[DaveEV]

Aloha DIYers! I've been thinking about EV conversions for a while, and now I've finally jumped in. Yes, I'm in Hawaii, shipping is crazy expensive, and so I'm trying to source from junkyards as much as possible for my first go at this. I have some basic tools and backyard, no lift or mechanic's tool chest. I've already gotten some of the major components, so I figured it was time to start a thread.

I'll try to post regular updates here, possible start some social media channel too.

I started with a general idea that I wanted to start with either a small, light sports car or the ever-popular in Hawaii Toyota Tacoma/4Runner as a chassis and figure out how to throw most of a Leaf in there. I've successfully found a '99 Miata as my starting point. Some keys as to why I selected this vehicle:

• I've previously owned and reparied two NA (first gen) Miata's. This NB is very similar.
• I plan for additional builds, so not concerned on getting it just right here (especially the range in this size car)
• The major prep work (removing engine, trans, A/C, power steering pump, exhaust) was already done
• Coilovers already installed, so final adjustment of ride height and dampening should be easy(-ier)
• This was a manual car, so clutch pedal and master cylinder are already installed if I decide to go that way
• Had extra wheels and radio I could sell to get some money back

Biggest decision after I towed this home was how I was going to get right gear reduction without the transmission. Seems my options are:

• stock replacement
• some kind of gear reduction
• try rear transaxle/gear/motor

I imagine you'll see a lot more of Charlie Brown. He's ready to put the top down and cruise... It's going to be a while bud.

 

[DaveEV]

I found a donor, not sure if I made best decision but I'm excited about the project! Facebook Marketplace had a 2014 Nissan Leaf available for parts. The battery was already spoken for, but the drivetrain and high voltage components were available, as was most of the interior. We agreed on a price, and they let me disconnect the pieces I wanted to not get cut (wires, hoses). Then they said they'd give me the whole front subframe, as it saved them time! Yikes! But okay! Feeling good that I have clean wires from J1772/CHAdeMO ports to batttery plug to start from.

In addition to the whole stack (with only one coolant line cut), I got the radiator/condenser assembly with the electric water pump, the drive selector, and accelerator pedal assembly. Eventually, I'll need to figure out how to control it all. I passed on getting any brake or steering system parts, as the Miata has lots of depowered steering and brake vacuum options.

 

[DaveEV]

As I build this thread, realizing I've missed a lot of pictures. I've used a chain hoist to move the Leaf subframe and motor. That is definitely a safety hazard, pics would have been worth it. I'm sure there will be more! Also, I asked Facebook if anyone wanted the gas out of the Miata. Someone had the setup I didn't want to spend money on (yet): 5gal gas can, 12v battery, 12v fuel pump, and hose to connect to the supply line in engine bay. Just connected everything and took the gas out. I'm sure there is more in there, and I'll drain it eventually, but building community! May have made a connection to local machinist, more to follow.

I've taken a few things off the Miata: muffler, emissions lines, brake vacuum lines, fuel injector harness, power steering lines. But the big news is I've separated the Leaf drive unit (can I use LDU or too confusing with Tesla LDU/SDU?) from the subframe. Axle nuts loosened and removed with cordless impact, but I needed to buy the right size socket and adapters. (I ordered sets of both as I'm planning for future use.) It took a bit of wrestling to get the axles out of the hubs, but eventually they came out without having to remove any more steering or suspension pieces. Then removed left, right, and rear motor mounts and lifted the drive components up and slide the rest of the subframe out from underneath. With any luck, I'll find a buyer for that thing who will haul it away.

 

[DaveEV]

Got a little work done this weekend. I've seen a couple teardowns of the Leaf DC/DC and inverter, but at this point I'm not that interested on whats inside or taking it apart. So, I
left all the cables on the DC/DC, removed the A/C compressor, disconnected hoses and cables from the motor, removed the 6 bolts mounting inverter to motor, removed the cover and 3 bolts for each phase of the electrical connection on the motor, and lifted the inverter from the motor. It took some leverage and shims, but more or less came straight up and off!

Bungees helped keep everything together until I got in my little shed. The are hard to see below, but there are guide pins to help keep things aligned when assembling inverter and motor.

