An M.G. Locost Build
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January 3, 2013
Lowering the Bar

Welcome to 2013. The roll bar is in, which means our chassis is almost complete, at least so far as we know. We think the only thing left to do is to weld the engine bay shelf to the frame. Plus a little grinding. And possibly a couple more brackets, but only because we decided at the last minute to vent our fuel tank to the MGB evaporative canister, and not to the open air, because that's the sort of responsible people we are. Once in a while.

  Removable Locost roll bar
click to enlarge

We foolishly gave away our evaporative emissions system with the donor chassis, so we had to buy a new one, and by new of course we mean new to us, i.e. slightly used off eBay. Not a major setback at $5 for the charcoal canister and $10 for the overflow tank, but now we need to find a place to mount them in the car. In a perfect world the charcoal canister would be located in the engine bay, but a) that's way too much work, and b) the world is not perfect. The trunk area will be fine.

Reinforcing the frame rails  
click to enlarge

The roll bar was our last big welding project. We decided that we wanted the bar to be removable, so we first had to make some pads, a.k.a. feet, and then bolt the pads to the frame. This turned out to be a lot more work than we really wanted to do, because the front feet had to bolt through a couple of frame rails, and so we had to reinforce those rails with spacers so the rails wouldn't crush the first time we torqued the roll bar bolts. This job took forever, for no particular reason that we can discern.

  Rear roll bar feet could've been a little narrower
click to enlarge

But we got the feet all bolted in, and they looked pretty darned good, although we weren't 100% sure that after we welded in all of the roll bar tubes we'd have enough clearance to to remove the bar as a unit. The rear feet measured 41-1/2" from edge to edge, and the distance between the upper frame tubes was only 40-1/2". But there seemed to be some wiggle room, so we were hopeful. Of course we could've made the feet only 40" apart, but that kind of forward thinking can take all the fun and excitement out of a project like this.

Welding on the various tubes and bars should've been the easy part, but it took all day. We ended up having to modify every tube in the kit. We lowered the main hoop 4", which meant re-cutting all the fish mouth ends on the diagonal and back braces to fit. We had to ditch the harness bar altogether because we couldn't squeeze it under the diagonal, although that was no big loss since we're not using harnesses. Plus the weight savings. Bonus.

Making the roll bar appear straight  
click to enlarge

Naturally we couldn't just throw this thing together. There's the saftey factor of course, but much more importantly, the roll bar sits out there on top of the frame for all the world to see, so it has to look good. Or at least look straight. If it turned to actually be straight, major bonus. We wanted nice weld beads, too, so we practiced on a couple of cut-off tube ends, which helped us find the proper setting on our Millermatic 140 at 8-1/2. Our practice beads weren't perfect, but they met our minimum standards of melting the metal all the way through.

Welding the main hoop to the front pads was easy enough, but all the other tubes could only be tack welded in place, because they were either upside down or other tubes got in the way. So we unbolted the tack-welded assembly, and with just a little wiggling we were able to extricate the thing from the car. Which was excellent. Even better was afterwards, setting the fully-welded bar back in the frame and having all the bolt holes line up. Either great execution or just incredibly lucky. Probably lucky. We'll take lucky.

So we're basically done with the chassis, for real this time, and it's been a pretty good year for the Locost overall. Hard to believe, but we're actually starting the third year of our build. A year ago we didn't have anything that even remotely resembled a Locost. We didn't even have a donor. We did have a couple of freshly-welded A-arms, thanks to our TIG-welding comrade in Berkeley. Back then that seemed like a big deal, a huge part of the build. After the A-arms, the chassis was supposed to be a walk in the park.

But of course it wasn't. More like hiking the Appalachian Trail. Not that we didn't have fun, but we ended up doing a lot more than we ever expected, and it took the better part of 2012. Now we're pretty much done building stuff, at least the kind of building that includes cutting, grinding, welding, and making a mess of the garage. And we're not really going to miss it. This year will be more about bolting stuff together. And painting, which we'll start as soon as the weather warms up, which in California should be any day now.

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Comments:  
posted March 15, 2013 at 15:36:08  
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