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Rate my build plan (c3 corvette)

23787 Views 80 Replies 10 Participants Last post by  MattsAwesomeStuff
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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Other than blowing your budget that sounds like a superb plan
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??
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
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
That battery (Bolt) looks very impressive!
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!
sent out an email to a very highly recommended fabrication shop called chuckle's garage

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!
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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