I looked at your drawing, as difficult as it was to tell what anything was attached to and how.
There will ALWAYS be different arcs. If you attach an additional strut to the strut rod, even if it's parallel to the pivot pin, the end that is attached to the LCA is traveling in an arc that is
perpendicular to the arc that the LCA is moving in. That's before you even consider how it will be attached to the strut, or that you'll be adding an additional load in the middle of the strut rod.
There is a reason why the original strut rod is at an angle. It's so that the arcs are
not perpendicular to each other. The different lengths mean that the arc have a different radius, but, they overlap at an angle with lessens the effect of the movement. And when you consider the relatively small amount of travel, the issue you have with the adjustable struts is not a problem.
You can not like it all you want, but if you install a set of adjustable strut rods and adjust them to the proper length you'll find that there is no binding within the range of travel of the LCA. I have, and it's not there. The arcs overlap well enough for that distance that it isn't an issue. The factory used large rubber bushings because they couldn't change the length of the strut rod, and needed the fudge factor of the big rubber bushings to make up for having large tolerances on the suspension points.
There are a lot of different manufacturers that use a single leg LCA and strut rod arrangement. Mustangs use it, GM used it on a lot of stuff, even 2wd Toyota Tacoma's use it. They all use a strut rod at a similar angle to what's used in the Mopar suspension. None of that is by accident. Meanwhile, you won't find anything that uses a dual strut rod arrangement with the strut rods tethered together. Too many moving parts tracing out different arcs while they all move up and down at different rates.
Your thinking is absolutely correct Rob.
That's a lot of work to do because someone didn't dial in enough positive caster. But by all means, do a crap load of unnecessary work because you don't understand how the
upgraded suspension works. Seems apt punishment for your continued and willful ignorance.
There are two different arcs, you guys are correct. The lengths are different, so they have different diameters too. But the strut rod and the LCA are not perpendicular, they're at an angle. So the strut rod doesn't just want to move the LCA forward and back, it pulls it in and out as well. These are all small components of movement though. The thing is that with the lengths of the strut rods, the length of the LCA's, and the amount of travel that they move in, the arcs don't diverge all that much. Not enough to be a problem.
And as I said before, the easiest way to see this is just to install everything. Install the LCA and strut rod, torsion bar, upper control arm and spindle. With that whole assembly together and the torsion bar adjuster plate and bolt removed, the suspension can be cycled up and down through its entire range of travel. Adjust the strut rod so the LCA is all the way forward against the poly (or delrin) LCA bushing. Then make small adjustments to the length of the strut rod until the LCA and suspension move up and down without binding. That's the process, and having done it a number of times with different components I can tell you that you can always get the suspension to move up and down without binding. Which means although there are different arcs, the angle they're at and their different radii mean that they overlap for the entire range of travel. Or at least well enough that it doesn't cause binding.
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