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Ze062 EV Corvette

7251 Views 72 Replies 8 Participants Last post by  brian_
today I officially started the conversion of my 1962 Corvette on a tube chassis with C5 suspension. For the planning details see my introduction thread here

The introduction post pretty much lays out the plans and configurations so I wont repeat those in the first post but I will bring each portion up to date and fill in details here as it is built.

first off is the battery conversion from 3P to 2P. I pulled apart the first module by using a chisel to cut the battery tab spot welds away from the bus bars. this confirmed the construction was as I had imagined as well as demonstrates the way to move forward. The tabs are also welded to each other, but I do not have to separate the tabs on side opposite the terminals since they are common polarity. I will have to separate those on the other side as well as flip one of the battery packs to make the polarity common. the sketch below shows the configuration of the 6 cell (in 3 housings) groups. I was able to separate the tabs by cutting the tabs right at the weld line. this leaves enough of the tab for several reassembly methods I am considering.

initial volt measurement shows these cells are fully charged so i am being careful to avoid any unwanted connections. the +/- cell arrangement in the single plastic housing has presented a special handling challenge so i am working on a way to separate these in the initial tab removal from the bus bars.

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Discussion Starter · #61 ·
there have been a few black friday deals on low-end purpose-built scanners. However I elected to use the available funds for a mig welder instead. I am going to work on the frame and battery for now, maybe mid next year I will look at a scanner again. hopefully an option to rent or borrow will pop up before then
 

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corvette is finally moved over to the north bay where it is accessible. I am still looking at scanning options. I really want to see if i can borrow an iPad pro 4th or 5th gen to scan it. Otherwise I may look at renting a handheld scanner once I get everything removed to make the areas I want scanned accessible.
check my instagram @Corvolt back a few months, i did a full photogrammetry scanner setup that worked shockingly well for about $800 in parts, i scanned the empty engine bay of a c3 corvette someone else was pulling the engine out of

for the camera i got a decent used one that'll also be used for my eventual youtube stuff
 

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Discussion Starter · #63 ·
check my instagram @Corvolt back a few months, i did a full photogrammetry scanner setup that worked shockingly well for about $800 in parts, i scanned the empty engine bay of a c3 corvette someone else was pulling the engine out of

for the camera i got a decent used one that'll also be used for my eventual youtube stuff
thanx I will review it. I already bought a digital SLR so maybe I have what I need.
 

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@Corvolt back a few months, i did a full photogrammetry scanner setup that worked shockingly well for about $800 in parts, i scanned the empty engine bay of a c3 corvette someone else was pulling the engine out of
[/QUOTE]
Just followed... Any write-up somewhere on this? Or a specific post?
 

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Discussion Starter · #67 ·
Hi,

sorry for the lack of updates. I have been upgrading/revising the power layout for my shop as well as a full blown bathroom remodel in the house. I have been watching Tim Allen's "Vik" build on youtube as well. A lot to see and some of the pitfalls of being an early adopter. its good he s flexible and adapting as needed and as the DIY stuff is improving. makes me hesitant to move to fast but impatient to move faster. hopefully the next guys will also implement a BMS for him, as it looked to me like they removed the Tesla BMS PCBA's without replacing them.
 

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for the chassis builders out there, how do you calculate the loads on the suspension hard points? this is my spreadsheet with assumptions. based on a theoretical 3000lb vehicle. any help will be appreciated.
With just an image, the underlying calculations (spreadsheet cell formulas) are not visible. That means I can't be sure how you are getting the values so I can't ask any helpful questions or provide any suggestions. Is the spreadsheet file available in some format, rather than just an image?
 

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Discussion Starter · #70 ·
doesn't let me post an excel file. but in a nutshell

static weight is the tot weight of 3000lbs x the f/r and l/r balance. for the rear and the left it is the x 1-balance
off camber is a tire lifted, so it is 1/2 the f/r balance x 3 x gravity
brake is tot weight x 1.5g X 80% front, 20% rear
accell is tot weight x 1.5g rear only
skid pad is to weight x f/r balance X 1.5 1-balance for rear

summaries are color coded and simple addition

if I can figure out a way to safely share the spreadsheet I will. I am thinking braking will also add a torque load to the arm which will produce an additional transverse force on the arm joints., accell would be the same for the rears. but have not quantified that yet. I set the g force high for brake, accell and skid. what I am hoping to gather is all of the abuse cases that are predictable as well.
 

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We did a suspension simulation in my freshman year.

The statics are the easy part.

You need to account for second and third order effects and write and solve diff eqs to get those forces.

You need models of tires and dampers. Springs is easy if they're linear. You need all of the masses and coefficients to compute those equations. Being a Mech E, you know how to build a FBD.

Lastly, you need road input. I used a step function pothole encounter.

Excel is NOT going to get you what you want, imo. Matlab is the closest tool I can think of if you don't want to write code.

I'd get you a listing, but....it was written onto punch cards and used an IBM 370 mainframe to solve it all, lol.
 

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Discussion Starter · #72 ·
no worries, I doubt any tube chassis builder is doing more than seat of the pants evaluation of a chassis design (along with iterative changes). I just want to get a good idea of the hardpoint loading and design the stiffest chassis for that input. just to see where it goes.
 

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doesn't let me post an excel file...
if I can figure out a way to safely share the spreadsheet I will.
(y)

static weight is the tot weight of 3000lbs x the f/r and l/r balance. for the rear and the left it is the x 1-balance
off camber is a tire lifted, so it is 1/2 the f/r balance x 3 x gravity
brake is tot weight x 1.5g X 80% front, 20% rear
accell is tot weight x 1.5g rear only
skid pad is to weight x f/r balance X 1.5 1-balance for rear

summaries are color coded and simple addition
That all looks reasonable to me.

... I am thinking braking will also add a torque load to the arm which will produce an additional transverse force on the arm joints., accell would be the same for the rears. but have not quantified that yet.
That's where it gets interesting. The initial calculations are all for forces at the tire contact patch, but that's not what is attached to suspension mounts. For instance, if a spring is halfway out a control arm, it is transmitting twice the contact patch vertical force to the mount (and the inboard mount of the control arm is pulling down on its mount, so the net vertical force on all mounts equals the weight of the vehicle. Lateral forces carried through multiple suspension elements, and compression or tensile forces on control arms with components in all three dimensions make life much more complex.

There are reasons that for anything past a first approximation, these forces are determined in 3D modeling software. :)
 
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