LocostUSA.com

Fabbed the mounting plates for the roll bar mounts. - The basic chassis structure is almost there. If I could just keep myself from being distracted by the other more fun stuff like mounting things I could close this chapter. Oh well, whatever it takes to keep me moving right?

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In God We Trust... All Others, Bring Data.

Miata based, custom chassis build in progress. First Drive!!! http://locostusa.com/forums/viewtopic.php?f=35&t=2269&start=375

I also got the exchanged rear fender from Emile. (Thanks again Emile!.) In case you missed a chapter we had to foot the bill to swap because I had two left rear fenders and he had two rights.
- Did I mention Coveland has poor customer service? I did? OK, just making sure we got that covered.
Anyway the new fender is pretty darn close in shape and it actually about twice as thick/heavy as the original, but at least Emile and I both have a matching set now.

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In God We Trust... All Others, Bring Data.

Miata based, custom chassis build in progress. First Drive!!! http://locostusa.com/forums/viewtopic.php?f=35&t=2269&start=375

And, last on this update is the e-brake. It's about 90% there. Where do you mount something that you need out of your way a nice easy reach without being awkward? Why in the passenger side of course. I ground off the mounts, flipped them 180° and welded them back on. I also got the pull mounts for the cables themselves set up but you can't see it in the picture. one more little mount for the single cable side and it's in!

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In God We Trust... All Others, Bring Data.

Miata based, custom chassis build in progress. First Drive!!! http://locostusa.com/forums/viewtopic.php?f=35&t=2269&start=375

Original 7's had the e-brake mounted under the dash

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The Lethal Locost
The Lethal Locost 2 - Even More Lethalerer

Hi RB, I was just looking at the model you posted for your frame. In the model it looks like one of your diagonal braces is maybe in the wrong place? I am not sure but I think there is a diagonal going down to the tube where the motor mount is, but in your model it goes to the outer bottom rail. That bay already has a diagonal going across it. The second diagonal in that area supports in the inner bottom rail.

Maybe you didn't build it that way, I did look thru your pictures- but couldn't tell or maybe I'm wrong...

Also was looking at your nice welds on your roll bar mount. Are you doing TIG, or do I need a lot more practice?

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

Hey R-B, love what you did for the rear suspension.

I'm starting my Miata-based build, and am intrigued with your design. How did you figure out the geometry? Do you have dimensions/measurements/drawings you can share, or could you walk me through the process you followed? I'm leaning towards a bolted-in rear Miata subframe, like Mark Rivera's, mainly because I can't determine how to go about creating my own IRS around the Miata diff. Any help on this aspect would be grately appreciated.

Thanks in advance.

Horizenjob, not all the braces in the model made it into the final chassis and I ended up adding some additional ones as I went along. Some of them were just for convenience like the round one I added for the park brake lever.
Things continued to change as I scoped out the packaging in real-life. Solid models can only take you so far when in the end it's all hand assembled anyway. If I were cutting structure or making molds on a 5-axis mill I would have been a lot more rigorous when building the model.
As-is everything fits very well. I'm sure I will add some more triangulation and gusset plates after I get the main structure complete.

And unfortunately no, I'm not using a TIG. It was about $1000 away from being in my budget. I did however sell the HF MIG buzz box (piece of junk), and the Lincoln 225 stick (AC only) for a total of about $250 so I could buy a very nice MIG before I started building. I went with the Lincoln PowerMIG 140 C and bought an 80 CF tank from Indiana O2 (ebay). I'm into the welder around $700-$750. It does run on 120 so it is very convenient, but it can't handle super thick pieces. Lucky for me the 0.125" plates are about as thick as I have ever needed to go.
Someday I will buy a TIG. Once you TIG you never want to go back!

Thanks for the compliments on my welding. I'm decent when I can go for it on a final weld from the get-go.
My tack welds look like crap and then my final welds have bumps in them because I'm too lazy to grind down the tacks. Oh well, it will all hold in the end.

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In God We Trust... All Others, Bring Data.

Miata based, custom chassis build in progress. First Drive!!! http://locostusa.com/forums/viewtopic.php?f=35&t=2269&start=375

Hondaman,
I never pulled together good solution for the diff mount in my solid model, mostly because I made the solid model before I had the donor. I didn't have a good model of the diff so I couldn't design the structure to bolt it to. Make sense?
Most of my design was pencil and paper aft of the rear bulkhead.
I used the free roll-center software (wishbone) I found on this site to locate my attach points. then I pretty much just made the upper and lower squares the right size to put the attach points where I needed them (inboard outboard.) Then I tacked the lower one in place, cut wood blocks to hold the upper one in place and tacked it. If you look at the log you can see the progression pretty clearly.
As far as actual dimenions I'll have to go digging. I don't have time this week but I'll see what I can find for you.

- fool around with wishbone, it's fairly user friendly if you're comfortable in DOS. There was a lot of guess and check to get the roll centers happy front to rear and to keep them from moving too much laterally.

PS Miata subframe is an easy way to go! you just build in a flat panel to bolt it upto. Check out JR's build for a nice execution of it.

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In God We Trust... All Others, Bring Data.

Miata based, custom chassis build in progress. First Drive!!! http://locostusa.com/forums/viewtopic.php?f=35&t=2269&start=375

A little off topic, but do you know what the roll center is for the Miata OEM rear frame? I am just wondering how it would work with the front design of the Locost.

BTW, I too like what you did with the rear!

Thanks,
Randy

It finally has a FACE!

I got the FLCA's built up and I just had to throw on some tires to see what it will look like. The front has been so skinny and un-finished for so long it was fun to see a little more meat up front!

I like it!

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In God We Trust... All Others, Bring Data.

Miata based, custom chassis build in progress. First Drive!!! http://locostusa.com/forums/viewtopic.php?f=35&t=2269&start=375

I had to go the split-tube approach on the front because of the angle. I may at a later date remake these with more elegant bent tubes, or re-install the front mounts at an angle so the rod end can go straight into the tube.
This works just fine for now.

(And yes, the steering rack still needs to be shortened. It's on my to-do list OK!?)

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In God We Trust... All Others, Bring Data.

Miata based, custom chassis build in progress. First Drive!!! http://locostusa.com/forums/viewtopic.php?f=35&t=2269&start=375

Something tells me that my UCA will need a slight redesign.

I will also be adding a brace where the shock pushrod will attach. More on that later.

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In God We Trust... All Others, Bring Data.

Miata based, custom chassis build in progress. First Drive!!! http://locostusa.com/forums/viewtopic.php?f=35&t=2269&start=375

These (coveland) fenders were obviously designed for tires of much larger diameter. They almost look silly unless they are quite a way off from the tire. I think I'll be cutting these down a bit. I don't plan on switching to my Enkei RPF01 ultralight / Falken Azenis RT615 combo for a while. (Yeah right, like that's ever going to be in the budget.

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In God We Trust... All Others, Bring Data.

Miata based, custom chassis build in progress. First Drive!!! http://locostusa.com/forums/viewtopic.php?f=35&t=2269&start=375

Yeah...better run down the the Harley shop and get something in a barbed-wire motif.

-dave "would you like some chrome with that?" hempy

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...nowadays people are so intellectually lazy and lethargic that they can't build ANYTHING with their hands. They'll spend hours watching whiny people marooned on an island, but won't spend a second adding anything to the world. -weconway
Visit my [Locost 7 build log]

Mmm... Imagine the road kill you could generate! What's that old saying about teaching a man to fish?