Could there be a stronger one made, sure, absolutely. But saying they do nothing, when even if they are designed for a 5mph crash so there isn't damage (which is a much higher load than cornering) doesn't do anything to stiffen this part of the car (which is badly needed with any front end setup, stock, yours, or anyone else's) is wrong. I did it first as an experiment and it seemed to work so why not keep it? Worst case I'd have to plug weld some holes shut with the MIG welder. Maybe in the future, I'll make some better ones. I have the USCT braces sitting here and they just plain aren't going to clear a 275 tire as far as I can tell so I can't use them to help. I got literally nothing done in 2023 until mid-September thanks to having hernia surgery which I wouldn't wish on my worst enemy.
The foundation in which any of this attaches is fundamental because otherwise the chassis of the car and the k-frame is flexing it's making everything else on the suspension less effective. The spot welds are popping at the connection of the inner fender aprons to the firewall piece. Those bars attach the firewall upper pinch weld to the inner fender aprons. Even small pieces will help the stiffness since they'll be more in tension/compression with cornering loads than in bending.
Do you have pictures of a k-frame failure where the spot welds broke? I have seen the tubes for the pivot pins crack and also the steering box brackets where I would assume it was stick welded in all likelihood at the factory. I would like to see that regardless. As was mentioned previously, the OE ones have gone hundreds of thousands of miles with unknown amount of abuse. In my case, the car is very high mileage, I don't know the exact amount but it was used as a daily in Flordia for 30 years, I used it for a daily for summers for 4 or 5, and has even survived the 275 tires for 9 years / over 10k miles and driving on the lovely Michigan roads with 252 lb/in wheel rate. When I got the car there literally wasn't a strut rod bushing at all on the right side. They're good pieces for something that was mass produced with quesitonable quality control, which is a testimate to the design philosphy. We're also now using tires 100 mm wider on 4" larger wheels with signifigantly more grip and 2.5x the spring rate. I mean showing failures (bending could be a failure also depending on what the conditions causing it were) on 50+ year old mass produced parts with hundreds of thousands of miles vs something that's newer and has relatively few miles driven on it is apples and oranges. Things made of steel can flex literally forever so long as the stress is below the fatigue limit. The things you have here to reduce flexing are limited only to the weld beads, the "over the tube" design, and the wall thickess/steel grade. Our world is full of examples of arches, gussets, general triangulation, tension rods, all to make things stiffer.
I don't have doubts in your workmanship on assembling it at all. My point being, its not optimized from a shape perspective for handling, especially in resisting bending/torsion. Relatively small changes can help it a lot. The goal of commenting is "constructive criticism" to say, well, if we put our minds together, can we improve it? I think that is really what racerjoe is after in the end, right? If you don't want to consider it, that's your choice also. No worries.
If we wanted to go all out here, why not tie into the frame rails behind the lower control arms? Excuse my sketching skills on snip and sketch, the scale might not be great, but basically have a yellow tab on both sides of the rail, a tube fits in the middle, you pick up the rear mounting point, and tie it back to the frame. Should spread the load out further and resist twisting/bending of the LCA attachment. Or widen the LCA completely and mount it further back on this point.
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Everything in a car is built by the cheapest bidder who meets quality standards and can stay in business. I am acutely aware of that on a daily basis at work.