What the engineer was probably talking about is averaged differential
temperatures on a track, probably using active measurement as you describe,
which I (and probably most of the FOT) don't have access to. The number simply
does you no good at all in static measurements that we are limited to. The
outside of a tire on a track is cooled more by the airflow down straights. The
amount of differential temperature is highly variable, depending on how you
take the corners, how long the straights are, and what you were doing just
before you stopped to take the measurements. It's of limited use, really only
good for determining tire pressure.
To set camber using tire temperatures you either need a short, tight track and
a lot of experience or a skid pad. A skid pad can be anywhere there's a big
enough patch of smooth pavement. You drive around in circles until you're
tired of it, and check your tire temps. The inside and outside temps are much
closer because you don't get enough speed to have highly variable cooling.
Nothing new in any of this, and I certainly didn't invent it. Penske, Donahue,
McLaren, and I'm sure Kastner knew all about it 40 years ago. If you get a
chance, show the engineer a printout of this email or just tell him what I
said. I bet dollars to donuts he'd agree completely. The problem with taking
advice from professionals is that we then have to translate what they say to
suit both our cars and the limited tools we have. Not easy.
On Sep 9, 2010, at 11:24 AM, MadMarx wrote:
> Bill,
>
> The Porsche engineer belongs to the 24h winning team on the Nordschleife
and
> belongs also to the works testing team.
> They do the temperature measurement with a datalogger during the test rides
> with infrared sensors and surely also with this needle type probes in the
> pits.
> I also asked him about my camber. He said, show me photos of your car
during
> cornering. After he looked closely to the photos he said that my car
suffers
> from tire roll and I have to compensate it with more camber than usual.
> Since I have gained the camber to this big value I gained 6 seconds on the
> Assen track.
>
> The good thing with me is that I listen to people and try things. I most
> cases professionals are right with their suggestions.
>
> Cheers
> Chris
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