Electric Supercar

MattsAwesomeStuff said:

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.

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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.

MattsAwesomeStuff said:

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.

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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.

snowdog said:

DIY aftermarket electronic parking brake.

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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.

blwnhr said:

It's a single button, dual colour, not two buttons.

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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.

blwnhr said:

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.

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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.

Duncan said:

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

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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.

4G63T said:

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.

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I assume that snowdog has a hydraulically power-assisted rack which is already not powered.

4G63T said:

Did you do similar to this conversion?

https://m.youtube.com/watch?v=KP3SkSfO9uQ

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Duncan said:

Watched the video
WHAT A LOT OF CRAP

I would not let that idiot anywhere near my steering

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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.

4G63T said:

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.

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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.

4G63T said:

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 ?

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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 Miata.net 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.

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.

MattsAwesomeStuff said:

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.

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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.

MattsAwesomeStuff said:

Solution perhaps from the aviation industry, to have deeper-sunk cutouts for the hinges...

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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.