Under trunk cubby

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OzRob

Member
Joined
Dec 14, 2017
Messages
9
Location
Sydney Australia
Hi! I’m a new member! I have a 2018 i3s on order for delivery here in Sydney in a few weeks time and, as a retired auto engineer (GM then Ford) and competent CAD designer/3D modeler I have a plan to improve the trunk space.
I’m not getting the REX version so there’s heaps of space under that floor in the trunk. I’m gonna undo the cover and design/make a plastic trunk extension, accessible when the carpet is lifted. Probably need a harder cover over the space to support the luggage above. Don’t worry! The new part WILL seal!
My questions are “has anyone done this before? If not, why not? And once I’ve done it, would there be a market for me to sell this part to other non-REXers?”
Thanks
 
Hey, that sounds like a good idea.

Interested to hear what it will be made from. Will it be insulated for hot/cold climate, and how easy would it be to install?
 
Such a modification has been proposed by several BEV owners since 2014, but I'm not aware of this modification having ever been implemented. I've been interested in this myself, but I'm not certain that the cubby size would be worth the effort and expense. Designing convenient access to this cubby might be challenging as well. With the trunk floor removed, I also drooled over the space available where the REx muffler would be, but accessing that space would be even more challenging.

Keep us informed about your progress. Good luck!
 
Hi Oz Rob,

I will buy one of these off you immediately. I've been thinking about it for a while but have no skills to create one, it would be great huh.

Only thing I ever found on the internet about it was this article https://bmwi3owner.com/2014/02/heat-pump-in-front/

If you do manage to produce a few PLEASE let me know.

Cheers
 
A guy on the i3 FB group made a subwoofer enclosure for the space, he shared the drawings. I would start there if I were you. I hope to do the same (sub enclosure) at some point in the future. Keep us posted.
 
Hypermiler said:
There is a rather professional version made by a German
That looks really nice. An English description can be found here.

However, it appears that the only cover over the storage boxes would be the carpeting and its backing. If so, placing anything heavy on the carpet over the storage boxes could be a problem.

I like to support quality products like this, but the shipping cost halfway around the world to Honolulu would be prohibitive. When I think about how we use our i3, I really don't need the additional storage very often, so I don't plan to order this product.
 
The price from Germany for that item is AU$650 plus freight! Given the size, bet the shipping cost is huge.

Nice design except the lack of info about the support below the carpet.

Hopefully OzRob comes up with a better and more economical solution.
 
Several in that forum, from an Ikea plastic box, through to aluminium and stainless versions.

The stainless was on offer in November. Looks good, but also not cheap, 439.99 €. Imagine the freight would also be expensive to here in Australia !

https://drive.google.com/file/d/1s6C4VkRo-iU784o1SDkh4_WHEep62tb-/view
 
Am in no way related to these guys and have a REx myself.

Looks like professional grade (PU coated stainless steel) to me. The earlier version referred to is a prototype of the same thing.

At any rate, as there is no VAT (19%!) for exported goods, I would guess that the item including shipping would be similar.
 
alohart said:
Another German i3 owner has built a solution that is less expensive (not all welded stainless steel) and has a proper cover that makes accessing the extra storage space much easier. If I could read German, I would read through the very long thread discussing designs for additional BEV storage because there are likely some pretty good ideas discussed.

I think there are websites that will translate for you if you really want to read through them. Thanks for the link, looks like some great ideas.

This was my favorite (joking).
46134


Just cut a hole and slide this plastic container in there, lol. He actually has it braced in another photo but still, wouldn't do this to my i3.
 
Thanks for the info about Wolfgang’s work. I’ve emailed him to get a shipping price - I wouldn’t be deterred by what he’s asking for the part itself and it looks well developed.
One issue that would stop me ever selling one in the US (and ought to stop anyone selling them anywhere else, except we have fewer litigious people) is that in a rear end crash, the trunk floor forms part of the crash structure. I.e. when the rear crumples, the metal floor of the trunk resists intrusion and stiffens the shell. Taking that away and fitting a plastic replacement- well, I’d do it myself, but...
 
Given the various options, OzRob are you still going to make them?

If there is an issue of strength, (I kinda doubt it because they are only screwed in with a few screws..), how about making one using carbon fibre? Would be done with a mold and would be at least as strong as the original if the engineer knows his stuff. Would be lighter than the stainless one from Wolfgang and could be designed more like the original boot floor cover.
 
Carbon fibre would be awesome - great idea. As far as the strength in rear end collisions is concerned, well the steel (I assume) panel might only be bolted down but those bolts are in sheer and the panel is in compression giving very high strength in the horizontal plane with little bending. Also when the steel does crumple, energy is absorbed which, unless you want to wear a neck brace for the rest of your life, (or worse) is worthwhile.
Once I get my car I’ll start pulling it to pieces (hey, it only cost $85k!) but I do that to any new car, and see what to work on first. Maybe the front (frunk) - gotta be loads more space there.
In the meanwhile, I’m tiling my garage floor to create a specific charging area!
Btw elsewhere on the forum I’ve seen debates around public charging vs home charging. With the price of electricity here (Sydney Australia) my first choice will be public chargers, which are largely free. Certainly the one at my local BMW dealer is, and it’s solar powered. And that makes so much more sense than using coal fired electricity from Energy Australia at home!
Robbo
 
It's an awesome car.

Will be interested to hear your process. We had our garage grinded flat and finished with epoxy finish. Nothing special done for the i3 area other than the charger install.

We also added solar to our roof, so we are kW neutral for the whole house including the i3. Wouldn't like to be charging from Coal :(
 
OzRob said:
As far as the strength in rear end collisions is concerned, well the steel (I assume) panel might only be bolted down but those bolts are in sheer and the panel is in compression giving very high strength in the horizontal plane with little bending.
The motor cover in our 2014 is made of a composite. I don't know whether it is CFRP or just fiberglass. The screws that attach it screw into neoprene nuts with a tightening torque of only 1 Nm. Can't be much collision protection in this setup, so I wouldn't worry about any 3rd-party replacement that provides additional storage.

I believe later i3's have a sheet aluminum rather than composite cover (cost-cutting?).
 
It’s CFRP Art, same as your roof. Probably stronger than it looks but I don’t think that piece is made for crash protection.
 
imolazhp said:
It’s CFRP Art, same as your roof.
Makes sense. BMW has lots of CF scraps left over from making the passenger cell, so why not use them to make the motor cover? Maybe this was costly enough that BMW decided to start using aluminum sheet instead in later i3's.
 
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