I am currently working on a 1973 Chrysler Newport Custom. I am having an issue with the steering not coming back to center after a turn.
As of today, I would have changed everything, new PS pump, gear box, rag joint, steering coupler, tie rods, balls joints, pitman and idler arms, shocks, control arm bushings and prob some I am forgetting. However the issue is still there.
I did take it to get an alignment and I added a picture below of it. They told me its the best they can do for the Caster. What I am missing here, how do I get more Caster?
View attachment 456056
View attachment 456057
View attachment 456058
The way to get maximum assist in returning the wheel to center after a turn is to set the control arms for maximum caster. Think of bicycle forks for a minute, as they are curved forward as they go from the handle bars down the forks to the bike wheel center. That tilts the forks backward at the top and forward at the bottom. This is called maximum caster. It also allows some cyclists to take their hands off the handle bars briefly and allow the bike to track straight under conditions when the road is smooth and even.
Thus achieving maximum return to center after a turn also helps improve the directional stability of our C bodies, which is sorely needed due to the recirculating ball type of steering gears that were used in the 70s as opposed to the best modern systems that use rack and pinion systems. Thus, your goal of achieving maximum returnability of the steering is a worthy goal for both steering wheel returnability and the best tracking down the road.
One of the main gripes I have with the Chrysler products of the 70s is the limited ability to achieve maximum caster in their designs (which probably was because the use of bias ply tires made it easier to achieve these goals with less caster than the use of radials).
The first step in aligning our cars is to set the suspension height exactly where you want it with the torsion bar adjusters.
Since we want to get maximum caster with our steering systems. This means you need to think about the upper control arm ball joint
being laid back as far as possible relative to the lower control arm ball joint (
like on a bicycle). To achieve this, the front of the upper control arm needs to be moved outward as much as possible and the rear of the control arm needs to be moved inward as much as possible in order to rotate the upper control arm ball joint to the rear as much as possible.
The second step in setting alignment is to achieve proper camber which means generally you have to compromise some of the adjustments for caster to get the camber set to specifications, so in doing this, you generally lose a little bit of the caster. Camber affects tire wear if the tire is not close to straight up and down, so the goal is to compromise the caster as little as possible to get acceptable camber.
The last step is to set the toe-in.
To get maximum caster then the front cam needs to have the thick part of the cam as far out as possible from the centerline of the vehicle and the rear cam needs to have the thick part inward as much as possible (think of it as rotating the upper ball joint counterclockwise to get it to move to the rear as much as possible).
Unfortunately, the guy that did your alignment did just the opposite so you have almost the least amount of caster available, which is just what you don't want to achieve your goal.
Get a guy that knows more about what he is doing with a Chrysler vehicle if you want maximum returnability and maximum tracking ability so you are not correcting the steering all the time to keep the car going in a straight line.
You have a very nice looking Newport.