# Rate my build plan (c3 corvette)



## joekitch (Sep 13, 2013)

Location: *San francisco, CA*

Budget: Like 15k for the donor car, and hopefully less than 20k for all the conversion parts and any labor costs.

Donor car: *1975 c3 corvette*. They're cheap, easy to convert the bumpers back to the wonderful 68-72 chrome bumper design, and have some decent safety equipment upgrades over the early cars. A clean 1975 is like 15k, a clean 1970 is 25k or more, YIKES

also, maybe some race car flair to it, need big rear tires to hold all that torque eh?













Motor: *Tesla model S P85 large rear drive unit* OR *Tesla model 3 performance rear drive unit*. *The entire tesla rear subframe and all the suspension components, fabricating mounts so it bolts onto the c3 ladder frame. * This could be relatively easy or the hardest, most expensive part of the entire project. The motor 3 motor is more efficient when not under heavy load, and FAR FAR better cooling capacity BUT nobody supports their firmware yet and it isn't clear how many years it'll be until the T-1C supports it.











Battery: *34kw of chevy volt batteries*. I'd like Gen2 but the Gen1s are half the price and only slightly lower capacity. Some in the engine bay with a battery enclosure to make it look like a V8 because yummy under hood candy, like ICON's derelict mercury EV did. the rest of the batteries go where the gas tank used to be, which may or may not hang lower and thus cause the full size spire tire sling to have to go away. Volt batteries have excellent high performance because of almost no voltage sag. They're also cheap, work very reliably, have a nice log-like form factor, and have built in excellent battery cooling. I'm hoping for 80+ miles of range











Cooling: *unsure yet*, but the water pump and electrically controller diverter valve out of a tesla. chevy volt batteries and the tesla motors have built in cooling systems so no need to screw around making chill plates.

Controller: *EV Controls T-1C*, pretty close to turn-key, i'd buy it from EV west specifically so i can lean on them for tech support and general info. This controller's already been used in a few tesla motor/chevy volt battery builds










Contactor: *unsure*

Power steering: *I really want to keep hydraulic power steering*, electric pump driven. It's wasteful but it feels so much better than electric power steering. EV West makes a belt fed pump but i'll probably re-use the one that came with the car. 

A/C: *MVP might omit this* since i live in a SF and A/C is kinda unnecessary 

Charger: Not sure how to get there, but i absolutely want to shoot for *a 50kw charger which interfaces with CCS*. With such a short range this feels like a heavy requirement for this to be driveable. There's some noises about CCS charging for DIY builds but this might be a wait and see, hopefully this becomes a mature thing soon (within a year). For 50kw, maybe just stack 5 of those 10kw tesla chargers...?

Safety: Haven't researched much but i would really like *switchable fuses between every 72 volts or so*, so at any given moment during assembly or maintenance, if i make an oopsie, i only get shocked with 72v before a fuse cuts it. Also, *inertial fuses* so in a crash, everything is isolated from everything else. Also, *a first responder safety line*, mimicking tesla's implementation with a BRIGHT RED WIRE right under the hood with a really obvious label on it. 










Timeline: *purchase the c3 within a few months, spend about a year* maintaining it, adding quality of life upgrades, more deeply researching the platform, more deeply researching the feasibility of my componentry and fabrication. HOPEFULLY buy most of the drivetrain bits in advance and *make sure the entire thing works on a bench*, THEN start converting in fall of 2020 and be done some point before fall of 2021


*So, what am i missing, what bad assumptions or assessments am i making, etc*


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## Duncan (Dec 8, 2008)

Other than blowing your budget that sounds like a superb plan


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## joekitch (Sep 13, 2013)

hmm, what would you say is more reasonable for the ev bits if not 20k?
i guess, on the upside, i can sell the engine and transmission and exhaust/fuel system/tank to a good home to make a couple grand back


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## brian_ (Feb 7, 2017)

The Tesla Model S/X drive unit places the motor behind the axle, and that's where the fuel tank is. This could be a packaging challenge, depending on the orientation of the battery modules. The overall plan seems workable, but a realistic look at how everything would go together would be required.


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## joekitch (Sep 13, 2013)

brian_ said:


> The Tesla Model S/X drive unit places the motor behind the axle, and that's where the fuel tank is. This could be a packaging challenge, depending on the orientation of the battery modules. The overall plan seems workable, but a realistic look at how everything would go together would be required.


i actually get a little lucky with this, the gas tank sits on top of the frame rails and the motor will be entirely under the rails, in a similar location to the stock diff although hanging out the back more














also, i did some rather rough fitment approximation using a c3 frame cad file i found somewhere, and a model s subframe i found somewhere else

the orange shaft is where i think the center of the axels are when the car's sitting on the ground


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## brian_ (Feb 7, 2017)

joekitch said:


> i actually get a little lucky with this, the gas tank sits on top of the frame rails ...


Right - I forgot about that detail from the last C3 discussion. It would be good to put a module under that tank level - mass up high is bad.


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## swoozle (Nov 13, 2011)

Are you sure you have enough room for two full Volt packs? I love those batteries, I have most of one pack in my car, but they are bulky and heavy compared to Telsa modules. Two full Volt packs will run 720-ish pounds. A little shy of twice as much as equivalent Tesla modules. Volumetrics are similar.


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## joekitch (Sep 13, 2013)

swoozle said:


> Are you sure you have enough room for two full Volt packs? I love those batteries, I have most of one pack in my car, but they are bulky and heavy compared to Telsa modules. Two full Volt packs will run 720-ish pounds. A little shy of twice as much as equivalent Tesla modules. Volumetrics are similar.


think so, did some quick and dirty cad work and the vast majority of the two packs can fit under the hood as a fake V8, with another long module or two going down the transmission tunnel since there's room, then a final 2 or 3x short modules taking up the gas tank
if i have to (hopefully i won't), i can consume some of the letter box "trunk" space with another module or two

by comparison, a big block chevy engine with all the fixins is like 600 pounds, not including exhaust headers and such, so 600 pounds of batteries in the engine bay is within expected bounds for mass, the th400 transmission is like 135 pounds which is another module or two, and a fully loaded 20 gal gas tank is 121 pound of mass plus the a few pounds in the weight of the tank itself.


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## MattsAwesomeStuff (Aug 10, 2017)

I like your approach to research and detail. Please keep posting here to show off your progress.

I've always wanted a C3 Vette, and I've liked the idea of doing an EV conversion of one for years. But instead I cheaped out and went with a poor man's Vette, the Opel GT. (If you're curious, thread here: https://www.diyelectriccar.com/forums/showthread.php?p=1046563 ). I'll be watching your build vicariously as the higher-budget higher-class upgrade I kinda wanted to do instead.

...

I think it's prudent to not be overly prescriptive of what you necessarily want, unless you're passionate about certain build details. Rather, figure what you want for performance, and then fill back on the stuff that can make that happen. You might be doing that, I'm not sure, just a general warning that you don't put the cart before the horse because maybe you'd be happier doing things a different way.

