heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Oh! Parts arrived for another project that I can work on if I need a break from the braces CAD (with, uh, more CAD...).



Found these when driving my in-laws' Mercedes SUV (GLB/C/E/something or other). Collapsible baskets aren't exactly a revolutionary invention, but this is a Mercedes OE part (p/n A2038400020) and it's only $16 brand new!

Here it is unfolded, M1 16" MacBook Pro for scale:



Plan is to design some mounts that the basket can clip into. Underside has a ton of features that I can use both for locating and retaining:



Mounts will likely get attached to the "ceiling" of the trunk (where the stock subs live), maybe even the trunk lid, we'll see.

I do want to make the mounts fairly platform agnostic. Each car is getting its own basket, so want to minimize the extra work required to make these compatible with each chassis.

[heinzboehmer]

Placed an order with one place whose website allowed me to order 5m, but we'll have to see if they actually fulfill my order

Yep, order cancelled because the minimum order quantity is 50m. Damn, I really don't want to have to order that much. Anyone need 49.5m of the stuff?

[bavarian3]

Also, quick side project to give myself a break from all the CAD work.

I've never been fully satisfied with the Kassel MAP sensor solution. It being so close to the throttle bodies means that the sensor sees huge fluctuations in readings with each revolution of the engine. This doesn't seem to affect drivability much, but it's never sat well with me. Additionally, the harness going to the sensor has to make some very sharp bends to make sure it's out of the way of the throttle linkage. Again, not something that affects how the car drives, but I didn't like it.

A week or so back, I noticed the CSL air rail was ~$400 after tax on ECS (and in stock in the US!), but closer to $800 through european sellers. NLA fear creeped in sooo I jumped on it:

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My original plan was to just kinda re-zip tie the harness I had made for the Kassel sensor and call it good. However, I found sketchy patchwork in the middle of the IAT harness that I had forgotten about and this ridiculous choice by Kassel for the MAP sensor connector (on the left):



For some reason, they used the wrong terminals, put no waterproofing grommets in there and picked a questionable wire gauge for one of the three wires. The connector housing is also clearly a knockoff with pretty bad tolerances. I would not be surprised at all if this is the cause for my intermittent MAP sensor code (which, admittedly, never seemed to affect how the car ran).

The stuff I laid out to the right are the closest replacements I could find in the stash. I rewired that part of the harness with those, but I've ordered the correct terminals and grommets and will replace soon.

I was already halfway into building a completely new harness, so I decided to just redo the entire thing. This is how I routed everything:

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As you can see, I ran my sub-harness directly into the bottom of the stock engine harness box thing by the brake booster. Not having that extra conduit snaking down the front of the harness box cleans up the engine bay nicely:

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I did briefly consider running the wires through the stock conduit that runs under the airbox and then making a slot (with a matching 3D printed grommet) in the hard plastic distribution block bolted to the engine for the IAT + MAP sub-harnesses, but ultimately decided that was way too far down the rabbit hole. I'll revisit and do it that way if I ever run out of projects

I, unfortunately, did not have the appropriate terminals for the IAT, so I left some slack in the harness and ordered some of those as well. Slack is tucked into the conduit for now, but I'll be swapping things when I get the parts. Getting the boots over the conduit is gonna be a fun adventure:

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(yes, I also ordered a new boot for the IAT)

Anyway, next up I printed karter16's Bosch MAP adapter out of PET-CF, for it's temp resistance. This filament has a heat deflection temperature of 205 C, so should work well for the application. Also grabbed the complementary hardware:

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Just like karter16 noted, the metal sleeve on the Bosch MAP just barely doesn't line up with the air rail. Dremel + a carbide bit made quick work of this though:

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Gave the sensor and adapter a quick scuff, then bonded them together with some CA glue. This part isn't really necessary, but I did it anyway cause why not.

Here's the final install:

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(yes, I know that's a 90 deg boot, straight one is in the mail)

The screws did start digging into the plastic on install, so they got torqued to "as much as I can turn just the bit with my fingers". I don't think this is gonna be an issue.

Datalogger is picking up readings from both sensors just like before, so I'm calling this a success. Huge thanks to karter16 for sharing the adapter and all the details surrounding it! Made my life so much easier.

You're on it! That was fast. Super helpful for me as I'm collecting parts. One more DM incoming =)

[heinzboehmer]

Yep, order cancelled because the minimum order quantity is 50m. Damn, I really don't want to have to order that much. Anyone need 49.5m of the stuff?

