E86 Front Triangulation Braces Retrofit

[heinzboehmer]

Got the braces and brackets back from cerakote today, which means this project is officially finished!

Here's some engine bay shots:





Only thing missing from the documentation is the weight of the stock cabin air filter housing. Hoping someone can help out here, for completeness. Maybe George Hill or karter16?

[heinzboehmer]

Weighed the final parts today. Here's where we landed at:



(sorry if it's a bit hard to read, I think I tried to stuff too much info into this table)

I unfortunately do not have my stock cabin air filter housing anymore (I chopped it up), so I can't weigh that. Going off of the RealOEM value makes it look like this project results in a net decrease in weight. Excellent!

Can someone help me by weighing their stock housing? Here's a comprehensive list of the components that I put on the scale. Would be great to do the same with the stock part for max apples-to-apples-ness:

- Housing
- Hood gasket
- Both water drain boots
- Air filter
- Filter cover
- Half of cable tray attached to housing
- Half of cable tray that snaps on
- T30 screws

[George Hill]

I’ll report back as soon as possible, looks rad though

[heinzboehmer]

Alright, have fun prototyping George Hill: https://cad.onshape.com/documents/fb...5f06a7a75341ec

You can export the .step/.stl files from the link above.

Also, I was curious, so I quoted the parts on sendcutsend. 7075 isn't really bendable, so I quoted in mild steel:



Price for one set is $57.58. Here's the same parts, but in higher quantities:



Drops down to $26.21 per set if you get 10 made. Downside is that post welding, rivnuts and powder coating, you're looking at almost twice the weight of the 7075 machined version.

Also, worth repeating in case others stumble upon this post in isolation: these are very rough prototypes with zero analysis or validation behind them. Do not blindly trust them.

[heinzboehmer]

im not exactly sure I follow your idea of bolting. So you mean drill through the cowl and insert bolts from the top down? The head of the bolt would sit under the cowl trim?

Yep! Exactly.

If you go the opposite direction, you'd end up with a rivnut (or the end of a rivet) in between the cowl and the chassis. I don't think there's gonna be enough space for that.

Actually I think I have an old one too I could probably section so we can see what the clearance is.

Ooh that would work too.

[George Hill]

heinzboehmer totally fair on the CAD file, that makes complete sense.

im not exactly sure I follow your idea of bolting. So you mean drill through the cowl and insert bolts from the top down? The head of the bolt would sit under the cowl trim?

I do have a cowl here. Actually I think I have an old one too I could probably section so we can see what the clearance is.

[heinzboehmer]

Actually, George Hill, do you have a cowl handy? Would be interesting to put some silicone mold putty down in between the chassis and the cowl and let it cure. Just to see how much clearance there actually is in between the two parts.

Cowl goes above the windshield and chassis dips down below. It's possible there's just barely enough space for a couple hex head bolts.

[heinzboehmer]

Heinz, would you be able to upload that sheet metal design to the drive? I'm curious what it would cost from SCS.

I'm hesitant to upload it because it's a very rough, back-of-the-napkin draft with absolutely zero validation. Wouldn't want someone to see it and assume it's tested, like the rest of the stuff in there.

I can spin off a copy of the CAD of that design for prototyping, though. Will do so when I get home and link it here.

Miles of room from the interior side without the heater case installed.



Also, I have a swivel head rivet gun. Without the S54 plenum installed I wonder if you could access it and rivet from the engine bay?

Wow! That's way more space than I expected.

Do swivel head rivnut tools exist? IMO, if you're going to the trouble of finding a way to drill holes for rivets, might as well drill them big enough to use rivnuts in the rear, for max serviceability.

Front would likely still need regular rivets because of interference with the cowl, but you can install those from the top, with the head of the rivet ending up sandwiched between the cowl and chassis.

Looking back through pictures, I think you can fit a right angle drill from the front with the blower motor out of the way:

[George Hill]

I kind of took Bry5on thread off the rails as we were discussing other attachment methods for the cowl bracket. heinzboehmer offered some other solutions and I wanted to explore that more so I thought it would make the most sense to bring that conversation to the thread here.

Heinz, would you be able to upload that sheet metal design to the drive? I'm curious what it would cost from SCS.

I'll print that out as well and see what it looks like for access.

Miles of room from the interior side without the heater case installed.




Also, I have a swivel head rivet gun. Without the S54 plenum installed I wonder if you could access it and rivet from the engine bay?

[heinzboehmer]

Now I'm doubly glad I asked! would not have thought to use the step file for additive printing! Can confirm the step files come out at the right dimensions :-) Thanks!

I think my previous post might have sounded a bit too assertive regarding what I think of the .step vs .stl debate, especially when it comes to additive manufacturing.

In theory, sure .step will give you more precise paths, but there's a lot of approximations involved in additive, given the layered approach (any features in z, corners, etc. are all approximated).

In practice though? Willing to bet the physical parts would be identical, given a high enough resolution.stl (min triangle height <= max machine resolution). Might just be a carryover from the CNC world.

But, at the end of the day, I'm pretty sure the manufacturers don't care what I think and they still seem to prefer .step sooo

Anyway, rant over. Glad the .step files work

[karter16]

Hmmm, maybe I messed up the scaling when exporting. Project units are mm.

Can you try the .step files? They're what I gave to the manufacturer, as most seem to prefer that format.

The preference feels justified since .step is parametric(ish), as opposed to the jumble of triangles you get in an .stl (decent analogy is .svg vs .jpg).

Now I'm doubly glad I asked! would not have thought to use the step file for additive printing! Can confirm the step files come out at the right dimensions :-) Thanks!

[heinzboehmer]

Apologies in advance if I'm being super dumb, but everything is telling me the STL files you uploaded for the strut brackets have the model as being super-tiny. Do I need to apply a scaling factor to these (I'm guessing it should be about 100x bigger? (dm instead of mm?))

Hmmm, maybe I messed up the scaling when exporting. Project units are mm.

Can you try the .step files? They're what I gave to the manufacturer, as most seem to prefer that format.

The preference feels justified since .step is parametric(ish), as opposed to the jumble of triangles you get in an .stl (decent analogy is .svg vs .jpg).

[karter16]

Also, I hadn't linked the CAD anywhere earlier because the parts weren't final and I didn't want people to end up with stale copies of it. However, the design is now about as final as it's gonna get, so I've added the CAD link to the documentation.

Apologies in advance if I'm being super dumb, but everything is telling me the STL files you uploaded for the strut brackets have the model as being super-tiny. Do I need to apply a scaling factor to these (I'm guessing it should be about 100x bigger? (dm instead of mm?))

[bigjae46]

My carbon fiber brackets have seen 3 track days with Hoosiers and Goodyear Supercar 3Rs at COTA and Eagle's Canyon Raceway. Lots of G-loads and they haven't exploded! Finally got the center bracket bonded.

https://nam3forum.com/forums/forum/main-forum/member-build-journals/6890-the-red-drift-machine-2026-nasa-tt4-adventures?p=350699#post350699

Heinz kindly sent a plastic version of the latest strut tower bracket so I will proceed with making a cast mold and then a CF copy.

[heinzboehmer]

Printed strut tower brackets have done 500 street miles + a track day and they still look perfect. Think I'm gonna sign off on them, as that's about as much testing as I can feasibly do in a reasonable timeframe. I'll update the design (and this thread) if they fail prematurely in the coming years.

Documentation has been updated and files have been uploaded to the drive.

Also, I hadn't linked the CAD anywhere earlier because the parts weren't final and I didn't want people to end up with stale copies of it. However, the design is now about as final as it's gonna get, so I've added the CAD link to the documentation.