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Electric Supercar

117028 Views 525 Replies 38 Participants Last post by  snowdog
Hello all,

I thought I would start a build thread. I have ordered a K1-attack kit car. I have started the assembly. My plan is to have a Tesla drive train. I am sourcing from EV-West. Hopefully that was a good company to partner with. I am waiting on batteries until the build is further along. I will definitely reach out to the forum for advice along the way. I am also documenting in YouTube. Feel free to follow along.
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I should have mentioned earlier that unless the thing being bolted imposes lower limits, an appropriate tightening torque is determined by the bolt itself, and there are published standards for that, by size and material grade. In a few minutes of online searching, you can probably become more qualified to specify a bolt torque than the guy who picked that bolt for the kit...
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I'm skeptical if you have enough clamping force to actually usefully create a decent enough thermal connection between the battery modules at the plate.

I'd think you'd need some long bolts at least between or around each battery pack and some decent boltdown force to hold them in contact.
For comparison, it is interesting to note how Chrysler attaches the same modules to the heat transfer plates of the Pacifica Hybrid.... which is also the mounting of the modules. Formed multi-part steel brackets surround the modules (in groups) and are bolted directly to the heat transfer plate.

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Does anybody have a pic of how the OEM mounts them?
The best image that I have been able to find is shown in my post above (post #161).
It looks like you had a clamping plate that was just bolted around the perimeter of the entire box. I was suggesting that they should have a clamping force around each module itself.
It appears from the image which I posted earlier (which has been used in several articles about the Pacifica Hybrid) that Chrysler uses a single frame to mount and clamp a group of three modules, stacked along the axis perpendicular to the cell planes. As long as the thermal management plate is sufficiently stiff across the long dimension of the cells, then it doesn't matter how long the uninterrupted cell stack is as far as clamping to that plate is concerned.
What I'm seeing there, is there are fasteners in the middle, holding the modules down. Not a frame spanning the entire box and only clamped around the edges.
I suspect that my earlier comments may not have been clear. I didn't intend to suggest that the whole 3X2 array of 6 module was held only around the periphery of the pack.

There are fasteners all the way around the periphery of each 3-module group, and there are electronics boxes stuck on top (unrelated to securing the modules), but I don't see anything going down between the modules at the 1/3 and 2/3 points along the combined stack. As far as clamping to the thermal management plate is concerned, you only need to clamp down along opposite edges of each module, separated by the long cell dimension.


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DIY aftermarket electronic parking brake.
It thought that sounded interesting, since there are conversions and other projects which use front suspension and brake hardware at the rear of the car and thus have no parking brake... but in fact this is a controller for the normal Tesla OEM parking brake, which uses a separate electric parking caliper from Brembo:
Pantera Electric Parking Brake Controllers
A good thing to know about if using OEM electric parking brakes outside of the complete original vehicle. :) On the other hand, a momentary push button with a colour-changing indication seems like a lousy interface. OEM installations usually use a pull-up/push-down switch, so it can be used without looking for an illumination colour.

I think that it should also be interlocked with the drive system, to avoid trying to drive away with the parking brakes locked, or engaging drive without either the service brake or parking brakes applied. This is particularly important with the Tesla Model S/X drive units, as they do not have a parking lock internal to the transaxle, so they are much more dependent on the parking brake than a vehicle with a transmission lock.
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It's a single button, dual colour, not two buttons.
Yes, I realize that... and that's the problem. Two distinct buttons (for apply and release) would work for a parking brake, but in the fine tradition of the idiotic on/off buttons so beloved of electronic device designers determined to save a buck, you have no idea what this thing is going to do unless you look at the colour of the illumination. I get the one-button thing on a $10 consumer device, but on a car costing tens of thousands of dollars it's just stupid; ironically, auto manufacturers normally handle the parking brake properly... then cheap out with a single pushbutton to control all of the multiple operating modes (off, accessory, engine run) of the vehicle.

