heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Check your toe

I see road force balancing (RFB) more as a diagnostic tool than something I would routinely do. I used RFB to determine how out of round a wheel was - can't always see it on a dynamic balancer or if the tire was bad (it happens). I never saw a situation where a RFB fixed a vibration issue where a dynamic balance couldn't. In some cases, a RFB made noise and vibration worse. Whoever is mounting a new tire needs to understanding the markings on the side of the tire to orient the high point of the tire with the valve stem which typically optimizes the balance.

IMO, RFB as a routine is the nitrogen of tire balancing - mostly useless, makes the shop more money, and is often "flat rated" by techs. Meaning they say they did it...but didn't do it.

That makes sense.

Due for an alignment soon, we'll see what the front is at. I always go with 0 toe up front, so not the best for tire wear.

[heinzboehmer]

Quick side project.

I had previously tried to fix the tab that's under the light on one of my C pillar covers by just gluing it back together, but the repair didn't stick:



So I came up with this:




A three piece replacement that mechanically interfaces with the remaining parts of the tab, so that it doesn't have to rely on the adhesive for strength. Chose ABS-GF for this and managed to print with no supports by setting the layer height to 0.08mm. Overhangs came out great.

You can see how the three pieces lock together against the remaining material in this cutaway:



To install, you need to trim the remaining plastic, mark out the location of the notches, then cut those bits away:





A bit more involved than just gluing the piece on, but it results in a super solid mechanical interface.

Here's an impact driver hanging from the replacement tab. Note that there is no adhesive present here:



In hindsight, running the above test was kinda dumb. If it failed, I would have had to source another pillar cover. It survived though, so we're good

For the final install, I did add a bit of epoxy in between the replacement tab and the pillar cover, for max strength. Seems to have worked out great!

[heinzboehmer]

Well, had to tackle another unplanned side project today.

Drove the car in the rain for the first time in a while and quickly learned that my windshield wiper stalk was not working correctly. The only setting that worked was the full blast intermittent one. Fortunately, I could flick it up and down quickly to trigger a single wipe, but having to do that for the entire drive got old pretty quick.

I did take the stalk apart to clean the dust out of it from my little track adventure, so must have not put it back together properly.

First, a quick overview of how the stalk works:

There are two perpendicular "tracks" on the circuit board that two separate wipers (think potentiometer wipers, not windshield wipers) "ride" on. One track is for up/down stalk movement and the other for in/out. Depending on the position of the stalk, the wipers connect different traces together, which sends out the appropriate signal to the LSZ (GM5? I forget where the wiper logic lives).

What's really cool is that wiper movement along the tracks is continuous and the mechanical detents for the stalk are completely decoupled from the electronics bits. Guessing this separation is why the action on these things feels so good. Can tune the feel without affecting the electronic characteristics.

A picture should help explain what this all means:



Housing parts:

A - Up/Down wiper riding on its track
B - In/Out wiper riding on its track (you can also see the linkage that transforms in/out stalk movement to left/right wiper movement)
C - Header for dial wheel (and "S" button)
D - Detent plate to discretize stalk movement (basically just a section of a hemisphere with a bunch of divots in it)

Stalk parts

A - Pin that moves Up/Down wiper
B - Lever that moves In/Out wiper (hard to see, but it's L shaped from the side)
C - Connector for dial wheel (and "S" button)
D - "Stylus" that follows detent plate

As you can imagine, this thing is a bit finicky to get back together, since have to make sure that the features that interface with both wipers are in their correct spots. The image above shows how I found the stalk when I took it apart. Close inspection revealed that the Up/Down pin was not sitting correctly in the wiper, which made the stalk work unexpectedly.

Took a couple tries, but managed to get it back together correctly. Probably could have avoided this if I had tested the stalk after I first took it apart, but oh well.

On the upside, I'm getting reeeally good at taking the steering wheel off. Can do it in a couple minutes now

[Arclitgold]

Wow, can’t believe you even had dust in there!

[heinzboehmer]

Wow, can’t believe you even had dust in there!

It got eeeeverywhere, it was crazy.

[heinzboehmer]

Aaand another of those quick side project things.

A pillar cover screw cover fabric (sorry) was starting to come off, so glued it back.

Peeled off half, masked, cleaned, sprayed super 77, waited until it was tacky, reattached.




Let that dry then did the exact same for the other half. You can see a little bit of the new adhesive exposed.



And done, they look brand new again:



(man, the lighting in that last picture is terrible, gotta find a better solution for photographing dark objects)

[heinzboehmer]

Long time no see. Been spending way to much time on house projects (which are nowhere near as fun as car projects), but have managed to find some time for a couple things.

First up, chipping away at that last 1% of the E86 bracing project.

Bought some 1/8" thick, 1/4" wide, closed cell, high temp silicone foam to seal up the flat surfaces on the modified HVAC plastics. The stuff I bought is rated for 200 C, so should be more than enough for this application. It came with an adhesive backing, but I used 3M emblem and trim adhesive to hold it in place, as the backing wasn't sticking to the print (no surprises there).

On the cabin air filter housing, I placed the foam where it's located on the stock part, as well as along the front edge that seals against the cover:



The firewall plug got foam on the flat areas that don't have 3D printed gaskets. Again, following a similar path to the stock part:





I also got rid of the retaining washers I printed for the cabin air filter housing torx fasteners. Unfortunate, cause it makes it pretty much impossible to lose those screws, but it makes them get in the way during removal/install.

