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FD - Camber adjustment based on tire temps

Old 07-06-09, 02:26 PM
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FD - Camber adjustment based on tire temps

Some particulars on the car:

3rd gen - lowered to ~ 25.5" at fender arch (with me in the car)

2.2 degrees camber front.
2.0 degrees camber rear ( I think - will have to double check)
Tires are 285/30/18 Kumho V710 at all corners/

Fronts at 26 PSI
Rears at 28 PSI

I took tire temps following several runs yesterday in 90f degree weather.

The temps were consistently hotter on the inside of the tire, indicating I could use a little less camber.

Tire temps would typically be 8-10f degrees hotter on the inside:

outside 90f
middle 95f
inside 99f

Based on experience, can anyone make some reasonable guesstimates as to how much camber I should take out to start with?
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Old 07-06-09, 03:10 PM
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99F? you should check with kumho, but 99F isnt hot enough...

for example the toyo we run is supposed to be 180-200F.

toyo has it on the website, i asuume kumho would too
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Old 07-06-09, 03:53 PM
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When are you taking the temps? If you've driven back to your paddock spot it's way too late and you will get hotter inside temps all the time because you just drove there on only the inside. And, IMO, IR thermometers are useless. Get a good probe style one so you can at least get a little below the surface.
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Old 07-06-09, 04:02 PM
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are these DD conditions or are you tracking this car? If so your not heating those tires up much at all!

I'd recommend pulling into cold pits and having your 'help' do a tire pressure check as like mentioned before, heading to the paddocks usually will show the cool down lap temps.
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Old 07-06-09, 04:26 PM
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9F? you should check with kumho, but 99F isnt hot enough...
I thought it seemed kind of low too.

It may be surface dependent - the racing surface where I was doesn't have a lot of grip.

IAC, when the temps got above 110, the tires felt greasy.
After that particular run, the temps were brought down by spraying some water on the tires and they felt good again.

But, back to the point, I am looking for pointers how much camber should be reduced to even out the temps.
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Old 07-06-09, 04:29 PM
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Clarification:

This is autox, not track. Sorry, forgot to include that.

Temps were taken with a probe pyrometer.

The focus here is not on the temps, but on the range of temperature across the tire.

The actual temperatures are not that important for this discussion.
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Old 07-06-09, 09:01 PM
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Old 07-06-09, 10:18 PM
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Nice article, thanks for the link.

I didn't know about the difference in how tires heat up in road racing vs. autocross.
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Old 07-06-09, 11:36 PM
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Autocross courses don't typically load the tire long and steadily enough to get good measurements. You are better off finding or setting up a skidpad, and be sure to take temps quickly after pulling off.

While Kumhos don't need much heat to work, only getting them 10deg above ambient seems strange. Either you weren't driving hard enough to get heat in them (doubtful), or you took the measurements too late. It's really a two person job to be able to pull off course or skidpad and take measurements immediately.

-Andy
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Old 07-07-09, 12:06 AM
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Originally Posted by AMRX7 View Post
Autocross courses don't typically load the tire long and steadily enough to get good measurements. You are better off finding or setting up a skidpad, and be sure to take temps quickly after pulling off.

While Kumhos don't need much heat to work, only getting them 10deg above ambient seems strange. Either you weren't driving hard enough to get heat in them (doubtful), or you took the measurements too late. It's really a two person job to be able to pull off course or skidpad and take measurements immediately.

-Andy
Thanks Andy. Now that you mention it, I think I've read before that someone should be waiting to take temps immediately, we'll do that next time.

A skid pad would be great, we just don't often have access to a facility for that.

The cars were definitely being driven hard: the 3 cars I measured were in the top 6 for the day.

The next time Evolution has a test'n'tune at Packwood I'm going to sign up for it, as they always setup a skid pad.
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