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Old 12-08-2005, 10:46 AM   #25
Scooby Specialist
Member#: 5817
Join Date: Apr 2001
Location: Atlanta, GA, USA
2005 STi


Originally Posted by makofoto
During an EVO Dial-In course ... we did timed runs on a Skid Pad. I tried my single adjustable Tein Flex's with 550/550 springs at Full Stiff all around, Full Soft all around, Full Stiff in front, soft in back, Full Soft in front, stiff in back ... to see those effects. Then narrowed the settings down so that I got my fastest times.

I then tried different air pressures using a pyrometer to get tire temperatures that were about 10 degrees warmer on the inside. Adding more air caused the center of the tire to heat up, less created more temperature on the outsides. It was very cut and dry. The problem with using a pyro after the car comes in off of a regular course ... is that the inside of the inside front tire gets dragged across the corners, if you have a decent amount of camber ... artificially giving one an elevated inside edge tire temperature.

I'm very consistent in these type of tests ... doing three lap runs within a tenth of a second of each other. Also got that type of consistency in the EVO 1 "run-off." Timing gear broke during Evo 2. :-(

Ideally it would have been good to have gone back to playing with the struts on the skid pad ... but there wasn't time for that.

The "ideal" strut settings on the skid pad resulted in wild oversteer on the transitional handling course. I had to soften the rear end rebound to control that. Also soften the rear sway bar one notch.

But optimal set-up is very course dependent. If we have a course with few transitional elements I need to loosen the car up, ... lots of slaloms and I soften the rear end ... using rebound, sway bar, rear camber, toe and/or tire pressure.
Mako - A couple of things that I noted from your post that seem odd. I also did the Evo dial-in school in Atlanta with Andy Hollis. The goal of measuring tire temps on the skidpad should be to have even temperatures across the face of the tire. If you are measuring tire temps coming off course, you would expect to have higher temps on the inside of the tire due to braking and acceleration, but the skidpad is just one big turn. Therefore, the ideal camber and tire pressure settings would give even temps on the skidpad rather than higher on the inside.

More importantly, we setup our shocks ("bracketed" them, as Andy called it) on the slalom. Basically slaloms are a series of turn-in and turn-out events, which is what you tune shocks for. The procedure was to turn rebound all the way down and work on compression settings until the tire started to skate slightly. Then we turned compression down a tad and worked on the rebound. I don't know how you would benefit from shock tuning in a steady-state situation such as a skidpad. The shocks will have much less effect there.
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