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Discussion Starter · #1 · (Edited)
Update / FAQ (2021-11-03):

Safety / coziness: Yup. I'm comfortable motorcycling, with my girlfriend.

From a 2015+ (6th gen / S550) Mustang with a performance package, stock: Super 8.8 diff (IRS, LSD), axles, hubs, maybe hub carriers / knuckles and brakes.

20x8" steel wheels (common on hot rods).

66.75" = 169.5cm track
114.6" = 291.0cm wheelbase
74.75" = 189.9cm width at tires
179.1" = 454.8cm length

The body is 87.5cm = 34.4" at the cabin (widest).

395V 860A = 340kW at the battery packs.

Estimating 2200 pounds total. Duncan's Dubious Device plus another Chevy Volt battery pack.

Original post:
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Tire Wheel Land vehicle Vehicle Car

Tire Wheel Vehicle Automotive tire Automotive lighting
Tire Wheel Vehicle Automotive tire Car

Wheel Tire Car Vehicle Automotive tire


4k 60fps video loops on my website: https://www.eternalmachinery.com/ecar/

$6,000, 864lb - Two Chevy Volt battery packs, used, 36.8kWh (beige)
$2,400, 156lb - NetGain Warp 9 motor (red)
$2,875, 16lb - Zilla 1k controller + hairball (green)
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$11,275, 1036lb

I could really use some more people telling me "That looks fun, you should build it."

Meant for street use, as a daily driver, at least when I don't need space for more than a passenger or a bag of groceries. Or heat? Not really sure about range, most places I go are within 34 miles, and I think 37kWh and the light vehicle weight should manage that?

Beyond that, the goal has become entirely whatever makes me shiver.

I'd love guesses on total vehicle weight. And all kinds of feedback. I haven't bought or built anything. Everything is negotiable.

I've gone back and forth between "ICE is so much cheaper" and "not having to deal with a drive shaft is great" a bunch. I think I've finally decided that I just can't make the drive shaft work to my taste. And used batteries are a little more reasonably priced. And this shape has made me tingly for years. So, time to start nailing down specifics, learn to weld, and learn to calculate suspension and steering geometry. And mock up the cabin and see if my girlfriend and I fit.

I'd particularly appreciate suggestions on the electric components. Used Chevy Volt packs seem like a decent option. The Soliton 1 became unavailable, the Zilla 1k came back. Everything fun seems to use a NetGain Warp 9 motor.

Having liquid cooled batteries and controller but an air cooled motor seems silly. The obvious solution to that seems like the NetGain Hyper 9, but... is it as fun?

I was so pleased with my modelling of the wiring, and then realized I accidentally did it all in series. I meant to split it into two parallel halves. They're 395V, 430A peak each. Do I want to double the amps or volts? 340kW peak should be fun, right? 28kWh usable, 37kWh total.

If I have some of the batteries in the front, and some in the back, and they're not split exactly in half, and I need to run two halves in parallel, I need to run four lengths of cable through the cabin, right? I have the batteries distributed as they are for perfect 50/50 weight balance. I also need to run a pair of coolant lines through the cabin. I'd be curious where emergency responders would like me to place all these things, in case they feel a need to cut me out of it.

Zilla 1k:
· Maximum Battery Current at 200V: 950 Amps = 190kW
· Maximum Battery Current at 300V: 885 Amps = 266kW
· Maximum Battery Current at 400V: 800 Amps = 320kW

So, yeah, looks like running the two packs in parallel for 395V 860A would be best?

Motor (output shaft) is bolted directly to the differential (pinion shaft, I'll need to get a coupler made). Changed ring and pinion gears to match motor RPM limit with, I don't know, 90mph? Looks like I need to use a front diff, to avoid problems with oil flow, since I have the diff oriented backwards. Not sure exactly which would be best. Definitely need an LSD. And one of the bigger problems is a lot of front diffs are significantly more lopsided than rear diffs, but possibly due to removable stub axles?

I'm in Southern New Hampshire.
 

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View attachment 124224

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Motor (output shaft) is bolted directly to the differential (pinion shaft, I'll need to get a coupler made). Changed ring and pinion gears to match motor RPM limit with, I don't know, 90mph? Looks like I need to use a front diff, to avoid problems with oil flow, since I have the diff oriented backwards. Not sure exactly which would be best. Definitely need an LSD. And one of the bigger problems is a lot of front diffs are significantly more lopsided than rear diffs, but possibly due to removable stub axles?
Whether they are live beam axles or final drives for independent front suspension, those front axles are only offset so that the propeller shaft can clear the engine. You can use the same centre section in a non-offset configuration. You might also not need a specifically front unit - the differential internals are the same, and some ring-and-pinion sets can run either way.
 

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Discussion Starter · #7 ·
it looks like a cool build!

