'73 Beetle chassis swapped w/ a '90 Miata - seemed like a good idea at first

Update: I'm no longer working with a '73 Super Beetle. I'm now using a '67 VW Type 3 Squareback. Yes that makes it the second Miata + Type 3 on GRM as well as the second two-seater station wagon on the forum (that I know of). It's a full blown movement!

Original post below:

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I started this project several months ago. I'll save you guys most of the the blah blah blah, but if you want to read the blah blah blah then please read it on my website here: http://dannix.net/lib/16 and specifically you can read about my research and why I started this project here and here. 

I'm combining these two cars into one:

The yellow car is a '73 Super Beetle. I chose a Super over the standard Beetle because its has fenders that are a little wider and the hood might have a better time fitting a radiator. And because it was the right price. I chose the Miata because its the only car that I could find that was narrow enough to fit under the beetle body (except for a Boxster, but that's for people of have money). More info about that in the links I posted above.

For fun, I made a youtube channel for this project. Here's a video of me trying to drive the Beetle: 

https://youtu.be/LK-n-g0rqEU

I need to stretch the Miata by about 6" to fit the wheelbase of the Super Beetle. So my first goal is to stretch is, put it back together again, and take it for a test drive. 

Here's all the steps I took to cut it in half: http://dannix.net/lib/meetle/cutting-in-half

And here's the video: 

https://youtu.be/zJCLZVXzt1E

Here's how I set the new wheelbase: 

https://youtu.be/SRNt9Tx4m6o

I'll have to completely cut the door sills off of the Miata, which is really the only thing holding the front half of the car to the back half (on a stock Miata, I mean, not one that was cut in half). Thankfully there was a good solution. Under the floorpan was a thin sheet metal tube that connected the front chassis rails and the rear chassis rails (the sections of the unibody that the front and rear subframes bolt to). I cut out the thin sheet metal and replaced it with 2x3x.125 steel tubes. Frame rails... 

And of course I have an accompanying blog post and video for the frame rails: 

https://youtu.be/sBK7u5--uBQ

So that about brings you guys up to speed.

I have the new driveshaft now - I had to have one custom made for $400. Unfortunitally they couldn't lengthen the old one because the u-joints were blown. I'm still working on extending the Miata's aluminum PPF. After that's done, I can extend and reconnect the brake lines, gas lines, e-brake cable, battery cable, etc. and then I'll have a running, driving, moving Miata that is 6" longer. I want to be able to drive it around the block before I chop into the Beetle and ruin two cars... wish me luck!

fantastic! very highly approved of.

So wrong, which is the best kind of right.

If you use one of these front ends, you can solve the upcoming Radiator Problem.

Stumbled onto this build somewhere else. Have been following along on your website. Interested to see how it turns out. 

Did you measure out where the Miata steering wheel/seat will be in comparison to the stock beetle steering wheel and seat?  Just interested to see how far back you will sit when done. 

Thanks guys! I haven't said this yet, but I've never done anything like this really. I mean, I've restored old cars and trucks and motorcycles, but never hacked them up quite like this. I'm new to fabricating in general (but I've watched a lot of Roadkill and Powerblock TV!). I'll be learning a whole lot, and please let me know if I'm doing anything wrong. Unless it's something I can't undo.

Somebeach: no I haven't done that yet but I really should. 

I got the floorpan extension finished and painted up. In this order: primer, seam sealer, and then paint (I used Eastwood's chassis black 2k rattlecan). I'll put a coat of rubberized undercoating on the bottom, and some insulation on the top. 

Note above the small fire extinguisher and squirt bottle filled with water. Its good to have those handy when welding and grinding near old cellulose insulation. 

Body stretch looks good so far, Get it!

I got the steel PPF extension finished and bolted on, and the new $400 driveshaft is installed, and you can barely see it but I have the e-brake cable extended by clamping on a new peice of cable to make it longer. It's kinda half-assed but I'm confident that it will hold even in an emergency brake situation. Speaking of brakes though, I don't want to half-ass the hard brake lines. I got some compression brake line fitting but returned them after reading about them online. Instead, I'll use a proper union which means I'll have to flare the ends. For that I picked up a double flare tool from HF but I'm learning that it is pretty hard to use. So the only hurdle that's left is the hard brake lines, then I'll have a Miata "death kart" and I want to drive it around the block and do some hard brakes and some hard accelerations before I cut up the Beetle for the next stage. New YouTube video coming very soon!

Some guys who are smarter than me on the Miata.net forum are expressing doubt about the steel PPF extension. It's recommended that I buy another PPF, and graph the two together. Take the two pieces to a professional aluminum welder.  I don't disagree that my method is half-assed but the truth is that I'm in a hurry to get these two cars smashed into one. Unless I'm wrong, I think the worst case scenario is that the aluminum will start to crack and fail as it wants to push upward during a hard acceleration. This would be bad on the driveshaft u-joints. My current thinking process is that if this starts to happen, then I'll add that crossmember after all. It would be no problem. Hell, maybe I'll do it before there's any issues. 

Your name wouldn't be Pete would it?

Just asking.

Eagerly following along!

You may be surprised at the amount of load that goes through an emergency brake cable. Definitely test that by reefing hard on the handle.

For the brake lines, get some new hard line from the auto parts store. The Mazda line is really, really hard to flare. The auto parts store will have pre-terminated line in various lengths as well, so you may be able to avoid flaring. If you are flaring your own, the trick is to get the cut nice and square and to chamfer both the inside and outside of the tube.

