heinzboehmer's 2002 Topaz 6MT Coupe

[Bry5on]

You can eliminate the S shaped wall because you’ve otherwise boxed the shape in by attaching it to the aluminum strut brace. Pretty sure that little wall will not have much contribution to strength and you can avoid weakening the material by eliminating welds. You might wind up just redesigning strut tower bases entirely when this is said and done though

If you’re doing new bases, you could also add fastener locations on the fender side for future gusseting to the corners of the windshield too. You know, for a future project..

[bigjae46]

Where do the E86 strut bars boit to? One of the existing press in studs?

[heinzboehmer]

Some updates.

First, my CD53 is back from the UK (with nothing changed), so I tested that in my car. Audio sounds as good as it did with the junkyard radio! This leads me to believe that the HK amp was the culprit after all. So, my PSA for the day is: service your HK amp!

And now the bigger/longer update. 3D scanner got put to use and I started designing the replacement strut bar brackets for the E86 braces. Here's both stock brackets scanned:



Before I started doing anything, I wanted to verify that the profiles of these are indeed symmetric (brackets themselves are not symmetric, passenger side has some extra clearance for the positive terminal):



Nice.

With that out of the way, I moved onto the actual design. As a reminder, my plan is to machine down the bosses on the stock brackets and sandwich them in between my brackets and the stock bar.

The only real constraint (besides the obvious spatial ones) is that I can't machine the brackets down too much. The passenger side one gets fairly thin where there's clearance for the positive terminal:



My plan is to fully machine down the bosses and just barely skim the rest of the surface to get it fairly flat. Quick measurements say that I'll be taking about 3.75 mm of material off, but I won't know for sure how much it ends up being until these are on the mill. I'll start with the hard one (passenger) and then copy whatever I do over to the other one. Hopefully I can get down to the shop soon.

Anyway, here's my initial approach for the bracket. There's a decent chunk of stuff to work around in these areas, so the funky geometry is a result of that:






These are designed to be laser cut, bent and welded. M8 press in studs will be used in my bracket and I'll drill the threads of the stock brackets out so that the new studs can pass through. M10 stud for the E86 brace is not shown, but it'll go somewhere in the protruding yellow section. I'll have to fit a prototype up in the car to see if that section is long enough, it might not be as is.

I still don't know if this current design is manufacturable, though. Some of the bends look like they'll be hard to pull off. Fortunately, I should be able to extend any problematic walls and then cut the piece down myself post bending.

The other concern I have is that the stock brackets don't leave a lot of room for gusseting the section with studs to the flat section that goes on the strut tower. I did my best with that S shaped wall, but there's no room to do much more than that. I think it should be fine, mostly because of these reasons:

1. Plan is to get these brackets made out of 4.75 mm thick 304 SS, so they should be tanks.
2. The stock brackets will help with the stiffness of the entire assembly. Remember I'm really only machining down the bosses, so they should be as strong in bending as they are now.

And that's about it for now on these. I really can't do much more until I get myself in the shop and machine the brackets.

[heinzboehmer]

Fantastic info! Thanks for the investigative work.

Glad I could help!

[bavarian3]

So this is what I saw when I took a quick look at the calipers yesterday morning:



As mentioned before, not super alarming, but still wanted to figure out why some bleeders appeared to be leaking.

Decided to remove all the bleeders and reclean the taper that they seal against. Calipers were fully dry when installed, so there was a possibility that some dirt/debris I hadn't been able to clean out had accumulated around the taper and was making the bleeders not seal well.

After doing that, I pressure tested them by pushing on the brake pedal as hard as I could for ~30s. Found no leaks on any of them

At the same time, I also decided to cut the dust caps in half, as I don't really like the design of them. Having the retaining ring sandwiched between the bleeder and caliper makes it hard to feel the torque on the bleeder and also means that the dust cap gets caught and spins around.

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"20230829_192052.jpg",":23133 1}[/ATTAH]

Left a little tab of material to make it easy to pull them off.

