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Hello,

Still waiting on my books (Keith Tanners and Ron Champion), but been reading the forums alot. Trying to learn all I can before I start. Plan on getting started soon, but do not have a donor yet. How much can I do without donor parts?

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John Jacobsen
Taylor, TX (near Austin)
Haynes frame Miata bits and pieces

Welcome John!

You don't need a donor at all, that's especially true if your someone who has accumulated various parts for one reason or another. I think people are successful both ways.

Here's a few differences.

- If you don't have a donor you get to choose how old the parts in your car are - they can be new or from a junk yard.

- A donor is likely cheaper if you are good at selling the parts you don't need, but then you have labor and dealing with getting rid of the parts. Some people just saw up the carcass when they are done and haul it to a recycle place.

- If you personally like a mix of parts, it's easier just to buy them.

- A Miata donor is the most well tread path and also a good solution, but they are not so available in much of the country.

- A middle ground may be a pallet of the useful parts from a store like "Flying Miata". No chassis to get rid of.

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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!"
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You can build the entire frame less mounting brackets. It would look pretty much just like this.

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Parts left out cost nothing and cause no problems!!

The dimensions that would be really nice to know before you start the frame:

1. The rear axle width. Turns out that the +2 (see below) is about perfect for an S10 solid axle. So if you're going solid rear, that rear axle kinda set the tone of the frame. But if you are going IRS then I guess you can make those half shafts any width you want them, just need to figure on building the rear of the car differently (see below on the Gibbs/Haynes book).

2. The engine. My +2 build would hold about anything stock SBC and smaller I think, both in terms of size and strength. But if you're one of the crazed fools who have a spare BBC or 440 Six-Pack you're gonna use, you might also want to consider a bit bigger tubes and bigger space. And life insurance, but I digress.

3. Butt space. If you or a significant other who will be your passenger is one biscuit shy of being called "Fluffy", or you want something other than the bench seats in the book (and the original Seven!) then you might consider a wider chassis. You might set up a little space with boxes, etc to simulate the narrow bench seats of the Book cockpit to see if this is what you want. The original Seven had 15" of butt space for the driver, the Book I think has 17", etc.



Totally unsolicited advice --

1. The Ron Champion "Cheap Sports Car" book was a great start. However, lots of builders figured out that there are some measurement issues, editing errors, etc. And then the really smart guys figured out how to make the frame stiffer, bigger (to fit American-sized butts and modern engines), etc. Most of these were incorporated into the Chris Gibbs book, "Build Your Own Sports Car: On a Budget" aka the "Haynes" book. Sadly it too is out of print, but there are used copies around, perhaps a nice friend can help you, etc.

Here is a PDF copy of it:
https://www.scribd.com/doc/259503500/Bu ... Sports-Car

It starts with a Ford Sierra donor as I recall, but there are plans out there using Miata bits. The thing is 2 inches wider and 2 inches longer and 1 inch taller than the Champion "book" frame (or "+221" in our slang).

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Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

For me, a book-sized frame is the only way to go. Building a larger frame is like buying a BMW Mini to try to capture the feel of the original Minis. It works for a lot of people I guess, just not me.

You can pretty much build the whole frame without a donor, except for the transmission tunnel, which includes the middle two H tubes, the G tubes, and possibly even the O1-O3 tubes, depending on your rear axle. It's best to have the drivetrain in hand, including the rear axle, before adding the tunnel.

I would also leave out the front upright (FU) tubes until you have your spindles, and know exactly where your front control arm pickup brackets are going to go.

And quite frankly, even the Book frame is huge compared to the original I sat in....

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Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

Very helpful replies, thank you all. I do plan on eventually getting a Miata donor, just wanted to get started while I am waiting for the right one. Im sure I will have one before I finish the frame. It is going to be a book frame.

Nick47 thats what I was wondering, what to wait on, thanks.

geek49203 thanks for the link to the book. I have more reading to do. Think Im gonna be ok size wise on the book frame Im only 5'5" and not to wide.

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John Jacobsen
Taylor, TX (near Austin)
Haynes frame Miata bits and pieces

If you are going down the Miata road why not build a Haynes version? There are supplementary drawings available to modify the design for a Miata donor.

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601

Ok I have alot of learning to do. I ordered Keith Tanners book, since the way I understand it this is the best one based on the Miata donor. Is that still considered a Haynes? Reading the Haynes book that geek49203 linked now.

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John Jacobsen
Taylor, TX (near Austin)
Haynes frame Miata bits and pieces

Sigh. I wish we would've talked first. Keith's work is great, and I once owned his book. HOWEVER you can get most of it by going to:

http://www.cheapsportscar.net/

Second, Keith starts out with a CMC kit, which of course went out of business what seems like a long time ago. Therefore, it is NOT considered a "Haynes", more akin to a Book chassis set up for a Miata donor or something? Last I heard, Keith's employer was selling the Westfield kit, and I think that is covered on the web site as well. So while you will want to pay attention to things like his modifications of the rear end, it's not exactly as helpful to a scratch builder.

If you're into the differences, contact Jack McCornack (one of the moderators here) and he'll be able to fill you in since he was one of the vendors for CMC. Hell, in any case, drop Jack an email and introduce yourself -- if you're gonna build one of these, Jack is a great guy to know. He's a great vendor and one of our resident geniuses-- his invention was in a James Bond movie, another put him into the EAA Hall of Fame, His rebodied locost won a mileage contest, etc. Hell, he might even understand the female mind?

http://www.kineticvehicles.com/
http://www.motherearthnews.com/biograph ... -mccornack

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Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

I haven't seen this anywhere, but are there plans available for a Miata IRS in a book frame? I'm sure the Haynes book has this for their frame, but what about book frame IRS builders? Is there anything out there with the tubes and dimensions all figured out?

I highly recommend choosing seats now because if you build the frame first and find you + the seat don't fit, that's a problem.

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Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

Ok so I guess my best option is a Haynes Frame since I am doing a Miata donor. What size is a Haynes? 442?

Good point on the seats. I should have a small racing seat. So shouldnt be a problem, but will get some measurements for ones Im looking at.

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John Jacobsen
Taylor, TX (near Austin)
Haynes frame Miata bits and pieces

221. 44" wide, outside of the rails. Which is 5" wider than the original Seven S3, or so I hear. I'm building the Haynes w/ a solid rear axle. edit -- yeah, I have the files, but you can download them at the link in the next post faster and better. Let me know if you have problems downloading. - g'03



Again, butt space as one of the 3 measurements. I'm sure if you look around on here someone has the measurements for the Miata bits, certainly the engine, and probably a few CAD files of at least the engine.

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Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

I think you might find some answers here: http://www.locostusa.com/forums/viewtopic.php?f=39&t=16942#p193049 Some of the links might be dead, but the important stuff is still active.
Walt