# Project Split Decision



## XS_MotorWorks (Sep 23, 2019)

Hi All,

I've decided to start a build thread and will definitely need some help. I've made a few kit cars over the years but now I've decided to make my own design so will see how it goes.

Here's the plan.
1. Create a custom frame using corvette C7 suspension 
2. Power will be provided by Tesla (ECU company choice as they want to make a controller)
3. Other EV parts will come from a 2012 Volt. Why because I got it for a great price (Free). I know the charger and batteries will need to be upgraded but it's a start
4. Body will be my own design.

Here is a picture of the frame along with the sister car (that's gas) and the Volt parts


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## brian_ (Feb 7, 2017)

XS_MotorWorks said:


> 3. Other EV parts will come from a 2012 Volt. Why because I got it for a great price (Free). I know the charger and batteries will need to be upgraded but it's a start.


Is this car going to be very small, or short range... or will it have two Volt packs or an entirely different battery after upgrading? The Volt battery is great for high power output for its size, but it doesn't have much capacity for an EV.

Where is the battery going? One option which no one seems to choose is to keep the Volt pack intact, in the original tee form, running across behind the seats and forward between the seats. It would be forward of where it is in a Volt, relative to the driver, but in the Volt is doesn't extend all the way forward to under the dash so there should be room.


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## XS_MotorWorks (Sep 23, 2019)

The car will be short range. It will be long (wheelbase is 107) low (4 Inch clearance) and wide.

The batteries will use the same configuration as the VOLT but I can add to the "T" section in both width and depth (I could also double them up but I don't want the weight up that high).

I plan on mounting the Tesla motor tomorrow after I get the rear suspension back on (just had the sub frame powder coated) so I can make sure the axle geometry is correct).


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## mkingham (Jun 4, 2018)

cant wait to see this come together ... subscribed!


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## XS_MotorWorks (Sep 23, 2019)

Well I made some good progress. Tesla motor is mounted. I've also got 16 kWh mounted. Found a home for 14 more. The last 2 are given me a bit of a challenge but I will get it worked out.


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## brian_ (Feb 7, 2017)

XS_MotorWorks said:


> I've also got 16 kWh mounted. Found a home for 14 more. The last 2 are given me a bit of a challenge but I will get it worked out.


I like this battery configuration - it's nice and low. Lots of people talk about putting modules in the centre tunnel, but it's not often actually done, because most stock tunnels are not large enough for production modules; the Volt modules are designed to go in a tunnel, and the custom vehicle structure can accommodate them.

Is there room for one more block between the two in the rear, or is that already the plan in that 14 kWh? It can be mounted inverted if necessary.


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## XS_MotorWorks (Sep 23, 2019)

In the picture the 2 packs behind the motor are 5 kWh each. The pack left over is 6 kWh and is made of three 2 kWh cells. So I might take the 1 kWh cell from the front and replace one of the 2 kWh cells. So each pack would be 15 kWh instead of the standard Vol pack of 16 kWh. That would fix the lay out but remove 2 kWh from the system.


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## brian_ (Feb 7, 2017)

XS_MotorWorks said:


> In the picture the 2 packs behind the motor are 5 kWh each. The pack left over is 6 kWh and is made of three 2 kWh cells. So I might take the 1 kWh cell from the front and replace one of the 2 kWh cells. So each pack would be 15 kWh instead of the standard Vol pack of 16 kWh. That would fix the lay out but remove 2 kWh from the system.


Just replace "cell" with "module" in that, and it makes more sense.

I don't quite get it, though... 


XS_MotorWorks said:


> I've also got 16 kWh mounted. Found a home for 14 more. The last 2 are given me a bit of a challenge...


but there are three modules totalling 6 kWh with no home (not just 2 modules or 2kWh) in the photo.

Of the modules in place (mounted or not) on the frame, there is a total of 26 kWh, and swapping a 1 kWh with a 2 kWh would still be only 28 kWh, and each string would need to be 14 kWh. Is there a place for one 2 kWh module which is not shown on the frame?

Perhaps I'm misunderstanding what is mounted and what is allocated a space.


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## XS_MotorWorks (Sep 23, 2019)

Sorry about the confusion. My first electric build and still trying to get the terms correct.