I might have found a place in the UK that will sell me just 1m of the tubing. Shipping is insane (like $50 for $5 of tubing), but maybe.

Remembered I have a scan of the engine bay with the braces installed, so drew up a super rough layout for the tubing to give me an idea of how much I need. I'll likely bring that big bend in a bunch in the real design, but I wanted an upper limit for length:



Measures right about 480mm, so my 50cm estimate was spot on. Seems like 1m would be enough.

To form it, I plan on 3D printing a jig. Here's a rough idea of what that will look like:



It'll be printed in sections so that I can heat the tubing up with a heat gun (away from the next meltable section) and then form it around the next bend. The ends of the jig will also have tapered flaring sections to make sure the tube can slide over the fittings:



<imaginary pic of heat gun heating up length of tubing sticking out of the jig>



The actual jig will have locating features between all the sections, so that they easily slot together and you don't need to be messing around with it while holding the rapidly cooling tubing. Additionally, it'll have clearance on the outside of all the bends, so you can wrap the tubing around the form (think brake line bender), as opposed to pushing it into a groove.

I'll also be printing a tool that clamps the ends of the tubing onto the fittings, to give it that nice OE look:



Wait a second...

All this brainstorming has made me come up with an excellent way to justify buying 50m of the stuff. Might not even need to jump through hoops to get less!

If someone has the OE CSL part (11617833647) installed and is willing to let me scan their car + the part, I can make a jig to recreate it. All of the designs for the tools (jig + crimp) will be open source, so people could just buy a length of tubing from me, print the tools and make themselves a replica part for their regular airbox installs. Will sell for material cost + shipping (likely <=$40 all in), so this should be a great way to save $150 and end up with what is essentially an OE part.

I could also form the tubing myself before shipping for some beer money. Buyers would then just need to heat up the fitting ends and crimp them on with the 3D printed tools.

I bet this will pique the interest of at least George Hill and kaiv!

Edit: I guess I could also recreate the tube for the stock intake, but not sure the market is big enough to justify the engineering time for that version.

[heinzboehmer]

Fun stuff arrived in the mail:




I only ordered four parts (one of each), but got duplicates of the smaller ones. I guess the people at sendcutsend saw my insane design and ran a couple through to make sure they were actually manufacturable. Heh.

Chopped off the bend extensions and cleaned up the edges with an angle grinder:





Of course I couldn't help myself and had to test fit on the car as well:






They fit great!

...which I guess isn't hugely surprising cause the CAD said they should. More of a testament to sendcutsend's accuracy.

And here's the latest version of an image you'll be very familiar with if you follow along with this journal:



Dropping the sheet metal brackets off with Tony (TC Design) early next week so that he can weld them up for me. After that, I just need to bond the stock brackets to them. Hopefully that means test drive before the end of next week!

3M never got back to me about whether or not the 07333 will survive powder coating cure temps. Need to bug them again. Finishing is a future problem though, I'm much more excited to see how this thing drives with the bracing

Also, found a BMW plastic plug (51711906001) that fits the 10mm hole in the engine bay harness box where the MAF wiring usually exits:



Quality is honestly way worse than I was expecting for a genuine part. Look at how shitty it looks compared to the plug in front of the DME. It wasn't expensive or anything, but it does kinda look like I just put some electrical tape over the hole.

Oh well, no one is ever gonna be looking at it. Plus, it's essentially hidden with the strut bracing installed.

[maupineda]

I might have found a place in the UK that will sell me just 1m of the tubing. Shipping is insane (like $50 for $5 of tubing), but maybe.

Remembered I have a scan of the engine bay with the braces installed, so drew up a super rough layout for the tubing to give me an idea of how much I need. I'll likely bring that big bend in a bunch in the real design, but I wanted an upper limit for length:



Measures right about 480mm, so my 50cm estimate was spot on. Seems like 1m would be enough.

To form it, I plan on 3D printing a jig. Here's a rough idea of what that will look like:



It'll be printed in sections so that I can heat the tubing up with a heat gun (away from the next meltable section) and then form it around the next bend. The ends of the jig will also have tapered flaring sections to make sure the tube can slide over the fittings:



<imaginary pic of heat gun heating up length of tubing sticking out of the jig>



The actual jig will have locating features between all the sections, so that they easily slot together and you don't need to be messing around with it while holding the rapidly cooling tubing. Additionally, it'll have clearance on the outside of all the bends, so you can wrap the tubing around the form (think brake line bender), as opposed to pushing it into a groove.

