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Learning how to build Lotus Seven replicas...together!
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PostPosted: Mon Sep 19, 2011 11:15 pm 
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Let me start with a short introduction. I'm Scott, and I live in Dallas.

Years ago, I owned a BPU Supra Turbo. It was awesome, and had about 450hp an 500 lb/ft of torque. The costs of operation were similarly staggering. While gas mileage was surprisingly good, tire life was quite poor. I was lucky to get 10k out of a set of rear tires. That wasn't because I was doing burnouts all the time (or at all). The high power levels, and the asymmetric tread pattern meant that I was going through tires that cost $150 each (those were the cheaper ones) with disturbing regularity. I also had some issues with my automatic (stupid I know) transmissions.

To make a long story short, I couldn't afford to keep the car, and I've missed it ever since. I've wanted to get the same excitement out of a more affordable package. For a while, I dreamed about spec Miata racing. Then, I actually sat in one. I'm 6'4, and at the time I was about 315 lbs. There was just no way that was happening.

Some years back, I read about the Locost. I was intrigued. It met my demands for affordability, both in construction and operation, and it sounded like a blast. I was pretty worried that I wouldn't fit in one, and then I found the 442 sized chassis. Oh, and I lost 75 lbs. Between the two, I'm pretty confident that I will fit.

Let me emphasize that I don't have any grand illusions about my engineering or fabricating prowess, so I really do welcome comments and suggestions throughout the process.

So, after a couple years of off and on research, I think I have settled on a plan. I want a little more power than the 1.8 Miata block, so I settled on the 2.3 duratec. I want an IRS setup, because I want a great handling car. I think the best source will be buying a wrecked Ford Ranger, and using it's engine and transmission, and perhaps using Miata stuff for the rest? Perhaps I'm better off using a Miata donor (I've heard the engine and transmission mate pretty easily) and buying the duratec separately.

In any case, I've started by building my build table.

I'm going to shoot for a metal framed table with an MDF surface.
Image

These are the legs for my table.

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I've drilled and threaded a hole into each foot so that I can level the table. My garage floor certainly isn't flat, but I'm hoping my table will be.

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PostPosted: Mon Sep 19, 2011 11:38 pm 
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Location: Holden, Alberta, Canada
Welcome aboard. Went for a ride in a Locost 7 w/2.3L out of a Mustang II that had a mild cam in it. What's that saying?? Oh yeah, I couldn't wipe that "sh*teating grin" off my face for a couple of days.

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PostPosted: Mon Sep 19, 2011 11:49 pm 
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What part of town are you in? I'm awfully close by. Well if you call FW close.

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PostPosted: Mon Sep 19, 2011 11:51 pm 
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With that engine your power to weight will be a bit better then your supra. Might need just a bit of motor work for that, but nothing major. Considering the car will be lighter and lower and have less traction it will feel a great deal more exiting! Plenty to look forward too.

Your table may not be very strong or stiff, so you might need some bracing under those tubes. People put the engine and transmission etc. on the table sometimes while their working things out, so you will want it pretty strong. You don't have to, just saying. For that reason, if you brace the legs down low for shelves or whatever, make it able to let an engine crane slide under the lower braces or whatever.

Some folks use the ranger transmission from the 2.3 or 4.0. Getting a Miata does get you a good IRS, and suspension upright, steering rack etc....

Oh and Welcome! :cheers:

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PostPosted: Tue Sep 20, 2011 12:25 am 
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I'm in SW Dallas near Grand Prairie and Duncanville, so Ft. Worth isn't too far a drive for me.

My table isn't completed yet. I'm planning on putting a horizontal cross tube at the mid point, and then tying that in to the legs with diagonal braces. Do you think I need to add diagonals from the midpoint of my not yet installed center bar to the corner diagonals too?


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PostPosted: Tue Sep 20, 2011 7:10 am 
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Howdy Scott and welcome to the group!

Your plan for using Miata bits and a Ford 2.3 powertrain sounds realistic, I'm pretty sure somebody in here has done that kind of thing. If they haven't you still can! There's lots to read in the builder's forum, and even a non-engineer (like me!) can gather enough knowledge to build a solid chassis and put together the mechanical systems that make up a Locost. The main thing is to enjoy yourself...

Feel free to ask questions, there's a lotta information stored inside various heads around these parts.

