diy adjustable strut rods
I'm curious about this. Does the pivot end of the LCA really move fore/aft to the same extent as the outboard end with rubber strut rod bushings. If the LCA socket is nice and snug in the LCA, I would think the tension of the torsion bar in the LCA socket would keep that end of the LCA pretty stationary from a fore/aft standpoint, would it not?
Also, with a rubber LCA bushings, I would think any fore/aft movement on the outboard end would translate into more of a tangential force (if that's even the correct term) between the LCA pin/bushing interface than any fore/aft motion at that pivot end. In that case, poly/delrin LCA bushings be much better at resisting that type of force, wouldn't they?
From a "worst case" standpoint the pivot end of the LCA certainly can't move more than what the strut rod allows, the worst case would be it moves exactly as much.
Now, having said that, I agree with you that the movement of the LCA at the pivot end will not be nearly as much as the movement at the K member end of the strut rod. With rubber bushings it would just be flex, allowing the LCA to angle back and forth so the ball joint end could move with the strut rod. Poly, and Delrin especially, will not allow that much flex in the material. But, because of how those bushings work (rotating on the pivot pins), they could theoretically allow some fore/aft slip. Personally I would think those bushings resisting any flex they would reduce the motion of the LCA fore/aft even more. With the torsion bars loaded the torsion bar isn't going to slide in the socket, so the LCA's aren't going to move fore/aft. And the fit on the Delrin bushings on the pin and in the LCA is tighter than with the poly bushings, so frankly I don't see those moving fore/aft at all, even if the strut rod bushings would allow it. But even with poly LCA bushings the LCA sliding fore/aft would mean that the LCA would have to be sliding on the torsion bar, or the torsion bar would have to be sliding in the sockets. And if the bars are loaded, that's not going to happen at all. Would it be possible if somehow the torsion bar became neutrally loaded while there was still some fore/aft force on the LCA? Maybe. But anyone that's changed a few set of torsion bars knows that even when everything is unloaded the torsion bars aren't all that easy to move anywhere, and that wouldn't account for the fore/aft force that would make the LCA move on the pins and the hex end of the bars.
The idea that the LCA's would
slide fore/aft on the pins while the car is traveling down the road, with any kind of bushings, is pretty much magical thinking IMHO. Theoretically possible? Perhaps. Something that would happen in the real world? Nah. I would still rather have adjustable strut rods with those kind of LCA bushings, but that's because of the binding the wrong length strut rod would have on the LCA travel, not because the LCA is gonna slide anywhere.
Now with rubber bushings that fore/aft movement is all just flex, and doesn't need any of the other stuff to move. So yeah, that's possible, as shown by the video showing the deflection of the strut rod bushings.