As it's a momentary signal to the control box it would be easy to use any kind of momentary toggle switch, including an OEM lever switch.
The OEM parking brake lever switches are not normally a single momentary contact - they have distinct apply and release directions. Since this control box is too stupid to understand distinct apply and release commands (it has only that single momentary contact input), the system can't be fixed with a better switch and any amount of external intelligence.
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As compared to a single ignition key which controls all the operating modes, as we've had since the 1930's? What do you see as the solution?
They key has multiple positions (with the start position momentary). The solutions are a rotary selector or a row of buttons (off/acc/run/start).

OEM electronic handbrakes are a single momentary up/down.
In the ones I have seen, the single switch has separate up and down movements (it is a double-throw centre-off momentary switch), not just up or just down.

Anyway, snowdog's one-pushbutton controller works, and much better than trying to make use the Tesla control system for the parking brake, or not having a parking brake at all. :)
We find brake lines leaking
I would be cautious about repeatedly tightening brake line fittings. If they're banjos with gaskets that might be okay, but hard lines with flare fittings are really only intended to be installed once; every time they are tightened parts distort.

From the post note about "brake lines" I wondered if you had an issue with the mix-and-match collection of components using incompatible fittings (fitting types typically used in North America and European are different), but if it is only one connection maybe that's not a problem.
We find the steering rack leaking
In the video, you say that it is a manual rack... but it has hydraulic fluid in it and fittings. Are you sure that it is a manual rack? My guess is that this is a power rack which has been internally bypassed to defeat the power assist, and hasn't had the fittings properly capped.

I would guess, given the use of Audi components for the front suspension, that this is a VAG (VW/Audi/etc) rack... but who knows. It's hard to find a manual rack in a modern production vehicle, and there will be the same issues with any brand. If wanting a manual rack using modern powered components, I assume that the cleanest installation would use a rack intended for use with an electrically powered column, but with a non-powered column (from a vehicle which uses an electrically or hydraulically powered rack)... but of course when this kit was designed electric steering assist was too new.
I took an old Subaru power steering rack apart

I found that the actual rack and pinion were grease lubricated - the power steering bits used hydraulic fluid

So for the rack in my car I simply capped off the inlets and outlets on the pinion part,
Drained the oil and connected the two ends of the actual ram on the rack together
That's an ideal situation for manual conversion, and it is apparently typical (the actual rack and pinion are greased, not lubricated by the power steering fluid).

In snowdog's case, we see two port plugs, but no bypass hose, suggesting that it is internally bypassed, unless there is also an external bypass hose or tube that I just didn't notice. It may be that the port plugs are just junk, and other than using proper plugs everything appropriate has already been done.

To Snowdog: if you have an actual powered steering rack and trying to use it as manual, I would highly recommend you convert it to manual as shown in that video.
I assume that snowdog has a hydraulically power-assisted rack which is already not powered.

Did you do similar to this conversion?
Watched the video

I would not let that idiot anywhere near my steering
For someone who does his own work on a competition vehicle, he seems to have a surprisingly poor grasp of automotive terminology. He tries to use an adjustable wrench instead of a properly-sized wrench, then when that isn't big enough he uses pliers on a hex nut - that alone would keep me from allowing him to touch my vehicle. He does seem to understand how the bits work... just not what they're called or how to work on them.

On reassembly of the part on which he uses the pliers, he clearly has no idea of what method to use or the significance of the spring loading torque.

Overall I agree with Duncan: regardless of the value of the de-powering approach, the guy who made this video would not be allowed to touch any component of my vehicle.

I’m not an engineer but from what little I know what he did makes sense. We are taking a steering rack engineered and designed to run with power steering fluid pressure assistance and trying to run it as a manual steering rack.

Internally it has a “disk“ on the rack that the fluid will push to power assist with steering. Disconnecting the pump and leaving fluid in it or simply draining it and leaving air will create resistance. The disk will act like a piston trying to push fluid or air. Not to mention the disk will drag against the cylinder wall. So at the very least I think it would be best to remove the that disk.
That makes sense. The part which you are suggesting to remove (and which he does remove) is the piston of the hydraulic cylinder which is formed by the rack housing (the cylinder) and the rack which moves within it (the piston shaft). Of course, our "expert" on video calls this piston a "valve-type setup" because it has a ring seal which looks like the seals on the spool valve, which someone told him is a valve.