SaltyDog said:

Your name wouldn't be Pete would it?

Just asking.

Eagerly following along!

Nope, that's someone else ;) I'm Danny. 

I did not have any trouble doing a union on the Miata brake line, but it is probably down to getting a flaring tool that was a step up from HF; not had any luck with the cheap ones they lend out at the parts store.

The lines are not that terrible to make full length if you use the cupro-nickel tube.

You are moving along nicely on this project. Cant wait to see the death cart video.

Pete

Keith Tanner said:

You may be surprised at the amount of load that goes through an emergency brake cable. Definitely test that by reefing hard on the handle.

For the brake lines, get some new hard line from the auto parts store. The Mazda line is really, really hard to flare. The auto parts store will have pre-terminated line in various lengths as well, so you may be able to avoid flaring. If you are flaring your own, the trick is to get the cut nice and square and to chamfer both the inside and outside of the tube.

You're right of course. I rammed the handle pretty good while siting in the garage, and I'll do it again on the deathkart test lap, hopefully later this week. 

I don't plan on using it for anything other than a parking brake, but they don't call it an emergency brake for nothing I guess.

NOHOME said:

I did not have any trouble doing a union on the Miata brake line, but it is probably down to getting a flaring tool that was a step up from HF; not had any luck with the cheap ones they lend out at the parts store.

The lines are not that terrible to make full length if you use the cupro-nickel tube.

 

You are moving along nicely on this project. Cant wait to see the death cart video.

 

Pete

Thanks man! I still look at your build from time to time for inspiration. I must admit that I've been having negative thoughts lately about the project, wishing that for this much effort I should have found a cooler car like your Volvo. Maybe that's why I'm in such a rush to get it finished. Before I change my mind about the whole project.

NOHOME said:

I did not have any trouble doing a union on the Miata brake line, but it is probably down to getting a flaring tool that was a step up from HF; not had any luck with the cheap ones they lend out at the parts store.

The auto parts store flaring tools are terrible. I use a Blue-Point. The Miata tube is harder to deal with than the bulk line I get, partly due to the paint and partly because they seem to be a harder material.

Your ride is plenty kool for the job. And you are doing a pretty good job, so no worries.

The trick is to never get in a hurry and keep your standards high.  Whatever you do, do it to a point where you are proud of the results. I put a lot of faith in my gut when I do something on the Molvo; if it does not feel right, I re-do it no matter how long it takes or cost.  If you settle for half-assed, the finished car will not be better than the sum of the parts.

My friends who come around to help have pretty much figured out that I am more in love with the problem than the solution, so leave me alone to do things the hard way!

Pete

Seating position seems difficult. 

Seems to me...

If you put Miata seats on the Miata floor pan you will not sit high enough to see out/over the Beetle sheet metal. 

If you use the high seat tracks of Beetle seats the Miata steering wheel may be too low.

The latest video is finally done uploading to YouTube, but the Grassroots forum still is glitching out when trying to embed videos

So you'll just have to follow this link: https://youtu.be/EWsafDgg2sI

thanks :)

John Welsh said:

Seating position seems difficult. 

Seems to me...

If you put Miata seats on the Miata floor pan you will not sit high enough to see out/over the Beetle sheet metal. 

If you use the high seat tracks of Beetle seats the Miata steering wheel may be too low.

 

You're right, the seats will for sure need to be raised, but I'm pretty sure I will be able to raise the steering wheel as well when I work on the dash. 

I'm more worried about the B pillar being next to my head and causing a blind spot (it's not shown in that blueprint because that's the convertable, which was the only blueprint for a Super Beetle that I could find)

I thought somewhere in my searchings, that there was some type of PPF delete kit. Would that be helpful here?

In reply to Somebeach :

In my mind, keeping as much Miata goodness as possible is the goal. Eliminating the PPF does away with a lot of high end Mazda engineering. Then replaces it with the builder's best effort.

While I applaud garage engineering, I also recognize that its hard to beat the factory at its own game.

And yeah...the v8 conversions do away with it and don't seem to have an issue.

Pete

I love crazy swaps, this qualifies as one

If it's a thing, it'll be found on the internet. I had no idea there were multiple people swapping Beetle bodies onto Miatae.  You're our kind of people.  Please keep us posted on your progress.

I love how many flavors there can be. Slammed track rat. Silly confusing cruisers. Anything a Miata can do, can we done under the Beetle disguise.

In reply to Brotus7 :

I don’t know why but now I want to see a Baja Miata beetle. With the pacos 3” lift on it. 

NOHOME said:

In reply to Somebeach :

In my mind, keeping as much Miata goodness as possible is the goal. Eliminating the PPF does away with a lot of high end Mazda engineering. Then replaces it with the builder's best effort.

 

While I applaud garage engineering, I also recognize that its hard to beat the factory at its own game.

And yeah...the v8 conversions do away with it and don't seem to have an issue.

Pete

If you're keeping the stock rear diff and trans, maintaining the PPF is probably the best choice. It's been shown that it's hard to anchor the nose of the diff otherwise and it's probably easier to modify the PPF than come up with other solutions. Going to an alternative rear usually means that's not plausible so you have to go to a different technique. And yeah, the cars don't seem to suffer terribly if you lose it but you do gain some NVH. The PPF setup does a nice job of keeping the whole drivetrain stiff where it needs to be, flexible where it needs to be and nicely isolated. It also eases production. Honestly, I don't know why we don't see it on RWD ubersaloons like the older M5s.

I am absolutely blown away that you have to make a Miata bigger to fit it under a bug.