I'll also be printing a tool that clamps the ends of the tubing onto the fittings, to give it that nice OE look:



Wait a second...

All this brainstorming has made me come up with an excellent way to justify buying 50m of the stuff. Might not even need to jump through hoops to get less!

If someone has the OE CSL part (11617833647) installed and is willing to let me scan their car + the part, I can make a jig to recreate it. All of the designs for the tools (jig + crimp) will be open source, so people could just buy a length of tubing from me, print the tools and make themselves a replica part for their regular airbox installs. Will sell for material cost + shipping (likely <=$40 all in), so this should be a great way to save $150 and end up with what is essentially an OE part.

I could also form the tubing myself before shipping for some beer money. Buyers would then just need to heat up the fitting ends and crimp them on with the 3D printed tools.

I bet this will pique the interest of at least George Hill and kaiv!

Edit: I guess I could also recreate the tube for the stock intake, but not sure the market is big enough to justify the engineering time for that version.

Heinz, you can scan mine, and in the process scan the opening on the front so I can design my snorkel?

[heinzboehmer]

Heinz, you can scan mine, and in the process scan the opening on the front so I can design my snorkel?

Thanks! I want to scan it in the M3 engine bay so that I can roughly copy the routing for my own version, so I'll probably just scan Slideways's car. Appreciate the offer though.

Down to scan you car for your snorkel whenever though! You know where to find me

[bigjae46]

Wow! That looks slick!

[heinzboehmer]

3M never got back to me about whether or not the 07333 will survive powder coating cure temps. Need to bug them again.

Just called 3M to ask and I was told the max temp this adhesive should be exposed to post-cure is 180 F. So right around the 80 C that the data sheet says not to exceed while curing.

Sounds like these parts are getting painted, not powder coated!

[heinzboehmer]

So I went through the trouble of adding fast charging to the Gauge.S ashtray housing because I knew it would come in handy at some point. Even though I don't really ever use it (my phone usually sits on the wireless charger), it's nice to have the option of plugging it in, especially when using it for navigation.

The couple times I have wanted to use it, I've been unable to because the board overheats and shuts off. Stuck a couple heatsinks on top of the ICs and it seems to have fixed the issue:



Previously, those capacitors were bent downwards and attached to the ICs with some double sided thermal tape. Interesting thermal management strategy...

Oh also this



Took the car back up to scenic spot for the first test drive with the braces installed. Driving impressions in a bit, first gonna dive into how we got here.

As previously mentioned, I took the brackets down to TC Design for welding. Overkill, but they build racecars everyday (including that PT cruiser featured in this journal many pages back), so I knew the quality of work would be great.

Scribbles for Tony:




Studs pressed in and welded up! Tony was able to turn them around in a couple hours:





Hard to tell, but I had Tony tack all the studs to the brackets. I was able to press them in to where they don't back out, but they spin if you apply any meaningful torque to them. I think I might have made the holes for them a bit too big. Data sheet gives a range and I targeted the middle of it, but seems like I should have targeted the lower end. Lesson learned.

Actually, same thing happened with the windshield attachment point, even after putting it in a hydraulic press. For that one, I just roughed up the surfaces and added a bunch of the 3M 07333. This is absolutely not what it's meant for, but I just need it to counter hold the studs a bit until friction takes over. Worked like a charm:



I shouldn't have designed this piece for press in studs. Captive bolts would have been a better choice. If this adhesive bandaid fix ever fails, I think I can mimic the captive fastener thing with low profile hex head bolts and 3D printed inserts. Again, what's holding the bolts captive takes almost no load, so no need to go crazy with it.

Back to the strut tower brackets. As mentioned previously, I planned on bonding both parts for max stiffness.

Started by doing the last bit of grinding to match the profile of the stock parts perfectly. I also had to grind some clearance on the ID so that the stock plastic covers can clip in, completely forgot to design that it before having them laser cut. Then roughed everything up and prepped with acetone + IPA:



Of course, no project is complete without a huge fire hazard:



(stood next to this for the entire half hour they were in there with an extinguisher ready)

Bonding went super smoothly cause I was able to use the studs and fastener holes to clamp both pieces together.