There is 6 kWh module that is in the upper left part of the picture that's not inside the frame rails (from the picture it actually looks like a 4 kWh)

Here are some better pictures.

Front 5 kWh (this is where I would take the 1 kWh from to balance the packs)









This is the center 11 kWh (The front and middle where taken out of the same Volt pack). For my build front and middle will make up one pack and right now that would be 16 kWh but after I take out the 1 kWh this pack will be 15 kWh









Both of those are mounted. I harvested the mounting plates from the Volt.

Now onto the rear section. These are not mounted yet but that's easy enough.
Each of these are 5 kWh and I can place another 5 kWh in the middle so the pack would also be at 15 kWh









So I just need to break up the front 5 kWh and make it a 4 kWh and than break up this 6 kWh and make this a 5 kWh. 









That would give me 30 kWh. Not great but the weight would be very low and between the tires.

Hopefully this all makes sense.


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## XS_MotorWorks (Sep 23, 2019)

Sorry about the confusion. This is my first electric build and I'm still trying to keep the terms straight.

In the picture in the upper left corner there is 6 kWh not inside the frame. Anyway I took some more pictures to explain my thoughts.

Right now I've got 5 kWh mounted up front ( this is where I would take the 1 kWh from)










Down the center I've got 11 kWh









Those two would make up one pack. Right now that's 16 but after I take the 1 kWh from up front it's going to be 15 kWh

In the back I've got 10 kWh with room for 15 kWh.









So my plan is to break up this 6 kWh and make it into a 5 kWh. 









Each pack would be 15 kWh for a total of 30 kWh. Range will be a bit limited but the weight is very low and right between the tires.


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## brian_ (Feb 7, 2017)

Thanks for the explanation, and the photos. 


XS_MotorWorks said:


> In the back I've got 10 kWh with room for 15 kWh.
> ...
> So my plan is to break up this 6 kWh and make it into a 5 kWh.


There's the key - one more block of three modules _will_ fit between the two already shown in the rear. 

It looks like the whole 6 kWh block would fit in the front (where the 5 kWh block is currently sitting; it looks made for a 6 kWh block), leaving the 5 kWh block to go to the rear, and fitting in all 32 kWh. Of course, it might not quite fit, and if it does the modules do need to be wired into two 48S sets (not one 42S set and one 54S set), so that would complicate the wiring. You could turn the tunnel set around to put the small module at the back, connect all but that small module and the front block together as one 96S 16 kWh string, and connect the three blocks in the back plus that one small module from the tunnel as the other 96S 16 kWh string... but I don't know if you can make that work in BMS connections.

If my character drawings make any sense (using "12" for a 12S 2 kWh module and "6" for a 6S 1 kWh module, and "-","|","/", and "\" for connections in a string)...
This is what you are planning:

```
12-12-6                  
|
12-12-6 6-12-12-12-12-12-12
      |                  |
12-12-6                  12
```
This is an alternative to fit in all of the modules:

```
12-12-6                  12
|                        |
12-12-6-6 12-12-12-12-12 12
        |              | |
12-12-6-/              \-12
```
It's interesting that the entire tunnel and front hold the same as the mid-rear location (where the engine is in this car's evil twin ).

This is the tidiest and best-distributed configuration of a battery I've seen, other than of course the underfloor approach... and this allows the seats to be significantly lower, which is valuable for this style of car.


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## XS_MotorWorks (Sep 23, 2019)

I can see from the pictures why you (or anyone) would think that I could have a 6 kWh up front. But there is one item which is not in the picture and its the steering column. If you look in the picture you will notice that the 5 kWh is pushed off to one side. That was to make room for the steering column, so putting the 6 kWh up front is not going to work (but it would have been a nice option) 

So I think the layout will be like this 


```
F                              12-12-6    B
R       12                     |          A
O        |  12-12-12-12-12-6   12-12-6    C
N       12-/                         |    K
T                              12-12-6
```


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## brian_ (Feb 7, 2017)

XS_MotorWorks said:


> If you look in the picture you will notice that the 5 kWh is pushed off to one side. That was to make room for the steering column, so putting the 6 kWh up front is not going to work (but it would have been a nice option)...


