Ordered gauges

I wanted to get a state of charge rather than a volt meter. I think it would be easier to see what % of charge is left rather than having to know what voltage was 80% State of Charge (SOC) or 50% SOC. None of the suppliers I found offered a state of charge for 156 volt system. Took some time, but I found the www.westach.com site – these are the suppliers of the gauges to Electo Automotive and EVparts – and they were happy to make a custom gauge for me. The Optima helpdesk questions@optimabatteries.com provided the numbers for 50% and 100% for their yellow top batteries, but unfortunately, the numbers aren’t linear, so the gauge would need to be set for the 0%, 50% and 100% voltage. Westach explained that they can only set 0% and 100%. After some thought, I went with the 50% SOC number for 0% (you shouldn’t go below 50% if you want to your batteries to last anyway). So the gauge will show the *useful* state of charge rather than actual. 80% SOC now shows as 40% - a little confusing, but I think I can live with it.
I ordered a 1000 amp gauge and, since the gauges will look different than stock, a matching temp gauge for the controller. I plan to put the 3 gauges in the stock instrument cluster.

Adapter in!

Adapter arrived today. It’s made out of two pieces not including the flywheel hub. Billet aluminum - looks like something off a hotrod.

Bought new welding kit on eBay

Bought a new Victor FirePower (medium duty) $133 w/ shipping from www.weldingsuppliesfromioc.com. New regulators, handle, tip, gauges and goggles. The handle has back fire suppressor, which sounds good to me. I know it’s not professional grade, but that’s okay for what I’m using it for.

More steel for rack

Bought more steel for the rear rack. I’ve been re-reading my welding book and think the tip I have is too small. Took it into a welding supply store and they told me it’s old and an off brand that will be hard to find.

Start rear rack

Bought some steel and started the rear rack. The layout is for 5 batteries: 2 length wise, 2 more length wise below them and one width-wise (is that a word) to the right. Should fit into a 28” x 14.5” rack. My welding sucks, by the way.

Motor, motor mounts in!

Got two boxes today from EvParts. The motor looks pretty big…

Sold more parts on craigslist

Sold the catalytic converter, radiator and intake tube – and also got some interest on a conversion too. Seems like theses Miata folks often have more than one car and are genuinely interested in what I’m up to. A couple asked if I could send them some info on electric Miata conversions.

Buy first welding set

Bought a used welding set: handle, torch, regulators tanks and a roll around rack. I didn’t want to spend a lot, and it looked okay to me.

Drop flywheel off for lightening

The stock Miata flywheel in 19 pounds. An ICE engine needs the flywheel to keep it revolving between power strokes. An electric motor doesn’t need one. So why keep the flywheel? It’s how the clutch is connected – and I want a clutch (some conversions don’t use clutches, but they are difficult to shift). The lighter the flywheel the better the acceleration – racers know this and use expensive ($500 and up) aluminum flywheels. My plan is to have the flywheel lightened. I called a local machine shop and they told me that only one shop in the Bay Area does this stuff. I gave him a call and he quoted me $160 to lighten it. The shop isn’t open on weekends so I arranged to drop it off on my lunch hour.

Ordered motor, motor mounts

Ordered the motor from www.evparts.com since they had the ring clamp that’s going to be the key part to my motor mount. I like the idea of spreading the money around for this project – keeps everybody in business… I also got a couple of biscuit style mounts since the stock motor mounts and location may not work for me.

Cut a hole in the trunk

I’ve got a couple of hours to spend on the car today and the next step is to cut the trunk for the rear battery rack. I measured the distance between the frame rails and it’s 28” - should be enough room for 5 batteries. Since you can’t really see the edge of the frame rails from the trunk, I used a drill from below to mark the corners of the cut. Using a metal ruler and a sharpie I marked out the area to be cut. I used a hand grinder with a cutting blade a little sloppy, but I can grind out the wavy edges later.

