build diary

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

November 28, 2005:
The big muffler sitting under the current exhaust.
Yup, it's too big. The exhaust system would sit too far away from the body for my taste.
entry 1078
The new hood underway compared to the original.
The black mess is some protective plastic that was intended to keep me from scratching the aluminum. I had to peel it back in order to anneal the metal.
entry 1079

November 30, 2005:
No work on the car recently because I've been preparing for another trip to California.
This is a short one though, just a long weekend. I'm going to be part of the pit crew for a couple of 2006 MX5 race cars in a 25-hour race. This should be interesting stuff. Caterham did very well in this race a couple of years ago but unfortunately they won't be there this year. I'll see if I pick up any good tips looking at this car.

It's time to set some goals for the Seven, though. Let's see, I'll get the suspension modelled by the end of the year and decide what path to take there. I'll also have the hood finished along with a new exhaust. There, a target! I'm not working at the feverish pace I was when I was coming to the finish of the initial build, am I?
entry 1080

December 6, 2005:
Back from the races!
Very little Seven-related activity although being that close to that many race cars managed to get me all itchy for more track time myself. The cars were, for the most part, nicely prepared by AWR. The biggest problem was that we had in setup was a lack of shock damping. The cars were running on stock shocks because they were so new and nothing else was available. We also had two cars with identical setups that worked differently - one oversteered enthusiastically, the other would not do anything but push. We worked away at finding solutions and it was very interesting watching the experienced racers do what they could to get the cars to work. They did get better but were never exceptional. Drivers from other teams were commenting on how the little guys bounced around. Unfortunately, we had a few problems over the course of the race (fulfilling our role as a development race) and were not in the hunt for a win by the time dawn rolled around. Shortly after, one of our cars also rolled around on the track a bit and became a good candidate for a Locost. The other droned across the line stuck in either 5th or 6th gear.

December 7, 2005:
Oooh, look at the pretty little Miata race car.
25 hours later, it was a Locost donor due to a small argument with another car.
entry 1082
Racing started at 11 am.
This is dawn the next morning.
entry 1083
A peek at the differential for the new MX5.
It looks like it should be a good option for a Seven. I didn't weigh it but it seemed quite light. And yes, it's smoking.
entry 1084

December 9, 2005:
For those who want a few more pictures from the races, there are some on the Flyin' Miata site.
This is a diary about the Seven, so I'm not going to digress too far.

The exhaust system is not going to be finished before the end of the year. I haven't sent the huge muffler back to Summit Racing yet and I have only about 12 days before I leave for the holidays. I will attempt to finish the hood though. I'm also learning SolidWorks (an extremely cool 3D prototyping program) to play with suspension bits.

Also on the suspension - this photo was referenced on the LocostUSA builder's forum. Those rockers are apparently stock motorcycle parts. I hadn't considered that approach - motorcycles tend to show up in junkyards with regularity so if I can identify a good part, I should be able to buy it fairly cheap. The design of the rocker is the difficult part of the inboard suspension, I'll let the highly-paid motorcycle engineers sort that out for me!
entry 1085

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