build diary

April 10, 2006:
Track day!
My goal: to beat my existing lap record of 1:05.585 seconds.

First, there was time for a bit of setup. After leaving the alignment rack, I put the car on the scales to cornerweight it. This went fairly easily. The end result had a 20 lb weight savings from last year, but more weight on the light right front wheel and a nice 45/55 weight distribution. Just what I'd hoped for with the battery relocation. An interesting thing happened though. I was finished with the scaling when I noticed that the right rear tire was very low. I'd forgotten to set my tire pressures before scaling. The left front was the one that had been flipped on the wheel and it turned out to be quite high. By adjusting the pressures, my cross weights went from 50.5% to 49.5%. This let me back off on the adjustments I'd made a touch and left me with the ideal 50% cross weighting. I also took some time to install the wiper wheelboxes - more on that in a future update.

On to the track. There's always a bit of chaos at this particular organization. At least, there was. I hadn't been to the last couple of days run by these guys and they've become much better than before. Unfortunately, a snafu meant the transponders hadn't been charged so we had to wait for a while before timing started. It's a bit of an odd setup. Due to the size of the track, only four cars run at a time. You get an out lap, three hot laps and an in lap. Then you line up for your next baby session a few minutes later.

The Seven felt strong. The first session, a heavily modified WRX pulled out on the track in front of me. It was driven by a friend who's usually pretty close in lap times. Well, he miscalculated. By the time we'd been around a couple of corners, I'd glued myself to his tail. He couldn't escape in the corners, under braking and - surprisingly - under power. It was pretty obvious that the Seven had too much rear roll stiffness so I removed the rear sway bar after a few laps. That helped although I still had corner exit oversteer. Of course, some of that could be the result of 145 hp trying to deal with only 400 lbs on each driving wheel. The problem with bottoming out the rear was completely gone and I was still able to drive over berms without any concerns. A slight softening of the rear shocks and the car felt nicely balanced.

My boss Bill showed up late and he could tell just from looking at the car that it was moving fast. The body roll that's plagued me for so long was gone. It felt pretty good but only the transponder would tell. Well, if I managed to pass sound check that is. My new muffler is no quieter than the previous one according to the sound meter although it sure doesn't sound as loud. I went back out with my little Supertrapp tip on...and it made no difference. Well, no wonder. It had fallen off on the first corner! We found it, stuck it on well (I'm not sure if it's going to come off now actually) and I was given the green light. Phew!

More entertainment came from the throttle cable. Coming out of turn 1, I noticed I'd lost my throttle cable. No problem, I knew it had just popped off the wheel I use to turn it 90 degrees. But why? I idled into an access road, pulled off the hood and restrung the cable. Now the throttle was stuck wide open! I managed to unstick it and drove back to the pits at 2000 rpm. After a bit of investigation I found that the throttle position sensor I was using was binding enough to prevent my throttles from closing properly. Odd, it's been on there for a while. No matter, I wasn't using it anyhow so I just removed it.

Ah, finally. The transponders showed up. We stuck one to the back of the Seven and I headed out. I didn't feel very smooth and figured I'd just run about 1:06 on my laps. To my delight, the time was a 1:04.630 with another to back it up! I was ecstatic. A new lap record for "not a kart" vehicles at the track!

Next session, 1:04.301. Not bad, I was shaving some time off.

While kicking around between sessions as the drifters covered the track with rubber (this is difficult to ignore as a car guy because it sounds like a constant accident!) and dirt, then swept off the dirt, Bill borrowed my new tire pressure gauge. He compared it to our tried-and-true Longacre one and discovered it was about 5 psi high! Hmm, that means my tires were currently at about 13 psi cold. Not ideal. We didn't have a temperature gauge so I'd simply been driving. I added 5 psi to get to the range I wanted and headed out for the next session. The car felt really good, with almost no tire noise and a more stable behaviour. I came in unsure. Was I simply feeling better or was the car actually faster? I knew that I'd been much smoother. The word came in on the radio - 1:03.777 with a following 1:03.8 to back it up. Much rejoicing in the pits from everyone! I went back out for a final set of laps and came back in with a 1:03.368 and a backup 1:03.439 and 1:03.582. Since my goal had simply been to match my earlier 1:05.585, you can imagine how happy I was to take over 2 seconds off. As far as I know, only one other car has only managed one lap below 1:06. There will be some competition when Skip Cannon shows up this summer with his 275 rwhp Caterham, but for the time being I'm very proud of my little toy.

Most importantly for my own skills, I'm very proud of the consistency. One of my competitors came over to let me know that I had to watch my back, he'd just pulled a 1:07. This was still 2.5 seconds off my pace at the time and his next fastest lap was a 1:09. True, when it comes to lap records it's all about That Single Fast Lap, but it's a faster driver who can consistently turn the same times.

