I've been planning this build for quite a while now and things are finally starting to get real. Sold my finished previous project car two weeks ago so I have the budget and space freed up for a new one. My 33 Hot Rod build date is just a month away now too. I picked up the rear drive unit I found for the project yesterday which is the first physical part in my possession - so I think I can officially start the build thread!
After months of researching feasibility of what I want to do I've nailed down the high level design of this project. I've done enough internal combustion projects and I wanted a completely new challenge, so this one is gonna be electrified. Here is the high level plan:
Motor:
Tesla Model 3 Performance rear drive unit. This seems like the best option for the 33 after researching and evaluating several options. I was lucky and found a really clean 980 motor (performance version) from a 2018 Model 3 with only 27,400 miles on it at a local dismantler. This has a 265KW (~355Hp) max output with the controller I'm looking at, and of course instant torque. Should be more than enough power to destroy the rear tires on command in what I think will end up being a 2500-2700lb car.
Rear Suspension:
I spent hours and hours working to see if any rear transverse electric motor would fit in with the FFR IRS setup, even with modifications, and it's quite clear that it just won't work. Factory Five took a look at the options I was considering as well and they came to the same conclusion. So I'm on my own for the rear bouncy part that holds the wheels. I considered using the entire Model 3 rear subframe/suspension but the track width is just too wide and it would look like kind of a hack job IMO. So, what I'm going to do is ditch the Tesla subframe and fab up the rear chassis for the Model 3 IRS. I'll 3D scan the complete rear subframe to make accurate CAD files, move the pivot points in to shorten the track width, and then redesign the rear of the chassis to accept the motor and suspension. This is pretty ambitious for me and I've had a few 'what the hell am I doing' moments - but I'm confident I can do it.
Batteries and other stuff:
With great help from Michael Bream at EV West in southern CA, at this point I'm planning on their LG Chem Super Cell battery packs. They will be wired 13 or 14 in series, 2 parallel which will get the required 400V and should provide about a 130ish mile range. That's plenty for a car like this. My top motor controller right now is the EV Controls T-2C. AEM has a really nice setup for the Model S motor but according to them they're not working on support for the Model 3 unfortunately. I'm still undecided on the BMS and charger.
This is the current layout for batteries along with a rough CAD model of the motor I found online. I plan to do a better scan of the actual motor I have soon. The chassis CAD model is made from images online but it's a reasonably good start. Once I get my kit I'll adjust the model to match exactly. Sure wish FFR would provide CAD models, but I understand that's their policy.
This is going to be a great build! I've been playing around with the same idea for a while in my head, especially after watching a build where someone used a Model S Performance rear motor in a K1 Attack kit.
The floor just seems perfect for battery storage, and a few more modules in the front.
Now that they've introduced the Ford Eluminator electric motor for kits, I've thought about seeing if that would work as well, that would definitely require a lot of rear suspension fab as it is just the motor you get. Like the Tesla motors it is also transversely mounted with outputs for 2 wheels, but so far other than the F-100 I havent seen it used outside of the Mach-E.
That will take a little while for controllers, etc. to be available, but might be a good option a couple years from now.
I've already subscribed and can't wait to see this build rolling!
This is going to be a great build! I've been playing around with the same idea for a while in my head, especially after watching a build where someone used a Model S Performance rear motor in a K1 Attack kit.
The floor just seems perfect for battery storage, and a few more modules in the front.
Now that they've introduced the Ford Eluminator electric motor for kits, I've thought about seeing if that would work as well, that would definitely require a lot of rear suspension fab as it is just the motor you get. Like the Tesla motors it is also transversely mounted with outputs for 2 wheels, but so far other than the F-100 I havent seen it used outside of the Mach-E.
That will take a little while for controllers, etc. to be available, but might be a good option a couple years from now.
I've already subscribed and can't wait to see this build rolling!
I've checked out that K1 build too. That's crazy power for that little car and he made it fit really well. Very cool build.
I looked at the Eluminator too but like you said it's just not there yet. Hopefully soon it'll all come together. I saw they displayed it at SEMA with an AEM controller but they (AEM) never returned phone calls or emails when I tried to get more info on it. I also saw mention of Cascadia Motion for the assumed inverter but their stuff is way too expensive in my opinion. They have a nice looking drive unit as well but they wanted close to $15k for it.
