March 30, 2008 - Autocross time!
The Corvette club was holding another autox, so I brought out the race car to see how the new suspension would sort out. Last time, I was hampered by the open differential but still posted a good time. Let's see how it works this time.
The lot was dusty and it was relatively cool, so it was a good test of the ability to put power down. Which turned out to be a challenge. Despite the Torsen diff, I was still getting wheelspin on the inside rear wheel exiting right turns. This is frustrating. It wasn't a problem on the track a few weeks back and it was only apparent on the tight confines of an autocross course, but still - I thought I had this licked. I'm going to do a little more poking around. Course workers confirm that the inside rear was simply unloaded and just spun up. A Torsen will go fully open when there's just no traction on one corner. I could throw in a preloaded Guru differential for the track day next weekend, or maybe I'll just let it stay as is so I can do a direct before/after comparison.
The first few runs showed that I had the ability to light up the rear tire(s) and slide the rear end around, but also that the car seemed to have some understeer in the few steady-state corners on the course. So I softened the front sway bar slightly to see if that sorted the problem. Yup, the car was much happier. It may be a little too biased towards oversteer now, but we'll find out next weekend on the kart track. Right now, it'll do exactly what I ask it to and can really be moved around on demand. Of course, that's with a maximum speed of 57 mph according to the rally computer. How will it do at 120?
I was also playing with the brake bias, thanks to the new pads. For a couple of runs, I had too much in the rear. The final braking zone took place in the middle of a big sweeper, so the car was unbalanced to begin with. On one run, I was countersteering fairly enthusiastically to keep the rear wheels behind me as the car wagged its tail into the corner. It worked, though, and a quick twist of the proportioning valve sorted that out. By the end of the day, I had the brakes dialed in pretty nicely and the car was mobile yet controllable under braking. Of course, I'll have to do it all over again once the new pads are installed.
So, how did it do? Well, there was an STi on sticky tires in attendance. Try as I might, I couldn't get within a half second of him. But Brandon and I were locked in a great battle. He has an extra 110 hp and Azenis tires, while I have the Toyo RA1s. It turned out to be an excellent match, going right down to the wire. The final margin was 0.079 seconds, with me being slightly faster. What a great race. I managed to come in second overall, which is not shabby at all. None of the Corvettes able to keep up with the three fiercely battling "metal cars". The fastest 'Vette was 1.8 seconds behind us.
Brandon, if you're going to strike a goofy pose for the picture, I'm going to take the picture!
tags: testing |
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