How is the MX-5 transmission so heavy?!?!?

Can you help me untangle the wires behind my television entertainment center?








But seriously. Holy shit man. This is intense. I'm staring at the wiring shots thinking maybe you're just messing with us. :eek:

Thanks for documenting this. It's really cool to watch.

I'm not sure those that don't know JV personally really understand what things like "I've checked every wire a bunch" really mean.

The built car is going to be amazing in execution. I so, so, so, hope the performance matches.

:lol:

Lol hat is funny :lol:

Also agree with the comments ... very cool to watch. It really amazes me that John is literally building his own car ...

It's big? :dunno:

The NC 6-speed is a pretty stout transmission, so maybe that's it? I don't really know. The RX-8 6-speed is essentially the same transmission with different gear ratios and a different bellhousing bolt pattern and it weighs the same.

Interestingly the K-Miata folks have come up with an adapter to use a 320Z with the Honda K motor. I would actually have loved to do that with the RX-8 but it would be a lot of work and the FC/FD RX-7 transmission is strong. My only concern is availability - RX-7s are getting old and it's getting harder to find transmissions. I think at some point I'll probably have a Jerico in the car but for now this will be a good solution.

I’m utterly puzzled as to why Mazda would put such a big, heavy, stout transmission in the Miata, though. I mean, the Getrag 420G is quite a bit less than 110lbs. for example.

It could be because of the whole PPF thing. The transmission case has to be rigid and strong enough for the moment arm tying the transmission to the diff.

But yeah, I don't know.

the wiring alone looks daunting.

and did I see that you're gong to put a turbocharger on too!?

Yes. Turbo on a 2.5L Duratec four cylinder running E85.

It should be good for 500-550hp at the crank before any detuning. Assuming I can get the car to ~ 2,600lbs or a little under, 4.7-5.2lbs/hp seems like it should move out pretty well while not upsetting the chassis balance or Cg of the RX-8 platform. :D

Do you have the 2.5L engine yet? Is there a preferred donor for the engine or did I miss that you already found one? I'm pretty excited for the finished product!

Interestingly, I picked up a 19k mile 2.5L out of a 2013 Ford Fusion about an hour after you posted that. I was monitoring eBay and saw that LKQ in Sterling was starting to discount their 2.5L engines... they seem to do this periodically, maybe when they get an excess of stock.

I sold the 2.0L out of the Miata a few days prior, so it was a no-brainer to move that money directly into the engine I needed. I also have an FD RX-7 transmission on the way, so when I get back from Mexico I should have a bunch of parts to mock up.

Just catching up. Jaw on the floor!!!

Just curious John, has this been done before? Just wondered if it is a popular conversion, or are you inventing the wheel.

Looking forward to progress reports

I think there is one running overseas somewhere using the 2 liter engine. But he cut the firewall a lot and removed the heater to make it fit. I'm not allowed to do that. As far as I know I'll be the only one with an untouched firewall, and the only one with a turbo.

I'm curious to see how the car works out in its element, but also curious about whether anyone outside the Solo community bases a build off yours. I'm hoping it will lead to more.

Yeah, I don't know. that would be cool. There are lots of LS RX-8s running around at this point. I think that engine appeals more to most people.

Hooray, we have a lift!

https://lh3.googleusercontent.com/do...=w1389-h781-no

Nice!

very cool.

I also like how you have a service ticket attached to the rear view mirror!

Awesome!

Yeah yeah, RX-8, awesome engine swap, blah blah. ;)

What I really want to know is, how do you like your MaxJax?

(Seriously, like everyone else I think this is a super-cool project and it inspires me to keep up my own struggles against the car gods...)

What is up with that ... did John open up a repair shop we don’t know about :D

The Max Jax is great! I confess I haven't actually used it (here) yet. The RX-8 is going to stay on jackstands for a bit longer. The service ticket was there from the previous owner who had the compression checked. When it failed he put it up for sale.

So I bought some parts! I got my 2.5L engine from a big dismantler on eBay. They periodically discount the crap out of them, so this 2.5L out of a Fusion with 18,000 miles was only $300. I got it in the garage today, stripped it of all the stuff I don't need and did an inspection. All seems well with it. But what I really wanted to do was put the coolant manifold on the back of the cylinder head and see how it fits.

https://lh3.googleusercontent.com/pf...=w1389-h781-no

That nice new aluminum casting is what I bought from the guy in Australia. It's a really nice piece of work! Fits perfectly. And it is so much thinner than the stock piece. This should solve a lot of the problems I had with clearance to the firewall. In the pic below I'm holding the stock water manifold. You can see it is almost two inches thicker than the new one.

https://lh3.googleusercontent.com/y3...u=w440-h781-no

The coolant routing will be a little different than the MX-5 installation, so I'll have to get creative with the radiator connections, but that's a problem for another day.

