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Why not just tap and put a helicoil in then thread a cap head bolt into the hole with some loctite. Seems easy enough if there’s enough depth in the counterbore.
Mostly for serviceability. Getting a bolt threaded in back there is harder than a nut.
I guess you could tap and thread in a stud, but at that point, the captive bolt approach is not that much more work.
Edit: Oh wait, I think I misunderstood this. Thought you were talking about threading a bolt in from below. Either this or karter16's flats suggestion would work, you barely need any force to hold the fastener in place before friction takes over.
Last edited by heinzboehmer; 06-05-2026, 03:58 PM.
Why not just tap and put a helicoil in then thread a cap head bolt into the hole with some loctite. Seems easy enough if there’s enough depth in the counterbore.
Just a note for anyone else international doing this project. I'm having significant trouble finding a source for the press in studs. The best option I've got so far is to purchase from the same place Heinz did and pay a $250USD minimum + ~$400USD international shipping. Which obviously I'm not going to do.
I'm wondering if my best option is to modify the firewall bracket components to take captive bolts, and use bolts instead of press in studs for the E86 brace attachment points on the strut brackets.
Woah, that's not great. Hit me up and I'll ship some to you. I have extras since they're only sold in packs of many.
Otherwise, yes, captive bolts are the solution. Could argue that that's how I should have designed the E86 attachment point from the start. There's more than enough room in there, but machining a hexagonal bore is not an easy task. I think a round bore with a key + a 3D printed/laser cut insert is a probably the best way to go about it. The bores are at an angle, so you might even be able to get away without the key and just have the geometry of the insert keep it from spinning when it's bolted up to the windshield mount.
As designed, a super low profile socket head bolt (e.g. McMaster 91223A462) with a 3D printed insert would fit, but it's not ideal:
Seems like a bit of a hack vs just modifying the design to fit a hex bolt with a retainer prior to getting it machined.
Unfortunately, there is simply no room under the modified strut tower brackets for anything except the press in studs.
Just a note for anyone else international doing this project. I'm having significant trouble finding a source for the press in studs. The best option I've got so far is to purchase from the same place Heinz did and pay a $250USD minimum + ~$400USD international shipping. Which obviously I'm not going to do.
I'm wondering if my best option is to modify the firewall bracket components to take captive bolts, and use bolts instead of press in studs for the E86 brace attachment points on the strut brackets.
I keep forgetting to weigh that that stuff, was going to do that, do you think a regular bathroom scale is accurate enough?
Maybe stand on the scale then hold the item? Sometimes I wonder if those scales are less accurate at the bottom end of their range.
I weighed everything with a kitchen/coffee scale to get precision down to within a gram. A bit tricky to balance everything on it, but doable. Shipping scale is by far the easiest and most reliable tool for the job though.
Don't think your typical bathroom scale will work well here. I'm expecting the weight of the part to be in the 2-3 kg range, which is likely within the real world tolerance range of that type of scale (unless you have some fancy, high precision bathroom scale ).
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