build diary

March 19, 2006:
The reconfigured sump, ready to weld on to the tank.
entry 1155
The sump is in along with a couple of baffles to cut down on sloshing.
I'll have foam in the tank as well. The baffles don't go all the way to the top so I can actually put the foam in the tank.
entry 1156
The back of tank is on.
Only one more panel left. Of course it will probably turn out to be the biggest hassle of the lot.
entry 1157
Before I weld the top on, I think I'll add a couple of straps like this to keep the sump nicely filled.
Of course, in the current state I figure I won't have fuel starvation until I'm down to about a cup of fuel and pulling a high-g corner.
entry 1158

March 21, 2006:
After cutting, sanding and welding all weekend I took the tank home to see how it fit in the car.
It slipped in with millimeters to spare past the roll bar but then wouldn't clear a tube at the bottom. The sump was hanging up. I peered underneath and discovered that a weld bead I'd run around the outside of the joint (it's fully welded inside) was hitting the tube. I ground that flat and the tank popped right in to place. It's as if it were designed for this car! Hang on...

I did a few happy dances as one did not seem to be enough. I could not be more proud of this tank. I've decided to put a couple of zip-tie anchor points on the outside to make it easier to hold hoses in place. I picked the sealant up yesterday as well. On the Locost mailing list, I was asked why not aluminum? Well, after paying for the Kreem sealant it's not cost. I don't know how to weld aluminum and I'm on a bit of a schedule to be ready for the Car and Driver test. But I do have to say that if I did it again, I'd certainly consider alloy. The finished tank is just under 16 lbs compared to about 8 lbs for the previous plastic one. That weight gain is about the difference between my new battery and the old so there's no real change overall. I won't have to run as much fuel to avoid starvation on the track so that's nice. Plus of course the weight distribution is much better.

The preparation for the magazine test continues. I've been told they're going to be doing instrumented testing so I'm nervous about that - what if the car only does a 0-60 run in 10 seconds? Well, a Caterham SV 160 does the sprint in 4.9, but that doesn't reassure me much. I've ordered some new springs, going to 500 lb in the front and 250 in the rear. Heikki thinks the 500 is far too soft but I think I can improve the wheel rate with some shock mount tweaking. He's also driving a pure track car and doesn't have sway bars. I don't feel the front on my car is too soft anyhow, it's the rear that needs beefing up. Will I regret this? Probably. But I'll have to make the mistake first. I can see Heikki shaking his head from here.
entry 1159

We just got a plasma cutter at work.
I can't stop finding reasons to use it. Like this one.
entry 1160
In the car! I could not be happier with the fit.
entry 1161
A shot of the tank from the rear.
The sump is quite obvious here.
entry 1162
The sump from the side.
The fuel line is just hanging off here as I had been checking the clearance for the nuts. The ugly welding along the seams is not needed, it's fully welded inside.
entry 1163

March 22, 2006:
I used a smoke machine to check for leaks last night.
It runs a couple of psi of pressure and is great for finding air leaks. A couple showed up and I decided to weld all the seams in the tank from the outside as well as the inside just to be sure. That stopped the smoke leaks, but when I filled the tank with methyl ethyl ketone to degrease it I found a couple more. I've decided to grind all the exterior welds down to check them for pinholes and also because, well, it'll look prettier! With the tight fit in the car it's likely any external welds will cause installation problems anyhow. The coating should stop the pinholes but I'd rather use that as a backup instead of relying on it. The current plan is to finish that grinding and cleanup tonight, then coat the tank tomorrow.
entry 1164

Using a smoke machine to check for leaks.
I found a couple. This picture was taken after I was done - you can't test with the gas cap off!
entry 1165

March 23, 2006:
Last night I spent a bit more time fixing little leaks.
Not squirters but slow drips. The sealant would take of that but I'd feel better having metal to back it up. Then I degreased the tank with methyl ethyl ketone (MEK) and filled it full of Kreem Tank Prep A. From the smell of it and from my reading, that's basically just dilute phosphoric acid. So is Metal Etch, so I used part of a bottle of that to get to the desired concentration. I left the tank to stew overnight - longer than required for a new tank, but the timing worked out for me.