Drain tank and plug holes

I’ve got the car up on jacks as I pull out the exhaust system and fuel lines. I was originally planning to pull out the gas tank to use that space for 3 or 4 batteries but it looks like a bad idea. You need to pull the read subframe, differential and transmission to get the tank out! Plan B was to cut the sheetmetal from the interior and trunk area and pull the tank from above, but the tank is shaped like an inverted T and won’t come out from the top. I never liked the idea of having batteries in the passenger space anyway and there would need to be some tricky racks and tie downs for the batteries in that spot. I decided to leave the tank and put the 3 – 4 batteries under the hood by the firewall instead. I bought a siphon pump and drained the tank. I bought some rubber plumbing plugs at a hardware store and removed and plugged the vent and fuel inlet.

Ordered adapter

Electro Automotive http://www.electroauto.com/ has the dimensions for an adapter that will connect an electric motor to a Miata transmission. This is a tricky part since it properly off set to position the clutch and flywheel where they were before. Plus, a special flange is needed to connect the flywheel to the motor’s shaft. Best to leave this to a professional.

Engine out

Today’s the day, but that’s not my picture. It’s from a great Miata site, www.miata.net. Also, I didn't pull the tranny, but a great picture, just the same... Anyway, rented an engine hoist for $35 and spent the next 6 or so hours pulling it out. The instructions in the Miata Enthusiast's Manual were real good, except for the part about disconnecting the relay under the dash to disable the fuel pump. They wrote it using an English car and said they weren’t sure if it was the same for a US car. Well, it is. It’s a bright yellow relay, just like an English car. Other than that, it went out nice and easy. Took the flywheel and clutch off, since I’ll need them later, and called the buyer to bring his truck over – saves money on the hoist rental if you can get it to the buyer within the same 24 hour period.

Drain AC system

Found a guy willing to buy my engine for $100. I might have been able to get more, but I can’t get really started until the engine is out and it’s easier to sell it when the buyer can hear it run in the car rather than sitting in the corner of your garage. The waiting is getting to me, so need to let it go. So the AC needs to professionally emptied because the R12 coolant is nasty stuff. Found out there are only two places in SF that do it. I picked one, topped off the coolant (leaky water pump) and drove off. After $35 and an hour it was done. Car rides pretty nice, too.

Order wiring diagrams

No wiring diagrams in the manual! What were they thinking? Luckily, you can find most anything on the web. Got a set of diagrams by a company calling themselves Automotive Hobbyists. http://www.ahdol.com

Miata Repair Manual

Ordered manual on Amazon Mazda MX-5 Miata 1.6: Enthusiast Workshop Manual
I'll be needing it for instructions on pulling the engine and, after the conversion, for brakes and other non ICE maintenance. It's not an official shop manual, but it will hopefully be more readable.

Got a car!

I’ve been monitoring CraigsList for Miatas for a while. I’m looking for first generation – ‘90 to ’96 – preferably ’94 or later because they have a passenger air bag. Has to be manual transmission, the rest is a trade off - does it make more sense to fix it or pay for it up front. So I thought I found a car, but while trying to arrange to see it, a better car popped up. It’s a ’92 with a straight body, replaced top, AC, manual steering, alloys and a blown head gasket. Went up and looked at it and found that ir wasn’t the head gasket, but a leaky water pump. Nice, that makes the resell of the engine a little easier. For an extra $100 they even delivered it.

Welding class

Did a little research and found that Oxy Acetylene was the easiest to learn and the equipment was the cheapest. Bought a book on it that made it sound pretty doable. Still a class would give me a chance to ask questions and have a better handle on safety issues and the like. There are a bunch of classes offered at city colleges, but they are too long for my needs and you need to sign up at the beginning of the session. I found a class at a tech center called Tech Shop. They give you instruction on stuff, wave soldering, plasma cutting, etc., then you can buy time on their equipment. They had an Oxy Acetylene class at 35$ for one hour. Good deal. Now I’m dangerous. www.techshop.ws

Planning, planning, planning...

I’ve been thinking about converting a car for a while almost a year now. I’ve researched other conversions, joined some EV mail groups and read a few books. I decided to focus on converting a Miata, they are light, aerodynamic, cheap and plentiful. I put together a spreadsheet to compare different components and voltages. And the best combination of speed, range and cost got me came out at 156 volts with a 9” WarP and a Zilla 1K. Next was to sell the concept to my wife. Luckily she is pretty understanding of my eccentricities and went along with the idea.