Donor: Love it.

Budget: $35k is enough to give you some options.

Motor: I have a feeling you're kind of set on something this powerful, or that you'd rather not bother. So, that's cool, you can make this work and your layout seems to work for the powertrain. Budget will be eaten significantly, but, it's a good foundation for the rest of the build.

Batteries: You're going with the most expensive drivetrain, and the cheapest batteries. There is nothing wrong with Volt batteries, except that they're overbuilt. That is, they are bulky and heavy for their energy density. That's going to hurt performance and range. They are cheap though. It's really the only other way to keep your budget down though, as it's usually the single most expensive component.

You're better off with Volt packs than, say, Leaf packs. But unless you're finding something less popular, Volt and Tesla are kind of the two options for you, and you might not be able to afford Tesla.

Battery prices for salvaged OEM packs may continue to fall in the future, so, if you're planning on being done in 2 years, you might want to hold off and just make the purchase later. Some of us (me, I think) kinda talked too much about how great Volt packs are for off-grid storage and their prices are double what they were a year ago, but generally I think other packs should become cheaper. You could even design for a specific form factor and just make the purchase last minute.

Cooling: Generally cooling is nearly a non-issue, and can be solved by just about anything. A half-assed plan is fine, you'll just "do something" when the time is right, and it'll take a bit longer than you hoped, but, not a lot to worry about.

Controller: The drive unit for the tesla comes with a controller of sorts. You might as well use it rather than spend $3500 on another controller. I think Damien (EVBMW.com) has a kit you can build yourself that can control Tesla drivetrains.

Contactor: Anything, solve it when you solve it.

Power steering: Re-using one but electrically powering the hydraulics is fine.

A/C: You could just plumb one from another EV, but, it's not essential to the car working, so, maybe plan for it space-wise but otherwise upgrade it when you want it.

Charger: You might have to scale back your expectations on how fast you can charge on the road.

Safety: Safety line is a good idea. Your battery pack fuses, sure.


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## joekitch (Sep 13, 2013)

I definitely could go the more bespoke route like what Damien did but i'm specifically looking for more turn-key stuff to reduce the unknowns and more importantly, get tech support for if things go weird

drivetrain wise, i'm going for the model S rear + 34kw volt batteries because it's been proving in multiple projects by now, i really like things that have been done before because it becomes a solved problem with fewer unknowns.

priority wise: *Horsepower, handling, fast charging, and simplicity of components*. That means range isn't important, lower weight is a priority, and being able to push tons of amps consistently is important. Volt packs sort of fall out naturally from those requirements. As for the tesla motor, i just find it'd be more livable vs the old school warp DC builds, also more aftermarket support both now and in the future. There's a reason EV west is changing some of their kits over to a tesla small drive unit architecture instead of the siemens motors.

Model 3 motor would be better but...well....nobody is supporting that yet, and even if they supported it a year from now it'll be a while before it's proven. 

also the volt price per kilowatt is crazy cheap. I can get 34kw for like, 4 grand at the most. 34kw of tesla packs. Even if i can get full packs for $1000 a piece, that's still $7000 for 7 tesla packs (37.1 kw)

And wiring up 37kw of tesla packs in order to get 350-400v nominal, that's a lot of S and not a lot of P, voltage saaaaaaag



examples of what 34kw of volt packs + p85 rear can is able to do:
this 818 uses the T-1C controller, it's their shop car
https://www.youtube.com/watch?v=F6ITzRiAUTg




blue lightning uses a more traditional ECU by motec with a ton of custom software fiddling to make it into an ev management system
https://www.youtube.com/watch?v=t3F-8QnmNW0


I'm waffling on adapting the model s subframe over though, it may be much less fab work to just weld motor mounts to the cross members around where the diff is in the stock c3 frame, the motor might need to sit at a weird angle though, sort of cocked upwards in the back. 
Problem is, the leaf spring in the stock c3 uses the diff itself as a central suspension member! Not sure how to adapt that to the model S motor?


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## Duncan (Dec 8, 2008)

To Matt's point about waiting for a while 

The Volt packs are now a limited resource - they stopped making the Volt a while back

If you wait 2 years they may well be unobtainable!

Two parts to that - future proofing - and price
Is something else going to "replace" the Volt packs?

How many Chevy Bolts are being sold??


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## joekitch (Sep 13, 2013)

If that's a factor i'd look at the packs used in the VW architectures, personally, because they're pretty good and will be EVERYWHERE soon
the two BIG problems with those are
1) unknown platform, like, haven't been used in a lot of conversions 
2) no built in cooling so i have to machine a lot of chill plates and design my battery boxe(s) around those chill plates. 

those are both huge mitigating factors imo, unless chill plate fab/positioning isn't as big of a problem as i thought


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## Duncan (Dec 8, 2008)

Hi
As far as I know only the Nissan Leaf does NOT have liquid cooling - I'm pretty sure the new VW's will have liquid cooling


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## joekitch (Sep 13, 2013)

correct, they will have liquid cooling in the car
but if you separate out the modules, they do not have liquid cooling built into them. the Volt and tesla packs have cooling chill plates essentially baked into their form factor










see, this chevy Bolt battery pack disassembly video, the chill plate is designed to fit in that big pack but it doesn't split apart into smaller chill plates
https://youtu.be/ssU2mjiNi_Q?t=5348

the battery modules themselves:
https://youtu.be/ssU2mjiNi_Q?t=4058

so, if you want cooling, you'll have to make your own chill plates :/


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## Duncan (Dec 8, 2008)

Flat coolant plates are easy to make 

I made one for my controller - all you need is a thick aluminium plate and drill some long holes with liquid connectors 

The actual Chevy ones will be lighter and cheaper for them to make - but we can easily make something that does that job


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## Duncan (Dec 8, 2008)

That battery (Bolt) looks very impressive!


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## joekitch (Sep 13, 2013)

Duncan said:


> Flat coolant plates are easy to make
> 
> I made one for my controller - all you need is a thick aluminium plate and drill some long holes with liquid connectors
> 
> The actual Chevy ones will be lighter and cheaper for them to make - but we can easily make something that does that job


the plates are easy but you have to design your entire battery box architecture around including those chill plates in the right locations, and bolting the batteries to them in the right orientation etc.
with the volt packs it's just like, line em up and plug your coolant lines into the coolant ports on em

also, i literally can't find a chevy bolt battery module for sale, not even car-part has them yet


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## brian_ (Feb 7, 2017)

joekitch said:


> Problem is, the leaf spring in the stock c3 uses the diff itself as a central suspension member! Not sure how to adapt that to the model S motor?


I assume that you're referring to the use of the final drive (diff) case as structure. Some sort of framework could probably be built, but most people would probably just do a conversion from the leaf spring to coils (coil-over shocks).