I took a hard look at fitting the Model S stuff in the Hot Rod but kept hitting walls. The track with is way too big to make the stock subframe work. In the intended motor orientation (rear of the wheels) I couldn't see any good way to reestablish the lower control arm mounts with how steep the trunk of the car slopes down. The stock coilover mount needed modification too. You can reverse the S motor with an oil pump impeller change but then you run into major suspension interferences. The S power sounds good on paper but in reality the thing would be undrivable without tuning it way down anyway. Look at the Model S powered Superformance Cobra videos as an example.
The Model 3 is just the right fit for this car. It puts the motor forward of the axles where there's plenty of room, and the suspension pivot points can be pulled inward a fair amount without hitting the motor. I'm still deciding between the stock separated coil/shock approach, and integrating the coilovers that come with the FFR kit. I'm leaning towards coilovers though. Shouldn't be too difficult to fit them up and then I'll have the adjustability.
I am going to assume that you are building a roadster. I am not tall at all (5'10"), and with the seat bolted to the floor, I am almost to tall for the coupe.
I am going to assume that you are building a roadster. I am not tall at all (5'10"), and with the seat bolted to the floor, I am almost to tall for the coupe.
Yes. I'm planning on the soft top only. I haven't driven the 33 before but I've looked them over close at SEMA a few times. Pedal spacing and footbox room will be easy since it won't have the big trans tunnel. I also ordered the tilt column. I'm right at 6' tall and based on the checking around I did it seems like it will be fine. I do want adjustable seats though - hopefully I can pull that off.
I've driven a MK4. It was a little tight but comfortable enough.
Sounds like you have definitely done your homework. I was also thinking that having the rear-motor and batteries under the floor will let you skip the trans tunnel and give you more foot room, even though you don't have a clutch pedal to worry about, I know there isn't a lot of room there.
Are you going to run AC? Looked into that yet? With more hybrids out there and electric compressors I am hoping its not too hard to set something up like that.
Are you going to run AC? Looked into that yet? With more hybrids out there and electric compressors I am hoping its not too hard to set something up like that.
No, I don't think I want AC in it. We'll see how things go but for now I'm thinking just a heater.
No, I don't think I want AC in it. We'll see how things go but for now I'm thinking just a heater.
I have AC in the hot rod coupe and use it. In my Cobra, I just have heated seats and a heater and it is enough. If I was building an EV, I would just use the heated seats and call it a day.
I have AC in the hot rod coupe and use it. In my Cobra, I just have heated seats and a heater and it is enough. If I was building an EV, I would just use the heated seats and call it a day.
After several hours messing with the scanner I was able to piece together a first pass scan of the Tesla subframe. I took a few quick larger measurements and it's close. I might have to make cylinders to bolt in where the suspension links mount to provide larger surfaces to scan. I tried it here with just the bolts and I'm not sure it's going to give me the best results.
A recent issue of Hot Rod magazine had two big articles on EV conversions. One used the Tesla engine and the other the Ford package. Might be of some interest.
A recent issue of Hot Rod magazine had two big articles on EV conversions. One used the Tesla engine and the other the Ford package. Might be of some interest.
Made good progress on the scanning and CAD work for the drive unit and suspension. I have the suspension pivot locations pretty accurate it looks like. I assembled most of the links to the hub and everything lines up really well. I'm not going to use the Tesla main lower control arm because it's kind of ugly stamped metal. I ordered aftermarket ones from Mountain Pass Performance that are much nicer and will allow for easier conversion to coilover. I'll probably end up getting their full set for the nicer look and extra adjustability.
That is Way Cool! I am amazed at how far this technology has come in the few years I've been out of the workforce. Please keep posting, even the small steps. I and many others are avidly following your build.
Keith HR #894
That is Way Cool! I am amazed at how far this technology has come in the few years I've been out of the workforce. Please keep posting, even the small steps. I and many others are avidly following your build.
Keith HR #894
Thanks Keith. Sorry, I forgot to let you know I started the build thread.
No kidding on the scanner technology progress. About 7-8 years ago we bought a scanner at work and pretty much never used it because it was such a pain in the rear. It was something like $45k too if I remember right. This one I bought is infinitely better and much easier to use for a fraction of the price. Still a big investment for me but I don't think I could do this build without it. Maybe I'll try to make a little money on the side with it at some point. We'll see...
Wow! I did a centerline check on the subframe scan results. This is drawing a line from the small pivot cylinders on each side, then placing a point at the mid point of each line. I fit a plane to three of the points and used that to check where the rest of the centerline points are relative to the plane. It's dead on! I actually expected some error but this is perfect.
I need to do more work on the motor scan because I had trouble extracting exact centerlines for the mounts. The 3D printed cylinder trick should work though. Once I get that I'll be able to fully locate the suspension in the chassis CAD model.