I also got the third-gen RX-7 transmission I talked about before. I don't have the bellhousing that will mate it to this engine (the guy who makes the water pipe makes the bellhousing) but I did put it side by side with the MX-5 transmission and sure enough, the shifter is 4" rearward compared to the MX-5. I think this will work perfectly... or at least it'll put the shifter really close to the stock location. If it's an inch forward or backward that's fine, but 4" forward was going to make things really challenging. It's a nice bonus that the FD 5-speed is very strong. My tape measure slipped as I was taking this pic so it's a little wonky but you get the idea.

https://lh3.googleusercontent.com/i4...=w1389-h781-no

Yikes. Three months and a day since my last update.

Well. I've been waiting on some parts to arrive as well as some free time, and those two things fell into place this weekend.

First, I had sent out a new set of lower control arms from a Series 2 RX-8 so Fusion Works Fabrication could convert them to spherical bearings. Spherical bearings are nice because they eliminate all the slop associated with rubber bushings, and don't have any tendency to bind like Delrin bushings can. I wish I could claim some sweet fab skill for these, but all I did was provide a credit card number. :lol: Anyway, they look pimp!

https://lh3.googleusercontent.com/XJ...=w1106-h622-no

https://lh3.googleusercontent.com/me...=w1382-h777-no

https://lh3.googleusercontent.com/mv...=w1382-h777-no

I can't actually install these at the moment, because I'm having a tubular front subframe made for the car. In the meantime, the guy who did these will be doing a set of rear control links as well, so very shortly the car will have no rubber bushings at all! I will have a set of delrin upper control arm bushings for the front, only because they're not multi-axis bushings and I can build them with an offset for more front camber.

The next thing I'd been waiting on is a kit from Ronin Speed Works to convert the final drive to a Ford 8.8 IRS out of a 2007-2010 Explorer. These differentials have a bunch of LSD options (torsen, clutch type, etc) and a whole mess of ratios available. The motivation here is twofold. One, they're practially indestructible - there are RX-7 guys using these diffs in > 1,000hp drag cars with no failures. And two, the stock RX-8 final drive ratios are not well suited to the transmission I'll be using and the engine's relatively low redline. The kit retails for $1,250 but the guys agreed to give me a discount of $250 if I posted a complete install guide and a review as well as feedback on durability once I'm competing with it.

The kit is really well packed and comes with everything. I'll go into what "everything" is as I go along.

https://lh3.googleusercontent.com/JH...=w1382-h777-no

The first piece in the kit is this rear mount. This will bolt to the rear cover of the final drive unit, and the ears will accept bushings and then fit to the rear mount on the RX-8 subframe without modification.

https://lh3.googleusercontent.com/S4...=w1382-h777-no

The welds on this piece are really well done. It's made of 3/8" thick steel plate which has been laser cut and it's gorgeous.

https://lh3.googleusercontent.com/y2...=w1382-h777-no

This plate will bolt around the rear cover of the diff. But first I need to cut the factory Ford rear mounts off of the rear cover. I pulled the cover off to do this and broke out my angle grinder.

https://lh3.googleusercontent.com/Ac...=w1382-h777-no

Yes, the diff is upside down in this picture. The inside houses an open differential with 3.73 gears. I think that's the gear ratio I'll start off with, but I may need to go shorter in the future and rev the engine higher. We'll see. Either way, the ring and pinion look to be in good shape. The Explorer this came out of only had 70,000 miles and I got the axles from it as well, which will be important later.

https://lh3.googleusercontent.com/kD...=w1382-h777-no

I didn't get a great picture of the rear cover with the ears cut off, but you can kind of see it in the top of this photo. I also had to grind down the rear cover at the pry points. They were proud of the mating surface for the rear cover plate, so 1/8" needed to come off of them. This wasn't in the instructions but it clearly didn't fit well without grinding them down.

https://lh3.googleusercontent.com/w6...=w1382-h777-no

https://lh3.googleusercontent.com/Oz...=w1382-h777-no

You can see how the plate fits flush against the rear diff cover with the bosses ground down a bit.

https://lh3.googleusercontent.com/Vv...=w1382-h777-no

I'm at a bit of a standstill until I make the bushings for the front and rear mounts of the diff. The Ronin guys expect you to use the factory Ford (rubber) front mount and a stock RX-8 rear mount, but I'm going to machine solid bushings for both. Anyway... the next thing that needs to happen is to assemble the custom axles. Obviously an RX-8 rear half-shaft is not going to work with the Ford diff, and an Explorer axle will not work with the RX-8 rear hubs. So the Ronin guys give you new custom chrome-moly axles which are designed to mate to the Explorer CV joint on the inside and the RX-8 CV joint on the outside. Because they're constant velocity joints rather than standard U-joints, the difference in design between the two won't cause any vibrations or binding.