A bigger problems is the use of the axle shafts as suspension links (which has nothing to do with the leaf spring), so the final drive (diff) output bearings need to handle lateral forces (cornering loads) as pushing and pulling on the axle shafts. The solution is to not use C3 suspension... it's just hopelessly antiquated, and incompatible with any modern drive hardware. On the other hand, apparently swing-axle Triumph Spitfires have used Hitachi (used by Nissan and Subaru) diffs without destroying them... so some sort of hack might be possible.

If you don't want to use the Tesla suspension and subframe, an option would be the C5 components on a custom subframe; the Tesla powered Mercedes Vito shows this is possible with a large Tesla drive unit.


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## brian_ (Feb 7, 2017)

Duncan said:


> As far as I know only the Nissan Leaf does NOT have liquid cooling...


There have been others, but the Leaf is the only common modern EV without liquid cooling, and the only one without active cooling (there have been some with forced air).



joekitch said:


> the Volt and tesla packs have cooling chill plates essentially baked into their form factor


Yes, and they're the only ones as far as I know. Even Rivian's pack design for their proposed pickup and SUV use plates under the modules... and they even use cylindrical cells like Tesla.

Rivian does bring an interesting idea: apparently they are sandwiching chill plates with modules on the top and bottom of the plates, getting double use out of each plate and eliminating a large unused face. Of course that make the packaging challenges worse, especially since the plate must go on one specific face of the module.

And we shouldn't call them "chill" plates, because they heat the battery under some conditions.


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## brian_ (Feb 7, 2017)

Duncan said:


> Is something else going to "replace" the Volt packs?


I think that's a good question. The Bolt seems obvious, but has the same problem as other mainstream EVs: with 60 kWh pack capacity and the modules all in series, using a fraction of the pack which fits in a conversion means getting a fraction of the operating voltage. That might work out well for brushed DC motors and aftermarket motors intended for industrial vehicles (e.g. the HPEVS AC series), but is a concern for salvaged EV motors that are designed for the voltage of a full 96S pack.

Some people are starting to use the LG Chem modules from the Chrysler Pacifica Hybrid. Like the Volt, the modules total 96S but are only ~16 kWh in total, since (like the Volt) it is a plug-in hybrid. Logically the Mitsubishi Outlander PHEV would be a similar source, but I don't know if those will ever be common.


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## brian_ (Feb 7, 2017)

joekitch said:


> If that's a factor i'd look at the packs used in the VW architectures, personally, because they're pretty good and will be EVERYWHERE soon
> the two BIG problems with those are
> 1) unknown platform, like, haven't been used in a lot of conversions
> 2) ...


It isn't just unknown, it's multiple platforms. VW has talked about their "MEB" EV-specific platform for a long time, but every VW Group EV produced so far has been on an adapted engine-driven platform, and even the coming Porsche Taycan - which apparently has an EV-specific platform - is not on MEB. It's not at all clear to me that that the EV components will be consistent between those vehicles and what they will be building.


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## MattsAwesomeStuff (Aug 10, 2017)

joekitch said:


> drivetrain wise, i'm going for the model S rear + 34kw volt batteries because it's been proving in multiple projects by now, i really like things that have been done before because it becomes a solved problem with fewer unknowns.


From an outsider's perspective... there are complicated parts of an EV build, and there are simple parts of an EV build. When you absorb it all at once, it all seems equally complicated. So I understand your "go with a known working solution" approach.

However, just so you can make an informed decision... Controllers and motors are agnostic about where the voltage comes from. So while you might be thinking "I want batteries I know will work with X", and intimidated from leaving this known pairing of motor and batteries, that's largely an unfounded fear.

Volt batteries are pretty high power density, but other than that, any battery system you choose would work fine with the Tesla motor. There's really no matching concerns at all. If you wanted to choose a different battery pack, everything will be fine and not additionally complicated. (Also, Tesla batteries for sure were designed for use with Tesla motors , if you want "proven" solutions then this is proven several orders of magnitude more ).



> That means range isn't important, lower weight is a priority


So, that's a huge tradeoff right there.

If lower weight is a priority, then lose range.

If lower weight is a priority, then don't use Volt packs because they are very bulky and heavy for their energy capacity. You could get much lower weight for the same range (like, double) by switching to a different battery.



> and being able to push tons of amps consistently is important. Volt packs sort of fall out naturally from those requirements.


Not really. Volt packs have awesome power capacity, but terrible energy capacity. 



> As for the tesla motor, i just find it'd be more livable vs the old school warp DC builds, also more aftermarket support both now and in the future.


Tesla motors are definitely more awesome than some old DC motor. Regen available, more power, etc. No argument there.

But I'm not sure what aftermarket support you're thinking should/could exist for a DC motor, to ever weigh into your decisions. I.E. What or why would you ever need for support? Change the bearings ever 15 years maybe? They'll be $10 each from any store, standardized for decades. Want it to go faster? Give it more voltage. They're as simple as soup.

I think this is another place your evenly-spread fear of "support" is misplaced. 



> There's a reason EV west is changing some of their kits over to a tesla small drive unit architecture instead of the siemens motors.


Cost is probably the reason. Marketing is probably another. People want stuff with Tesla parts in it. There will be enough crashed, pre-engineered Teslas to supply EV West for as much business as they'll ever have. Certainly more than some system they're patching together themselves in low quantities.



> Model 3 motor would be better but...well....nobody is supporting that yet, and even if they supported it a year from now it'll be a while before it's proven.


Damien just got offered a Model 3 front and rear (they're different) motor on consignment basis that some of his community is trying to crowdfund to pay for. And a few other options. But you're correct. Volunteer open-source controllers are probably the most-abandoned and slowest-progressing facet of DIY EVs. Too highly specialized knowledge required, too huge of commitments to make.



> And wiring up 37kw of tesla packs in order to get 350-400v nominal, that's a lot of S and not a lot of P, voltage saaaaaaag


I get where you're coming from, but, when you apples-to-apples it, I don't think that's how it works out. There's no free lunch.

Watts per pound or watts per KWh are going to be fairly comparable. You'll avoid voltage sag by increasing the size of the pack, sure, but keeping the pack size the same? Now it's just down to chemistry. Volt packs are from a hybrid so they're optimized to be a little more power heavy, but they're also old tech and twice the weight.

...

Anyway, it's your project, just trying to help make sure you're making the right choices for you for the right reasons.


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## brian_ (Feb 7, 2017)

joekitch said:


> priority wise: *Horsepower, handling, fast charging, and simplicity of components*. That means range isn't important, lower weight is a priority, and being able to push tons of amps consistently is important. Volt packs sort of fall out naturally from those requirements.





MattsAwesomeStuff said:


> Volt batteries are pretty high power density
> ...
> Volt packs have awesome power capacity, but terrible energy capacity.


For a given voltage, "tons of amps" means "tons of power": this with "range isn't important" is a description of a need for high power, not high energy capacity.


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## MattsAwesomeStuff (Aug 10, 2017)

> For a given voltage, "tons of amps" means "tons of power": this with "range isn't important" is a description of a need for high power, not high energy capacity.


Right. But, is range that much of a non-issue?