Yep, I missed the front-steer rack location, visible in an early photo. Without the steering column in place, it wasn't obvious.

The omitted 6S (1 kWh) modules are only 6% of the pack energy and voltage, so it shouldn't be a big deal. Those Tesla large drive units ran on only 84S (versus your planned 90S) batteries with the 14-module variants of the Model S.


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## XS_MotorWorks (Sep 23, 2019)

Charging is working. I'm using two Chevy Volt chargers with a thunderstruck EVCC


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## XS_MotorWorks (Sep 23, 2019)

I've finally gotten the basic rolling chassis done. I was able to place a total of 30 kWh in the chassis in two 15 kWh packs. 15 kWh in the rear (pack 1) 11 kWh down the center and 4 kWh up front (pack 2). I going to sand the chassis and put a cheap coat of paint on it to stop the rust. When completed I going to get it powder coated. Now I've got to start working on the rest of the chassis which will be 1 5/8 tubing.


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## EVmattyP (May 12, 2019)

Wow, I'm about 5hrs away from you but I'd love to come up and help out with this build. Happy to lend a hand in exchange for gleaning knowledge!


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## XS_MotorWorks (Sep 23, 2019)

Sure...I could always use a hand. I'm actually building two cars 
1. Gas 
1. Electric. 

I've got a build vlog but havent shared as it covers both cars but if your interested take a look https://youtube.com/xsmotorworks and shoot me a PM.

Cheers,
Brian


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## XS_MotorWorks (Sep 23, 2019)

Slowly but surely. It's getting done.









mocking up the charger and dc-dc
















Batteries are mounted

















What do you think?


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## brian_ (Feb 7, 2017)

It's good to see everything coming together. 

These photos show the car from new angles, and now with the wheels. The drive unit is turned to be ahead of the axle line, apparently by turning it over (keeping the rotation direction but making the bottom into the top)... right? It also looks like the motor is very high - is the drive unit tilted up at the front?


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## XS_MotorWorks (Sep 23, 2019)

Correct the motor has been flipped from the OEM position. I've got to redo the lubrication pump because of this but that is not a big deal. 

It's real not to high. I think its just the angle. Top of the motor is 25 inches off the group.


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## brian_ (Feb 7, 2017)

XS_MotorWorks said:


> Correct the motor has been flipped from the OEM position. I've got to redo the lubrication pump because of this but that is not a big deal.


I assume that it is just the oil pickup that needs to be modified.



XS_MotorWorks said:


> It's real not to high. I think its just the angle. Top of the motor is 25 inches off the group.


So it is tilted up, right? The stock Tesla rear installation has the bottom of the motor essentially flush with the bottom on the final drive housing portion of the transaxle case, so the top of the motor is a few inches lower than that. The Model S/X front motor is higher, because it is rotated up to sit over the front edge of the larger (16-module) battery case. In this type of car, low is good, but packaging all that battery volume is a challenge.


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## XS_MotorWorks (Sep 23, 2019)

brian_ said:


> I assume that it is just the oil pickup that needs to be modified.


Unfortunately not. Pump is not self priming. Ugh




brian_ said:


> So it is tilted up, right? The stock Tesla rear installation has the bottom of the motor essentially flush with the bottom on the final drive housing portion of the transaxle case, so the top of the motor is a few inches lower than that. The Model S/X front motor is higher, because it is rotated up to sit over the front edge of the larger (16-module) battery case. In this type of car, low is good, but packaging all that battery volume is a challenge.


From factory location its about 12 degrees up. That's as low as I could manage. Positive is the weight is in front of the tires.


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## brian_ (Feb 7, 2017)

XS_MotorWorks said:


> Pump is not self priming. Ugh






XS_MotorWorks said:


> From factory location its about 12 degrees up. That's as low as I could manage. Positive is the weight is in front of the tires.


So maybe only a couple of inches higher than stock.  The tires might be shorter than the stock Tesla size, exaggerating the motor height, and of course the frame is very low, which accentuates the drive unit height as well.

