Jun 11, 2006 update to the Mazda STS2 Miata project car

STS2 - Peru Tour and Pro Solo

Fresh off of a victory at Mineral Wells in the Pro Solo, we set our sights on Grissom AFB in Peru, IN. This is a fabulous site which replicates much of what characterizes the old Nationals site at Forbes Field in Topeka: super-grippy concrete with an undulating surface peppered by nasty bumps and various hard obstacles like surface mount nav lights and refueling outlets. With all the grip, we knew we’d have to go back to our concrete setup that we developed for Atwater, but we’d likely have to make some shock changes to deal with the bumps.

But first we had to get there. Our tow up was going along just peachy until we reached a ridiculous section of I-70 just outside of Indianapolis. Mile after mile of huge potholes took its toll on our trailer finally ripping a chunk out of the sidewall and blowing out one of the tires. Collateral damage crumpled up the aluminum trailer fender into a ball, but just barely nicked the Miata’s wheel. Another inch and it would have opened up a hole in the car’s sheet metal like a beer can. It was a close call, but 30 minutes to remove the damaged fender and pop on a spare and we were on our way. Many thanks to C-Stock hotshoe Chris Harvey of the Tire Rack who hand delivered a new pair of trailer tires the next day.

Making good use of the practice course on Friday before the Tour, we initially tried to go one step farther than we had at Atwater by running the Racing Beat 5/8” rear bar at the stiffer setting, but the car was just too loose to be consistently fast. And the actual Tour course was likely to be faster, so that tendency would just get worse. We went back to the softer stock bar and the car settled down.

Next, we played with the shocks. At previous events, we had been running the compression on full stiff and the rebound right in the middle on both ends of the car. The practice course ran right across a couple of the typical Peru bumps and was noticeably nervous, especially in a power-on situation. Dropping the compression two clicks (out of eight) improved the situation, but the car lost some responsiveness on turn-in. In the end, we put the fronts back up to full stiff compression and left the rears two clicks down. This provided the best balance of crisp turn-in with power-on compliance.

The actual Tour courses could not have been better for the car. Saturday featured big sweeping 180’s followed by pure acceleration zones. Our recent weight reduction and power mods played out perfectly, and the car just carved through the turns. Sunday’s course was more transition-oriented and the surface got a lot grippier. Many drivers had reported picking up a corner entry push in their cars, including my co-driver (Ann). I chose to just drive around it, but for her final run we upped the rear rebound by two clicks and the car was much improved. We’ll save that one in the notebook for future reference.

In the end, quick time each day by a second notched another win for our project car!

The following weekend was the Pro Solo, featuring a pair of transition-heavy mirror-image courses. On these tighter courses, we found we had picked up a mid-corner push. This is typical when going from a more open course to a tighter one, so we dialed it out by going to the stiffer setting on the 5/8” rear bar. The handling was now very well balanced and we were able to drive aggressively through the transitions while nicely carving the 90’s. With this setup we were able to take the class win by well over a second and earned Top Qualifier position for the Super Challenge. The weekend did end on a slightly sour note as one small error (sleeping at the light) knocked us out in the second round of the Challenge. Still, the points earned helped to solidify our mid-season lead for the Overall title. Still plenty of season left for others to move ahead, though.

Next Stop: Heartland Park Topeka for some “quality time” time on the new Nats surface.

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