Is the Volt actually the most power-dense option per pound?

Like, people rave about how they're power-dense per KWh (size of a pack), but, how much of that is just because it's actually pretty crappy in terms of KWh? Meaning you grab a pack of similar KWh, it compares favorably, but compare it to a pack of similar weight, it does not.

I haven't looked up the chart in a long time. I didn't think they were actually all that great.


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## joekitch (Sep 13, 2013)

i'll admit i'm going off just stuff i've read.
volt packs have great power density, bad energy density, are VERY inexpensive per kilowatt, well researched and known, and have cooling capacity baked into them instead of having to engineering chill plate placement
so if a want a simple(ish) install that can run 400 volts and have really good power density i'm kinda stuck

BUT! *If there's some alternative out there which does most of the same stuff but has a better energy density i'm all for it*, i just don't know what's out there that'll satisfy that. 
Pacifica battery? maybe? I just don't know

for a split second i was thinking of using two of those model 3 long modules, one through the transmission tunnel and another cocked at an angle in the engine bay but....the two short(er) modules are only 72v each, 144v nominal :/

as you mentioned yeah, it's hard to get 400v out of half the packs out of some of these systems since the modules are all P and very little S


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## brian_ (Feb 7, 2017)

joekitch said:


> for a split second i was thinking of using two of those model 3 long modules, one through the transmission tunnel and another cocked at an angle in the engine bay but....the two short(er) modules are only 72v each, 144v nominal :/


I had the same thought, but those modules are almost 1/4 of the width of the Model 3 floor, so they would be too wide for a tunnel.

The Model 3 battery has three characteristics which are different from that of the typical modern EV:

cylindrical cells (21 x 70 mm in this case), like all Teslas - this doesn't matter when working at the module level
thermal management by fluid circulating in internal tubing, like the Model S/X - I see this as a good thing
an abnormally small number of modules (two at 23S, two at 25S), meaning that each one is abnormally large and high-voltage - this makes no difference to the basic problem that half a pack is half-voltage, but gives less configuration flexibility



joekitch said:


> as you mentioned yeah, it's hard to get 400v out of half the packs out of some of these systems since the modules are all P and very little S


I would say that's the issue with all of current EV battery packs, not just some of them. If some production EV were using a much higher pack voltage then it would potentially be a source of modules that would total the desired 400 V or so in a smaller pack... but everything current is very similar, with most being 96S and the only a small variation around that.


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## remy_martian (Feb 4, 2019)

joekitch said:


> If that's a factor i'd look at the packs used in the VW architectures, personally, because they're pretty good and will be EVERYWHERE soon


IMO, we'll have fusion power plants well before VW produces anything, other than their stalling-oriented BS, in volume...


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## Tremelune (Dec 8, 2009)

Great project, great platform!

By far your hardest task will be to replace the rear subframe. I know people do wild swaps all the time, but that is _very_ unknown territory. It seems extraordinarily difficult to me. The success rate of a project seems to decrease precipitously with how long it takes to complete...I would aim for the simplest project that would produce a car you had a use for and wanted to drive.

If it were my project, I'd keep the transmission and use a different motor. The horsepower is in the batteries, and the torque you can get out of some of these motors is astounding. Yes, you'll still have to drag the gearbox around with a diff and rear axle, but it will make installation of the motor _much_ simpler, and open up some flexibility with regard to battery voltage, motors, and gearing. You'll learn a lot, and have something to play with when you're on the road...and then you'll know for _real_ what's lacking and what's not (and it might surprise you). You might even get the gumption to do another one "right" if you have a success to drive.

...All that said, an old Corvette with a Tesla rear would be really sweet. How do the track widths compare?

The Model 3 is by _far_ the best-selling EV in the US at the moment, so those batteries won't stay expensive forever (though they'll never be cheap, as there are too many uses for good batteries once the price is right). Every time someone crashes a Tesla, an EV project gets its wings...


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## brian_ (Feb 7, 2017)

remy_martian said:


> IMO, we'll have fusion power plants well before VW produces anything, other than their stalling-oriented BS, in volume...


The meaning of "in volume" depends on the observer. So far from the VW group there have been at least the e-Golf and the Audi e-tron SUV.

The e-Golf is somewhere between a stick-some-batteries-in-it conversion like the Focus Electric and the EV-derived-from-existing platform like the Leaf. At least at one point it was the best-selling EV in Europe, at a couple thousand units a month. Is that "in volume"?

The Audi e-tron SUV is also a production vehicle, but expensive, just being released, and intended to be relatively low volume. It is derived from the MLB platform, but nearly unique, so it almost the from-the-ground-up EV that the world is supposedly waiting for. We'll know in a year if it sells in volume.

While there are many thousands of production VW EVs out there, I think it will be at least a couple more years before we have an idea of what the VW commodity components turn out to be.


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## brian_ (Feb 7, 2017)

Tremelune said:


> The Model 3 is by _far_ the best-selling EV in the US at the moment, so those batteries won't stay expensive forever...


The modules will still be awkwardly long, though...


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## XS_MotorWorks (Sep 23, 2019)

You brought up handling as a concern. I too had that same concern and that's why I choose to NOT use the Tesla sub cradle. It's not a simple A arm design and I was having a hard time calculating the scrub radius/mounting height and camber. Just a word of caution. You might have already thought about those things.


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## joekitch (Sep 13, 2013)

XS_MotorWorks said:


> You brought up handling as a concern. I too had that same concern and that's why I choose to NOT use the Tesla sub cradle. It's not a simple A arm design and I was having a hard time calculating the scrub radius/mounting height and camber. Just a word of caution. You might have already thought about those things.


i have not, i assumed it'd be good, and at the very least better than a leaf spring suspension setup designed in the late 50s

is the model 3's setup significantly better?


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## brian_ (Feb 7, 2017)

There's nothing wrong with the rear suspension design of the Tesla Model S/X, although the geometry is somewhat difficult to follow. It is essentially the same in design (although different in specific dimensions) as the "integral link" design used by Ford/Jaguar, Alfa Romeo, and others.

There's also nothing wrong with the leaf spring in the Corvette suspension (of any generation using them, which is C2 through C7 for the rear); it is just the spring, and not a control link, so it does not affect the geometry of the suspension at all. The C3 suspension is obsolete and undesirable, because it uses the axle shafts as control links and has horrible toe control.

I'm sure that the complete Tesla suspension would be a substantial upgrade compared to the C3's stock setup, but other designs might be easier to work with. If all you want of the C3 is the body, I'm pretty sure that there is at least one company which will sell you a completely new frame with C5/6/7 suspension front and rear (which is double A-arm at both ends), designed to fit a C3 body... but that chassis alone would consume your entire conversion budget.