Here are the axle shafts they send. Beefy!

https://lh3.googleusercontent.com/f2...=w1382-h777-no

Here's an Explorer half-shaft.

https://lh3.googleusercontent.com/ja...=w1382-h777-no

I only need this end of it... the inner CV joint.

https://lh3.googleusercontent.com/Co...=w1382-h777-no

To disassemble it, the band clamps holding the boots on get opened up. The boot slides up the shaft and the inner CV cup just comes off - the only thing holding it on is the boot which seems common with American cars. Once the cup is off, the CV joint is exposed. There is a small circlip holding this on, which comes off easily with a circlip pliers.

https://lh3.googleusercontent.com/N4...=w1382-h777-no

The circlip, which gets re-used.

https://lh3.googleusercontent.com/Kk...=w1382-h777-no

A three-jaw puller extracts the CV from the Explorer axle shaft.

https://lh3.googleusercontent.com/J1...=w1382-h777-no

All the bits I need from the Explorer axles. The rest hits the bin.

https://lh3.googleusercontent.com/ul...=w1382-h777-no

The boots slide onto the axle shafts, then theb CV joints install using a 32mm socket and a deadblow, followed by the circlip. I'm going to stop here on the inboard side and move to the RX-8 axles.

https://lh3.googleusercontent.com/FO...=w1382-h777-no

The kit uses the outer CV joints and stubs from a 6-speed RX-8. They're very beefy and hold up to a lot of abuse. Disassembly is largely the same as the Ford axles in the beginning. Remove the boot, clean off the grease.

https://lh3.googleusercontent.com/2K...=w1382-h777-no

The difference is the RX-8 outer CV joint is held in place with a blind circlip. To get the outer CV off, you need to either pull it out or strike it off. I put the axle in my vise, put a block of wood on the CV joint and smacked it with my 10lb mini-sledge. It came off no problem.

https://lh3.googleusercontent.com/Y8...=w1382-h777-no

The RX-8 CV joint looks a bit different than the Ford, and is fairly common for Japanese and European cars.

https://lh3.googleusercontent.com/rw...=w1382-h777-no

Here's that little bugger of a circlip, now installed on the new Ronin axles.

https://lh3.googleusercontent.com/4d...=w1382-h777-no

Ready to install on the new axle shafts. It's a little fiddly to get them on, because that circlip needs to be closed up with a pliers enough to allow the CV splines to engage. Once it clears the chamfer, it slides in with a little help from a deadblow.

https://lh3.googleusercontent.com/aY...=w1382-h777-no

After greasing everything up, the new boots can slide on and the retaining rings can be clamped into place. It's important to try to get the excess air out of these before clamping them down. Here the retaining clips are in place but not crimped.

https://lh3.googleusercontent.com/Cz...=w1382-h777-no

I actually bought the correct tool to clamp these, back when I was working on Matt's car. It makes this job a snap.

https://lh3.googleusercontent.com/e4...=w1382-h777-no

https://lh3.googleusercontent.com/cz...=w1382-h777-no

And that's where I'm going to leave it for now. The Ford CV shells use a weird rubber adapter that the boot clamps around. New ones didn't come with the boot kit that the Ronin guys sent, and the ones from the Explorer were a little dry rotted so I'm going to order new ones before wrapping up the axles.

I designed the bushings I need to make and ordered materials, so the next thing will be installing the bushings. Then I can get the diff mounted in the subframe using the rear mounts, and prepare to weld in the front cradle. In our next installment... :)

I found time last night to make the bushings for the rear mount on the lathe. Here's the rear mount bolted to the modified rear cover of the 8.8.

https://lh3.googleusercontent.com/VU...=w1382-h777-no

Bushing without its center sleeve. The bushings are the same dimensions as the factory RX-8 bushings, roughly.

https://lh3.googleusercontent.com/fS...=w1382-h777-no

https://lh3.googleusercontent.com/9D...=w1382-h777-no

https://lh3.googleusercontent.com/_9...=w1382-h777-no

https://lh3.googleusercontent.com/fQ...=w1382-h777-no

https://lh3.googleusercontent.com/Pf...=w1382-h777-no

Damn this is fun to watch come together.

:+1

I was expecting to have made more progress at this point, but ... life.

Yeah, but, IMHO it is much better to take your time than rush and make mistakes.

