Advantages of aftermarket upper:lower control arms
Can you elaborate on this? Do poly LCA bushings place the LCA in a different location? I've got a set on my 66 Dart with stock strut rods and didn't notice any issues when I reassembled it, though I haven't put any miles on the car yet either.
Yes, they can put the LCA in a slightly different location.
But the bigger issue is the strut rod. The factory strut rods are "one size fits most", and get away with that because of the large rubber bushings they use, as well as the rubber bushings at the LCA. The LCA and the strut rod both move in an arc, and those arcs are at an angle to each other. So, at the ends of the range of suspension travel the arcs are moving away from each other. The factory used large rubber bushings to deal with this, but that also allows the LCA to move around more under braking and acceleration. When you start replacing rubber with poly, there isn't as much give. And as a result, the length of the strut rod becomes a lot more critical. So to keep things from binding, you need to tune the length of the strut rod to match your car and its range of travel. If you've lowered your car that range of travel is different, if you've swapped out bump stops that range of travel can be different, etc. And so the adjustable strut rod allows you to set the length of the strut rod so that there's no binding within the range of suspension travel that
your car has. The further from factory you get, the more important this is. The adjustable strut rod isn't to set the alignment, but rather to get the LCA to move freely without binding through its range of travel. Once that length is set it shouldn't need to be changed, but it's easier to buy an adjustable strut rod than make a non-adjustable strut rod the right length for your car.
People get all up in arms when I say that if you're running poly or Delrin LCA bushings you need adjustable strut rods, and greaseable LCA pins for poly specifically. Poly and Delrin LCA bushings function differently than the OE rubber bushings. With the rubber bushing, nothing is spinning. All the movement of the suspension is flex in the rubber. Which is why the OE rubber bushings tear if you don't tighten the pivot nuts at ride height (in the center of the range of travel). It also adds resistance and binding into the suspension at the extreme ends of the range of travel. Poly and delrin bushings rotate on the LCA pivot pins, unlike rubber. Which is why poly has to be lubricated and IMO requires greaseable pins. Delrin is self lubricating, so, not necessary with those. But because of that, they have the same resistance to movement all the way through the entire range of travel, resistance that's less than with rubber for more accurate handling. Smooth, low resistance travel without binding is the goal, and the rubber bushings do not help with that. But, the poly bushings are not maintenance free, and adjustable strut rods require some tuning, trial and error, and sitting around moving the suspension back and forth through its range of travel while they're adjusted. For a cruiser that's a lot of work for little gain compared to rubber bushings and non-adjustable strut rods. But for more performance oriented handling, it's important.
