A-Body (Plymouth Valiant/Dodge Dart/Duster/etc.) Suspension Repairs and Upgrades
If you need new leaf springs (sagging rear susension), try Performance Suspension Technology (1.800.247.2288), Kanter Auto Parts (800-526-1096), or The Paddock (1.800.428.4319). You may also want to follow Stephen W. Coleman's advice to look up Detroit Spring, near Troy, Michigan. Kanter sells new leaf springs at $350/pair or coil-over booster shocks, which may help do the same job, at $90/pair.
If you have a sagging front suspension on a 1970s A-body, try adjusting the front torsion bars. There is an adjustment bolt in each lower control arm. You may need to use heat, penetrating oil, and a big bar. Chris Jardine added that:
Many second generation A-body Chrysler products had a problem with the rear mount for the torsion bar. Water collects in the channel and rust occurs. After a decade or so the channel that the mount is welded into rusts through and the mount twists and that side of the car falls onto the rebounce (sp?) bumper. If this is what happened you will need to find a local frame/suspension/alignment shop that has someone who has welded in new material to replace the rusted stuff and then realign the ride height when done.
Paul Clark wrote:
(Responding to a post about a very visible angle to the front wheels, which was only helped a little by replacing the ball joints)
This angle is probably caused by a worn upper control arm (UCA) bushing or two. It's hard to detect this with the 'jiggle test', because unlike tie rods, ball joints, and pitman arms, the preload of the front springs keeps them too tight to budge by hand even if there's a half inch of play on 'em. I had this problem with my '64 GT too. You can often see it though by putting the car on a jackstand and then putting a jack under the lower control arm. As you jack it up, the pivot point (inner part of upper control arm) should pivot but not shift; often it gets so bad that the rubber bushing is completely gone in there and you're running metal on metal. You can also see this because the bolt that goes through the UCA is no longer centered because the bushing is gone. If you can see a visible tilt to the wheel, as you describe, this is probably the case. If you can see shiny silver on the pivot bolt, your bushings are shot.
To repair this, you have to pull the upper control arms, which is easy enough (jack the car up, remove the wheel, pop the upper ball joint with a pickle fork, and remove the bolt that UCA pivots on) but the hard part is getting the old bushing out of the UCA. The 'regular' way to do it is with a hydraulic press (at your local machine shop), though I've heard enough stories of people who figured out how to do it using a vice or some kind of jig with a hydraulic jack, and using pieces of pipe or sockets as fittings.
The cheap and dirty way is to get a whole new UCA with decent bushings from your local salvage yard. AFAIK all A-bodies, at least 63 and up, interchange. In fact, I have a pile of extras lying around in my garage- you can have one for free if you stop by in person :) I expect the cost of shipping one is more than the cost of a junkyard piece. Note that if you do this, the left and right side aren't interchangeable- they're mirror images of each other.
If you do the 'correct' fix and replace the bushings, you'll need two for each side, and if you're going to all that trouble, you might consider upgrading polyeurethane bushings, which are much stiffer and give a firmer, more stable ride. One brand (PST) calls theirs 'polygraphite', which just means they impregnate the polyurethane with graphite for lubrication and increased life. Bushings aren't terribly expensive- I seem to recall the 10-20$ range each, though don't take my word for it. The improvement in your handling will be spectacular!
Lower Control Arm bushings seem to wear out less frequently, which is good because they're more hassle to replace- but I'll leave that description to others, cause I haven't done it (yet.) It usually involves burning out the old bushing and, such, and you have to remove the t-bars to get to them.