Rusty is right, the strut rods are not there for caster adjustment and using them to adjust caster, instead of adjusting them properly, could create binding and other alignment issues.
Look, the strut rod is there because of the single pivot style of LCA. Because there's only one pivot the LCA has the tendency to flex forward/backward on the LCA bushings. The purpose of the strut rod (also called a "brake reaction rod) is to keep the LCA from flopping around too much under braking, acceleration, hard cornering, etc. The thing is that the strut rod and the LCA are at an angle to each other and have pivots that are at an angle to each other, so the end of the strut rod and the end of the LCA do not want to trace out the same arc as the suspension travels. So at the extreme ends of that arc you can get binding as the strut rod wants to pull on the LCA. So you have to keep in mind that the strut rods move in two different planes, fore/aft and up/down. You want them to not allow fore/aft movement of the LCA, but freely allow up/down movement.
The factory used large, soft, rubber strut rod bushings. The benefit to that is they flex a lot, so the length of the strut rod doesn't have to be perfect. Which is good if you have large factory tolerances like these cars do. So when the LCA moves up and down the strut rod follows and the strut rod bushing is compressed as the strut rod angles up or down. The rubber is soft so it compresses easily and you shouldn't have a ton of binding on the LCA. The down side is that large rubber strut rod bushing will also compress and extend a lot under braking and acceleration, which means that the strut rod isn't controlling the forward/backward motion of the LCA very well. That means when your braking, accelerating, or cornering your LCA is moving forward and backward, and that causes caster changes. Which is not what you want for accurate handling.
The adjustable strut rods use heim joints, so, they pivot up and down with no resistance at all, which is a huge improvement. And, under fore/aft movement of the LCA they can't compress or extend at all, also a huge improvement. The drawback is that they still travel in an arc that's not parallel to the LCA, and because there's no flex that means the length of the strut rod is critical so that you don't get binding within the range of travel of the LCA. Which is why on installation you need to adjust the length of the strut rod and cycle the suspension up and down and make adjustments until there's no binding in the suspension travel from bump stop to bump stop.
Poly strut rod bushings are kind of problematic. They reduce the fore/aft movement of the LCA, which is good, because of how stiff they are. So you get fewer caster changes. But the problem is they still work like a big cushion bushing when the strut rod travels up and down with the LCA, and because the poly is really hard the strut rod will resist the up/down movement of the LCA, which is NOT good. And because the poly strut rod bushings don't compress a ton, the length of the strut rod is a lot more important than it is with the big soft rubber factory bushing. Maybe not quite as critical as with an adjustable strut rod, but usually people use poly strut rod bushings on stock strut rods, which gives you no length adjustment at all. So now you've eliminated the give in the bushings but are still stuck with loose factory tolerances that can cause binding. So unless you tune the length of the strut rod or adjust the thickness of the poly strut rod bushing you may end up with a lot of binding, and either way you have more resistance to up/down travel.
If you're going to run poly LCA bushings, you should also run adjustable strut rods. Same reasoning, the factory LCA bushings are soft and allow for more slop (and looser tolerances). If you install poly bushings at the LCA you eliminate a lot of that slop, but now you have to account for the loose tolerances elsewhere (like at the strut rod). Poly bushings also work totally different than the rubber LCA bushings, the poly bushings rotate on the LCA pivot pins so the tolerance is different, and the LCA can slide on the pins. So the length of the strut rod is more critical with poly LCA bushings.
If it’s not a race car, don’t waste your money on the adjustable strut bars
Totally disagree.
I run adjustable strut rods on all of my cars, and they're all street cars. Having accurate steering and suspension changes is not just something a "race car" benefits from. When adjusted properly, adjustable strut rods make a huge difference in tightening up the handling and the accuracy of the suspension responses. With rubber strut rod bushings and factory strut rods your caster is constantly changing under load, which makes the handling feel sloppy and unpredictable.
Strut rod deflection