Time to make the bushings for the front of the final drive. Bit of a weird configuration, so I made the bushing as two pieces, a complex shape that presses into the front ears of the diff, and a disc to serve as the lower isolator. The Ronin guys sent me a link to a guy that makes something like this, but I thought the version I came up with was a little better designed and didn't rely solely on the press-fit to hold the diff in.

https://lh3.googleusercontent.com/yx...=w1382-h777-no

Sorry the pics are so dark.

https://lh3.googleusercontent.com/8d...=w1382-h777-no

With the front cradle mocked up. Everything fits surprisingly well. The Ronin guys did a really nice job with the front piece. I think just a little minor grinding will be necessary to tighten up the gaps for a nice weld. I have a bit more work to do before this is ready to weld but it's mostly just prep.

https://lh3.googleusercontent.com/p9...=w1382-h777-no

This is a shot of the rear bushings I made, fitted to the Ronin plate, bolted to the RX-8 subframe.

https://lh3.googleusercontent.com/rL...=w1382-h777-no

This is the front mount, with the bottom isolator bushing installed. You can see the gap from the Ronin front plate to the subframe is just a bit on the large side, probably okay for a MIG weld but a bit too large for a TIG.

https://lh3.googleusercontent.com/_1...=w1382-h777-no

Looking good

Continuing work on the 8.8 swap. Final test fit before grinding everything clean and welding.

https://lh3.googleusercontent.com/lM...=w1382-h777-no

Good fitment to the front of the subframe, TIG welding this was not a problem at all.

https://lh3.googleusercontent.com/Xa...=w1382-h777-no

We also put a bead on the underside, where the rear of the front plate meets the RX-8 subframe.

https://lh3.googleusercontent.com/iC...=w1382-h777-no

Cleaned, primed, and rattle-canned black.

https://lh3.googleusercontent.com/kz...=w1382-h777-no

Here's a close-up of the lower "legs" of the front plate welded to the subframe.

https://lh3.googleusercontent.com/l6...=w1382-h777-no

Another close-up of the welding on the front plate / subframe interface, as well as the front bushings, with the final drive installed. There were no fitment issues after welding.

https://lh3.googleusercontent.com/fu...=w1382-h777-no

Top down view with the final drive all bolted up. Looks like it was meant to go there! The Ronin kit is awesome...

https://lh3.googleusercontent.com/Zd...=w1382-h777-no

https://lh3.googleusercontent.com/tN...=w1382-h777-no

https://lh3.googleusercontent.com/s7...=w1382-h777-no

After a shitload of work, I got the engine to fit. It probably needs to move forward another ~ 0.5" so I can tilt it backwards another degree, but this is it sitting on modified stock engine mounts on the subframe. The steering rack is just about in place - one of the hard lines is just touching the crank pulley. I can re-route that hard line and solve that issue. This is a huge deal - having stock steering geometry will eliminate one big thing to re-engineer.

Best part, I don't think I'll need to dry sump the engine anymore. I'm pretty sure I can modify a stock MX-5 oil pan to clear the subframe crossmember.

https://lh3.googleusercontent.com/2i...=w1382-h777-no

https://lh3.googleusercontent.com/9P...=w1382-h777-no

Three cars gave their life for this build. Unreal. All of it quite hard, IMHO, but that wiring harness will haunt my dreams.

Well... three cars gave their life, but not for this build. I like to think that the Fusion and MX-5 that I scavenged parts for just had the little "organ donor" box checked on their license :)

Nothing so far has been hard, from a fabrication standpoint. What's been challenging and time-consuming is trying to figure out all the inter-dependencies. Example: I started working on fitting the engine in the car almost immediately after buying the MX-5 (which is now gone). I could get it to fit, but not in a way where the steering rack would bolt up. So I raised the nose of the engine to clear the rack. Now the driveline angles are all wrong. So I raised the rear. Then it hit the cowl. So I decided to dry sump the motor (thinner oil pan). That added a bunch of unwanted complexity and cost.

I ended up rolling the dice on an aftermarket subframe which gave me the clearance I needed up front, and cutting the cowl sheet metal after a lot of discussion with the rules advisory committee about whether that was legal or not. That was the real breakthrough - once we determined that was legal it made the rest of it possible.

With the rear differential mounted and the engine roughly where it wants to be, I can order the bellhousing, mount the transmission, and finalize the engine location, mounts, and transmission mount once I get the driveline angles correct. That will enable completion of the wiring, work on the fuel system, relocating the ABS unit, etc. I still will need a custom oil pan. In an MX-5, the engine sits well aft of the subframe cross-bar. In this application, the front edge of the oil pan is above the cross-bar. So I need an oil pan that is two inches shallower in that location. Interestingly... one just popped up on eBay (something custom). Fate? ;)

It's frustrating to me that it's taken me so long to get all this figured out, but there is no instruction manual and I've never done something of this magnitude before.

Anyway thanks for coming along on the journey.