Here's what I have observed.
Both systems can perform extremely well but, for the vast majority of us, to make the torsion bar system work requires replacing or modifying most of the TB system anyway.
Of course it does. Like Dion said, it's called rebuilding 50+ year old suspension. Why do you want to compare a 100% brand new system with aftermarket components to original 50+ year old parts?
It ends up being a long way from stock to get the performance these guys are getting.
What's stock about any of the coil over conversions? Nothing. Again, why do you want to compare fancy aftermarket components to stock ones?
Its useless to use TB and factory K-Frame without removing it and rewelding all the seams and installing the required gussets.
Useless? No. Not at all. That depends entirely on your planned use of the car. I ran my Challenger for 70k+ miles with 1.12" torsion bars and 275/40/17's on the street without touching the K member.
Now, will I gusset and seam weld that K before that car goes back on the road? Absolutely. But I'm not planning on using the car like most people do.
Boxing LCA's , replacing Upper control arms with Tubular , experimenting with T-Bars , Installing a better sway bar, upgrading shocks, upgrading steering box to Firm Feel specs or going with a Borgeson replacement.
Same thing again. Why do you want to compare a coil over conversion that has all of these parts already to a factory stock system?
And then, let's look at what Tim has done. Well, he's experimented with spring rates. He's upgraded to a better sway bar. He has a brand new rack with his brand new HDK. I guess he hasn't switched out shocks yet, but that's it.
That's what's necessary to tune a suspension. ANY suspension. You could run a decent torsion bar suspension without doing that, again, it just depends on your planned use. There are plenty of people here that just buy 1.03" torsion bars and run them with RCD's and call it a day, and they have decent handling cars. Not anywhere near Tim's level, but you don't need coil overs to do that.
In a nutshell, the members on here who are running TB based suspension have addressed all the shortcomings and ended up with exceptional handling cars.
The aftermarket has also responded and companies like HDK and RMS have executed fantastic handling and durable systems as well but using a well designed and executed bolt in platform that is much easier to implement for the average enthusiast.
What part of the torsion bar system doesn't bolt in? Everything I've done is bolt in with exception of the K frame welding and gusseting. And there are aftermarket parts and options for every part of the torsion bar system, except for maybe the spindles.
I mean, I run the same UCA's as Tim does. Tubular LCA's, 1.12" torsion bars, delrin LCA bushings, adjustable strut rods, etc. My suspension is just as well designed and executed, and if you leave out the chassis stiffening that I've done, which is even MORE necessary on a coil over conversion, well, what's the advantage? A rack. Some header clearance that doesn't even get you to a different set of headers.
I am not in the Autocross expert category as the posters on here but I do have track time on road courses. (Just came back from 4 days at Barbour Motorsports in Alabama) so I get how a well engineered suspension system is needed if you want to be competitive.
As for my experience?
9000 trouble free miles on my Alter-k-ation RMS suspension, normal tire wear, no breakage (Drag racing and "spirited" winding back road excursions ) .
I have no doubt the HDK system would perform the same.
Same. 40k+ miles on my Duster's torsion bar suspension since I rebuilt it. A few less on some of my upgraded parts like my SPC UCA's, but they weren't changed out because of any failures, just upgrades. And yeah, 70k+ miles on my Challenger with a fairly similar parts list. It did have a failure, the CAP tubular LCA, but that was a welding issue on those parts and certainly there are coil over conversions that have had failures too (not HDK or RMS that I'm aware of though).
I just don't see many of the points you're trying to make as valid. There's nothing "custom" about the suspension on my Duster, it's all off the shelf parts with exception of the welding and gusseting I did on the K frame.
But we are talking about handling and options/ideas on how. In some ways, it was a natural evolution when some of us concluded that a bolt in kit isn’t a direction we would go.
Assuming they kept the ABS tone ring.