When I went to reinstall them, I realized why I had seen brake fluid pooled around the base of the bleeder. Here's what happens when you install them:

[video=youtube;522CzbLwKpA]https://www.youtube.com/watch?v=522Czdeo]

As you can see, installing the dust cap forces any brake fluid left in the bleeder past the threads. Makes sense since these things seal at the bottom taper and not on the threads. Something like this is what's happening:

[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"51vl5p0C-achmentid":231332}[/ATTCH]

This was super easy to see with the dust caps cut in half, but much harder when they're installed unmodified. So leading theory is that when I initially bled the calipers, there were no leaks, but there was some brake fluid left in the bleeders that was pushed out by the dust caps. This must have pooled under the dust cap retaining ring —making it hard to see when cleaning up— and eventually dripped out when I took the car out for a drive.

Anyway, mystery solved and fortunately there aren't any leaks on my calipers!

Fantastic info! Thanks for the investigative work.

[heinzboehmer]

Timeserts installed and fitment of hardware validated with 3D printed fasteners:




Looking good!

I need to temporarily swap back to the stock airbox this week for, uh, no reason. I'll likely bond this in when everything is out.

[heinzboehmer]

Heinz, who did you commission to machine out the brackets?

I got them manufactured through Protolabs. Chose the longest lead time they offered to get the cheapest price. Came out to around $1k.

Went with Protolabs because that was the best balance of price and lead time out of the typical big online manufactuters. There were WAY cheaper options (almost exclusively overseas), but none of them would tell me the composition of the material they would be using, so I decided against them.

Of course, someone recommended this place a few days after I placed my order with Protolabs: https://www.rapidaxis.com Local, all machining done in house and comparable prices. I would have gone with them had I known about them earlier. Oh well.

I'll likely be using them for powder coating and maybe even for 3D printing the molds for the CF cabin air filter housing and firewall plug (since they're too big for my printer and would need to be printed in sections).

Anyway, this is likely a way more detailed answer than what you were looking for, but it reminded me of some details I had yet to document. I'll also be posting a detailed cost breakdown of everything once it's all finished.

[maupineda]

Heinz, who did you commission to machine out the brackets?

[heinzboehmer]

That looks relly nice! It's ashame that it will be covered up.

Right?

At least the braces will peek out a little

[bigjae46]

That looks relly nice! It's ashame that it will be covered up.

[heinzboehmer]

Hell yeah

[heinzboehmer]

Very close indeed! You can always trim the corners of the existing duct that hide behind the bumper to buy yourself some extra clearance if you're a couple millimeters off. You planning to make it clip in 'backwards' using the slots for the foglight mount? That would be slick.

Yep! That's the plan. Think that should constrain it enough, but might add another pickup point if necessary.

[Bry5on]

Very close indeed! You can always trim the corners of the existing duct that hide behind the bumper to buy yourself some extra clearance if you're a couple millimeters off. You planning to make it clip in 'backwards' using the slots for the foglight mount? That would be slick.

[heinzboehmer]

Cool man! The first half of the strut brace mold weights 25lbs! lol...I think made it too big and wasted a lot of material. I have more casting urethane on the way. Hopefully get to finish the mold by end of next week.

Nice! Excited to see how it turns out.

It will also need to be two piece if you want to fit it in the Bambu print envelope I think. It’ll be close!

Yeah, it's definitely gonna be tight, but I might just be able to get away with it:



(overlaid picture is not taken dead on, but gives a good enough estimate of size)

[Bry5on]

Also, finally caved and bought a 3D scanner. I've been needing one more and more for recent projects and it was just time. Should help speed up development for upcoming things.

Few short term projects that will benefit from it (in no particular order):

• Strut brace bracket reinforcement plates with an extra pickup point for the E86 braces.
• Clearancing/remaking of the stock cabin air filter housing and firewall plug to accommodate the E86 braces.
• A version of Bryson's CSL duct that uses the entire bumper opening as a feed. Fog lights will get deleted and a passenger side plug will be designed for max aero gains

I like to open source everything I make for many reasons, but I don't think I'm gonna be doing that for the last bullet, unless Bryson okays it. I've been testing and printing his design and there's no way I can keep his IP from bleeding into my version. Would be a big asshole move on my part to release something that's largely based on someone else's design.

Only saving grace of my design is that it will most likely end up requiring permanent modification of the bumper (i.e. cutting the fog light mounting flange off), so I'm guessing that significantly less people will be interested in it.

It will also need to be two piece if you want to fit it in the Bambu print envelope I think. It’ll be close!