25 May 2009

Wife’s back tomorrow so that’s the end of the unlimited guy-time-in-the-garage, though a lot got done: fuel tank, coolant system, rear body treatment, diffuser framework, the body framwork on the sides, more-or-less, and the muffler has plenty of space. The curved corners need flanges welded on but that’s not hard.

What’s next? Probably finish up the rear fender area. Instead of aluminum panels some may be steel this time around, welded on. Typically 0.050″ aluminum is used, so going with 0.030″ steel means it weighs the same, costs less, and saves time by not requiring rivets. After that? Maybe suspension arms, a very detailed and fiddly task since fully-dimensioned fixture drawings are needed for the book.

24 May 2009

The chassis is now fully welded – well, the structural portion.

Regarding the rear of the car, I changed my mind – again. Two trailer fenders had been purchased as a cheap source of an otherwise impossible-to-make curved corner radius. I wasn’t going to use them because the rear was going to be the traditional Seven back end. However, since they’d be dropped into the trash can it was worth a shot to see if they’d work out. Turns out they work great – since the chassis was originally designed to use them in the first place. Soooo, they’ll be used, which dictates the rear of the car will have a curved panel like a ’30’s hot-rod. Some will like it, some won’t, but I do, and builders can do whatever they like!

In the second picture, the white flange is what the rear fender attaches to, while the rusty fender dictates the rear cover perimeter. The fender will get narrowed down so that only the curved flange and enough material to create a flange is kept. Note the last picture with some incentive sitting roughly where it’ll mount – the turbocharger – pretty exciting.

In other news I’m reading Smokey Yunick’s autobiography and it’s great. Raw, harsh, many typos, he repeats himself, but it’s great stuff, unedited, just like how people talk in real life. Kind of like sitting with him on a porch and listening to his adventures – hard to put down. Check out Best Damn Garage In Town by Smokey Yunick. Years ago I had some questions about one of his magazine articles and called his shop, never dreaming that when I asked about it, they say, “Oh, you need to speak to Smokey, hold on.” Never in a million years did I think he’d take time to talk to me.

23 May 2009

Welding continues and will be done tomorrow – which is just as well. Getting the chassis completely welded is a good milestone so I’m taking off some time from that to work on the manuscript. It’s good timing, working on the car for two weeks straight is enough for a bit. In that time the car’s extended its lead on the manuscript so it now needs to catch up. It’s all good though, nothing in the last two weeks has involved precision numbers that aren’t already in the book.

Not knowing chassis weight was killing me so since the wife’s out of town the bathroom scale was borrowed… 240 lbs. This number would not surprise mechanical engineers who use fancy CAD that totals all material weight, or designers who calculate it. I didn’t bother because, well, it doesn’t matter. The chassis is built per SCCA tubing rules and basically, the chassis is the body, so it is what it is. I have a spreadsheet with every weight on it; with the corrected weights, not including driver or gas, the total is 1365 lbs. I suspect I’ll be lucky if it stays below 1500 lbs. We’ll see.

Years ago I watched an excellent PBS show called “Plane Crazy,” about a guy who sets out to design, build, and fly an airplane in 30 days! It’s an excellent education in human nature, what happens when people put themselves in impossible situations. As far as I know it’s now only available on VHS on the used market but if you’re considering building a car it’s very worthwhile viewing. I just bought myself a copy.

My brother stopped by in his Super Stalker, lamenting how it seems like someone always wants to race him – this time it was a Viper. He said the first time he got the jump on the Viper and the guy had a hard time catching up. Second time the Viper got the jump and slowly pulled away. Not bad considering both the cost factor and that the Stalker can out-brake and out-corner it.

22 May 2009

Added the four tubes that finish up the rear suspension and the last main structural tube behind the engine.

Cleaned off the table and before welding started I thought you’d like a “big picture” perspective – I’m 6′. I don’t currently have the chassis scales so can’t weigh it but I’m guessing it’s about 170 lbs or so… we’ll see. My brother points out that I claim this will weigh 300 lbs less than Kimini, but he can’t see where all that weight’s going to come from (Kimini weighed 1600 lbs.) Good point, since Mini doors, Lexan windows, and a carbon fiber roof don’t weigh much, and worse, I’m using heavier wheels and tires and a larger fuel tank. Eh, it is what it is.

Some details are being put off such as the air inlets and diffuser. There may be a couple more tubes behind the engine but they’ll wait until the engine is back in place. I’ve also been putting off how I want the rear end to look. What I would “like” is a curved “trunk” look of a 30’s hot rod. Trouble is, a nasty panel that is curved in two dimensions is needed, which I simply don’t have the ability to do. Short of that is the traditional “Seven” look, with a single curved panel wrapping round the tail. Eh, I don’t know, we’ll see. The rear styling treatment has been a hotly-debated issue on the forum, but of course everyone ignores how hard it is to actually fabricate the various ideas…

It occurred to me that that the chassis table has served its purpose and is not needed much longer. Trouble is, I don’t have storage space for the stuff under the table – that is the storage space. Once all the engine parts are sent off that’ll free up some space, plus selling off parts I don’t need (Honda shifter and cylinder head) will free up more room. Getting rid of the table means whatever metal shavings I produce while adding the remaining bits will drop down into all the boxes… Eh, we’ll see. There’s still a million brackets to fab and install, plus the scuttle, and panels, and electrical, and engine, and….

21 May 2009

The rack mount is done, requiring, as always, endless mocking-up, measuring, and re-measuring to make sure all is well. Shims will be used for the final adjustment to dial out bumpsteer. There is no diagonal in the bay because it is small enough that the floorpan will handle side forces.