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## joekitch (Sep 13, 2013)

brian_ said:


> I'm sure that the complete Tesla suspension would be a substantial upgrade compared to the C3's stock setup, but other designs might be easier to work with. If all you want of the C3 is the body, I'm pretty sure that there is at least one company which will sell you a completely new frame with C5/6/7 suspension front and rear (which is double A-arm at both ends), designed to fit a C3 body... but that chassis alone would consume your entire conversion budget.



yyup, 
http://roadstershop.com/product/full-chassis/1968-82-corvette-chassis/
https://www.streetshopinc.com/chassis-packages/1968-1982-c3-replacement-chassis.html
they're like 17 to 25k depending on options
if i was keeping the gas engine i'd do something like that.

there are various full coil conversion kits for the c3 which eliminate needing the diff case but those are also incredibly expensive.
https://www.ridetech.com/products/suspension-packages/product-3292/
if i'm going to drop 6 grand on something i'd rather it be fabricating subframe mounts, since even with this coilover system.....still need to fabricate mounts for the tesla motor.

also the problem with keeping the transmission/diff and using a DC motor in the engine bay is that'll take a lot of space that batteries could go in, and it keeps the sub-par rear suspension


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## brian_ (Feb 7, 2017)

joekitch said:


> there are various full coil conversion kits for the c3 which eliminate needing the diff case but those are also incredibly expensive.
> https://www.ridetech.com/products/suspension-packages/product-3292/
> if i'm going to drop 6 grand on something i'd rather it be fabricating subframe mounts, since even with this coilover system.....still need to fabricate mounts for the tesla motor.


... and they only fix the small irritation of the leaf spring mounting frame, leaving you with the problem of axle shafts as suspension members.


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## XS_MotorWorks (Sep 23, 2019)

While it is a good modern setup the problem is lack of adjustability. They have the advantage of CAD and can model the suspension travel. So you will want to make sure you have the axle center at the same ride height as factory and build your mounting points from that location as the factory or you might find yourself with a camber problem and the factory setup doesn't allow for much adjustment.


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## joekitch (Sep 13, 2013)

ah, that's what you were getting at, yikes, i had not considered that

another thing i hadn't considered, i think this detroit speed kit solves the axle shafts as suspension members problem
https://www.detroitspeed.com/1963-1...3-82-corvette-stock-differential-041740-group
....for $8,800 

Although this is making me lean a little more towards the model 3 setup, not sure if that has better adjustment though?

as for track width, there's this c3 image









and this for the model 3









*the concern is, is the 3's track actually narrower?* the problem with these images is..... it's measured rotor to rotor or wheel edge to wheel edge? the c3 image measures both separately which helps 
hopefully this means the rotor-to-rotor of the 3 is 62, meaning i get a free 4 inches wider in the rear which is GOOD because i actually WANT to go for a widebody setup to keep this thing on the road!


gains:
-better cooling
-better efficiency
-better adjustment(?)
-more aftermarket support(?)
-better track aligntment 
losses: 
-not nearly as well understood so far, no turn key systems support it and there's some skepticism if they even will for a while
-possibly narrower track(?)
-slightly lower peak power. Scuttlebutt is that the 3's rear drive can do reliably 500hp with some software tweaking, but that monster p90 rear melon can smash out 600+


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## joekitch (Sep 13, 2013)

although, counterpoint, adding aftermarket adjustment systems to the model s suspension isn't too bad
https://evtuning.com/products/adjustable-camber-bushings-for-tesla-model-s-and-x


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## Tremelune (Dec 8, 2009)

joekitch said:


> Scuttlebutt is that the 3's rear drive can do reliably 500hp with some software tweaking, but that monster p90 rear melon can smash out 600+


...If the batteries can handle it. The 3's torque is limited by how much current the batteries can deliver at once. The P90 pulls something like 1500A.


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## XS_MotorWorks (Sep 23, 2019)

I don't have access to a model 3 but your track image got me thinking. I not sure your going to be able to fit the unit between the frame rails. Not sure if you seen my build thread but I making a custom frame and using C7 suspension components. The Tesla unit was so wide I had to pocket the upper frame so I could use the C7 sub cradle. Anyway my point is the C7 is much wider than the C3. 

So do you know what the distance is between the rails?


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## brian_ (Feb 7, 2017)

joekitch said:


> ... i think this detroit speed kit solves the axle shafts as suspension members problem
> https://www.detroitspeed.com/1963-1...3-82-corvette-stock-differential-041740-group
> ....for $8,800


Yes, DECAlink completely replaces the Corvette's rear suspension with a sound multi-link suspension that does not use the axle shafts. It uses two longitudinal links per side, similar to the stock suspension in that respect, for compatibility with the C3 structure; as a result, it doesn't need an extensive subframe. If I were upgrading a C3 and wanting to keep the structure close to stock, I think this would be a good choice... but the probability that I would ever spend tens of thousands of dollars to upgrade a C3 is zero.


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## brian_ (Feb 7, 2017)

*Tesla Model 3 suspension and drive unit*



joekitch said:


> Although this is making me lean a little more towards the model 3 setup, not sure if that has better adjustment though?


At least from the top, the Model 3 rear suspension appears to be a more typical 5-link-per-side design (with steel links rather than aluminum), first popularized by the Mercedes W201 series but now widely used on vehicles with performance as a high priority.

For those trying to model suspension kinematics, these suspensions work essentially like double A-arms, with the virtual ball joints at the locations where the lines of the links intersect, somewhere within the wheel volume; the track control rod is essentially the steering tie rod.

I don't see any adjustment in the upper links in that photo, and there is the expected cam adjustment on the inboard end of the toe control link; I have no idea if there is any adjustment in the lower links, but I would guess not.

You can see the subframe, upper links, toe link, one lower link (the one with the spring and shock) and swaybar in Tesla's image from the online configurator.

Note that the Model 3 rear drive unit places the motor ahead of the axle line (just like all of the drive units for platforms designed for transverse engines, including all front-wheel-drive EVs and the Smart ForTwo ED and Mitsubishi i-MiEV). The photo linked above is taken from ahead of the drive unit and suspension; note the motor on the left of the photo (right-hand side of the car), with the gearbox to the motor's right in the photo (left-hand side of the car), inverter on the end of the gearbox, and final drive (diff) on the back side of the gearbox.



joekitch said:


> *the concern is, is the 3's track actually narrower?* the problem with these images is..... it's measured rotor to rotor or wheel edge to wheel edge? the c3 image measures both separately which helps
> hopefully this means the rotor-to-rotor of the 3 is 62, meaning i get a free 4 inches wider in the rear which is GOOD because i actually WANT to go for a widebody setup to keep this thing on the road!


Track is the lateral distance between the centres of the tires, as shown in the C3 drawing - not the same as the hub face spacing unless the wheel/hub offset is zero. So yes, the Model 3 is narrower than the Model S and X, but still (moderately) wider than the C3. The Model 3 seems like a good match for this project in this respect - fender flares would be needed to cover the few inches of extra track plus the extra tire width (stock C3 tires were narrow by today's standards).


