom this week-end?

froggy47

Thanks, not looking for alignment suggestions in this thread, just the previously mentioned.

ipuig

Using tire temps to set up your alignment for autocross is a waste of time in my opnion, this method is more appropiate for road racing. Plenty of "how-to" self alignment methods in this forum.

John Shiels

The last urn you make will affect the temps and the track configurations a lot more in AX than RR. Even in RR the last turn can change temp readings. AX is short I would just go for the fastest settings.

0Anthony @ LGMotorsports

I agree with John,

Can you even get enough temp in them to get a reading? It generally takes us a few laps on the car to get the tires up to temp and pressure to get any kind of good readings from it.

There would have to be differences in the temps depending on track conditions and run speeds but I think you would have to get a good set of data and make some changes to see what your results are from that based on how the car ran the course.

TedDBere

In autox the tires get plenty hot! But the readings are not as useful as roadracing.

I've found that as long as you get no more than a 10 degree difference across the tread you're in the right range.

When I used to test with the probe thermometer they'd be between 160 and 170 degrees accross the tread. Any more than a 10 degree difference required some input (pressure or camber). The toe was where I wanted it so I wouldn't adjust toe based on temperatures.

You are limited in stock class with the amount of camber you can get into the car so the outer edges would typically run a little hottter. I got the middle temps to come up to the inside edge temps and was happy with that. Once you've max'd out your camber and have the toe where you want it the tire temps are really only good for checking the pressures in the front tires...which change dramatically over 3 runs. The rear temps can be used to check camber too.

Once I figured where I wanted the pressures the probe went back into storage and I haven't pulled it out in 3 years.

0MomentumAutosports

Common MISconception that you want the tire temps even at least in road racing. I would expect them to be MORE even in autocrossing.

Anyhow, I tend to agree with the others that you would likely just tune for optimum feel. Autocrossing requires a lot of driver comfort to be fast vs max grip. Obviously a car that handles well and has good grip is even better!

froggy47

Still need a book/link/tech paper on tire temps vs handling.

To clarify a bit:

1) Plenty of heat generated in autox tires
2) Not interested in (just) stock (limited) alignments
3) Personally have seen two National Solo Champs using tire temps to adjust "something" at practice events

Someone must have come across a tech paper on using these pyrometers to change alignment.

0MomentumAutosports

I am pretty positive that you won't find what you are looking for, at least beyond the basics that you can find by googling.

Just because a couple of national champions were doing it, doesn't mean that it will benefit you. A lot of the time they have logged 100s of runs, both good and bad- and have trended what THEIR car does and less on the "theory".

Real Time tire temps are the right way to do it, but you don't find that in most amateur racing.

I would be more than happy to answer specific questions, but if you just want broad info it's already out there.

The tire temp data is going to be dominated by the last few corners you run through..

Bill Dearborn

Unless you are autocrossing on a Go Kart track instead of a cone course I doubt you could get meaniingful data in the 3 or 4 runs you get on any one day. When autocrossing with Kumho 710s I never saw a tire temp above 135 degrees running a 1 to a 1 1/2 minute course. On a Go Kart track I had peope reading the temps as soon as I exited the course into the exit lane. Three temps on each tire. I did use the temps to adjust pressure by get the tires to end the run at close to the same temperature. Doing that I was making the assumption if they were about the same temp that they must be doing equal amounts of work. Don't know if its true but when I checked cold pressures the next day they were about where I had set them using another method.

Bill

John Shiels

I would get some books like this. http://www.amazon.com/Secrets-Solo-R.../dp/0962057312

There are many books on the subject of car handling and set up. Book are cheap and there forever for reference. They are also cheap compared to all the other crap we spend money on.

0Anthony @ LGMotorsports

If the car can get the heat into the tire, then I aggree with the above statement....need to keep them about 10 degree's apart, inside to middle, middle to outside.

To high in the middle...to much pressure
To high on the outside...to little camber
To high on the inside could be toe or to much camber....need to look at tire wear

Remember when you take the readings, get the wear patch..not going to be much going on on the far outside edge of the tire unless it just has way to little camber in it.

Now combine that with pressures and also need to compare to rear to see what kind of push or over steer there is with it as well.

0MomentumAutosports

I actually think for a high power autocross car you should have MUCH higher inside edge temperature than outside, probably as much as 20*

TedDBere

When the rules limit your camber then getting 20 degrees hotter on the inside is rather difficult....

0MomentumAutosports

said that is not an issue..

TedDBere

Bob: Here's a simple guide for you. Not sure it's what you're looking for but it's fairly straight forward: http://www.elephantracing.com/techtopic/tiretemp.htm

froggy47

Thanks Ted,

That's EXACTLY what I needed.



And thanks all you guys that had bits & pieces of the same chart.

froggy47

Ya know, that's what a guy whose opinion I trust told me last weekend. 10-20 degrees. Hotter inside. I guess the way to get that kind of delta is much more neg that what would be avail with stock settings. More than what you may want on a track car even.

I'm thinking between 10 to 20 deg hotter insides would work out. For a high hp rwd car in autox, I don't think the settings that result in EVEN temp across the tire are appropriate at all.

I calc'd the ideal tire pressures using in + out /2 vs center
reading & was 2 degrees delta (and spot on for some tires) so the pyrometer likes my pressures. The car felt like it was on rails both days & the course was VERY transition heavy. One 3 sec. straight & everything else was turning.

My in/out deltas were 20 deg front 10 deg rear on the warmer/sunny day and 10 deg front 5 deg rear on the cloudy day. Averages.

Thank you all, guys, I really owe a lot to a bunch of guys on this forum for teaching how these cars work & how to set them up.

ipuig

From the posted link:

"Temperature readings should be taken when tires are fully warmed up, typically after 5 to 10 hot laps on the track. Readings should be taken immediately after the last hot lap, no cool down allowed".

This is not possible during autocross, hence my initial statement that this is a waste of time for autocrossing. Good luck with your goal.