It's not just theoretical, it's literally how the suspension on these cars works. If you've ever bothered to take the time to cycle the suspension on these cars back and forth through the entire range of travel with factory and aftermarket parts and compare the differences you can literally SEE and FEEL what I'm talking about. I run the set up just like I described it, and I run it on the street. Between my '72 Challenger and my '74 Duster I have over 100k street driven miles on poly bushings in various different locations, as well as on my adjustable strut rods. I put over 70k street driven miles on "dynamic strut bars" identical to the ones QA1 sells now. They work, and they're significant improvement over stock.
It's not "road race stuff" either. It's performance handling "stuff". Properly tuned it's not harsh either. More than likely your suspension was harsh with the poly bushings because your undersized .88" torsion bars were still allowing the suspension to bottom out, and if you replaced the factory rubber bump stops with poly ones that would be harsh. All the components have to work together, if you just slap poly bushings in with all the factory parts and do nothing else they will not perform as they're intended.
Poly bushings that are squeaking are improperly lubricated. Just the simple truth, nothing you say will change that because it's just reality. This is why I always install poly bushings with a way to lubricate them. Unlike rubber bushings poly bushings are not maintenance free, they must be lubricated. They're not any different than any other high performance part- they're not like factory parts that you can install and forget about for 100k miles. Lubricate poly bushings on a regular interval (like greaseable ball joints) with the proper poly grease and they will never squeak. What happens when your ball joints dry out? The wear rapidly and start making noise. Same exact thing with poly bushings, it's literally the same concept.
The OP's 225 /6 has very little to do with how well his car handles. You can have a great handling car with a 225. It might not have as much power as a V8 equipped car, but there's no reason it has to handle like a barge like it did from the factory just because it has a /6 in it.
And there's proof that these parts work all over the place. You can look up how the Hotchkis Challenger compared to a Challenger SRT8. You can look up how the Hotchkis taxi performed on TireRack's track compared to the 3 series BMW's they normally use. With some relatively simple upgrades you can take these cars out of the last century and get them to handle on par with plenty of new cars. And for a car that is frequently driven on the street, that will mean you can actually drive the thing without worrying about getting wrapped around a pole or left in the dust by a new 4 banger commuter car. You take the theory of suspension design, apply it to the suspension on these cars, and make practical upgrades to match the suspensions function with modern tires that grip better than what the factory ever designed this suspension for.
You still miss my point. I am not talking autocross or road racing. Been there done all that. I'm talking about a street car you can drive all day long, be rock solid on the road and easily take any corner one would encounter on a real road. If the OP starts with a factory HP suspension, rubber bushings and all. Replaces all loose components, and torques everything to spec, and gets a good alignment he would probably be happy. Especially compared to the nothing suspension they put on /6 cars. When I did the 66 I wanted to go back to original, but was pleasantly surprised with the result. No need to worry about last century, I've put 250,00 street miles on a 96 Neon ACR. I've driven Porshe, Vettes, 2009 Challenger R/T, the 66 Formula S does fine with the original leaf springs, control arms, front sway bar, Bilstein shocks, 16:1 factory manual box, and whimpy .88 torsion bars. All that being said, The rebuilt suspension on the 67 Barracuda will replace polygraphite bushings with rubber. The only trick pieces will be Firm Feel upper control arms with rubber bushings, a roller bearing idler arm, and a 20:1 manual box. Everything is a compromise somewhere. I've done my time with polygraphite and high dollar for little gain stuff. What you want is not necessarily what I want.