Using a rack from a column-powered electrically assisted steering system would avoid any hydraulics in the rack.

As for the pinion side, there is the valves that direct fluid per the steering wheel input. For this to work, a slight “free play“ exists in the steering wheel. If you steer left the valves will move to direct fluid appropriate to push the disk in cylinder left. And Vise Versa. At this point why not just remove this valves and weld the two halves solid ?
It isn't quite free play, since the way the rotary valve works requires that it be springy, rather than just loose, so increased force by the driver results in increased resistance the two parts of the pinon shaft as connected by a torsion bar (which is springy but has no free play) and a loose set of splines (as a backup, and limit on torsional movement). I agree that ideally this would be locked solid, and I realize that a custom pinion shaft is probably unreasonable, but there must be a better way than welding on a shaft with an integral gear, if you understand how it is put together. The heat-affected zone after welding is huge.

Using a rack from a column-powered electrically assisted steering system would eliminate all of the hydraulics, including this valve; the sensing function would be in the column (which wouldn't be used).

This video was offered by YouTube on the side when I watched the first video:
The ULTIMATE Guide For How To De-Power A Miata Steering Rack
This guy gives more clear directions, apparently knows what he is talking about, and has a better tool set... but still uses one adjustable wrench on a nut, and uses a screwdriver as a punch. This guy installs the lash adjuster properly, and explains what he is doing. This is, again, a Mazda MX-5 example, and all the details will vary between racks, so much of the nice detail is of no value to snowdog.
There was another MX-5 rack depowering video offered. I watched it in fast-forward jumps: it is the same piston removal without rotary valve locking as the second video (and this guy is better equipped than the second one, and everyone knows more about what they're doing the first guy).

In this version, the piston is removed, but the rotary valve is left alone. For someone starting from a stock rack, it would be interesting to remove the rack piston first, then drive the car and assess the result before locking the rotary valve as a second stage if that seems worthwhile... and if that second stage is done, to assess whether it made a useful difference. This video shows how much angular travel is allowed in the pinion shaft (again, for an MX-5): Miata spool valve slop.

In a quick survey of online material, it appears that welding the rotary valve is common (at least for the MX-5), but not universal. Many would consider Flyin' Miata to be the ultimate Miata (MX-5) experts, and their depowering guide does not modify the valve. A discussion suggests that the valve accounts for one-third of the compliance in the steering system of a specific example Miata (including tires). There are few references to other models of cars, probably because few modern cars are light enough to use manual steering with a ratio as quick as a typical power-assisted rack.

A discussion in a forum for the Factory Five 818 kit - which is very comparable to snowdog's kit - suggests that they generally want manual steering (to avoid power steering complications) and typically de-power the stock (Subaru in this case) rack, with or without welding the components of the pinion shaft.
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The Electraliner story is interesting, but I think it belongs in its own thread. I suppose the point is... EV West's attention is with another project.
Double pack might be doing it! You have original BMS IIRC, that would likely cause an address conflict.
Original BMS? The modules are intended for a Chrysler Pacifica Hybrid, and were purchased separately, not salvaged from a Pacifica. Snowdog, you're not using Pacifica BMS, are you?
The above post is spam, stealing my text from an earlier post and inserting spam links. Do not follow the links. The account is a spammer.
This is too late to be useful, but I would have made the mounting brackets on the lid for the struts larger, to spread the load out. I've had this sort of mount tear out of storage compartment doors on my motorhome, and had to add plates, because the force on those struts is surprisingly high.

Most simply, the hinge fulcrum has to be behind the farthest-back part of the trunk, or, like a teeter-totter, when one side goes up, the other side is going to dip down.
By "behind", you mean "beyond the opening", which is forward in this case (because it's a front-hinged lid), but yes, that's basically how it works.

The solution for a simple hinge is already in place in this design, with the curved hinge arms, but the pivot point just needed to be better placed... as has already been realized and executed.

The other common solution, to avoid having the lid move too far toward stuff above the hinge area, is to use a four-bar linkage hinge. That's commonly found in the engine hoods of older North American cars. With this sort of design, the hinges could probably be moved further apart for stability... perhaps even at the corners where they should be.