 

[DaveEV]

I sized the Leaf radiator and Leaf Drive Assembly (LDA is what I'll call it from now on) to see what might fit. The radiator is about 3 inches too wide, so I'll find a Miata one and use that. I am fairly convinced that the LDA can fit in back, possibly including the inverter and DC/DC. I need to drop the rear subframe to remove the fuel tank, so I will have both on the ground to confirm some measurements and see if I can get a fabricator over to look at what needs to be done to the subframe. I'm sure one of the cross members will need to be cut, but not sure if it's possible to make some sort of alternative.

I did a little of the prep work to remove the subframe. I'm going to try and leave the brakes connected until I'm sure about what I'm doing with the LDA. It's ready to come down, just need a second set of hands.

 

[windraver]

I found it's best to use the stock radiator of your car in almost all cases since it already fits your chassis. Since the system doesn't run that hot, you can actually opt for a smaller radiator. For my case my CRX had a "half radiator" which I used.

The only part from the leaf you want from the radiator is the water pump when it comes to cooling since it's an electric water pump.

 

[DaveEV]

Wow... pulled off the fuel filler neck and there's a wee bit of rust...

 

[windraver]

Wow... pulled off the fuel filler neck and there's a wee bit of rust...
View attachment 131640

Good thing you don't need it anymore!

 

[DaveEV]

Contemplating my driveline decision, any thoughts from the community are appreciated...

• Can't find Miata manual trans on Oahu. car-part.com lists one, but I called the yard and it's gone
• I did find great deal on BMW Getrag 5 speed. I'm in touch with KMiata who has a swap kit, see if they'll package together just what I need for direct drive (EM57->adapter/coupler->Getrag->custom driveshaft->miata diff)
• Have local machinist coming early next week to look at LDA and Miata subframe for possible rear mount... That means subframe is coming down soon!

I might wait for a Miata trans as the KMiata kit will be pretty pricey. And I'll probably get impatient, miss out on the Getrag, and be left with the LDA rear-mount... What does this group think?

 

[windraver]

If you go with the coupler to driveshaft approach, you should see @Electric Land Cruiser build

If you decide to relocate the EM57 to the rear (which is really small btw), you will just need custom axles and you can reference my build.

I would suggest taking a look at the size of the actual leaf EM57 motor and comparing it to the Miata drivetrain and see what the size difference is. From what I've taken away, there is much of a benefit of keeping our manual transmission despite the fact I really do miss the fun of shifting through gears.

And before you actually decide all the above, figure out where you can actually place the batteries. Keeping them together really makes the project easier but the Miata is basically the same size as my CRX so you really don't have much room to place those batteries. That might determine where and how you place the motor, inverter, and PDM. Extending the PDM, inverter, and motor wiring is many times easier than battery BMS wiring extension because the BMS wires may be high voltage and you'll need safety cut offs.

When I was considering the coupler adapter plate approach, I found this here:

https://bratindustries.net/

They have both coupler and adapter plate which solves the Leaf half of the work. You'd then need a machine shop to help you mate the other half.

 

[remy_martian]

@Bratitude ^

 

[Electric Land Cruiser]

I would recommend mounting the drive unit in the rear like Windraver says. A manual transmission takes up valuable space and weight for no appreciable gain. That is if the LDA can fit in the rear subframe of the Miata, it might fit but it would be tight. The gas tank is above it which when removed would provide clearance. Miatas are tiny, tiny cars. If I was doing a small sportscar build I would do a MR2 Spyder with Leaf drive unit in the rear, half the battery in the rear, half the battery in the frunk. That would be an awesome car. Like Windravers CRX but RWD.

 

[DaveEV]

I would recommend mounting the drive unit in the rear like Windraver says. A manual transmission takes up valuable space and weight for no appreciable gain. That is if the LDA can fit in the rear subframe of the Miata, it might fit but it would be tight. The gas tank is above it which when removed would provide clearance. Miatas are tiny, tiny cars. If I was doing a small sportscar build I would do a MR2 Spyder with Leaf drive unit in the rear, half the battery in the rear, half the battery in the frunk. That would be an awesome car. Like Windravers CRX but RWD.

Thank you both! Definitely following the both builds as I want to Toyota truck after this, and the CRX has similar space issues. I really like that BlackBox which would be great for everything RWD/4x4, including this Miata.

I'm dropping the subframe and fuel tank this week, having a machinist friend come over and talk about possibilities. I'm sure there is space (maybe even with inverter mounted), just some cutting and welding to be done. I don't have a battery yet, so not sure what my DC/DC and BMS look like. Rear mount would definitely clean up the battery issues you've identified for me, thanks for making sure I'm considering that. I think if I had a Leaf pack I'd have to split between front and trunk regardless. Almost time to start measuring and planning that stage!