Not to spoil the fun though, my first impressions were "are you sure you wanna use battery boxes as front and rear crash structures...?"
Thank you. Yup, safety is not a high priority in this design. I figure it's significantly safer than my motorcycle, and I'm comfortable with that.
Whether they are live beam axles or final drives for independent front suspension, those front axles are only offset so that the propeller shaft can clear the engine. You can use the same centre section in a non-offset configuration. You might also not need a specifically front unit - the differential internals are the same, and some ring-and-pinion sets can run either way.
That is very helpful, thank you. Do you know of any specific examples that would work? Or how best to find them?

Seems like something that came with an LSD would be nice, but maybe not, since I need to change the gear ratio anyway. It would also be nice to use a rear diff that can handle the rotation / oil flow, so I can use the original axles (without removing the stub shaft(?)).

Are there any with a centered pinion, equal length half shafts, and an offset ring gear? (Not important, but I'm curious, I like symmetry.)
I understand the tandem seating arrangement, but there's no one I would want and be able to sit with this way. You may find it works, but a serious mockup (with sides, not just two spots marked on the floor) would certainly be required.
Yeah, I'm thinking just passengers I'd ride a motorcycle with. And definitely need a mockup with walls and a roof.
That may have been true several years ago.
Can you give me examples that are fun without a Warp 9 motor now? Other than snowdog's electric supercar, with a Tesla subframe, which I believe would be too wide for this body, and cost $56,499.37 for the build as of March?
 

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Can you give me examples that are fun without a Warp 9 motor now? Other than snowdog's electric supercar, with a Tesla subframe, which I believe would be too wide for this body, and cost $56,499.37 for the build as of March?
There are many swaps using Tesla drive units or any other common modern EV (e.g. Leaf), and all will have more power available than any WarP 9 can produce; they don't need to be as expensive as snowdog's car, but none will be the $1,000 that some people seem to think an EV can be built for with a free forklift motor, homebuilt controller, and some miracle deal on a salvaged battery.
 

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Seems like something that came with an LSD would be nice, but maybe not, since I need to change the gear ratio anyway.
Since the same ring and pinion gears worth with limited-slip and open differentials of the same final drive model, you can change the ratio without losing the LSD. You can also find something with the right ratio and replace the open diff with a limited-slip, but it would have to have a limited-slip available.
 

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It's not my style but it looks like fun! I say build it but I agree I'd go with a modern EV motor. Maybe LEAF motor and transaxle with custom controller. The LEAF motor is small and 100-150lbs or something so pretty light. Can make 300+kw with custom inverter (and the right batteries).
 

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Discussion Starter · #12 ·
There are many swaps using Tesla drive units or any other common modern EV (e.g. Leaf), and all will have more power available than any WarP 9 can produce; they don't need to be as expensive as snowdog's car, but none will be the $1,000 that some people seem to think an EV can be built for with a free forklift motor, homebuilt controller, and some miracle deal on a salvaged battery.
Thank you. Is there any way to get a Limited Slip Differential with a Leaf motor?
 

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Are there any with a centered pinion, equal length half shafts, and an offset ring gear? (Not important, but I'm curious, I like symmetry.)
Looking for examples, it appears that all conventional (not high pinion) front differentials have the ring and pinion gears cut the same as at the rear, so a rear unit can simply be turned around (and the motor rotational direction set appropriately). Typically rear final drive units are set up for equal-length half-shafts and a centred pinion shaft.

In a discussion of Dennis Palatov's 2019 Pikes Peak Racecar, we had a look at the complete chassis:
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A 2020 article mentioned that the car was run on the salt flat at Bonneville (in 2019) and included this interesting view of the D2EV without bodywork or battery packs:
I'm reasonably certain that the front final drive unit is normally used at the rear, and is simply turned and placed in the front. Some members of this forum worked on that car, so they might know what was used, but as far as I know they were not on the mechanical side.
 

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but none will be the $1,000
1000 euro was the challenge. Bit more wiggle room.

I could really use some more people telling me "That looks fun, you should build it."
Doesn't matter what we think, if you think it looks fun, then go build it. It's certainly different, which means, maybe almost no one would think it's cool except you. That's okay, you build the car that's perfect for you, not us.

The Soliton 1 became unavailable, the Zilla 1k came back.
So... Damien threw together a quick 1000+ amp DC mod board for the stupidly-cheap salvaged Prius Gen 2 controller ($150 at most, lots are grabbing them for $50).

Though, he never really finalized or produced the design. EV8 over on the OpenInverter forums was smart enough to read that design and build a quick sample board of it on some perfboard... without writing any of it down, just keeping it all in his head. I think he stuck it into his RX8, and was disappointed by only 265 hp out of it or somesuch before he I think melted his motor or something (controller was fine). He's moved onto an AC build now.