Solution perhaps from the aviation industry, to have deeper-sunk cutouts for the hinges...
But you don't have to do that. The aircraft cabin can't have the door hinges protruding substantially into the interior (as the curved hinge arms need to be to clear the edge of the opening), but the car's trunk can. It might even fit them at the corners in this case.

What's crazy about this whole thing is that the lid is apparently intended for access to the engine and to the trunk. With no engine and no useful storage in the forward part, there's no need to a hinged panel to access the front of this compartment; therefore, it could have been built with a simple and effective trunk lid for the rear part, and a removable panel for the front held by screws or quarter-turn fasteners. Sorry if that was already considered in an earlier video which I haven't watched.

As for the garage door clearance... you know the solution. If you change opener hardware, this would be a good time to switch to a side-mounted (wall-mounted) opener.
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Hmm, no what I saw was that he put both hinges in the centerline of the car so now it's all weeble-wobbley. It's minimally functional, but crappy, and will probably buck and shake at speed even when closed.
All I meant was that the hinge point was moved forward, as it needed to be. I agree that the narrow hinge configuration introduces another problem.

Hinges protruding down into the car solves the problem of the edge of the trunk having some gap when opened, but does not solve the problem of the pivot point being located too close to the lid and any panel past that tilting down, not up. The rotation point determines where the lid pivots around. I'm not sure there was room to put them out wider, as that's kind of where the seat-scoop things are.
I don't think you understand what I meant. The curved hinge arm doesn't fix anything itself, it is only required to allow the hinge axis to be further ahead of the opening edge. Due to the headrest fairings, the offset from hinge axis to opening would be very large.

What really makes me shake my head about this whole thing is that the lid looks like an original part of the kit, and so there should be a hinge system already worked out for it by the "manufacturer" of the "kit". Perhaps that was covered in an earlier video.
When I saw what you were trying to do, I wondered about using a hinge assembly like some older cars used. Kind of a cantilever system rather than a simple pivot hinge. I really don't know if they would work, but something like this:
Yes, there are few design variations, and that's what I was referring to in this:
The other common solution, to avoid having the lid move too far toward stuff above the hinge area, is to use a four-bar linkage hinge. That's commonly found in the engine hoods of older North American cars. With this sort of design, the hinges could probably be moved further apart for stability... perhaps even at the corners where they should be.​
All of our vehicles have a name that is routinely used for them, but not in the sense of a personal name... our Mazda 3 is called "the Mazda", the Toyota Sienna is "the van", etc. Each is unique only within our fleet (we only have one car from Mazda, one van-type vehicle, etc).

I had one vehicle that came with a name from the previous owner, which was "Rodney" (that's the car, not the owner). It made sense to her, but not to me, so I didn't use it.

I would only name a car that I had created, and was substantially different from any production vehicle - this project certainly qualifies. I would give it something like a model name (as if it is the prototype), rather than a personal name (for an individual). But what I would do doesn't matter, of course.

Naming your own car though is a bit pretentious, it's like giving yourself a nickname.
But it's your car, not you. Don't you name your own pets? I don't see a difference.
The trunk lid configuration makes much more sense now. If I understand some comments correctly, the original design hinged the engine cover at the rear where there was an essentially straight rear edge, which would have been much more appropriate for that leading edge shape, and it had either a separate trunk lid or no trunk lid at all. When the kit design doesn't suit the desired configuration, "simple" changes can get very complicated... or perhaps "rich learning experiences".

At some point the car becomes a custom, built with some K-1 frame and body parts. Perhaps a good name would be Tikaton, which - in case it's not obvious - is "not a kit", written in reverse so it's less obvious. :)
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Pets need a name that they understand refers to them, for purposes of instruction.

I did not name my goldfish, as they wouldn't recognize it.
A trainable pet's name needs to be recognizable to them, but it doesn't matter to the pet what the name means to anyone else. It seems likely that the car has been and addressed by the owner - perhaps with profanities attached - and it's not going to understand no matter what name is chosen... although if some personal digital assistant is added it could be trained to recognize its name: "Tikaton, what is your state of charge?", followed by "Why the **** can't you tell me?"
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