Take care-
JD Kemp

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PostPosted: Tue Sep 20, 2011 8:28 am 
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Location: Cave Creek, AZ
Scott,

Welcome.

Your work table wont be strong enough in the middle with those 1" square tubes, they are not "tall" enough for the long distances between the vertical legs. You will need to put in strengthening ribs from leg to leg, either out of MDF glued and screwed to the bottom side of your top plate or with 20 gauge or thicker metal studs with the top plate screwed to them.

Diagonal braces in two planes will keep the whole thing from "scissoring" when you lean on it, but a shear plate made out of MDF on the back side will do the same. As stated earlier, put in a lower shelf to store misc stuff on under the top surface but make the supports for the shelf high enough off the ground so that you can get a "cherry picker" style of engine lift under it.

Tom

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PostPosted: Tue Sep 20, 2011 9:05 am 
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Welcome. One bit of advise. Get the engine and transmission before completing the frame, otherwise, you will probably have to redo some of it.


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PostPosted: Tue Sep 20, 2011 8:09 pm 
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Location: Connersville, Indiana
To clarify. The only Mazda trans that will bolt to the Ford Duratec are the ones for the 2.0 and the one used in the 2.3 Duratec equipped pickup. The 2.3 Ranger from 2002 up is the only Ford transmission that will bolt up. It may be possible to stuff the gearset from a 4.0 box into the 2.3 casting. The castings appear to be the same, but I don't know. The lure of the 4.0 gears is a closer ratio transmission.

Bill


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PostPosted: Tue Sep 20, 2011 9:03 pm 
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Location: Fort Worth, Texas
I travel to the GP, Mansfield area just about every week for business so one day after work we'll have to get together.

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PostPosted: Tue Sep 20, 2011 11:28 pm 
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Here is my progress for today. Have no fear, there are more braces still to come.

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PostPosted: Wed Sep 28, 2011 11:17 pm 
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More diagonal braces welded in.

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PostPosted: Thu Sep 29, 2011 12:37 am 
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Put some cross tubes where the lower part of the brace meets the uprights. Then you can slide in a piece of ply or mdf for a storage shelf, you won't regret it. My table is made of wood and I put upper cross pieces in every 12" then MDF on top of that. Like horizenjob says, you'll be putting weight on that table fitting the engine, trans, diff, rims, tires, blah, blah, blah, it all adds up.

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2 down, 2 to go

'If man built it, man can fix it'

"No one ever told me I couldn't do it."

http://www.locostusa.com/forums/viewtopic.php?f=35&t=12234

http://www.locostusa.com/forums/viewtopic.php?f=35&t=14030


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PostPosted: Thu Sep 29, 2011 11:00 pm 
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I agree, I think the table needs to be able to distribute the force of the cars weight evenly through several locations to ground.
There are too many unsupported points that will cause flex as weight is added to the table.
In my example below the weight is distributed to the four corners which are then in turn supported by the angled 1x1 inch tube.
This table easily supported my cars weight with engine and suspension in place and a minimum of tubing.
Basically cheap and simple.

Al

Image

Image

Image

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PostPosted: Wed Oct 05, 2011 10:35 am 
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raceral wrote:
I agree, I think the table needs to be able to distribute the force of the cars weight evenly through several locations to ground.
There are too many unsupported points that will cause flex as weight is added to the table.
In my example below the weight is distributed to the four corners which are then in turn supported by the angled 1x1 inch tube.
This table easily supported my cars weight with engine and suspension in place and a minimum of tubing.
Basically cheap and simple.

Al



Another nice job, Al.

I don't mean to hijack this thread, but my next task is coming up with a build table design and making it, so this build table conversation is of keen interest to me. Besides keeping the table from flexing, I've been a little obsessed about two other issues:

1) How to make sure the plywood or MDF is truly flat for layout;

2) If I should bother to make sure the plywood/MDF top perfectly level, so I can use my electronic, Harbor Freight angle gauge to get indications of angles of members as I build the chassis.

If the table is on casters (a very nice idea) then #2 is out because my garage floor slopes about 2 degrees by design and it won't stay level once I move it. I'm not sure keeping it level is all that important, but it would be convenient. Being able to move the table could be very helpful.

Helping with #1 would be keeping the top rail of the table, the thing the plywood sets on, really flat and square. How did you ensure your table's top rail was really flat and square when you built it, Al? Or, did you just trust that the RHS tubing was "straight enough?"

Cheers,

Lonnie

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