heinzboehmer's 2002 Topaz 6MT Coupe

[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.

[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]

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.

[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]

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.

[heinzboehmer]

Fun bit of electrical debugging today.

Car has been ultra stinky in the cabin lately and after some sitting-in-stop-and-go-traffic experimentation, I started to suspect that the auto recirculation wasn't working correctly. I mean, root cause of the smell is definitely the shitty SSV1 headers -> section 1 interface, but if the AUC sensor is faulty, then the A/C will always pull (stinky) air from outside. Read codes on the IHKA and yep, the sensor was apparently bad. INPA read 0V from it, so decided to investigate further.

Turns out the thing comes apart fairly easily. Here's how to take it apart for future reference:






Unfortunately, the electronics are fully potted, but I guess that's to be expected of something that is fairly exposed to the elements.

Anyway, plugged it into the harness and probed with a multimeter just to see if it was reacting at all. Turns out the sensor was working just fine, so the issue must have been something with the connector or harness.

Fired up INPA again and to my surprise, it was reading it now. Here's me testing the sensor by spraying some isopropyl alcohol close to it:

Put the sensor back together and INPA was once again reporting 0V. Hmmm

Finally discovered that I could get INPA to read it if I removed the weather seal from the connector. This thing:



Seal was pretty dirty, so I cleaned and lubed it up. Aaand INPA reads it! Guess the dirty seal wasn't letting the connector fully seat.

I did also slightly bend all the inner connection tabs on each of the pins in case they were a bit worn, but I don't think that did much. Pretty sure the issue was the seal.



I do wish the IHKA somehow communicated the issue (not letting you use the auto recirculation feature, for instance), but glad it was a quick fix. Will periodically check for codes, but hopeful that this will fix the issue.

[heinzboehmer]

This is only tangentially related to the M3, but thought I'd document/share cause, sometimes, living in the future is pretty cool.

Only took 3 days to go from designing this in CAD to having it fully assembled and in service. That includes the time needed to have sendcutsend laser cut and ship all the parts, as well as the time needed to print all the internal reinforcements.

For context, a small section of my workbench is dedicated to electronics. I figured dust and grime from working on the cars would be an issue for those types of projects, so I designed an 18th century slidey door thing to cover the whole thing up:



Started work on it and got about 90% through before I lost all motivation. Remaining work involved routing the channel for the door and I just really didn't want to deal with the mess. Don't have proper dust collection in the garage, so doing anything wood related really sucks. Thing sat like this for an embarrassingly long time:



Anyway, back to living in the future. Finally decided that it was stupid to be wasting so much workspace, so I switched strategies and decided to build a cover for it instead:






Structure is just some laser cut 1/8" MDF with printed ABS reinforcements bonded in. Also added rubber edge trim to the sealing surface and printed TPU feet around the locating pins (not pictured).

Happy with how it came out and amazed at how little effort and time it required. As per usual, should have done this a long time ago

[heinzboehmer]

RPM (2600-3000ish), but it seems louder and more unbearable at higher speeds. I think adding the updated rear bench insulator would help reduce it.

Interesting. Maybe something in the clutch assembly? Can't think of anything that would make that noise and be related to RPM. Especially if it sounds like it's coming from the rear of the car.

[SQ13]

My car has the wheel hop issue too in wet conditions. Recently noticed it in the Cayman as well.

Is yours RPM or speed related?

RPM (2600-3000ish), but it seems louder and more unbearable at higher speeds. I think adding the updated rear bench insulator would help reduce it.

[heinzboehmer]

Yeah you're not the only one who has told me that they experience the same thing. Guess it's just inherent to the rear suspension design. Oh well, at least it only does it in a straight line.

[maupineda]

My car can get wheel hop too in the dry. B8 dampers. It was a bit worse with the H&R shocks original to the coil over kit.

[heinzboehmer]

Wheel hop was starting to get pretty bad, likely exacerbated by all the rear biased weight savings that has happened over the past year or so. Turned down the rebound on the rear dampers by quite a bit (it's at a half turn from full soft now) and it feels pretty good now. More testing to come.

Update: Still wheel hops like crazy when losing traction in a straight line, in the wet. Damn.

Seems fine if I initiate a slide in the wet and in all conditions in the dry. Granted, I didn't go and do burnouts when it was dry, but still. For sure an improvement over how it was before though.

[heinzboehmer]

Don't forget the rear deck speakers

Pre-facelift, so no logos on those from the factory

[Obioban]

Ha. I, too, unbranded my speakers-- even without the fabric peeling. I just don't like logos everywhere.

Don't forget the rear deck speakers

[heinzboehmer]

The fabric on the front tweeter covers was starting to peel off, so got some non-HK covers to replace them:




It's a stupid detail, but I do like the all black cover more.

Since the door cards were off, I took the opportunity to fix a rattle inside the passenger door. Sounded like the clip that holds the window regulator cable in the middle of the door had broken off, so was prepared to zip tie it. However, I found that the cable just wasn't clipped in. Clip still felt nice and pliable, so I just clipped the cable back in. We'll see if it pops back out or not.

Also, found no witness marks on the door from the bavsound speaker Bry5on. Must be a coupe vs wagon difference.