This is the rough motor placement along with the stock Model 3 suspension pivot points. Next I need to pull the pivots inboard to get the width where it should be. I can start thinking about the chassis/suspension design at that point but I won't be able to do much in detail until I get my kit. The chassis CAD model needs to be correct first.
This is cool stuff! I too have used 3D scanners at work with very mixed results. We recently tested a system from Faro scanning our product and overlaying over our own models in Inventor with very inconsistent results. We still felt like it wasn't there yet for our application and ended up rejecting the capital proposal. I had no idea that there were units available at a price point like that within reach of an individual. Still quite the investment, but perhaps as you say there is a way to make it earn it's keep so to say lol!
It's really cool to see all the work that you are doing. I'm both jealous and impressed!
Spent a while today working on the CAD file. I started with the ideal situation matching the Ford rear end width of 59.75" hub to hub. That would give me the most flexibility with wheel selection, but it looks pretty tight in terms of making new chassis mounting. I was hoping to be able to use square tubing with simple mount flanges but I can get more elaborate if need be. I can also push it back out a bit too. It just means less dish on the wheels and likely custom backspacing.
I should receive the new lower control arms Thursday and will add them in once I get the part modeled.
I got the MPP lower control arms today - scanned them and made a CAD model for the assembly. I've also done a bit of work thinking out the chassis changes needed (in green). I definitely see a path to make it all work which is a big relief. Whether the final ends up exactly like this or not at least there doesn't seem to be any major show stopper problems right now. It also looks like I might be able to keep the stock rear deck support struts. The front upper control arm interference doesn't look as bad as I was expecting. I might be able to just notch out clearance spots and add some gussets to cover any strength loss.
Really hope I have the chassis CAD model close. That could change things if not..
That does look feasible / reasonable with no exotic parts to fab. Is your delivery date scheduled yet? I'm looking forward to seeing how close the initial model is to the delivered hardware.
I'm not sure on exact delivery date. I have a 5/14 date from FFR which I think is a pick up date. I already scheduled Stewart but don't have an arrival date yet. I'm assuming end of May or early June?
Got a few new toys today.. The rear trailing arms are backordered which is no big deal of course. These will be a nice upgrade from the stock Tesla arms.
I talked with the transport company last week. They'll pick up the kit later this week, maybe early next and I should have it here by end of the month.
I got word from the transport company that the kit will be here Sunday! I went ahead and ordered the batteries too just so I have them for working out the layout and mounting. I have the wiring plan re-sorted out in CAD now also. I had to change it from the 13 series, 2 parallel layout I was originally assuming, to 2 parallel, 13 series after more education from EV West. Not only is that the better way to wire them as I've learned, it will also make it a bit easier to interconnect - fewer custom bus bars needed.
Something worth noting here in case it helps someone else out later - I spent somewhere north of 2 hours of research trying to figure out the HV DC input lead polarity for the Model 3 motor. The connectors are marked with "1" and "2" but no obvious indication of positive and negative. I couldn't find an answer online but the place I got the motor was willing to allow me to just measure it on a full pack (they didn't know the answer either). I decided to go ahead and cut the one connector off since I'll be splicing that end anyway. I also decided to remove the ugly orange electrical tape that was on the harness leads and look what I found under it taped to each lead. I just had to laugh...
Busy day yesterday doing inventory and finding a place for all the parts. The backorder list wasn't too bad. The biggest ones were the steering column and front hubs.
Unfortunately they sent me an IRS chassis instead of the basic 4 link. Must have been some crossed wires on the order because I originally had it as IRS and then changed it to 4 link when I figured out the Tesla motor wouldn't fit. I got the 4 link arms though which is odd. Oh well... It's not a huge deal, just more to remove. I'll try to cut it out clean in a larger assembly. Maybe someone could make use of it.
If no one else jumps on it, I could certainly make use of the plates / mounting config. I've got to raise my mounts up a significant amount and was dreading cutting up the frame before I knew it all could fit. This would let me tack in a second set of mounts before cutting my existing ones out.
Edit.... thinking about it, may not be as helpful as I was initially thinking since I only plan to adjust the differential position and not the a-arms as well. I'll go back to my original plan
If no one else jumps on it, I could certainly make use of the plates / mounting config. I've got to raise my mounts up a significant amount and was dreading cutting up the frame before I knew it all could fit. This would let me tack in a second set of mounts before cutting my existing ones out.
Ok, sounds good. I'll let you know when I have it separated.
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Originally Posted by Pat Landymore
