Am getting around to installing some adjustable strut rods i fabbed up. I measured and cut carefully to get the same overall length or so i thought. with everything installed at ride height the lower control arm is obviously not perpendicular to the front frame rail. it should be right? have been searching the net to find some info on dimensions for the front end but no luck so far. anybody got some suggestions? car is a 68 Dart with a complete 74 valiant k and suspension/ disk brake setup. race only, when i built it ten years ago used complete poly bushing rebuild kit, had it aligned and have been racing since. had alignment checked 3 years ago, needed no adjustments. those poly bushing are unbeilevably stiff but look as good as the day i put them in. tubular uppers with rod ends are going in next. nothing is bent or broken car drove fine when i put it up for the winter, just doing some upgrades.

I'm assuming your looking down at the arm from the top. Pulling the arm forward will only help. It will create additional positive caster. On a Mopar drag car there is never enough. I did the math this way. 3.14 x distance between upper & lower balljoints. Divide this number by 360. example: My B-Body spindle diminsion is approx 8.5" 8.5 x 3.14 / 360 = .074" Pulling the arm forward .074" should increase caster 1 Degree. Since the strut rod is at an angle it will have to be shorter than .074 per degree. My bet is make it .200" shorter.
Doug

Doug,your absolutely correct.We take the stock strut rod and machine a little off the washer stop ridge on the front of the rod and a little off the back stop where it bottoms in the lower control arm.Also we machine the taper and stop lip on the mounting pin(bolt) of the lower control arm.The easy way is to use the adjustable strut,but we seen many times that people tend to pull the lower control arm to far putting it in a binding position.

Doug, yes looking down at the lower arm. It was obvious even from the side view that the strut was too long. So should the lower be perpendicular to the frame rail at ride height. With my measurements i ended up with 1 inch of thread engagement for the initial install when it didn,t look right. that left 1/2 inch of thread available in the rod end, i used a small square and adjusted the strut to get it square. It took 1/4 inch to square up the lower. I never really looked at it before disassembly, with the spindle and disk and caliper installed you couldn,t clearly see how it all fit anyway.

I redid my math with my son who is an engineer. I should have used 8.5" as a radius for the caster change calculations. We also have now taken into acount the angle of the strut rod in relationship to the vehicle center line. We calculated the fact that the strut rod locates inboard of the lower ball joint as well. With all this being said and done, this is what we ended up with. Moving the lower arm forward by shortening the strut rod will change caster by 1 degree for every .100" length change. Thus moving the lower arm forward by shortening the strut rod .200" will net you 2 degrees additional positive caster. Hopefully your rod end C/L is in line with your lower control arm pivot C/L. If not you will be in for some toe change as well.
Doug