I get the idea of using the Tesla drive unit because it produces lots of power in stock form, but it's at least a little amusing to customize the unit and its installation to put the motor ahead of the axle line, when just about every other drive unit in production (including Tesla's own units in the Mercedes B200e, Toyota RAV4 EV, and Model 3 at the rear) puts the motor ahead of the axle line in stock form.


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## XS_MotorWorks (Sep 23, 2019)

Got the scales out over the weekend and the car currently weighs 1909 lb. That with the two charges and DC-DC. I hope the completed car will be in the 2500 2700 range.


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## brian_ (Feb 7, 2017)

It's good to see a builder who has a set of scales and takes the time to use them. 

LF = 414, RF = 349
LR = 560, RR = 586

LF+RR = 1000
RF+LR = 909

The weights are diagonally biased, which doesn't matter because the suspension wasn't adjusted to remove that... so the individual wheel weights aren't meaningful, but front-to-back and left-to-right distributions are.

Front total = 763
Rear total = 1146
F:R is 40:60

That distribution seems reasonable to me, but of course it will change somewhat as the car is finished.

Left total: 974
Right total: 935

Even though the front battery pack is offset to the right, the motor on the left side still biases the whole vehicle to the left, even without the steering column etc which will also go on the left. It's not a big difference, but it shows how important that big lump of iron and copper is.


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## snowdog (Oct 22, 2018)

I love following your progress. Thanks for all of the posts.


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## XS_MotorWorks (Sep 23, 2019)

Chargers are mounted tested and working correctly. DC-DC is mounted (still need to test). Wiring the BMS now. Just need to finish the coolant system.


















I had to change the wiring in the charger to be a side exit. I also deleted used wires.


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## XS_MotorWorks (Sep 23, 2019)

Good start to the year. 
Both Volt chargers are working
Volt DC-DC is working
BMS is configured on first pack
Pack 1 is @ 370 volts

Hopefully I be able to get the motor to spin next week.

build vlog is @ https://www.youtube.com/xsmotorworks if anyone is interested


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## XS_MotorWorks (Sep 23, 2019)

Here is my lasted update (posted here first)....Very close get getting the motor to spin....

The wood is temporary. This is the layout for the high voltage. I'm going to build a aluminium box around the parts.

I've order 14 gauge wire to connect chargers and DC-DC converter.


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## EVmattyP (May 12, 2019)

Loving the updates! Still want to get with you when you have some time. Hit me up when you get some down time and aren't so busy.


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## XS_MotorWorks (Sep 23, 2019)

Sent you a PM


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## XS_MotorWorks (Sep 23, 2019)

Final placement of the windshield is complete. Visibility is what you expect, meaning your low to the ground and it’s hard to completely see all aspects of the front. That said it’s the same view you get when you sit in a Lamborghini. Next up I will be scanning the windshield (chassis is already scanned) and developing the body in CAD.


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## brian_ (Feb 7, 2017)

I like the idea of wrapping a body around the important parts, rather than trying to fit things into a body. Of course, this is way beyond the skills and abilities of most of us.

What is the windshield from? I assume it's from a regular production car... Corvette?


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## EVmattyP (May 12, 2019)

brian_ said:


> I like the idea of wrapping a body around the important parts, rather than trying to fit things into a body. Of course, this is way beyond the skills and abilities of most of us.


Agreed! I've always preferred when somethings form follows it's function. I have this obsession with efficiency over aesthetics and I think too often people try to design a products looks first.... think Fisker.

I've been really looking into Styrofoam carving lately as a way to make body panels. I think it would be amazing to form your panels shape with foam and then cover it in carbon fiber cloth or vinyl or CFRP and then once hardened just shave/sand off the foam under neath to reveal your new panel. Foam is cheap and easy to work with and allows for lots of mistakes with low cost penalties....but probably not the level of fit and finish you'd get from a Mercedes!


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## brian_ (Feb 7, 2017)

EVmattyP said:


> I've been really looking into Styrofoam carving lately as a way to make body panels. I think it would be amazing to form your panels shape with foam and then cover it in carbon fiber cloth or vinyl or CFRP and then once hardened just shave/sand off the foam under neath to reveal your new panel. Foam is cheap and easy to work with and allows for lots of mistakes with low cost penalties....but probably not the level of fit and finish you'd get from a Mercedes!


