Adjustable Strut Rods
Can someone school me on these please? I would have thought the way the bottom control arm is mounted on the pin and the torsion bar in the back of it, that there would be limited movement available in this area? Am I wrong?
The torsion bars can slide in their sockets by about a 1/4" or so. Yes, they'll keep the LCA from sliding out of the K frame entirely, but that amount of movement would cause significant alignment changes.
As for the way the LCA is mounted on the pin, all that keeps the LCA on the pin with the OE LCA bushings is a friction fit between the rubber bushing and the inner and outer shells. The LCA can come right off the pin if the bushing fails. When I pulled apart the original suspension on my '71 GT the LCA's fell right off the pins after the torsion bars and strut rods were removed, the bushings were shot.
The strut rods were meant to control the LCA's from moving too far forward or aft under braking, turning, suspension loads etc. The original design uses large rubber bushings, which allows the LCA to flex forward and backward, which results in alignment changes. Particularly caster settings. The original strut rods are a fixed length, so, the large rubber bushing allowed for the factory chassis and suspension tolerances to work. They're a "one size fits most" type deal, some cars they fit well, most cars they fit ok, and on some caused a decent amount of binding. But as long as the factory alignment numbers were reached it didn't matter to the factory.
The adjustable, heim jointed strut rods solve a lot of these issues. They allow you to tune the length of the strut rod to fit YOUR car. Because they don't have a ton of flex, they reduce caster and alignment changes for a more accurate feel. When polyurethane, polygraphite or Delrin LCA bushings are used adjustable strut rods are really necessary because of how those bushings work- because the bushings are hard, and the LCA pins can spin and slide on the bushings a more accurate LCA position is important. Also, because the hard bushings allow less flex the length of the strut rod is more critical. Eliminating the slop that all those big rubber bushings is good for handling, but it also means the tolerances have to be better and the length of the strut rod has to be more accurate.
I put more than 70k street miles on the QA1 style adjustable strut rods I have on my Challenger with no issues. I've put nearly 20k street miles on my Duster with adjustable strut rods. The only drawback is that it takes longer to set them up initially, you need to tune the length and check for binding throughout the suspension travel range. Once that's done, they're better in every way. Guys like
@autoxcuda and Peter
@BergmanAutoCraft have run them on road courses for years. They're a proven improvement over the stock pieces.
