build diary
<< | show individual entries | >>October 12, 2005: 
Aluminum cutting and bending fun - it's time for a new hood!
entry 1057
October 14, 2005:
So, what's up with the hood? I was trying to motivate myself to get into the garage to work on it on Wednesday night.
Then I remembered that this car stuff is supposed to be fun. So I turned my back on the garage and did something else. I'll just have to run with a backwards hood at the track.
entry 1058
October 17, 2005:
My advance copy of the book arrived on Friday!
It looks great. Watch this space for availability.
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.
entry 1059
The Aspen track isn't a big one, but it's a lot of fun.
entry 1060
It's not that my car has evil handling tendencies, it's just that driving like this is so much fun!
Besides, the pictures look cool. The runoff behind me is where you end up if you lose your brakes on the straight.
entry 1061
Playing with Ben and his SV.
entry 1062
Once in a while traffic would get a little bunched up, but it was easy enough to pass.
But check out that view! Yes, that's snow in the middle of October as I drive in a t-shirt.
entry 1063
I fought the cone and the cone won.
I have a little work ahead of me but there should be no major cosmetic damage with a new rock shield and a bit of 'glass work.
entry 1064
October 19, 2005:
Well, the trackday rush has worn off so I'm starting to look at the car again.
The LR tire is showing dramatic wear on the inside while the RR is nice and even. I think it's time to stop messing around with home alignment tools and pay the money to put this car on a rack. At least I'll then be starting with a reasonable setup upon which to make changes.
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.
entry 1065
October 25, 2005:
More suspension thinking.
I'd like to do a pushrod front end, but that won't happen anytime soon. I'll probably start by simply putting in 50% stiffer springs front and rear. This will take a bit of money but I think it will really help the car. It will let me run a lower ride height on the street - possibly the big difference between myself and the GRM car - with less concern for bottoming. I'm also thinking about using the winter to do some more changes such as a new fuel tank and possibly my pushrod front with new lower front control arms. Who knows, right now I'm happy to just play with the Mini.
entry 1066
October 26, 2005:
It might seem as if there's very little going on with the Seven at the moment.
That's not actually true. Sure, there's very little work going on at night. But I'm working on some interesting related projects. One is a design project that's going to be very fun. A friend also just bought a Caterham SV with the plan to put his turbo Miata engine inside. I'll probably be involved in that (woohoo!) and it's going to be some very interesting engineering. The biggest problem (based on the scientific method of looking at pictures) appears to be the size of the transmission tunnel, probably followed by the steering column location. He doesn't seem quite as eager as I to start cutting up the footwells for bellhousing room. Wimp.
entry 1067
October 31, 2005:
Sadly, the orange and black car is not playing on Hallowe'en.
I did buy it a treat though. A new muffler! It's a Magnaflow that's 27" long and 6" in diameter, a big change from my current 14" x 3.5" resonator. I don't really have a problem with the car being too quiet and the long muffler will do a better job of quieting down the full-throttle bark than a shorter one. The inlet and outlet are 2.5" which should be more than enough to flow what I need. This will look monstrous compared to my current little piece but it was obvious at the Se7en tour meet that this is a normal size.
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!
entry 1068
November 11, 2005:
I received an email from Scott Whitehead yesterday.
He'd been looking through my pictures and this one caught his eye. He strongly recommended a diagonal brace to prevent the box section joining the lower control arms from twisting. The front mounting points are well anchored to the bulkhead but there's nothing stopping the rear from being forced out of shape. Makes sense. Since most Sevens are built with a live axle it's not usually an issue. The upper arms should be well located due to the large plate joining them. One more thing to add to the winter refurb list.
In the meantime, I've been designing front suspensions in my head. In the shower this morning, I was working on the new fuel tank design. Baffling of the wide tank is going to be a challenge. Do I put in hinged flaps to allow fuel in to the compartment with the pickup but not out? Caterham apparently uses this trick. Maybe just a swirl tank. A cool trick I read about is to have the return line from the fuel injection dump back into the swirl tank. That makes sense to me, although I can there's potential for the fuel to start to heat up. How do I make all these changes and keep the weight under control? All this design is fun.
entry 1069
November 14, 2005:
It's here!
My big box of books showed up today. I'm not happy with how the writeup has been done on Amazon, but the book is finally available. In a couple of days, you'll be able to buy it through this site. If you're interested in a copy, please wait until then - it nets me another couple of dollars that way. Thanks.
Any other news? Well, my house is better insulated now although the Seven has seen no action. I'll have to sketch up my ideas for the front pushrod suspension soon and show them off, although I do want to figure out what the front and rear geometries are doing and if I should tweak them. That involves some quality time with my tape measure and I just haven't been all that motivated recently. It's really tempting to just stick some stiff springs and bigger swaybars on there to stop the bloody thing from moving around on the suspension too much. This won't improve the street ride much, which is ironic given my "coming soon!" muffler that should make the car much nicer to drive without a helmet.