Last task on this project is to sand and paint the strut tower brackets, then it'll actually be 100% complete!


Next thing I did was solve a squeak that has been driving me crazy for the past couple weeks. It sounded like it was coming from some interior plastic in the rear, but I was unable to replicate it in the garage. I went around and put tesa tape on the interfaces of basically all of the plastics back there, which seemed to solve some micro-squeaks, but the main squeak was just as loud as ever.

Finally stumbled on this:

Sprayed the seals/interfaces with soapy water one at a time and when I got to the striker, the squeak completely went away. So weird.

I did spray the striker dead on, so it's possible that some of the water got behind the trim and lubricated these two bushings:



So, I don't really know what was causing the noise, but I can say that cleaning and Krytoxing all the components in the latch and striker assembly has made the noise go away. Mental sanity restored.

Did the same thing on the driver's side, of course.

Only other thing worth noting is this highly professional fix I did to one of the rear bolsters:



This has been broken since forever and I had previously tried epoxying it back together, but I guess the repair didn't hold. Should be permanent now since it's got epoxy AND zip ties!

[Pklauser]

Love a good squeak fix. Haven't heard of Krytox before, interesting. Is that your go-to for lubricating door seals and stuff too?

[heinzboehmer]

Love a good squeak fix. Haven't heard of Krytox before, interesting. Is that your go-to for lubricating door seals and stuff too?

Krytox is awesome, I keep a needle nose bottle of the 103 (thinner, runnier) and a tube of the 207 (thicker, more of a paste) handy in the garage. It's compatible with virtually all materials and has a wide temp range.

It's super inert and safe to use on rubber, but not sure I would use it for door seals. It never dries, so seems like it would get messy pretty quick in that area. I think a rubber safe lubricant that dries out is a better choice.

[heinzboehmer]

Posted this in the E86 braces DIY thread a few days ago:

Alright I'm calling this project (including documentation!) 99.9% done. Just have two small TODOs to get through before I can call it 100%:

1. Weigh the modified cabin air filter housing/firewall plug + a stock cabin air filter housing and add to documentation.
2. Sand and paint the strut tower brackets.

Was thinking about the best way to approach (2) and quickly came to the realization that my hate for painting is so strong, I'd rather find a way around that altogether.

So, instead of spending a couple hours painting my existing brackets, I have decided to spend tens of hours redesigning the brackets so that they can be printed/cast/machined in one piece. Here's where I am right now:



Progress will likely be slow, since the existing brackets work just fine, but it's nice to have a low stakes project to work on whenever I have a few hours to sit on the couch. Will post more updates when I have them.

[heinzboehmer]

Stock left bracket recreated:




This is mostly a 1:1 copy, but not quite. The one key difference is the geometry where the "ledge" with the two studs for the strut bar meets the main body of the bracket. The stock part has a huge chunk of material missing from that area and I opted to keep most of it and throw a big fillet at it. This should make it a little stronger with no impact on packaging:




Additionally, I did not include any of the weight savings features on the bottom of the part. I'm pretty set on 3D printing the final parts, so I can skip that altogether and gain the savings back with infill.

Next up is recreating the right bracket, which is basically the same, except it has an extra cutout for the positive battery terminal. After that, I can work on grafting the E86 brace pickup points onto the brackets and slotting the strut tower nut holes so that these work without camber plates.

Out of curiosity, I quoted a print in aluminum (AlSi10Mg, specifically) and it came out comically close to the price of the real BMW part:




Last thing worth discussing is that this CAD work was much more straightforward than I expected. I think the sheet metal approach was great for prototyping and validation, but this approach is much more inline with the rest of the parts that make up this project. I'm excited to get these done and manufactured. In hindsight, I should have gone down this path from the start.

[Bry5on]

What style of modeling did you use for this one? Hilarious that the price is within a few bucks.

[heinzboehmer]

What style of modeling did you use for this one? Hilarious that the price is within a few bucks.

Hmmm, I don't know how to answer that question. I feel like I'm missing some formal eduction on this topic to be able to do so. I'd describe the style as stumbling through the design and backtracking a bunch until I have something that looks good

In all seriousness, the approach was to start with the two objects from a few posts ago and then extrude a bunch of cuts in them. Not entirely sure what style that would constitute.

Also, both stock brackets recreated now:



The cut for the positive terminal looks it would compromise the strength of the bracket a bunch. The thinnest point measures right at 3.6mm, which is not terrible, but still.



My plan is to get rid of the bosses on the bottom entirely and extrude the bottom surface of the bracket down all the way to the strut tower surface. Will yield another 3mm of material and more bearing area to take the extra load from the E86 braces. If anyone with the early style strut towers wants to recreate this, they could always give the version with bosses a shot.

And now onto the fun bit: modifying them!

[Bry5on]

That would be solid modeling, versus shell (or surface) modeling. Some of the contours looked pretty 3D so I thought you might have been practicing shell. I find it much harder.

[heinzboehmer]

That would be solid modeling, versus shell (or surface) modeling. Some of the contours looked pretty 3D so I thought you might have been practicing shell. I find it much harder.

Oh! I've briefly played around with surface modeling and agreed, it's much harder. Something about the infinitesimally thin objects makes my brain trip out.