How should my duster handle
I actually do agree...people who turn the steering wheel without the car rolling are poor drivers. These are the same people who have cars that break and/or require repairs....my cars never, ever break. I've also never worn out a set of brake pads in under 100K miles.
As for the idea that if you upgrade the tires, you must 'upgrade' the rest of the suspension....that is 'magazine talk' which is founded in the need for their advertisers to sell more stuff.
I have had many old Mopars with 100% stock suspension and modern radials. They drove very well. Sure, you can make other changes but they're not necessary and are often 'downgrades' as much as upgrades. Human nature- along with magazine talk - is to assume any change must be an 'upgrade' if it's shiny and has clever stickers on it. Companies spend more money than you and I have together in studying how to appeal to that side of our brains.
Many parts sold for suspension are pure garbage...polyurethane bushings are at the top of that list but so are a lot of the fancy shocks and springs and sway bars. Too many guys buy a bunch of expensive parts and never bother sorting them out or even finding out if they work well.
I am all for modifying cars....but the mods have to work and work well. If you have an A Body that has mods that actually perform, that's what it's all about. But for every car like that I see 10 that are bolt-on specials.
The 'Gold Standard' of any Mopar suspension is to be 100% fresh and 100% stock. That is the starting point from which all mods are judged. It's a good starting point because, unlike other cars of the era, Mopars rolled out the door with a suspension that still holds its own 60 years later.
If your cars don't break or require repairs, you're not using them. Parts wear out if you drive.
"magazine talk"- uh, no. If you increase the coefficient of friction of your tires, you can transfer more force into the suspension. It's simple physics. The bias ply tires that the factory suspension was designed around had terrible traction, especially under cornering loads. Even your basic BFG TA radial has significantly improved traction compared to factory bias ply's. That means under cornering, braking, and acceleration you can put more force into the suspension than the factory wheel rates were designed to compensate for. Faster acceleration, shorter stopping distances, and sharper handling. Now, if you drive like a little old lady, maybe you don't notice any of that. If you
don't drive like a little old lady, you should immediately notice that there's too much body roll under any significant cornering. You should also notice a MASSIVE amount of understeer, as well as frequent suspension bottoming even at the factory prescribed ride height. The factory wheel rates are simply too soft, and were even too soft from the factory because that was the public demand at the time (cloud like ride, not handling). The result does not "drive well", unless you never put any significant load into the suspension.
Polyurethane bushings are not "pure garbage". And quite frankly the fact you think that explains that you really don't understand very much about suspension. I will happily admit that polyurethane bushings are not right for every circumstance or build, that's definitely true. They also must be maintained in a way that's different from rubber bushings, because they are quite different from rubber bushings. Most, if not ALL, of the complaints I've seen here on this board about poly bushings are user error- poor installation and maintenance. They're not rubber, they don't act like rubber, they aren't installed like rubber, and they must not be maintained the same way as rubber. Properly installed and maintained poly bushings will outperform rubber bushings in pretty much any performance standard you can come up with. Like any suspension upgrade, they must be matched to work with the rest of the suspension components.
Shocks are in fact what keep the wheels on the ground, so, again, if you think "fancy shocks" are garbage or unnecessary it says more about you than it does them. This is really simple. If you improve your tires, you increase the loads the suspension can be exposed to. If you increase the wheel rates to better manage those increased suspension loads, you also need to have shocks that can handle the increased wheel rates and still properly dampen the spring force. Factory shocks will not, especially if you increase the wheel rate above 200 lb/in (which you should).
Sway bars are a great way to increase wheel rates without adding wheel rate all the time. There are some different schools of thought on spring rates, sway bar rates and their combined wheel rates depending on who you listen to. Dick Gulstrand and Herb Adams, for example, have exactly the opposite opinion on spring and sway bar rates. Dick Gulstrand was very much of the opinion that sway bars were only for fine tuning, so you should run poly bushings and higher spring rates with smaller sway bars to tune. Herb Adams believed in springing cars as softly as possible and then running gigantic sway bars to increase the wheel rates. Needless to say both have quite the reputation and history of success, and some of that is driver style. But saying you don't need to change out sway bars from factory if you've already changed out tires from factory is just ignorance.
Mopars 60 years later handle like the old muscle car barges that they are, and in 100% factory condition will lose any race that has 2 corners to the average modern commuter car. The factory designs greatest advantage was its adjustability, and being able to lower the factory suspension with just the torsion bars. That change in geometry suits the needs of radial tires VERY well, which is why these Mopars respond and handle so well when you lower them 1"-2", increase the torsion bar size so the wheel rate matches that of a modern car (200-300 lb/in wheel rate), and run modern wheels and tires with a modern alignment (based on the SKOSH chart to as wild as your set up). Because when you do that the suspension geometry, camber curves, bump steer etc all match VERY WELL to the needs of a modern radial tire.
If you don't do that, the suspension geometry, camber curves, bump steer etc are all very much set up for bias ply tires, which have totally different geometry needs.
