diy adjustable strut rods
I have read here not to use poly LCA bushings on OE strut rods,
so even with poly strut rod bushing?? Just a weekend driver.
Here's the deal. The strut rod works in two different planes, keeping the LCA located fore/aft under acceleration and braking but also tracking the LCA up and down as it travels. In the fore/aft direction you want the strut rod bushings to be stiff, so poly seems like a good idea. But then as the strut rod moves up and down, you want the strut rod bushings to be soft, to prevent binding up the LCA travel, and in that area poly is a bad idea. The hard poly bushings will add more resistance to the up and down travel of the LCA, and you don't want that. The other thing is that because the poly doesn't compress much, the thickness of the bushing becomes more important- it can push the LCA backward from it's intended location if the poly bushings are too thick, which they sometimes are.
The factory rubber bushings, on the other hand, are the opposite. They compress very easily, so they don't add a bunch of binding when the LCA travels up and down. The problem with them is they also compress very easily in the fore/aft direction, which allows the LCA to flex forward and backward, which changes the caster. You can see how much movement the factory rubber strut rod bushings allow here, which also gives you an indiction of how much flex is allowed by the factory rubber LCA bushings. This is just a drive around the block too, not any kind of hard cornering, accelerating or braking.
✂️ Strut rod deflection
Getting back to your question, you can run poly LCA bushings with rubber strut rod bushings. The result will look different for your LCA movement though, because the LCA will slide on the LCA pivot pin when the strut rod bushings compress and stretch. Now, that movement will be exactly the same amount as allowed by the factory rubber LCA bushings, it's just slip instead of flex. The fore/aft motion of the LCA is controlled by the strut rod and its bushings, so the amount of deflection at the LCA will depend entirely on the strut rod bushings. Again, if you watch the video clip another member took, you can see the rubber strut rod bushings completely compressing on either side depending on the direction of motion. That's a lot of flex.
I covered it already here and in plenty of other places, I personally think adjustable strut rods are necessary any time you start changing out rubber for poly or delrin. The reason is simple, the factory tolerances were LOOSE and the big soft rubber bushings meant that the loose tolerances were "ok", because you had plenty of give in the system if things weren't quite lined up right. If you start replacing rubber with poly and delrin, the give and flex in the suspension system starts to go away, and the tolerances become more and more important. And things like the "one size fits most" strut rods start doing things you don't want them to do, like changing the location of the LCA. Which is why the adjustable strut rods are a big improvement, because you can set the length of the strut rod so there's no binding in the vertical travel of the LCA, and the LCA is located where it should be.