And ready to drive!



I still need to give the brackets a final sand to smooth out any adhesive drips and get them painted, but they're good for now.

Onto driving impressions:

The car feels incredible! Exactly the same as how I remember Bry5on's car feeling when he first installed the Slon brace. Drove it back to back with and without the braces, just to make sure I wasn't making things up. Can confirm that there's a very tangible difference.

Front end is super eager to follow what your hands are telling it to do now. Makes it feel like the steering is quicker even though the ratio hasn't changed. It feels weird to not have to do any mid corner corrections, after driving the car for so long without this bracing. Now you can essentially just point it where you want it to go and it'll go there. I'd compare it to the difference when going from a grippy street tire (e.g. PS4S) to a 200tw track tire (on track of course).

I also noticed that I can steer the car with the throttle much more precisely in corners. Very much a welcome change.

A friend described the change super accurately: feels like the front wheels are pointing in the same direction now

Think this is the first time I've ever thought the car needs more spring rate. Feels like the suspension is getting left behind with the increase in chassis stiffness. Can't wait to get the Bryson braces installed for max stiffness gains. Then I'll go chasing suspension/CG adjustments.



P.S. HVAC plastics aren't ready yet, so they weren't installed for the test drive. The intake is LOUD with them out of the way, wow. Definitely gonna have to make my versions as thin as I can get away with. Think this will require carbon + some airy core (e.g cork, for thermal reasons), not printed plastics.

[karter16]

Congratulations man - you must be so stoked with how this has turned out!!! It's been awesome following along and seeing you bring this together. Very, very cool.

[heinzboehmer]

Congratulations man - you must be so stoked with how this has turned out!!! It's been awesome following along and seeing you bring this together. Very, very cool.

Man, you have no idea. I'm so happy with how this turned out. Took me forever cause I didn't know what I was doing, but the end result is so worth it.



Have a bit more seat time now and all of the above is still true. It's hilarious how much more capable the chassis feels now. I think what has most surprised me is the throttle steer thing. I wasn't expecting it to be this noticeable. You can give it throttle mid corner and it keeps turning, whereas the front would just kinda wash out before. It feels like it has SO much more grip.

Have a track day coming up in a couple weeks, so will really put these things to the test then. Gotta hurry up with the HVAC plastics though. Still lots of CAD ahead of me...

Also, one thing I forgot to mention earlier is that the stock BMW nuts for both the E86 braces and the E46 strut bar do not like my studs. The nuts are oval shaped so they don't back out, but they're meant to be used on fairly short studs. With these longer ones, the top threads start to get mangled as you thread the nut in. For now, I just ran a tap through all the nuts so that the threads are no longer oval. I likely need a better solution though, as the nuts under the windshield are facing the floor and could potentially back out. Cut down the studs? Get some nyloc nuts? Not sure yet, have to give it more thought.

[Bry5on]

Do your threads have a radius on the outer ridge? Those BMW nuts are designed for rolled thread fasteners, so if your studs have cut thread fasteners, you could be fighting that.

On the cork insulation topic - you can apply the cork or other insulation of choice (zotek peel and stick foam is phenomenal...) to the engine bay side of the HVAC housing which would allow you to print it. Hell, you could also just print it out of PPA or something rated above 150C or so with a 'closed cell' inner support structure for thermal insulation. I think the factory parts are fiberglass filled nylon (eg: PPA-GF). That's a 3D print for the win situation.

[0-60motorsports]

Thats awesome news! I would love to do that to the car one day.

[heinzboehmer]

Do your threads have a radius on the outer ridge? Those BMW nuts are designed for rolled thread fasteners, so if your studs have cut thread fasteners, you could be fighting that.

They do not, I think you're right on the money with this one.

Hell, you could also just print it out of PPA or something rated above 150C or so with a 'closed cell' inner support structure for thermal insulation. I think the factory parts are fiberglass filled nylon (eg: PPA-GF). That's a 3D print for the win situation.

Factory parts are both stamped UP-GF, so very similar. Interesting idea about the using the infill as thermal insulation! I'll have to mess around with that.

Ideally, I'd like to make these parts much lighter than the stock ones, since I'm going through the trouble of remaking them entirely. Will have to see what the weights end up at before making a material choice.

Thats awesome news! I would love to do that to the car one day.

I'll share the designs for everything once I've sorted out all the small details!