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## joekitch (Sep 13, 2013)

hmm, double checked my cad model i have of a c3 frame
https://www.3dcontentcentral.com/download-model.aspx?catalogid=171&id=401155

i recently checked out a pretty cool race built C3 and measured the inter-frame distance right by where the gas tank sits, reads a little less than 39 inches

https://photos.app.goo.gl/G8YffM9MUTgxmBcB8

i use tinker cad as a quick an dirty alignment tool and the c3 frame seems to line up perfectly, i scaled it down by 100 to fit into tinkercad, and it's 10mm between the same two rear frame members on the model, which is pretty much exactly one one hundredth of 39, *so the c3 frame is very close to accurate.*

the model s subframe piece cad though, not so sure about that one. I'll download this super accurate model and cross reference
https://grabcad.com/library/tesla-rear-drive-unit-1


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## joekitch (Sep 13, 2013)

really wish i could embed images from google drive
anyway, the motor model is quite validated and sits just right in the subframe model so that seems accurate too

unfortunately the giant can impacts that crossmember bit, so that'll have to be cut off and a new crossmember welded up 
https://drive.google.com/file/d/1WOz5oaK8srJ2t_ot8tWBb4p5Ygk_Get1/view?usp=sharing

another benefit of a model 3 subframe setup: the motor's quite a bit smaller


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## XS_MotorWorks (Sep 23, 2019)

I did some quick measurement on the Tesla model S cradle so you could verify









Distance B ....Looks like 43.5









Distance A ....Is about 41.75









Distance C ... approx 23.625










Your also have to give some thought about your Rims. The factory rotors and calipers are large and I don't think your going to be able to use a rim smaller they the factory (19").


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## joekitch (Sep 13, 2013)

XS_MotorWorks said:


> Your also have to give some thought about your Rims. The factory rotors and calipers are large and I don't think your going to be able to use a rim smaller they the factory (19").


ah, thank you for the measurements
19" wheels are just too damn big for the c3, 18 is already pushing it, the model 3 can do 18s so i guess that's yet another reason to get a 3 subframe over an S


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## brian_ (Feb 7, 2017)

joekitch said:


> unfortunately the giant can impacts that crossmember bit, so that'll have to be cut off and a new crossmember welded up
> https://drive.google.com/file/d/1WOz5oaK8srJ2t_ot8tWBb4p5Ygk_Get1/view?usp=sharing
> 
> another benefit of a model 3 subframe setup: the motor's quite a bit smaller


My guess is that crossmember is there primarily for the final drive and leaf spring carrier, so it may not need to be replaced at all.

The other obvious way to address motor bulk is to use the Tesla Model S/X small drive unit. While never used by Tesla as the only motor for a vehicle (it's only in AWD variants), and obviously less powerful than the large drive unit, it might still provide better performance than most stock C3s.

The Model 3 motor isn't just smaller - it's mounted ahead of the axle line, changing what it might run into. The Model 3 subframe is also differently shaped, due to the different suspension.


I see the name "corvolt" in an image filename. "Volt" made me think of "Bolt" - you could use the 150 kW Chevrolet Bolt motor instead of a Tesla, and not get anywhere near that crossmember.


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## joekitch (Sep 13, 2013)

Eh, small drive unit tops out around 300. It's certainly nice, but not enough for a proper american sports car.

really wish i could get a 3d scan of a model 3 subframe/motor, but it doesn't seem to be a thing yet :/
the motor being a little forward just means it might intrude into the cabin fiberglass a little, i may need to add a hump into where the cargo area is

CorVolt as in, Volt batteries. CorBolt honestly just sounds odd, also that motor is meh.


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## brian_ (Feb 7, 2017)

XS_MotorWorks said:


> Your also have to give some thought about your Rims. The factory rotors and calipers are large and I don't think your going to be able to use a rim smaller they the factory (19").


Good catch. This is a common issue with modern components in older vehicles. The most common solution is to just use the large-diameter wheels, even if they often look strange with the old styling.

Using the smallest wheel size for a given model may require the selection of corresponding brakes.

Overall tire diameter can be an issue, too, but the G70-15 typical of this era of Corvette isn't far off the overall diameter of the tires on a Model S or Model 3 (and is actually taller than the 18" Model 3 tire). Of course tire sizes can be changed, but that affects motor speed for a given road speed.


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## brian_ (Feb 7, 2017)

joekitch said:


> Eh, small drive unit tops out around 300. It's certainly nice, but not enough for a proper american sports car.
> ...
> CorVolt as in, Volt batteries. CorBolt honestly just sounds odd, also that motor is meh.


Right, you would need either boost the Bolt or Tesla small motor output, or build a two-motor all-wheel-drive C3 (with either brand of drive units). 

And regardless of the motor or even the battery, "CorVolt" is a pretty good name for a Corvette EV.


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## joekitch (Sep 13, 2013)

brian_ said:


> Good catch. This is a common issue with modern components in older vehicles. The most common solution is to just use the large-diameter wheels, even if they often look strange with the old styling.
> 
> Using the smallest wheel size for a given model may require the selection of corresponding brakes.
> 
> Overall tire diameter can be an issue, too, but the G70-15 typical of this era of Corvette isn't far off the overall diameter of the tires on a Model S or Model 3 (and is actually taller than the 18" Model 3 tire). Of course tire sizes can be changed, but that affects motor speed for a given road speed.


similar diameter yes, but 19s give you a noticeably worse ride. I always always opt for 18s whenever possible because they still look quite good, but you have enough sidewall to properly ride.

the very old school 15" wheels with super meaty tires looks period correct but has its own handling problems, so i have no interest in that form factor either

As for the name, i was literally planning to replace the stock lettering of "vette" with "volt", maybe add in a dash in the middle to keep the same number of letters


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## brian_ (Feb 7, 2017)

joekitch said:


> similar diameter yes, but 19s give you a noticeably worse ride. I always always opt for 18s whenever possible because they still look quite good, but you have enough sidewall to properly ride.
> 
> the very old school 15" wheels with super meaty tires looks period correct but has its own handling problems, so i have no interest in that form factor either


Yes, appearance is only the start of the problems with excessive wheel diameter, or really inadequate sidewall height. Very short sidewalls are especially bad with suspension that isn't suited to them. The largest wheel / shortest sidewall combination for almost any production vehicle is not really suitable for normal street use.


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## joekitch (Sep 13, 2013)

brian_ said:


> Very short sidewalls are especially bad with suspension that isn't suited to them.


thankfully, 18s are well understood on c3s, they seem to work very well for good handling
19s.....much less so, wouldn't trust em


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## joekitch (Sep 13, 2013)

related unrelated, just shot out a few emails to a lot of the conversion shops to ask where they are in model 3 motor controller support. Polykup, zeroEV, stealthEV, HSR motors.
i know EV controls has it on their roadmap, and EV west hasn't bothered with them since the older large rear drive units and the small front drive units are fine for them for now.

apparently damien and group are doing a bit of a raffle on a motor to fund open source control board development, which is neat, and might be the only way to accelerate this
https://openinverter.org/forum/viewtopic.php?f=10&t=184&start=10

Zero EV has one taken apart but it'll take some time before they have a solution
057 technology says they're in the r&d phase for it, so it's on the horizon, but still quite a ways off


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## Duncan (Dec 8, 2008)

joekitch said:


> thankfully, 18s are well understood on c3s, they seem to work very well for good handling
> 19s.....much less so, wouldn't trust em


But if you are using Tesla suspension then you ARE using suspension that will work with the 19's!


