heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Also, found the datasheet for this sensor (attached to this post). Looks like it's almost entirely self contained and requires very little supporting bits. It's very likely that all that's inside the BMW box is the orange sensor itself and a resistor. At least this is what the example circuit that the manufacturer included in the datasheet looks like.

They're everywhere on eBay for cheap, but most of them ship from China, so no idea about quality/genuineness. I did find a seller in the US with a bunch of NOS parts, so ordered a couple to add to the stash in case the sensor on the car ever fails.

[Obioban]

Ha, that's the most modern DIYer cover. CAD, lasered parts, 3d printed brackets/feet. You just need to work a Pi into there somewhere, and you'll have it all.

[heinzboehmer]

Ha, that's the most modern DIYer cover. CAD, lasered parts, 3d printed brackets/feet. You just need to work a Pi into there somewhere, and you'll have it all.

Craziest part is that it was both cheaper and quicker to do it this way than by hand.

[heinzboehmer]

Now that we're on the topic of overengineered things, here's a look at the project that I started working on this past weekend.

Have always wanted the driver's side euro cubby, but I assumed it would require a dash swap, so never actually considered doing it. However, something prompted me to look at the area again and I noticed something interesting about the construction of the dash. I suspect the dashes were made like this:

• Inner hard candy shell is formed (same part for all markets).
• Outer vinyl layer is formed with different geometry depending on target market.
• Inner and outer layers fixed in some sort of jig and foam injected between them to take up any space.

Hit up the junkyard with Bry5on and 3D scanned/destructively disassembled some dash cutoffs:




Suspicions all but confirmed! Inner layer has the locating features, the necessary recess and what appear to be cut reference lines for the euro cubby. Here are some pics stolen from e46fanatics that show how the cubby fits with the dash, for reference:







Seems like I can just cut a hole in the dash and throw the cubby in.

But of course I won't. I want it to look as close to stock as possible. The last pic above shows just how different the geometry of the dash is, which makes my life a little harder. Fortunately, the foam comes off of the vinyl very easily, which can then be formed into shape somehow.

Some pics of the destructive testing I did on the junkyard parts, mostly to see how well the vinyl holds its shape after heating up and cooling back down (answer is extremely well):




Here's my plan for how I'm going to approach this:

1. From the inside of the dash, cut the necessary opening in just the inner hard plastic layer.
2. Rip out all the foam in that area, but do not touch the vinyl.
3. Make any necessary relief cuts in the vinyl (will need to experiment with the junkyard dashes a lot, as the vinyl rips quite easily)
4. Thermoform the vinyl into its new shape.
5. Fill void between inner layer and vinyl with foaming adhesive.

And to thermoform the vinyl I've designed this:


Just a set of dies that heat up and are bolted together. I still need to figure out the shape that the vinyl has to be in, but that should be fairly straightforward once I receive the euro cubby in the mail.

I will likely need to design two different inner dies, one for thermoforming and another for holding everything in place while the glue cures.

Very much an unnecessary amount of work for a thing that can store a couple pairs of sunglasses, but it'll be a fun project!


Also, not as interesting as the stuff above, but I picked up a near perfect set of rear seat trim pieces at the junkyard. Mine had a bunch of broken posts/clips and weren't looking great. Top is new, bottom is old:

[heinzboehmer]

Suspicions confirmed!

Thanks to bmwfnatic for posting pics of the euro dash in this thread: https://nam3forum.com/forums/forum/m...536#post291536

A couple comparisons to the inner shell I separated from the junkyard dash cutoff.

Front:




Back:




Now need to wait for the cubby to show up, scan that + the US inner shell and then make the necessary tooling to re-form the dash.

[Obioban]

Feels like it make more sense to cut the hole and have a bezel on the part you insert to hide the ugly edges.

[heinzboehmer]

Feels like it make more sense to cut the hole and have a bezel on the part you insert to hide the ugly edges.

That would be the sensible thing to do, but I would not be happy with the final result.

Plus, modeling the bezel is about the same amount of work as modeling the die, so not a ton more wasted time.

[discoelk]

I've wanted to do this mod for years but always assumed the easiest/cleanest way would be to just import a euro dash. I respect the endeavor here.

[heinzboehmer]

I've wanted to do this mod for years but always assumed the easiest/cleanest way would be to just import a euro dash. I respect the endeavor here.

I always assumed the same, which is why I never truly looked into doing the retrofit. If everything works out as planned, this should be a ~1hr job after all the quirks of the tooling are figured out.

Euro cubby arrives next week, will try to find some time then to make some more progress on this.

[M3Garand]

Great build

[Obioban]

I always assumed the same, which is why I never truly looked into doing the retrofit. If everything works out as planned, this should be a ~1hr job after all the quirks of the tooling are figured out.

Euro cubby arrives next week, will try to find some time then to make some more progress on this.

You thinking about... renting this tool out?

[heinzboehmer]

You thinking about... renting this tool out?

I figured others would be interested in the tool. Happy to rent it out if it actually works.

I'll post all the CAD stuff too in case anyone wants to make their own. The tool will be entirely made of 3D printed and laser cut parts as well as off the shelf electronics and hardware. <$150 all in.

[George Hill]

You thinking about... renting this tool out?

Put me in line too. I've always liked this cubby and this is a super clever solution.

[heinzboehmer]

Put me in line too. I've always liked this cubby and this is a super clever solution.

Totally!

[heinzboehmer]

A few quick distractions from the (obviously more important) euro cubby project.

First up, yearly brake flush. Didn't see tons of bubbles, but fluid had seen better days:



With the car up in the air, I also replaced the trim around the RTABs, as it was starting to fall apart:




Unfortunately, I also noticed this while under the car:




Guess the years are starting to catch up to the M3...

Fortunately the rust was super minor and there was tons of good metal underneath:




I also found a tiny bit of rust on the tabs that hold the plastic panels and the v brace mounting points. But, once again, lots of good metal underneath:







Strategy for solving this is the following:

• Expose good, bare metal
• Few coats of POR15
• Wait for it to fully dry
• Clean with isopropyl alcohol
• Hit the area with a heat gun to make sure there is absolutely zero moisture left
• Few coats of rubberized undercoating
• Few coats of SEM EZ Coat in olive green
• Reassemble and act as if nothing ever happened

Since I was going to be spraying thick undercoat, I needed to figure out how to mask the areas where the rubber grommets and v brace attach to. Decided to print out some plugs to leave a nice perimeter around the holes in the chassis.

Given that I was printing the plugs, I was able to precisely control the clearance between the undercoat and grommets/v brace. Opted for a much tighter clearance than factory (1.5 mm for grommets, 3mm for v brace):






Grommet plug is a three piece TPU/ABS design. The tapered insert screws into the plug and expands the TPU against the chassis. This keeps it firmly in place, but also allows for easy removal.

V brace plug is just ABS with a threaded portion that screws into the chassis. Only important feature is the taper on the plug used to leave room for the welds on the v brace boss.

My hope is that a tighter clearance will help keep rocks and other road debris from chipping away the POR15, which should help this repair last longer.

Here's how everything came out:




End result is okay. By no means professional grade, but I'm incredibly incompetent when it comes to anything paint related. It is raining this weekend, so a couple drives should be enough to hide any imperfections. Just happy that the rust is properly addressed!