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:
- Plan is to get these brackets made out of 4.75 mm thick 304 SS, so they should be tanks.
- 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.
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