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## joekitch (Sep 13, 2013)

Duncan said:


> But if you are using Tesla suspension then you ARE using suspension that will work with the 19's!


in the rear, yes, but not the front, unless i get some aftermarket suspension geometry upgrade for the fronts. 
Although the front's pretty competent in general so, maybe it'll be fine with just a coilover upgrade?


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## joekitch (Sep 13, 2013)

sent out an email to a very highly recommended fabrication shop called chuckle's garage https://www.chucklesgarage.com/ 

going to try to get a very rough (plus or minus a grand) estimate on how much this might be for a shop to do....and more importantly, what i could do on my end to reduce that cost like more detailed modeling in CAD and getting CNC machined mount hardware....maybe...

The person who recommended this shop claimed that when he used to do this stuff back in 2012, suspension swaps were anywhere between $6500 and $10,000 depending on complexity.


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## Duncan (Dec 8, 2008)

joekitch said:


> sent out an email to a very highly recommended fabrication shop called chuckle's garage https://www.chucklesgarage.com/
> 
> going to try to get a very rough (plus or minus a grand) estimate on how much this might be for a shop to do....and more importantly, what i could do on my end to reduce that cost like more detailed modeling in CAD and getting CNC machined mount hardware....maybe...
> 
> The person who recommended this shop claimed that when he used to do this stuff back in 2012, suspension swaps were anywhere between $6500 and $10,000 depending on complexity.


I built my whole car for less than that!


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## kstegath (Nov 4, 2008)

Your budget is $15k plus another $20k - right?
I converted my C3 about 10 years ago. Lots of pictures at: Advanced-ev.com


Space for batteries isn't the big issue. If you're going to race this thing, the big issue is keeping them low in the car and between the front and rear wheels.
I used twenty-three lead-acid Odyssey PC1500 - 12V, 50lbs
Total pack weighs 1,150 lbs
Mounted 11 in the front and 12 in the rear - The rear was easy
Weight distribution:
Scales at a recycle center showed
Total weight: 3,860 lbs
 Front: 1,880 lbs
Rear: 2,120 lbs


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## joekitch (Sep 13, 2013)

kstegath said:


> Your budget is $15k plus another $20k - right?
> I converted my C3 about 10 years ago. Lots of pictures at: Advanced-ev.com
> 
> 
> ...


oh dang i remember seeing your build multiple times, seems like the only electric c3 out there.
that warp 11 mount is quite cool
ever thought about bringing it back with modern batteries? could cut that pack weight in half for the same range, get the curb weight back to what it was stock

also, where'd you get the cad model of the frame?


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## joekitch (Sep 13, 2013)

also, new battery possibility.
for about the same nominal voltage and the same capacity (36kw) i can build this smart EV battery box, which will take up much less space and weigh more like 600lbs instead of 900lbs
https://youtu.be/hp4eyaZzwts?t=154

only problem is, that many smart ev modules is liks $7800, phew


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## joekitch (Sep 13, 2013)

also, revisiting the idea of getting an aftermarket tube chassis, after talking with an expert fabricator about my subrame swap idea. he didn't want to give a quote or estimate but claimed it wouldn't be that difficult, just pretty time consuming to plan out since you can't exactly trial and error this, only got one frame. His wordage was along the lines of "if the client doesn't have 20 to 30 grand to sink into this, they probably shouldn't try".
and even after putting that subframe in, the amount of chassis flex this setup could introduce is pretty high, with the C3's frame being famously flexy and noodly, this would be bad.

enter: tube chassis

http://www.sriiimotorsports.com/196382corvette.html

the advantages being 
i get a proper modern rear IRS setup, tons of chassis rigidity i'd otherwise have to weld into a stock c3 frame
extremely good ride/handling balance on par with a modern corvette
you even get more engine bay space for batteries since the front suspension geometry is less bulky.
Importantly, all that rigidity makes the motor mounting itself FAAAR easier, i'd only need some thin steel bits to bolt into the motor casing's mount points. 

if you look at the model 3's subframe 










the actual parts which hold the motor into the subframe, they're just thin little bits, that's all. That'd be incredibly trivial to model in cad and weld to a good tube chassis, and again because of the massive stiffness in said tube chassis i almost don't have to think about where those mounts go in terms of stressing it. so, that negates basically all the motor mounting hardship

But as previously observed, these things are crazy expensive. A stage two c6 style setup (with shocks/brakes/suspension) is *$21,000 * 

on the other hand...
There's some forum scuttlebutt which claims a 5 or 6 point roll bar can offer immense improvements in stability for not that much investment, on top of adding frame gussets here and there
Since most of the cost is just planning and engineering, i'd be happy to do a ton of that in cad on my own over some months, modeling stresses and such, and then have a "solved problem" to give to the expert welders who just weld it in. This fabricator fellow even offered to give occasional pointers


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## kstegath (Nov 4, 2008)

I used Solidworks for all the CAD files.


I was (am) going to replace the Pb-acid with Leaf modules and rework the car for racing.

But I needed to get the car to the track and I didn't want an ICE truck... so I decided to convert a tow vehicle.


I chose a 1962 Mack Model B-46.
A lot of photos on Flickr: https://www.flickr.com/photos/emack/albums


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## Tremelune (Dec 8, 2009)

That is one cool truck. Got a thread for that conversion...?


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## brian_ (Feb 7, 2017)

joekitch said:


> ... Importantly, all that rigidity makes the motor mounting itself FAAAR easier, i'd only need some thin steel bits to bolt into the motor casing's mount points.
> 
> if you look at the model 3's subframe
> ...
> the actual parts which hold the motor into the subframe, they're just thin little bits, that's all. That'd be incredibly trivial to model in cad and weld to a good tube chassis, and again because of the massive stiffness in said tube chassis i almost don't have to think about where those mounts go in terms of stressing it. so, that negates basically all the motor mounting hardship


Yes, the drive unit mounts are relatively thin stamped plates, but they are strong in the vertical direction. Vertical is the important direction because the weight of the drive unit and reaction to axle torque are all vertical forces (although there is horizontal force in proportion to the drive unit mass and acceleration). These are not trivial forces, so mount design and placement of the mounts on the frame are important.

These mounts are easier than mounts for the subframe or direct mounts for suspension components, which take high forces in all directions.



joekitch said:


> There's some forum scuttlebutt which claims a 5 or 6 point roll bar can offer immense improvements in stability for not that much investment, on top of adding frame gussets here and there...


That makes sense. The flexibility of the stock frame results from the whole frame being in nearly one plane; the cage makes it into a big and much more sound box. Even in a unibody adding a cage can make a noticeable difference in flex and handling.