It's a well-proven technique, although in most applications the foam (or much of it) remains in the finished product, often as the core of a double-skinned structural body. One challenge is that since the outer surface is not formed against a mould, it takes a lot of filling and sanding to get a good finish.

Burt Rutan's VariEze aircraft is a classic example, but there are other aircraft, small travel trailers, and lots of boats which have been built this way. And surfboards...

Quick links for those not already familiar with this approach:
An Overview of How to Work with Fiberglass Over Foam
Moldless Composite Construction
Building Composite Aircraft Part 1


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## XS_MotorWorks (Sep 23, 2019)

So i guess I didn't mention that I also built this to make the body









Here a MR2 decklid that was made with the machine.









After carbon fiber clear coat (not the same as paint)


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## XS_MotorWorks (Sep 23, 2019)

Oh and the windshield is non OEM Lamborghini Aventador (still expensive though)


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## EVmattyP (May 12, 2019)

xs_motorworks said:


> so i guess i didn't mention that i also built this to make the body


get out of my head!


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## brian_ (Feb 7, 2017)

XS_MotorWorks said:


> Oh and the windshield is non OEM Lamborghini Aventador (still expensive though)


Interesting... I guess it's whatever sits at the desired angle and has suitable height, width, and curvature. Using something production and therefore available (whether OEM or aftermarket) is certainly the only way to go, given that it will likely need to be replaced at some point in the life of the vehicle.


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## XS_MotorWorks (Sep 23, 2019)

Glass is the biggest problem (to me) when building your own car. You can get a custom windshield made made but that is expensive and believe it or not I am doing things on the cheap.

Tesla setup $1600
Batteries $1100 each
Charger(s) $150 each

Corvette parts were from totaled cars.


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## MattsAwesomeStuff (Aug 10, 2017)

Damn. I figured this was a pricey build, not a cheap one.

You got a Tesla LDU for $1600?

Anyway, no questions and nothing to contribute, but, I'm enjoying watching your progress.


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## XS_MotorWorks (Sep 23, 2019)

Yes...I know most wont believe it but its true. The key is to CALL small salvage yards. They dismantle and sell upstream. Lots of the small ones only a phone number on the web. This one came out of SC


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## hakeemuchiha (Dec 9, 2019)

Great seeing your build on here. I've been following your build on Facebook for a while and assumed it was an expensive build as well. 

Seeing the price you got the Tesla rear drive unit for makes me regret buying my leaf motor lol.


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## XS_MotorWorks (Sep 23, 2019)

So far the single most expensive part has been the BMS. That was $2400 (ouch). The windshield is a close second at 2k. But I was limited on windshield options given the angle I wanted. I even found the rear tires as a close out (they came out with a newer version) and these were deeply discounted.


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## XS_MotorWorks (Sep 23, 2019)

Just about done with the high voltage layout. I'm still planning to add a precharge relay.


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## Tomdb (Jan 28, 2013)

Are you fusing all outputs? It does not look like it.


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## XS_MotorWorks (Sep 23, 2019)

I think your saying do I have a fuse on the Charger(s) and DC-DC?


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## Tomdb (Jan 28, 2013)

Yes if the only things coming out the box besides the motor then yes.


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## XS_MotorWorks (Sep 23, 2019)

I was actually going to run an inline fuse for the chargers and DC-DC. But now I think it will make more sense to go ahead an and them into the distribution box.


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## XS_MotorWorks (Sep 23, 2019)

Progress...It's spinning. 
[url=https://flic.kr/p/2ipu8rw]Untitled by Brian Denton, on Flickr[/URL]


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## MattsAwesomeStuff (Aug 10, 2017)

> Progress...It's spinning.


Lol. Video didn't embed here, but, your 2 second narration on flickr is hillarious


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## XS_MotorWorks (Sep 23, 2019)

Making progress but I still have a long way to go. The car will be on display at the Atlanta Intentional Auto Show.


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## EVmattyP (May 12, 2019)

Looking great. I'd love to just drive it around without any body panels! Just weld on a decent roll cage and it would be the ultimate Ariel Atom!


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## XS_MotorWorks (Sep 23, 2019)

Well after a NUMBER of set backs I back at it....


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