This morning I came in early to discover a couple of spots where the acid solution had escaped past the tape and made a nice mess on the workbench despite a bunch of prophylactic paper towels. Ah, let's just call it art. I rinsed out the tank and used Kreem Tank Prep B (aka MEK) to get rid of any water. Then it was time to play with the Kreem goo itself. Pour it in, rotate the tank all over to let it coat, let it sit, rotate the tank all over, drain and let dry. The second coat will go on in a couple of hours and then I'll let it cure for a few days as I play with plumbing and painting the outside. Then, finally, I'll have the tank done.
entry 1166

Mmmm, chemicals.
This is what it takes to seal up a gas tank. The aluminum tape in particular is very useful. Also note the attractive finish on the workbench after a small acid leak.
entry 1167

March 27, 2006:
No work over the weekend as I was in Denver picking up some random parts.
I learned a few interesting things and had a chance to crawl all over Skip Cannon's turbo Miata powered Caterham. He's doing a really nice job and examining the car really underscores the difference between a Locost and a Caterham. Where mine seems to subscribe to the "I'm not sure how strong this should be, so let's use big tube" theory, the Caterham has delicate tubes that are carefully placed. There's a lot to be learned from these cars and a few of their designs will be transferred to my car shortly.
entry 1168

March 28, 2006:
I spent some time fooling around with wipers last night.
Those who have read my book will see a reference to the wipers being installed. Well, that was artistic licence. I've had the parts for some time but never installed them on the car. I received an education in the mix-and-match Lucas wiper system. It turns out that if I try to use all my undamaged parts, I'll have less than 90 degrees of sweep. This is due to an early wiper motor and late model "wheelboxes". The combination of gearing is all wrong. I'll poke around and see if I can find the parts I need to make this work. After striking out on the wipers I cut the foam for the fuel tank and spent some time cleaning out the holes so all the fittings can be installed. Now it's just a matter of the final bracketry and then paint. Hopefully tonight.

Andy from Titan Motorsports showed up again today with a truckload of very sexy parts. Most of them were for various Miatas we have at the shop but a set of roller-barrel throttle bodies would fit the Seven nicely. Time for some dyno fun!

Chris Fiaccone suggested that my backwards louvres could be solved by cutting out the offending parts and inserting some mesh. Not a half-bad idea. Mark Rivera (who is showing amazing daily progress on his car) is going to send me a pre-punched sheet of aluminum that I will bend up for a new hood. But in the meantime, I might give Chris' suggestion a try.
entry 1169

Sexy roller barrel throttle bodies.
No restrictions here!
entry 1170

March 30, 2006:
I removed the original battery tray (surprisingly heavy!
) and welded in a couple of short bars to help support the fuel tank. The tank was dropped back in and, um, didn't want to fit. It was wedging up against the rear uprights and forcing the sump against a frame crossmember. Why? Good question. With a little push the tank dropped in but I've lost about a millimeter of clearance that I sorely needed. At least the tank does still go in with a little push. Hopefully it'll still do that once painted. At worst, a bit of bending on the rear uprights will bring back my millimeter. The good thing is that it makes it easier for me to build a good "tank restraint" system if the tank doesn't want to move in the first place!
entry 1171

A new bar to support the fuel tank.
entry 1172
This little bracket will hold up the fuel pump.
There will also be a couple of clamps holding it to the frame member.
entry 1173

March 31, 2006:
No work done on my part last night other than some experimentation with an old roll cage and a Corbeau seat on my rally Miata.
However, a few others have been working on my behalf. Mark Rivera took a bit of time out of his manic build to punch some louvres in a sheet of aluminum for a new hood. Thanks to a small error, he had to use 0.060" metal which carries a bit of a weight penalty but I'll live with that. The louvres are also 4" wide instead of the 3" I used before so we changed the pattern around a bit. How will it look and will I be able to bend it? Well, it's 3003 alloy this time which is softer than the 5052 I've used in the past. The hood is definitely resisting efforts to go together easily!

Jim at Coveland Motorsports managed to dig the wheelbox I need out of an old Spitfire and will be sending it my way. Thanks to both Jim and Rod McLellan of the Octagon Motor Group for answering my questions about the details of Lucas wiper systems. It's a ski weekend so this is my last break before the Car and Driver test. I'll enjoy it while I can!
entry 1174

My new hood!
Some assembly required. Mark Rivera punched these louvres and will ship me the sheet of aluminum.
entry 1175
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