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## joekitch (Sep 13, 2013)

kstegath said:


> I used Solidworks for all the CAD files.


are those cad files available to share? like on grabcad or something?





kstegath said:


> I was (am) going to replace the Pb-acid with Leaf modules and rework the car for racing.


good, although, might want to make some chill plates, those leaf batteries don't last too long without em

However did you need to do some stuff to counter the c3's floppiness? or did you leave that alone and its fine? 
if your build is upwards of 600 ft lbs of torque with no bad effects on frame flex, i'm far less worried


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## Duncan (Dec 8, 2008)

When you are talking chassis design you can use CAD

Or you can get old school and make yourself a decent build table and just make the chassis to go between the mounting points of the subframes (easy) or suspension (bit more difficult

Cut the steel to fit and if you are not sure of your welding tack it together and get the expert to finish the welds


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## joekitch (Sep 13, 2013)

Duncan said:


> When you are talking chassis design you can use CAD
> 
> Or you can get old school and make yourself a decent build table and just make the chassis to go between the mounting points of the subframes (easy) or suspension (bit more difficult
> 
> Cut the steel to fit and if you are not sure of your welding tack it together and get the expert to finish the welds


i'm thinking of cadding up some square-ish mount adapters, i'm not sure how best to describe their shape and can't find any examples online, so i threw something together in tinkercad.
imagine this shape but made of four thick pieces of steel intersecting and welding together into the boxy shape
of course, the danger with this approach is cadding something that won't actually fit in the real world due to reasons.

If i could, i'd rent one of those 3d scanner things, take all the rear suspension off a c3, put the entire rear assembly from an S under the suspended c3 and line everything up then do a detailed 3d scan of the gap between the two pieces and use THAT to cad up a beefy interface mount

cost effective hand held 3d scanner rentals when


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## Tremelune (Dec 8, 2009)

I was thinking the same shit for fabbing up motor mounts for my awkward Mini subframe...


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## brian_ (Feb 7, 2017)

joekitch said:


> i'm thinking of cadding up some square-ish mount adapters...
> imagine this shape but made of four thick pieces of steel intersecting and welding together into the boxy shape


The subframe mounts are so close to the frame members that this simple approach looks like it would be suitable. But why does the mount box extend to the structure of the subframe, instead of ending level with the face of the block in the middle of the mount? Or have I misinterpreted the image?


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## brian_ (Feb 7, 2017)

joekitch said:


> also, new battery possibility.
> for about the same nominal voltage and the same capacity (36kw) i can build this smart EV battery box, which will take up much less space and weigh more like 600lbs instead of 900lbs
> https://youtu.be/hp4eyaZzwts?t=154
> 
> only problem is, that many smart ev modules is liks $7800, phew


Since those are Tesla modules for the Smart (each generation of Smart ForTwo ED seems to use a different battery supplier), these would presumably have the same performance (per weight or volume) as the more common Tesla Model S/X modules; both are filled with Panasonic 18650 cells.

I understand that the point of this selection to get a module with fewer cells in parallel (22p15s versus 74p6s), so the target pack voltage is reached with a lower total pack mass and bulk. It would take only 6 of the smaller Smart modules (totalling only 252 pounds of modules) to get 90s, but that wouldn't handle enough power, so modules need to be paralleled to be adequate and the result is a 504 pound (plus structure and housing) 44p90s pack, as in the video. You end up with lots of modules, and only 200 amp output capacity.


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## kstegath (Nov 4, 2008)

I just posted some CAD models (Solidworks) of the frame on Grabcad.


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## joekitch (Sep 13, 2013)

kstegath said:


> I just posted some CAD models (Solidworks) of the frame on Grabcad.


https://grabcad.com/library/c3-corvette-frame-1

nice, thank you
did you super dupe validate all the measurements, or is this more of a rough model to get an idea


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## MattsAwesomeStuff (Aug 10, 2017)

Just FYI: https://www.diyelectriccar.com/forums/showthread.php?p=1047545

You two should watch each other's threads. You're solving the same problems on the same vehicle.


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## onairlikeclouds (Aug 24, 2019)

Hi, 

I was wondering if I could be part of your build. I'm also in the San Francisco area. I tried private messaging you. Let me know.


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## MattsAwesomeStuff (Aug 10, 2017)

There's some weird rule about not being able to send or receive PMs until you have a certain number of posts, I think.


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## joekitch (Sep 13, 2013)

onairlikeclouds said:


> Hi,
> 
> I was wondering if I could be part of your build. I'm also in the San Francisco area. I tried private messaging you. Let me know.


got your pm and your email, replied to said email


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## joekitch (Sep 13, 2013)

some days i feel like that always sunny conspiracy meme but, with c3 corvette suspension geometry

ok so, hold up, listen
what if
listen guys
what if i took the detroitspeed decalink rear kit.....

https://youtube.com/watch?v=-_QvhXUyqSc 

https://www.detroitspeed.com/detroi...remote-shocks-30-spline-axles-600hp-041741-dr

https://www.facebook.com/detroitspe...803914911813/2117803784911826/?type=3&theater

https://www.chevyhardcore.com/news/...orvettes-handling-with-detroit-speed-part-ii/

...and threw in some thick cut steel motor mount fingers on the frame/decalink to fit the model 3's diff opening where the decalink half shafts go? Since the decalink kit completely removes the diff as a suspension member, no more weird forces on the model 3 motor.

also the model 3 motor is already in the configuration i need (ass-first) so it'll fit in the gap where the diff was. Might need to cut some of the body but that's whatever at this point. 

cheaper than the $17500 for a replacement frame, will perform about as well, and simplifies motor mounting decently, no more subframe mount design


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## joekitch (Sep 13, 2013)

Finally purchased a car, a 1971 in black. 
Fully restored, and heavily modified by the previous owner with all kinds of upgrades.
I'll make a new thread for it though


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## joekitch (Sep 13, 2013)

current status: sitting in garage, looking at $1800 to register it due to use tax
also needs new tires, i got three but trying to find a very lightly used 235/45/18 pilot sprt 4s is proving difficult (new ones are $238 a piece, yikes)
it also needs some engine work to be daily driveable, probably just minor adjustments to the distributor etc.

also held up by costs and garage space, I'm getting 16k later in the summer, and 5k whenever i sell my miata, and at that point i'll start buying parts (yay)

but man, i could really use a two car garage to have work bench space and work space!


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## MattsAwesomeStuff (Aug 10, 2017)

joekitch said:


> but man, i could really use a two car garage to have work bench space and work space!


My car is 2/3 the size of yours, and I have _filled_ a 2-car garage, with lots of shelving to boot. I'm amazed at how much space a car is when taken apart, and when you're working on different parts of it at the same time. It wasn't something I gave much thought to, but I've been completely wrong about it.

I almost planned on working in a 10x15 storage unit originally. Which is like, 1/3 the size. Barely enough to fit the vehicle, and I thought "This'll be enough room, how much more could I need?" A lot more, apparently.


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