An M.G. Locost Build
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October 20, 2011
The New Jig

Building a Locost is definitely a learning experience, and what we're learning most is that we donít have a lot of experience. After drilling and tapping the second (of four) upper control arm tubes, we got completely discouraged because the tap is getting all torn up, and the tapped holes are getting off-center, so the rod end screws into the tube at a slight angle, one or two degrees off. We ordered more of this tubing, and will keep making threaded ends until we get it right.

  The Old UCA Jig, now retired
click to enlarge

So we're not encouraged, but we are stubborn, which may work out just as well in the end. However, because we no longer have any faith in our precision fabrication skills, weíve modified our UCA jig. Or actually we built a whole new one. The old jig relied way too much on the threaded holes in the outboard tubes being perfectly centered, because it only aligned the tubes themselves. It wasn't our idea to do it this way, that's just how the pictures in the Locost book looked. Obviously they're better at tapping tubes than we are. Which wouldn't be a big surprise.

We made our new jig out of wood, just like the first one, because wood jigs are easy to build and easy to adjust when you find out you didn't build it very well. The only downside, as far as we can tell, is that they might char if you weld tubes while they're in the jig. Unfortunately this is sort of the purpose of a jig, to hold the tubes in place while you weld, but maybe the tubes can just be tacked together in the jig, then pried out and fully welded on a bench. That might work. Hopefully we'll find out soon enough one way or the other.

The new jig turning out perfectly-aligned A-arms  
click to enlarge

Our new jig has the rod ends screwed into the threaded tubes, and then mounted on a half-inch rod thatís lined up exactly parallel with the bushing tubes. That way, no matter how imprecisely the outboard tubes are cut or threaded, and we're pretty sure that no one can cut and thread them as imprecisely as we can, the rod ends will end up in perfect alignment with the bushing tubes. At least in theory. Possibly even in practice. It probably won't look perfect, but at least the suspension wonít bind. And so far it doesnít look all that bad. So far.

We're still looking around for a welder. Not the machine, an actual person. Most of the welders you see online are into ornamental stuff, which I take to be iron gates and the like. I suppose that's where the market is for welders, but even I could weld iron gates. I mean come on, how strong do they have to be? As long as the dog can't chew through it, you're good to go. What we're looking for in a welder is one of those seasoned old veterans. Maybe a former race car constructor. Someone who's worked for Roger Penske. Or McLaren. That would do it. We'll keep looking.


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