Bill took the Seven out for a few laps and complained about fuel starvation in some corners. He also mentioned the brakes weren't too impressive. He'd been driving the 2006 MX-5 which has aggressively servoed brakes and amazing stopping power, so I didn't think too much of it. I packed everything up in the car and jumped in to drive home - and discovered the brake pedal was super-soft. The front master cylinder was dry! Some feeling around showed a bit of a leak under the cylinder itself. I'll have to investigate that tomorrow. I drove home on the rear brakes and compression braking. I own an old Land Rover so I'm used to bad brakes. I also only managed to put 3.5 gallons in the fuel tank. Hmm, maybe those baffles didn't work so well after all.

So, after all that, how's the car? A couple of small problems, but I'm ready for Car and Driver in terms of performance and setup. The Seven rides like a Miata with performance suspension on the street and is a total riot on the track. The engine feels good and strong and the car is at the peak of its handling so far. I'm a little sunburnt, bruised and tired, but I couldn't be happier.
entry 1188

My new wipers!
They're not hooked up under the dash but the nerve-wracking part is done - I've drilled the holes. And yes, the impact gun is really useful for this installation. Maybe not at full power.
entry 1189
On the track!
It's obvious from this photo how much the car is improved. By comparison, see what it looked like in October in the same corner.
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Another track shot.
Just because. And here's the before shot.
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Artsy shot.
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April 11, 2006:
Last night I tore into the car again.
The nose and front fenders came off for a repaint so the car looks good at Car and Driver. The nose in particular was pretty battered with some missing paint due to a badge misadventure. Hopefully there's enough paint left from the original batch to cover it. I tightened some fittings on the front brakes and tonight I'll find out if that sealed everything. It looks as if the brake problem was simply a seeping fitting. I was putting a fair bit of pressure through the lines over the weekend! Mark commented that I had the speed in the straights of the fast Subarus, but the braking points of his naturally aspirated Miata with sticky tires. Anyhow, that was the accomplishment for last night. I'm pretty sure there was more but I can't think of what it might be. Oh well. The list of jobs to do before Texas doesn't seem to be getting any shorter, but it does seem to be more specific than before.
entry 1193

So, what does your car look like the day after setting a track record?
entry 1194
When transporting body parts for painting, it's important to take care of them.
This means putting them in the back seat of a 1966 Cadillac of course.
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April 13, 2006:
The car isn't getting any more together than it was.
Less so - last night I pulled off the scuttle. The instruments were remounted (a washer had escaped and the needles were dragging on the glass), a hole drilled for a new oil pressure light, wiring for the light was put in place, the windshield was measured up for reproduction, wiring was cleaned up and the brakes were bled. I've heard that the body parts are painted so I'll go pick those up later today. Tonight I hope to reassemble the car and drive it in to work tomorrow.
entry 1196

I seem to have conquered my fear of drilling holes in my fibreglass.
This is for an amazingly bright "you have no oil pressure!" light.
entry 1197
Time to work on the new windshield.
This one will probably be too low of course, but I reserve the right to make that error.
entry 1198

April 14, 2006:
A frustrating day.
I stuck all the various pieces back on the car so I could bring it in to work this morning. Paint the grille surround black, fit the Dzus fasteners, new foam tape for the bonnet, bolt on the front fenders, install the wheels, install new fuel injector connectors and tape up the wiring - you know, the usual. I also cut the new windshield template. I jumped into the car to bring it down to the glass shop and...nothing. It cranked enthusiastically (good little battery, that Odyssey!) but there was no fuel whatsoever. We pulled the ECU out and found a problem with the chip, so I changed that and loaded in my special programming. Finally, a few hours later (I have a very, very understanding boss) Tore off down the street to see if an upholstery shop could make a little tonneau cover and of course I'm a little late to get all this done before I leave next week. Then outside the upholstery shop, same deal. Nothing. I borrowed a screwdriver, popped the top off the ECU case and wiggled what we thought might be the problem and the car fired up. Argh. When I got back, it wouldn't start. Later in the day, going to pick up the glass (the Glass Brokerage once again came through with a same-day windshield for $40!) it fired right up. I'll be into the ECU again tonight. Not exactly what I wanted to do of course. I have a few other things I was planning on doing.

A little treatise on my new oil pressure light. I used to use a gauge for the oil pressure. The problem is that it's constantly moving (of course) and I'm afraid I'll miss it if a problem shows up. So I elected to go with a light that's right beside my rev gauge. This way, if it lights up I'll know to kill the engine immediately. Ideally I'll have both. Someday I'll revisit instrumentation and do it then. I did have to plug in a sender from a 1995 Miata to make this work but otherwise it was the same wiring.

The new vs the old.
Well, the template for the new anyhow. It's not a major change but I think it will really affect the look of the car.
entry 1200
The new oil pressure light.
It's the brightest light I could find at Radio Shack and is nice and visible.
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A gratuitous shot of the car.
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April 16, 2006:
Well, yesterday wasn't much better when it came to frustration.
I started by installing a new ECU and tidied up the wiring a bit. I even installed the ECU case on rubber isolators in case part of my problems were related to vibration (in the Seven? impossible!). I then turned to the windshield.

