Frame or chassis options for A bodies
What are the consequences that need to be addressed?
I only ask because I just wanted to make sure I knew what I was getting into. Thanks!
The torsion bar sockets and LCA pivot pin mounts should both be gusseted. I wouldn't say it's mandatory, and it's not a problem unique to larger torsion bars. I've seen torsion bar sockets that have torn out of the crossmember, same for the LCA pivot mounts in the K member, with just the stock suspension components. Some of that is because these are 40+ year old cars that are prone to rust, some of it is because the quality of the welds from the factory varied quite widely. Some cars wouldn't need anything, others might not hold up to the increased loads.
I've run my Challenger with 1.12" torsion bars for almost 8 years and probably some 60k miles without reinforcing anything in the chassis. Not the K member, not the torsion bar sockets, no subframe connectors, no torque boxes,
nothing. I run it with 275/40/17's on all 4 corners, the 1.12" Firm Feel torsion bars and Mopar XHD springs in the back. And it has rust holes in the floor. Now I wouldn't suggest doing the same, there's definitely some chassis flex (ok, a lot of chassis flex) that comes along with that combination. But the only parts I've actually broken were aftermarket parts I've put on the car (CAP tubular LCA's).
You also asked about the Bergman AutoCraft SPC UCA's. There's a couple reasons I bought them. One, the fact that they're double adjustable. Meaning, you can adjust the UCA's while they're bolted in place on the car. It's just a nice thing to have, especially if you want to fine tune your alignment. The other is that they use delrin bushings and not Heim joints. I completely wore out a couple of the heims on the Hotchkis UCA's on my Challenger in under 7k miles. Yes, my car gets used in all weather conditions and on the street, and Hotchkis very graciously replaced my heims at no charge and included their new heim boots that I did not originally run. That said, I doubt the new heims even with the boots will last 10k miles. And since the Hotchkis UCA's aren't double adjustable, that means multiple installs and adjustments to reset the alignment when the heims are changed. I don't like heims on the UCA's for that reason. Strut rods are a different story, they don't see anywhere near the same amount of load.
At any rate, other than a wider range of adjustability, you don't NEED the SPC arms. I have magnumforce non-adjustable, bushed, tubular UCA's on my Duster right now, they work fine and will get you to the modern alignment specs you should have with modern radial tires. The BAC SPC UCA's are just really nice, and the adjustability is great if you intend to make adjustments frequently (like changing your alignment for certain tracks, tires, etc.). The magnumforce UCA's will be reused on my Dart, which isn't going to be set up as aggressively as my Duster is.