I'm also reworking the website a bit to make it work better. Regular visitors should appreciate the updates and hopefully there will be lots of new visitors due to the book. A new URL - http://www.cheapsportscar.net - and a new server will be coming soon. Don't worry, the existing address will keep working. Any feature requests? Let me know via the guestbook or email! You won't be able to download the entire site but I can add things like RSS easily enough. I have a couple of features that I think will be pretty cool. True to the spirit of things, I'm building the code from scratch for this.
entry 1070
November 15, 2005:
The book - How To Build a Cheap Sports Car - is now available through this site.
Well, it's really through Amazon. They throw me a little commission for referring you. I could buy the books myself and resell them but you'd probably end up paying more. This way, you get it cheaper. We both win! Click on the link on the front page of the site or here. I'll post more details about what's in the book shortly.
entry 1071
November 18, 2005:
Wow, look at how shiny and new everything is!
The site is now running on the new server, http://www.cheapsportscar.net . Please change bookmarks. You'll also notice - at least, on your next visit - that the site will tell you about new updates since your last visit. I've been having fun with this. It's warmer working on the computer than in the garage right now, you see. Please be patient with the inevitable little bumps as I get everything up and running properly again.
entry 1072
November 21, 2005:
The books are starting to ship out, although I haven't heard from anyone yet who's received one.
Am I a little nervous about its reception? Of course!
I've been thinking more and more about what to do with respect to the suspension. I was recently provided with a set of measurements for the Miata suspension, front and rear. Should I just stick them on? I can't, the nose isn't wide enough. I will probably model them in a 3D program and see if I can get the same behaviour though. Rumour has it the roll center is extremely well controlled. I'm also going to model my current suspensions and see what the camber curves look like and if it does have a good ride height for roll center control. A call from the owner of the GRM Locost indicates that he is (probably) running on the front bumpstops. Combined with the lower CG thanks to the lower ride height, this might explain why his car seems to roll so much less. And sometimes I just wonder if I'm being too much of a perfectionist (whiner?) and I should just stick some stiffer springs and sway bars on the car and drive it. It's quite possible that all I really, really need is a good alignment done on a rack instead of at home.
I was thinking more about the handling of the car today while driving in to work in a Miata. I realised that while I'm giving the impression that it's a real handful to drive, it's actually very friendly. There aren't many cars that I'll purposely pitch into a big slide, certainly not with the sort of cornering speed and traction generated by the Seven. I want the car to be world-class and corner as fast as it possibly can. It should be superlative, not just impressive.
entry 1073
November 22, 2005:
Hey, a real update with real information in it!
My new muffler arrived today. It's monstrous. 6" in diameter and 27" long. It's a big change from the 3.5" resonator I have now. I suspect it will muffle the Seven almost completely. That's not such a bad thing, it's a vocal little beast and while I'll probably miss the flames and racket, this will let me hit full throttle without wincing. The resonator didn't really work well for actual muffling. I'll get used to this new monster eventually. Hopefully. Maybe I'll have to exchange it for a 4 x 22" one or something.
While reading various Carroll Smith books and Miata technical manuals (how sad is that?) I realised that I have a potential area of improvement. My shocks came with little hard bumpstops. Nothing fancy, just something to take the worst shock out of a bottoming. The original Miata came with a similar setup with a little more attention paid to the shape. In 1999, Mazda introduced a much softer bumpstop that looks remarkably like the ones described by Smith. They're made of urethane and according to Mazda, "Because urethane has damping force, the bump stopper reduces the skipping sensation experienced during strong laternal gravitational force on rough road surfaces and improves cornering". Hmm, I expect the engineer that wrote that was Japanese. But I have a set here off a Miata and I'll give them a try. Bill Ritzel, a Miata enthusiast, sent me some pictures of a clever plug wire cover he made. I think that will be a nice addition to the Seven and keep the wires from scuffing on the hood. Watch this space!
entry 1074
November 23, 2005: 
Miata bump stops.
If I remember correctly, the yellow one is from a 1999 model and the red is from a 2001. The yellow is noticeably stiffer. The profile of the red one is designed to give an intial soft damping that firms up. It will be interesting to see what these do.
entry 1075
The monster muffler.
That book is a typical 8.5 x 11" size. Have I overcompensated for my, umm, lack of muffling?
entry 1076
November 27, 2005:
I've decided that muffler will have to go.
The next size down should be just about perfect. I also decided today was the day to get the hood done. It's been very frustrating work though. I annealed the aluminum but it's not keen to bend. This forced me back to my wrestling technique used on the first hood. I'm not convinced it's turning out as well as that one did, perhaps it's a different alloy. There's a small imperfection in the bend (a medium shallow dent) that will be fairly obvious when light reflects off the hood. I'll have to see if I can tease it out somehow. Doing this job again was not part of the plan and I'm not enjoying it one bit. I have yet to find a picture of a hot rod with the louvres on backwards as they are on my original hood so the mistake was not just a matter of miscommunication.
I took some measurements of the suspension pickups today. I just have to measure the front uprights and I'll be able to model the suspension and see how well it's working. I could do this with the existing Excel sheet from the US Locost group but I'd rather design my own little suspension analysis program. Hey, I'm in this to learn.
Skip Cannon is a Miata-owning friend of mine who's caught the Seven bug after driving a Caterham SV at the Aspen track day a few weeks back. He wants to run a Miata motor in it though. He's not a web junkie like me but he does have a bit of a site up on the project.
entry 1077