Black & Tan 332iT

[Bry5on]

What do you think the manufacturing costs and easability would be for a bolt on piece?

I can have a heater case out of an E46 in under 1.5hrs 👀

The cost of drill bits and rivet nuts (or rivets), plus the cost of Heinz's design Just shoot a few strategically placed holes through it - although I think one of those holes would have to be right under the plastic windshield cowl which is not super great.

[George Hill]

The cost of drill bits and rivet nuts (or rivets), plus the cost of Heinz's design Just shoot a few strategically placed holes through it - although I think one of those holes would have to be right under the plastic windshield cowl which is not super great.

I wasn't sure if the bracket would need to be redesigned for a bolted method, but I guess as long as its bolted through something solid it should be fine.

Sounds like I need to fire up the printer and report back.

[heinzboehmer]

The cost of drill bits and rivet nuts (or rivets), plus the cost of Heinz's design Just shoot a few strategically placed holes through it - although I think one of those holes would have to be right under the plastic windshield cowl which is not super great.

+1. Just add some holes and run some bolts through.

All of the red locations look like they'd be fair game in the sense that the bolts wouldn't run into anything in the chassis:




Blue spots would land under the cowl, like Bryson said. Maybe some (big) rivets in these spots would be low profile enough to not interfere with the cowl? You definitely want fasteners up front though, that's the part of the mount that most wants to peel away from the chassis.

If you're going through the effort of redesigning for bolting, I would be inclined to attempt a sheet metal version. You don't need material along the top if you're not bonding, so a "sideways J"-shaped piece might work (maybe add a couple weld-on ribs for extra strength). The resulting parts is probably gonna be similar weight, but should be much cheaper to produce.

Give me a sec, let me draft up something real quick, just to explain the idea better.

Edit: Super rough, but something like this:


Maybe rotate the ribs inwards a bit to have them be more in line with the loads.

Here's the machined version overlaid, for reference:

[heinzboehmer]

This looks way better:




Ribs in line with loads and has space for fasteners in the corners of the topmost + frontmost surfaces.

The above parts should weigh ~300g if made of 7075. Add in weight of welds + rivnuts and you're getting awfully close to the 428g weight of the machined part. So yeah, really only worth exploring this route if you want to drive cost down. Otherwise, I'd stick with the proven machined design.