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And the ethanol angels cry out in joy,
For the Rod hath been bent;
And the Block hath been vented;
Lo, Behold!  The tow truck hath arrived.

The Book of Power, Chapter 3 Verse 10


This is a project I picked up on a whim about a year ago.  I was just looking for a late 60's small truck to modify since I am tired of dealing with CARB.  The first phase plans are to do a Miata swap, full suspension and driveline, since I have about 75% of those parts sitting around the shop.  Phase 2 will be to replace the Miata engine with either a K24Z3 or a Nissan Leaf motor backed up by a BMW DCT.  While it is ICE, E85 will be the primary fuel.  I also have a turbo kit for it (currently on my 91 Miata.)


The 91 Miata.  Slightly modified... CARB legal 2005 driveline swap, FM turbo, lots of 949 Racing and Supermiata parts.



Popcorn as picked up.




Choice bumper stickers.


Something missing?


OEM or aftermarket?


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And then it got stored on the lift for a year.  Was not sure what I wanted to do with it.  I really wanted to do the EV conversion, but the idea of adding 500+ lbs (and the cost) had me sitting on the sidelines.  But after a little shop clean-up, I noticed that I had almost all the parts to build it as a Miata.  My only real expenses would be the stuff that stays with it if I decide to go a different direction down the road.  The Miata parts were already for sale... I would just be postponing the sale of those parts.  So I got busy.


Body off and in storage.


Engine and front suspension out.


Stuff that is getting tossed... I have a "for free" ad in the classifieds if you are local and want to come get it.  It goes to the recycler 1st weekend of next month.




All 521 parts that are not still attached to the frame are going away.


And that is where it is at today.  Next step:  cutting and grinding.


Very simple model.  Now that I have better access I will improve it and add stiffness.


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You are correct.  Works fine on my computer, but not on my phone.  Must be a stored cookie thing to work on my computer.


Searched the site.  It appears linking from Google Photos does not work, I will need an Imgur (or similar) account.  Will fix the links in a bit.

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2 hours ago, mainer311 said:

So wait, you’re turning a 521 into a Miata?


We have a guy here in Colorado Springs, manages Pikes Peak Intn'l Raceway, has a 411 Wagon & a 521 with full Miata running gear & suspension.  I think he is bob3 here on Ratsun.......??  Anyway, I got a ride in the 521 around the track...............he is a CRAZY man, but a great driver!!

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4 minutes ago, yenpit said:


We have a guy here in Colorado Springs, manages Pikes Peak Intn'l Raceway, has a 411 Wagon & a 521 with full Miata running gear & suspension.  I think he is bob3 here on Ratsun.......??  Anyway, I got a ride in the 521 around the track...............he is a CRAZY man, but a great driver!!



Yup Bobs here somewhere lol

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50 minutes ago, yenpit said:


We have a guy here in Colorado Springs, manages Pikes Peak Intn'l Raceway, has a 411 Wagon & a 521 with full Miata running gear & suspension.  I think he is bob3 here on Ratsun.......??  Anyway, I got a ride in the 521 around the track...............he is a CRAZY man, but a great driver!!

Hmmmm, that sounds rad.

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Week 2


Cleaned up the workspace a bit and took some measurements.  When it comes time to start mounting the new subframes, I will do a better job of leveling the frame and lift, and not some really warped 2x12's.




Level enough for today's work.




Figuring out centerline of rear axle before disposing of the parts.




83mm in from the end of the frame, and was the same on both sides.  I tried to use a chisel to put a more permanent mark in the frame.





Or 251.3mm from here:




And it measured the same from the other side.  Just out of curiosity, I weighed it.




173 lbs, but the cross weight is all messed up.  For now I am blaming the 2x12's.  Will check better once I get the suspension back in.




Tared it with the jack stands on the pads.  Hope I don't have to bend it.


I have decided that I can ship these bits for a modest handling fee.  Does $20 per + shipping sound reasonable?  The lower arms have been spoken for as of now.  The ugliness on them is almost all AZ desert, where it had been sitting since 1986.



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This brings me to another point  (this is a copy/paste from a the Miata forums)


I have not mentioned this in detail on the Miata forums, but I recently bought a 1969 Datsun pickup to "Miatafy". It will be getting pretty much an entire Miata drop out and some bits of the tub. This implies that there won't be a Miata left when I am done with the donor car. As I am starting to build up a list of what is needed, I realized that I have everything sitting in my garage... in my 1991 project car, Mental. This car is so heavily modified that I cannot, in good conscience, sell it as is. The reality is that I drive this car less than 250 miles per year, mainly to the occasional car show / Kinod. In addition to the drop out, there is about $10k in parts I could sell off and fund the truck build.

It is a tough call for me. I have had the car for almost 12 years now. It was not a great starting point for a nice car. It had been hit on both ends. It was a BRG SE. I commuted in it for a couple of years. Blew 2 engines. Spent too much $$$. I also HATE dealing with selling stuff online. But it would mean a huge difference to the truck build to part it out. Emotional attachments to inanimate objects suck.

What do you think?

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Most threads I have seen on doing the Miata subframe swap seem to be along the lines of "I did this cool thing, see?"  I want to show how I am doing it instead of just showing that I did it.


Having said that, I doubt anyone wants to see pictures of the various mounting points cut out of the frame.  I will just say that I have started doing that, and it is a lot of work.  Made the shop stink.  I turned off the AC and have vented the shop so the people who have to work in it next week won't have to smell. it.  I think I will move it outside to finish the cutting and grinding even though it has been overly hot by Southern California standards.  I will try to get it all done in one shot.  I did buy a plasma cutter for this, but I am not sure if it is helping or hurting at this point.


I moved into my nice office and did some work in model space.  I wanted to match the ride height of my NA Miata, Mental.  I did not realize how low that car is.  There is a scant 3 inches between the frame rails and the ground... which is lower than we run our race cars.  when I tried to replicate that in Solidworks with the truck frame, I saw that I would have to chop the frame into parts, chop the subframes into parts, and then attempt to put them back together again.


Some explanation here:  The Miata was designed to have the lower control arms to be parallel to the ground at stock ride height.  In order to gain camber (and other reasons) we like to run the cars much lower that stock.  This alters the suspension geometry in a not very desirable way.  I figured as long as I was in control of where the hard points in the chassis are, I could correct for this.  Turns out that is not very doable without going to a tube frame (at least where the subframes are going to mount.) This would be beyond the scope of this project.


So I compromised.  I played around with the position of the subframes in SW until I had the best combination of subframe and frame cutting.  This would be equivalent to about 4.5" of ground clearance at the frame...  except that I can control where the top hats are going to mount and can add stroke to the shocks.  I need to come up with a target for frame to ground clearance at full bump and design the shocks around that.  Would it be too easy to do the same thing that everyone else has done?


Anyways, on to some virtual pictures.  There are 2 different tire sizes shown here.  One is based on a 15x9 225/50 and the other is a 17x9 245/40.  Both are 4x100.  This is just a representative sample, chances are I am going to use a x10 or wider anyways.  This kind of gives the idea of how much cutting of the frame and subframes is needed to hit my targets.  Even though this seems to be a simple drawing, it is nearly 1/2 a gigabyte of data and my computer is not happy with rendering it.  I would love to be able to put in all the control arms and some wheel models.  Those subframe scans are huge.






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Love the digital imagery.


I don't use a plasma for cutoff anymore. They make such a mess. Buy yourself a half a dozen 6" cutoff discs for your 4" grinder and surgically remove the brackets. About the same mess, but not as much stink, and a ton less cleanup on the frame.

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