diy adjustable strut rods
Dont hang me on the cross, but doesnt this just squash one side of the LCA bush against the tube, and possibly speeding up failure? And also how much adjustment can be had with this without compromising the bush?
Im happy to be educated
I think that a solid mounted fixed length with no "give", as it sweeps an arc will push and pull the lower arm as it moves above or below its normal at rest point. so i'd guess your comment is correct.
The rubber mounted strut would have some GIVE at the K member end and will still sweep an arc as the supension moves but the push and pull will be less because the K member mount allows some movement fore and aft. The impact on the lower bush would be dependent on how hard or soft the strut rod mounting was. As standard i assume some calculated effort was mode to provide a compromise.
solid mount and i think you will need less toe in.
gains in free movement and therfore better handling
loss in longevity of lower bush
potentially more changes in gemoerty as suspension travels that may or may not be of benefit dependent on roll tyres etc, i wouldn't want more bump steer for example .
greater potential to pull strut rod mount out of K frame and wrap lower arm back in a collision or clipping a curb stone at speed.
run higher spring rate and appropriate shocks and you probably limit impact becasue suspension travel will be reduced.
guess it comes down to intended use.
Dave
While I understand how the "theory" on this works, the simple reality is that it's not something that causes problems in practice.
First, the factory rubber bushings aren't some great thing. Yes, as the strut rod end travels in an arc up and down with the movement of the LCA, the changes created by the arc are absorbed by the bushing. So in theory the LCA moves straight up and down and less geometry changes occur. But the reality is the
opposite. The large, soft rubber bushings at the strut rod don't control the movement of the LCA very well at all and with acceleration, braking and cornering the road forces that come into the lower ball joint push the LCA forward and backward. This causes unwanted geometry changes all the time, because in the real world the suspension forces are almost never just up and down. Someone had a video posted here that was focused on the strut rod bushings as they drove around town, they were frequently fully compressed or fully stretched out. That's translates into a lot of LCA movement, which is absolutely changing geometry a ton. The arc doesn't create anywhere near a 1/2" of movement over the course of the full suspension travel, but the rubber strut rod bushings allow that much or more.
The adjustable strut rods with their heim pivot on the other hand do not allow the LCA to move fore/aft with acceleration, braking and cornering. The strut rod can only deflect up and down for the most part. The arc that the LCA end of the strut rod travels in of course will place fore/aft forces on the LCA. But that comes entirely from the arc, and the radius of that arc is still large. It is also not perpendicular to the LCA, and the LCA is itself traveling in an arc. So, the forces applied on the LCA from the strut rod having a fixed pivot are SMALL. Anyone that has installed a set of adjustable strut rods and adjusted them so that the LCA can travel through its full range of travel without binding knows this. Because you can in fact adjust the strut rod length so that there is NO binding or resistance within the full range of suspension travel. That window of proper adjustment is relatively small, about two full threads of the heims on my cars at any rate take the motion from a little binding to fully free and then back to a little binding at the extreme ends of LCA travel. But set properly there should be no binding or resistance. And if you use poly or Delrin bushings at the LCA, the binding is easily detected because the movement of the LCA when free has very little resistance, unlike with rubber bushings where all the LCA movement is from flex in the rubber bushing as it twists. That creates increasing resistance at the ends of the suspension travel by itself.
I've run adjustable strut rods on both my Challenger and my Duster, with over 100k miles logged between the two. I have run rubber LCA bushings, poly LCA bushings and Delrin LCA bushings during that time as I made various upgrades to the suspensions on both cars. I have had one rubber bushing fail, and it was around the 50k mile mark. There's nothing unusual or shortened about that life span, especially considering that the rubber bushings out there now are of pretty marginal quality. I'm sure I will now hear tales of factory bushings lasting 100k+ miles, but having myself seen multiple cars well under 100k miles with completely blown apart rubber bushings I don't think it's reasonable at all to say that 100k miles on factory rubber bushings should be expected. Possible maybe in some cases with better quality bushings that used to be around, but not now. The poly and Delrin LCA bushings that I've run since then show zero wear. When I installed Delrin LCA bushings in my Duster after about 10k miles the poly bushings I removed were indistinguishable from brand new bushings. And despite running 1.12" torsion bars and being lowered my combination of parts means that the available amount of suspension travel remains almost identical to factory, and the whole range is free from binding at the LCA as that's how I adjust the strut rods.
Greasable pins are not needed with Delrin bushings.
Greaseable pins
shouldn't be necessary with Delrin bushings. Based on my own experiences with fitting the Delrin bushings the Firm Feel greaseable LCA pins were by far the best fit with regard to tolerances, and I tried both stock and aftermarket pins with mine. And while the Delrin is supposed to be self lubricating, well, being able to add a shot of grease once and while isn't a bad thing. It won't hurt the Delrin any. And if the Delrin turns out not be 100% self lubricating a shot of grease might extend their life substantially.
