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build diary << | show individual entries | >>October 9, 2005:
Aluminum cutting and bending fun - it's time for a new hood!
Saturday was the track day at the Aspen Sports Car Club. This is a private track with dues and costs that are in line with what you might expect from one of Colorado's areas of fiscal unreality, but I guess I can understand it more than a high-buck golf club membership. The track itself has a reputation for being unforgiving if you go off - talk of "safety boulders" can be heard - but the reality isn't quite as fearsome as that. Yes, there's nowhere to go but a deep gravel pit and a tire wall if you have a real problem at the end of the straight, but on a track day there's nothing wrong with leaving a little margin for error. The track itself has a lot of character and an fun rhythm with a couple of corners that require quite a combination of technique and nerve. It's a much different track than the kart track I've been on recently despite being about the same length. I can see how it might be a good one to drive for years - there are enough challenges to keep it interesting. So how did the day go? Well, it was eventful. We left early in the morning and towed the Seven up to Aspen. The car then refused to start, fouling its plugs immediately. Since I was "close" to home I hadn't brought along a full set of tools or spares, but Bill let me steal a set of plugs from one of the Miatas to get the Seven running. Once it was happy, we put the fouled plugs in one at a time and eventually had a happy car. I went to familiarise myself with the track and discovered the car was very upset at full throttle below about 6500 rpm. A quick peek at the computer display for the engine management showed me it was running really lean. When I'd tuned the car in Grand Junction on the dyno, we hadn't spent any time on the areas just below full throttle. Thanks to the high altitude and low air density at the Aspen track, these areas were now full throttle. I pulled into the pits and we hooked up the laptop. 2 minutes later, I headed back on to the track with a transformed car. After a couple of sessions to learn the track, we did a quick tire temp check. I'd tried raising the pressures after seeing Toyo's recommendations for a 38 psi target, but the numbers were much too high in the middle and it was obvious that I really wanted something lower. A big thanks to Ben from Rocky Mountain Sports Cars for taking the pressures and temperatures for me. We then saddled up and went out to play. Ben had brought the red Caterham SV that I saw in Moab. It was fitted with a Zetec engine from the SVT Focus. It's rated for 200 hp. Weight is apparently similar to my car. The tires were Avon CR500's that were getting a little tired and the car was set up for street use. How did it compare to my Seven? I was happy to see that our acceleration wasn't really any different on the straights - hmm, one of us has our power output wrong. Ben's a Formula Ford driver and was definitely quicker through a few sections, but between my tires and better brakes I was able to keep him in sight as long as I didn't make any mistakes. He'd gain a couple of car lengths per lap, mostly through one corner that was particularly technical. We had to deal with a fair bit of traffic on the small track though, as we were travelling pretty quickly. One other driver commented, "I expected them to be fast, but not THAT fast!" after we double-teamed him on the straight as if he was parked. The Seven did pretty well. I'm starting to wonder if there is any camber change in the front suspension because it's still working the outside of the front tire even with more than 4 degrees of camber. It's also rolling more than I'd like but the balance is excellent. The car would oversteer or understeer depending on how I was driving it. The corner in front of the pits was particularly well suited to hanging out the tail so I had a little fun with this. Ben though it was entertaining to watch and was impressed that I was able to control it well - there's the advantage of growing up in the snow. If I was trying to go fast, I could whip around the corner with a very neutral balance. There was one small problem as the brakes started to drag when the car got hot. There wasn't enough free play in the brake pedal so as the fluid expanded, there was nowhere for it to go. I fixed that quickly by adjusting the master cylinders and I'll insulate the new brake lines better. I was feeling good. Then I made a mistake. Coming in to turn 3 and playing with lines, I let the back end walk out a bit. This set me up to run right over the cone at the apex. No problem, I've done the same at autocrosses. This time, however, the cone came off the front tire and slammed into the rear fender. I thought at first I'd caught the cone under the car, but a look at the car in the pits made it obvious I had ripped the fender halfway off the car. The damage wasn't too severe but I couldn't keep driving like that. 5 minutes later, I had the fender off and went back out - I was smart enough to put quick disconnects on all the light wiring during the build process. The car felt a little uncertain with the right rear tire loaded up until it all of a sudden started feeling flat. Halfway back to the pits (crawling along in first gear) I realised that I'd forgotten to torque the lug nuts due to my distraction when working on the car and talking to people. A stupid mistake, especially considering that I'm usually quite anal about the lug nuts. No damage done other than to my self-image, I headed back out. Bill Cardell was out in the Caterham as a passenger this time. We had a huge amount of fun playing around with Ben still gaining slightly on me every lap. Bill then jumped into the driver's seat and we played a bit. His feet didn't fit the Caterham pedals properly and it wasn't his car so he wasn't as fast as Ben had. Still, we came in just giggling from the fun of chasing each other around. Overall, a good day even if I'm left with some repair work. I didn't do all the testing I'd planned and I suspect I'm going to regret that shortly. It was really good sharing the track with Ben as well as the usual Miata folks. Bill and Teri from Flyin' Miata were there with a couple of our very fast Miatas, one of which was just bursting with horsepower. It was the only car that could outaccelerate me down the straight but we were turning equivalent track times on the same rubber. Janel had a chance to try the Seven on the track and her "just a couple of laps" turned into about 15 as she played around with it. At the end of the day, Bill and Teri took the Jeep back to Grand Junction as Janel and I drove the two high-speed Miatas, both of whom have been in Car and Driver at some point. Ah, it's a rough life. The Aspen track isn't a big one, but it's a lot of fun. I had an interesting conversation with the owner of the ex-GRM car. He's been watching this page and starting to wonder if he should be having any trouble with his car! He pointed me towards series of photographs (4 pages worth!) of his car at an autocross. The roll that plagues me is almost completely absent! The worst roll I could find on his car can be seen in this photo - compare it with my own. He runs Miata rear sway bars front and rear (much smaller than my front bar) and is not lacking in the tire department. It appears that his car sits a fair bit lower than mine, making me wonder if he's cornering on the bumpstops although he claims lots of suspension travel. But still, it's like a different car. He's running 2 degrees of negative front and rear with nice even tire temps. Perhaps CMC threw in a set of stiffer springs on this build. GRM has no idea and of course CMC can't tell us. It's very curious. I think I'm going to put on some stiff springs based on Heikki's suggestions and just tie the car down. The 25% stiffer springs I was expecting from GAZ didn't work out so I'm looking for something else, closer to a 100% increase in the front.
I've decided to do another refit on the car. It will be a few (cold) months before the Seven hits the road or track again, but it will be a better car when it does. In the meantime I'll work on the Mini, the 323 GTX and even the house. Weird! |