So a couple of us said "Stop, wait... can you share what you built?" and he's too busy to get around to doing it, said he'd have to write it all down. So I was like "No, just, share what you did, whatever you used to build it" and he was like "Oh, I just built it in my head". And then with some slight nagging, he's come around to "Okay fine, didn't think anyone was still doing DC builds... I'll try to get around to it sometime after the next couple weeks." That was, yesterday.

Anyway, point being, for something close to almost free, you can repurpose a Prius Gen 2 inverter and go melt a motor if you want to, depending on how good you are about reading schematics or, how patient you are and gambling that EV8 will find time to publish something more crowd-friendly.

Everything fun seems to use a NetGain Warp 9 motor.
Don't pay for a Warp 9. Use a forklift motor if that's where you're at. Pretty much same thing, and you can get one for ~$150 in scrap value, (I got several for free). Some people say they have trouble finding these, but, I'd say the massive majority are still able to do so without much hassle at all. Call up forklift repair places in your city, ask if they have any old traction motors around "Just in case" that you could buy from them, or any junkers in the yard you could pull the motor off yourself. There's a massive 130-page thread in the motor forums here about how to do this.

Seems to me you can easily get both motor and controller for a DC build for well under $500. Under $200 if you're persuasive.
 

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Discussion Starter · #16 ·
Looking for examples, it appears that all conventional (not high pinion) front differentials have the ring and pinion gears cut the same as at the rear, so a rear unit can simply be turned around (and the motor rotational direction set appropriately). Typically rear final drive units are set up for equal-length half-shafts and a centred pinion shaft.

In a discussion of Dennis Palatov's 2019 Pikes Peak Racecar, we had a look at the complete chassis:

I'm reasonably certain that the front final drive unit is normally used at the rear, and is simply turned and placed in the front. Some members of this forum worked on that car, so they might know what was used, but as far as I know they were not on the mechanical side.
That's great, thank you. So I should be able to use a Ford 8.8" rear diff, which seems very popular for custom things, just oriented as a front diff? Its pinion is horizontally offset by 2", are you considering that centered?

Wow, I used to follow Palatov's stuff a lot when he was working on the DP1, I had no idea he won Pikes Peak a bunch of times.
 

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So I should be able to use a Ford 8.8" rear diff, which seems very popular for custom things, just oriented as a front diff?
Yes, that's in most Ford cars with IRS, RWD/AWD, and a longitudinal engine. There is a range of ring-and-pinion sets for it to change the ratio. Stronger versions built since 2015 are called the "Super 8.8"; some parts are not interchangeable between the versions (apparently pinion bearing etc. for the "super" come from the Ford 9.75 unit) so get the one you want from the beginning. The Mustang has used a Super 8.8 with IRS since 2015. It comes in both aluminum and iron housings.

Its pinion is horizontally offset by 2", are you considering that centered?
Yes, that's what I was thinking of as close enough. There's no good reason for an auto designer to require the propeller shaft to be exactly centred, so I'm not surprised that they vary by that much.
 

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Discussion Starter · #19 ·
Yes, that's in most Ford cars with IRS, RWD/AWD, and a longitudinal engine. There is a range of ring-and-pinion sets for it to change the ratio. Stronger versions built since 2015 are called the "Super 8.8"; some parts are not interchangeable between the versions (apparently pinion bearing etc. for the "super" come from the Ford 9.75 unit) so get the one you want from the beginning. The Mustang has used a Super 8.8 with IRS since 2015. It comes in both aluminum and iron housings.

Yes, that's what I was thinking of as close enough. There's no good reason for an auto designer to require the propeller shaft to be exactly centred, so I'm not surprised that they vary by that much.
Great, thank you. Yeah, I had a feeling. In such a narrow bodied and symmetrical car, it's noticable, but I can cope. You can't see it because this quick render has a black background, but the offset gives me a fine place to tuck the charger.
Triangle Gas Electric blue Symmetry Art

A miata donor, or at least the rear sub frame with diff and suspension would be MUCH easier to start with than a Ford rear end. Check out the Exocet for clues. The electric motor could be directly coupled to the diff and still be behind the rear seat
Many possibilities in life would be much easier than attempting this project. But using the Miata rear suspension... would not give me the inboard coilovers I want. I want to do the suspension much like an FSAE car (with outboard brakes).

But I do often think about building a regular locost 7 or T-bucket for practice.
 

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A miata donor, or at least the rear sub frame with diff and suspension would be MUCH easier to start with than a Ford rear end. Check out the Exocet for clues.
Yes, it would be easier, but the Miata subframe would be wide compared to the desired body; the Exocet is not a narrow tandem-seat vehicle.

The electric motor could be directly coupled to the diff and still be behind the rear seat
Yes, but the final drive unit would be facing the wrong way... although the suspension with an early Miata subframe would probably be usable turned around.
 
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