Started in on the remaining tubes on the rear suspension. Tomorrow I’ll get the second argon tank filled in anticipation of a long welding session, finishing up the main chassis. The engine gasket set arrived so everything is set for delivery to the engine builder next week 🙂

Tried fitting up the stainless firewall but found it’s very hard to put into position. It’ll have to be cut in half, either vertically or horizontally to ease installation. Either way there needs to be a large removable section for engine access. Depending upon the chosen engine, the front may be difficult to get at if the intake manifold prevents access from above. Access from below is not possible either if a full floorpan is used.

20 May 2009

Pedal mount is done; the tube layout is a little clunky but much simpler than Kimini and far more accessible. It’s took all day due to endless mock-it-up-and-sit-in-the-seat-and-check-how-it-feels-then-get-out-and-fiddle-with-it-then-get-back-in-and-check-it-again. Note the large open bay to the right which will be the storage area. The plan is to drop the floor some since no one needs two feet of vertical foot well. The goal is to allow storing a helmet and all the gear up front so it doesn’t have to be carried into every restaurant you walk into.

In other news the coated pistons finally arrived, thought there was brief panic as the invoice has someone else’s name on it(!) but everything turned out okay. Once the gasket set arrives (supposedly tomorrow) everything will be sent to the engine builder – expensive but exciting.

So what’s next… probably the diffuser tubes, though I still don’t know what I want the back of the car to look like. Well, I do know, and that’s a curved rear end that looks like a hot-rod. Trouble is I don’t have the tools to create curved panels in 3D to give a nice radius – sharp-edged corners look bad. There’s always the traditional Lotus Seven rear end which is pretty straight forward. Guess I better make up my mind soon.

19 May 2009

Okay, the center tunnel is figured out. As shown, the two lower holes support the coolant lines. The top hole is for the bleed lines (which may be fairly large OD if silicon hose is used.) The large tube at the top serves several purposes: it provides a smooth surface for the center tunnel (I don’t like resting my elbow on square corners,) it serves as a through-passage for shifter cables, clutch line, brake lines, and electrical. If that all doesn’t fit they can run below (and yes, there will be gaskets in each hole to prevent wear).

The large top tube also provides a physical support for the shifter assembly and possibly the e-brake. The only thing I wonder about is what happens with that tube in a wreck. Worst-case it gets shoved through the firewall, punctures the fuel tank, and creates a really impressive fireball. For that to happen, the front of the car has to get crushed about 3 ft plus another foot into the passenger compartment for it to reach the firewall – which seems pretty unlikely. However, I’ll probably drill 1.5″ holes along the bottom of the tube to make sure it buckles instead, and the holes will also double as passageways for cables or hoses to pass between the upper and lower cable-ways.

Note sure what to do next. The steering parts are on the way so that can’t happen until they show up. Doing some panels would be a nice change of pace, though I think it would be best to fully weld the chassis first (so it assumes its final shape due to whatever heat-warpage happens). No point drilling rivet holes only to have them shift during final welding. Maybe it’s time to add the rest of the tubes at the rear, around the suspension area and diffuser, then final weld the chassis… The only catch is that I haven’t made up my mind how I want to handle the body work around the rear, nevermind the side vents. Since that’ll use smaller tubing it shouldn’t affect the overall chassis. Oh, and there’s the pedal assembly mount to finish in order to get rid of all the clamps and wood!

18 May 2009

Stared at the center tunnel area for a while to figure out how to best support the coolant lines. Drove down to the metal supply outlet and picked out the needed material, then when standing in the checkout line, a better design came to mind. Sigh, put the material back and had to think about it some more. Yup, change of plans, cheaper, simpler, and lighter wins again. Go get different material and drive home before I changed my mind yet again. Pictures tomorrow.

17 May 2009

The coolant lines and swirl tank plumbing is mocked up; the two coolant lines stack above each other along the centerline of the car. Also finished is modifying the radiator, moving the lower hose fitting, plugging the hole, and replacing the radiator cap with a bleeder fitting. It’s nice to have the radiator completely modified, though it still needs to be leak-checked.

As for the center “tunnel” (all 1.5″ of it), it’ll have a removable side panel for access. I’ll probably use round 1.5″ tubing for the top to give the shifter something solid to mount to.

16 May 2009

Welded the oil return AN fitting to the side of the pan, done now so it’s not forgotten before everything is delivered to the engine builder – just waiting on the gasket set and coated pistons.

Welded the radiator filler neck to the top of the accumulator tank but tank construction has to wait until the engine’s back in. It has to miss the engine and fuel filler hose while leaving room for the overflow tank. One possible use for the left-over pipe is serving as a custom intake manifold, but all in good time 😉

After that, things wondered a bit. The center “tunnel” (such as it is) is next, but it’s closely tied to the shifter, which depends where the steering wheel goes, which dictates steering shaft routing – the everything-is-connected-to-everything-else thing. Soooo, hours were spent moving the steering wheel and pedals around until they felt perfect. What’s nice is how the steering mated right up to the stock collapsible lower Miata steering shaft. This avoids having to buy steering U-joints at up to $80 each. Oh, and mocking this up confirms that a steering quick-release isn’t an option – it’s a necessity.

With that set it naturally dictates where the shifter goes. This answers the question of whether a stock Honda shifter will work – no it won’t. Not from lack of function – it’s just too big. That’s okay, a nice shifter is a cool side-project and makes the car look much more “business” than a collection of junk-yard parts.