One of the things I did with this latest piece of glass was make it symmetrical. My previous versions were not. The bending of the channel went quite easily after all my hard-earned lessons last time. The plywood was 0.8mm thicker this time which actually made things a little more difficult. The nice thing about a symmetrical top is that instead of having to set up my bending tool twice, I simply turned the piece of channel around and did both sides that way. A bit of Scotchbrite on the aluminum and it looks really good. I hopped into the Seven to run down to work because I wanted to touch up some welding on the side support. That went well - and the Seven refused to start. It was the same symptoms as before except that I never managed to get it running again. I spent a long time on the phone with my friend and boss Bill to no avail. The current thinking is that something in my original ECU is damaging the processors in the chips. I'll try a new chip in this new ECU and see what happens. Argh.

Today was set aside to do some work on my trailer. It's been having some cracking problems where a loose fender once vibrated badly. I've been patching it up but it was time to fix that for good. Some hefty angle iron and some fun with the plasma cutter and it's much better. I wouldn't tow a 3000 lb vehicle on it, but 1300? No problem.

Once that was done I stuck the windshield on the side supports and went to bolt it up. Uhoh. My previous glass wasn't symmetrical because my scuttle isn't symmetrical. I also put the side supports a little too high and it was difficult to get the windshield level as it teeter-tottered on a high point in the middle of the scuttle. Some choice words, some oversize holes and it's done. The flat top makes a level mounting crucial. So how does it look? Fantastic. The rounded top has bugged me since I first put the windshield on the car. The new design, about 1.5" lower in the middle, looks much more aggressive and is still out of my sight line. It was a little frustrating but I'm done.

And that concludes the last full day I have to work on the Seven before the Texas meet. Mark Rivera reports that his car is running well. With a 12 psi turbo on the engine, it should really scoot. Chris Fiaccone's bike-engined car will also make mine look slow. I'm going to look like the sad also-ran!
entry 1203

April 17, 2006:
Exorcised!
Jeremy figured it out. With one of the ECUs attached to the simulator, he started twiddling dials. He poked one and the injectors woke up. What was it? The throttle position sensor (TPS) signal. I hadn't played with it because I "knew" it couldn't be the problem. Above a certain value, it was preventing the injectors from firing. With the wiring for the TPS removed, there was a phantom signal that was changing with heat. With a cold ECU, it would sometimes be low enough to let the injectors fire. As things warmed up, it would rise to the point where the car wouldn't get fuel. See, the ECU has a setup where if you crank on wide open throttle, it won't fire the injectors to help clear a flooded condition. This is what was being triggered. I solved the phantom signal problem by installing a jumper between the TPS signal input and the reference voltage coming out of the ECU. No more heat-related variance and a nice consistent start. The odd thing is that the TPS has been removed from the car for months. I trimmed some wires back when cleaning up the engine bay and that's when the signal must have started to creep. Very odd. I must admit that if your car is going to develop this problem, it should always develop it at the Flyin' Miata shop where there is more gathered Miata wiring knowledge and diagnostic tools than anywhere else on the planet. A big thanks to Jeremy for finding the trigger for the problem and an even bigger thanks to Bill who spent hours with me on trying to chase this down.

So, with two more evenings before I leave, I have only a few things to do. First is to bend up the new hood. The flat, louvred sheet arrived today. I may chicken out and get a local fabrication shop to help me as I'm scared to screw it up. I'll also cut a new stone shield for the driver's side, as the new one on the passenger's side makes it look battered. Pack the trailer, gather the tools (the garage is a little, umm, chaotic) and I'm pretty much ready to go. I hope so anyhow.
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ECU hassles are just what I don't need at this point.
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The new rubber isolators for the ECU.
In case anyone doesn't accuse me of being "locost", they're old bicycle inner tubes!
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A bad picture of the new windshield.
With the grille in place and the filter sticking out through the hood, it's one mean looking little car right now.
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April 18, 2006:
The new hood is finished.
It took a few hours - I don't want to figure just how many - but it worked far better than the original one. I sucked it up and went at it by myself. Instead of 0.050" 5052 alloy, this one is 0.060" 3003 and it's much easier to work. It doesn't exactly fall in to place but I was able to shape it nicely. The 5052 needed to be over-bent and then sprung back while the 3003 is soft enough to simply push it into place. A comparison of the fit of the hoods shows a massive improvement over my original and I'm very happy with it. I used a Scotchbrite wheel to do some final shaping and the finish is smooth and even. Even better is the fact that the louvres are not embarassingly backwards. They're also higher quality than my last one. A win overall!

One thing I did change that made the fabrication easier had to do with the lower edge. Instead of folding it under, I cut it off level with the frame rail. I then riveted a piece of alumimum channel along the inner edge to act as a support. This channel was left over from my original windshield fabrication - it was the stuff that I couldn't bend without kinking. Now I don't want it to bend so it's perfect. I'm not crazy about the rivets along the edge of the hood but I'll live with that.

So, what's left before I leave? I'd like to replace that stone shield, I want to ensure the fuel pump is clean and I have to pack. And that's about it! Wow. I do have to thank my girlfriend Janel for keeping me alive during this thrash. If it wasn't for her dropping by the shop with food I'd probably have starved to death.
entry 1208

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