Steve's Miata-Based Build

[skou]

Hi All!

So, I finally took the plunge and bought a 1994 Miata a couple of days ago to start my Locost journey. I just moved back from Chile to the USA about 6 months ago. Chile has some fairly restrictive laws about "prototype" cars, so up until now my car-building aspirations have been limited to a lot of research and daydreaming.

Here are some photos of the donor. The car only has 116,000 miles on it, but the front end has been through a couple of accidents already. $1100 off of Craigslist, but I still have to tow it from Portland to Boise. I really like the proportions of the Caterham 7 CSR and my vision for this poor, beat-up little car is something like the photo below.

I am really looking forward to not only learning from everyone on this forum but contributing as well!

Cheers,
Steve

[rust_bucket]

Welcome! Looks like a GREAT donor. - You'll make back a LOT of your cost selling off the various bits you don't need.

I too like the CSR look. - Just a word of caution, the Miata DOHC engine is TALL and doesnt' lend itself well to a low hoodline. - Look at that CSR picture you posted and see how far down the oil pan hangs. Scary! The miata pan would be even lower.

I went with a standard nose cone because I like the un-stretched proportions, but as concessions I had to raise it an inch, tilt it an inch and I'll still have a 1 - 1.5 inch "power bulge" in the hood to clear the cam cover.

Good luck! I look forward to watching the build!
Next time your in the SLC area from Boise, shoot me a PM and I'll take you for a ride.

[skou]

Thanks for the advice and invitation. I know the Miata mill is tall and that I may have to make some compromises. I had wanted to spend some more time looking at donor options, but that ad in Craigslist was like a siren's song...before I even knew what was happening, I had my checkbook in hand, dumbfounded, scrawling a signature!

What do you think of a dry sump? I read somewhere it only buys about an inch off the depth of the sump.

[KB58]

Dry-sumps are great, but...

They're around $2000, and do indeed lesson the oil pan depth. However, keep in mind that the transmission bellhousing typically (not sure about a Miata) hangs down just as far as the pan, so you'll still have the original problem, just a foot further back...

[rust_bucket]

I think a dry sump gaining you an inch or so is realistic...
See this pic

viewtopic.php?f=35&t=2269&start=15

Your decision to go Miata wasn't rash though (OK it may have been rash for you... but it wasn't unwise)
The Miata is a GREAT donor for locosts and there are a lot of Miata based build logs (like mine, hempy's, chet's etc etc.) out there to reference not to mention great books like Keith Tanner's. You can get quite a ways down the learning curve, just by reading up on what others have done.

[skou]

Rust_Bucket (or can I just call you Rusty ),

Was your frame based on Book dimensions? I came across an interesting discussion about the difference in cowl location on Book-derived frames versus Caterham CSR's here:

http://grassrootsmotorsports.com/forum/ ... 266/page2/

At a wee 5'-7", I think I can live with a bit less legroom and push the firewall and engine back a few inches. Hopefully, that will free up enough headroom to clear the valve cover under the hood.

If I could just get my hands on some accurate dimensions of the 1.8L BP enginer, a quick CAD layout would answer a lot of my concerns. Anybody??

[rust_bucket]

Rust_Bucket (or can I just call you Rusty ),

Was your frame based on Book dimensions? I came across an interesting discussion about the difference in cowl location on Book-derived frames versus Caterham CSR's here:

http://grassrootsmotorsports.com/forum/ ... 266/page2/

At a wee 5'-7", I think I can live with a bit less legroom and push the firewall and engine back a few inches. Hopefully, that will free up enough headroom to clear the valve cover under the hood.

If I could just get my hands on some accurate dimensions of the 1.8L BP enginer, a quick CAD layout would answer a lot of my concerns. Anybody??

"Rusty" is just fine. - My frame was loosly based on the book. It's wider(+2), shorter (in length by around 4 in) and taller(0 at the nose rising to +1 at the dash) as compared to a book frame. Also my lower rails don't taper in as severely as a book frame, they run right to the front lower cross bar. I ran the taper all the way back to the dash so the scuttle is tapered rather than square as in the book, offset the trans tunnel and made it narrower, and the rear end is custom IRS to fit the miata diff and uprights,... so I guess the answer to the question should be: "No, it is not a book frame at all."

GRM forum link... - I couldn't get the link to work. I'll search there sometime when I'm bored.

As far as pushing the firewall back, I did and I would again. I also pushed the dash back quite a bit. Book frames have a LONG distance between the wheel and dash, it looks goofy in my estimation and you have to be a gorilla to reach any knobs...

[skou]

Does anyone have a Solidworks model of a nose cone based on George Cushing's dimensions I could use? I found a model of the Gibbs frame on the Haynes Roadster Forum and I want to add various nose cones, hoods and cowls to see how they would look.

[skou]

Not much to report except that between frequent visits to HF (it just happens to be on my new way to and from work ), I came across a pretty good price for a 2 ton foldable engine crane at AutoPartsDealer.com for $141.99 with free shipping, if anyone is interested. Ordered it last night.

My wife and I are picking up the donor this weekend. I promised her a romantic weekend for Mother's Day in Portland with just a "little errand" in between. I have also made some progress with my virtual build which I will be using to check clearances, styling and such. I am still struggling with the nose cone, but the chassis and other body bits and pieces are coming along. Attached are some progress renderings. The wheels are dimensionally correct 15" x 7" J rims with a 4 x 100 bolt circle and 40mm positive offset. I am going to put some 205/50R15's on them to check the internal clearance in the fenders. The rear fender is 9" wide with a 30" OD and 20 degree rearward flare. Even with the rearward flare, it doesn't come near to being flush with the back of the chassis. I'll probably end up cutting a couple of inches off the back end of the Gibbs chassis if not required for the Miata IRS.

If anybody wants the 3D models as they progress, just PM me....

[chetcpo]

Wow, that's pretty amazing stuff right there.

[skou]

The Miata made it home without incident. Now the fun really starts!

[Glen]

I'd love to get the models if they're in solidworks (fingers crossed)

[skou]

PM me with your e-mail address.

[skou]

The first casualty . This is what I get for cutting corners and trying to wrestle out the dashboard without fully lowering the steering column out of the way and removing the combination switch first...one dead combination switch . It wasn't a painless death either. With a spine chilling crunch, I tore the wiper stalk right off, exposing a jagged hole in the switch casing with sickly white lubricant slowly oozing out! Otherwise, gutting the Miata is coming along quite well . I hope to pull the engine, transmission and front sub-frame tomorrow.

Anyone by chance have a spare NA combination switch they would be willing to part with?

[dhempy]

Hi, Steve...first time caller.

Looks like you've got a good thing going. Can't beat a Miata for an American donor, and your sweet CAD skillz are mad! (I think that's what the kids are calling it these days...I might be a few years behind the times.) Bummer about the switch...if that's the only thing you foobar, you're ahead of the game. Ebay can help you out there. Call Flyin' Miata first, though...they're great, and they've got a soft spot for Sevens.

Have fun and keep posting!

-dave