 

[DaveEV]

With a little help from some friends, I've dropped the subframe and gas tank. I couldn't break either axle nut, need MORE leverage! Not sure popping the axles out of the diff was a good idea, but I had help and really wanted to get that gas tank down! I only cut one wire group, which I'm pretty sure was for the pump. I still need to go back and get all the fuel lines and junk out, but it sure seems like there is a LOT OF ROOM! Can't wait to start measuring things out!

I took off lower control arms from subframe, disconnected UCA at hub. I stripped one of the swaybar hex bolt things, so that's staying on for now.

Trying to use some plastic bags to keep the gunk out. I'll either reuse or try and sell the differential.

Can't see them, but bungies are holding the brake calipers. There were a bunch of little 10/12mm bolts for the fuel lines, filters, whatever canister is in that box... But tank has 4x 14mm bolts. Probably good mounting points if part of the battery pack ends up going here. Your thoughts?

Rear subframe with UCAs and differential still attached. Forward is toward top of photo. Should be solid for mounting the LDA, either forward or reverse, but one of the crossmembers is going to need reconstruction.

This sure seems like a lot of room! Maybe mount LDA in reverse, swap some wiring, and mount 1/3 of battery pack here. Thoughts?

I hope to give the LDA, subframe, and maybe the diff to someone who can get it mounted. Probably have them do the axle mashup too, so I can get that all measured right. Does anyone have this done already? I need to check the NB vs RX8 track and axle specs, maybe InductiveAuto's EX-8 has good template for axles?

Battery is probably next big step. Hoping @windraver and I can figure out how to ship 48 Leaf modules to Hawaii!

 

[DaveEV]

Apparently my NB Miata track width is 1440 mm Rear, and RX8 is 1505 mm. Also, one guy succinctly says NC Miata and RX8 half-shafts are not interchangeable at either end. Couldn't find NB :/ But maybe I almost know the pieces and sizes now? Miata outer, EX8 (less 32.5mm[65/2]) shaft, Leaf inner?

 

[DaveEV]

Gas tank is all the way out, and it looks like I'll be able to sell the pump and float unit. Nice. Since I'm going to mount a part of my battery pack up here, I'm wondering if I could cut the tank and use as a base. It already has holes to mount to chassis, maybe needs some reinforcement. Feedback appreciated!

I think mounting the motor in the rear is too much. There are some other things I could try, but I'll try to be a little more straight forward. Drive assembly is two wide to fit between lower control arms, in both front/back and left/right directions.

 

[GassedOut]

Gas tank is all the way out, and it looks like I'll be able to sell the pump and float unit. Nice. Since I'm going to mount a part of my battery pack up here, I'm wondering if I could cut the tank and use as a base. It already has holes to mount to chassis, maybe needs some reinforcement. Feedback appreciated!

Gas tanks are pretty thin metal. I doubt it would have much structural integrity (and more importantly, battery-supporting strength) once it's no longer a fully boxed shape. But, if you were to cut away most of the skin and use the mounting points to build back in a reinforced frame, I could see that being useful.

For years, I wanted to do an engine swap on my Miata -- K-series, Ecotec, LFX -- but sinking that much money into a dying technology (ICE) was hard to justify. Converting it to electric kept tempting me, but every time I researched it, I was dissuaded by the packaging difficulties you're encountering. I'm hoping battery density improves dramatically in the coming years, but I'm definitely following your build with interest in the meantime!

 

[Electric Land Cruiser]

View attachment 131736

Above that panel is the parcel shelf, between it and the trunk there is even more dead space. You can access it from the interior if you remove the seats and soft top. I think the LDA will fit in the subframe. Make a jig to hold the important parts and cut away what you dont need then weld in bracing. It actually looks really promising! The LEAF drive unit is pretty small.

 

[windraver]

If you take off the existing motor mounts, the motor is quite small. There are a bunch of excess parts that don't need to be on the motor. Even in the CRX, a very small car, it might've been possible to rear mount the motor.

 

[Tremelune]

If you can fit it where the diff is without having to reengineer the suspension, that would be huge. Like, you'll have to cut and weld, but as long as you didn't mess with the mount points, axles can be made for a grand. The gearing is good, and you'd have a lot more space for batteries. Cool project.