Clemson Sports Car Club

These were the tire temps I took from my last race - These were 20+ heat cycle R6s, 205/50/15 front, 225/45/15 rears. I tried to get into the pits as quick as possible but it was a long pit road before I could get to my helper so I'm sure the actual on track stuff is higher. The turn right before the pits was a long 180* high speed (85-90mph) right hander fwiw.

LF - out = 136, mid = 143, in = 145 (total spread 9)
RF - out = 130, mid = 140, in = 148 (total spread 18 )
LR - out = 148, mid = 150, in = 156 (total spread 8 )
RR - out = 135, mid = 145, in = 142 (total spread 10)

pressures were
LF - cold = 30, hot = 36
RF - cold = 30, hot = 35
LR - cold = 29, hot = 36
RR - cold = 29, hot = 35

corner weights (if it helps) total = 2594lbs on this weigh in (lightest was 2579)
LF - 569
RF - 573
LR - 771
RR - 681

(48.2% LF - RR cross weight)

1.) am I running the right amount of camber or should look at more?? less??
2.) that RR appearing to be too high on the pressure is odd, any ideas why at the same pressure as the LR that it would be too high? This was at TWS going CW, so there were a few more rights than lefts
3.) little bit outside just tires, but I need to add 75lbs ballast - aim towards the RR as much as possible or...?

Appreciate the help - I won't have much time before NASA Nats to get these dialed in any closer so the more homework I can do to get it closer before the event starts is helpful

I typically like to see the mid temp be as close to exactly in the middle of the inside and outside as possible (by adjusting pressure) and I like to see the same temp across the entire tire. I don't argue with my pyrometer; if it says to run one tire lower than the rest I do it. Hard to say what driving straight down pit lane would do, though I imagine it would raise the inside temp a lot and middle a little.

What I'd do:

kbrew8991 Wrote:LF - out = 136, mid = 143, in = 145 (total spread 9)
RF - out = 130, mid = 140, in = 148 (total spread 18 )
LR - out = 148, mid = 150, in = 156 (total spread 8 )
RR - out = 135, mid = 145, in = 142 (total spread 10)

LF: Pressure is pretty close
RF: Pressure may be good
LR: more pressure, maybe 2 PSI?
RR: Very high pressure, drop it a couple PSI (5 to start?) and keep judging based on further data points

Keep in mind different tracks would potentially need different pressures - in the miata I have one setup I start with and when taking temps I change accordingly for that particular course.

I'd look into more negative front camber. Rear looks like it may be good. I'm saying this as a F/R basis as I like matching front and rear camber (due too much auto-xing?)

Of course, that's what I'd do...

consensus here:
http://www.roadraceautox.com/showthread.php?t=24697

spread between 10-15* works for Rs... should be closer to 200* and 40psi hot though, which is prob not possible / ideal for as old as they are. Less than that leaves cornering grip out there and starts to try and cord the outside.

so its about as close a guess as I've got to just leave the cambers alone, tweak the rear toe to get the balance where I want, and see what it is at Miller... there's nothing drastically off so it may not be a good idea to change anything.

Camber looks great. In a perfect world I generally shoot for 10-15 degres hotter on the interior edge verses the exterior edge.

Use only a probe pyrometer, IR is useless IMO.

How was the car handling, entry, mid and exit? Better in left handers vs. right handers? etc.

Once you get your set-up dialed in as close as yours is, I would shoot for balanced hot pressures and use a lb or two to adjust the balance front to rear or left handers vs. right handers.

But what do I know about tires?

Brian Wrote:But what do I know about tires?

Some reason i burst out laughing at this.

getting there on setup - overall it was a bit loose so I tried to quell that with less rear tire pressure, though in an ideal world I would have had toe plates and dialed in a bit more rear toe-in

there is only so much you can do with a car that by and large is stock (by rules more or less)