Torsion Bars... Best Diameter for a Lowered Street / Autocross car?

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I run Mopar performance 1.14 bars and a double adjustable shock in my 69 Valiant...good combo for all around driving. I was going to run 1.20 bars but was going to have to modify the TTI headers at that size so I went with 1.14s.
 
this is a great thread on this topic. I too was looking into learnings on the TBar and how to tune. I have 1.03" TBars on my demon that started as a /6 but now has a BB. Having come from the world of auto-x and track, the demon is a big step down from my little RSX in terms of handling. Trying to get something that would at least hang with my little RSX on curves
 
Joeycurl said:
this is a great thread on this topic. I too was looking into learnings on the TBar and how to tune. I have 1.03" TBars on my demon that started as a /6 but now has a BB. Having come from the world of auto-x and track, the demon is a big step down from my little RSX in terms of handling. Trying to get something that would at least hang with my little RSX on curves
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Tires are more important than the BB in my opinion. Nowadays it’s easy to have an aluminum headed BB that doesn’t weigh all that much more than a small block with iron heads.

Handling well is all about matching your components to work with each other. You can take a look at my post earlier in this thread, I’d happily put the handling of my car up against most newer cars without traction control. But you have to build a system that works together starting at the tires and working all the way back to the chassis to do that.
 
Been a while sense I chimed in here... mainly b/c my shop was destroyed in a Derecho (land hurricane) in summer 2020 that put everything on hold. My Demon is in storage... but the new shop (2x biggee!!) is built and should be fully finished in about 1mo or so. Anyway... it will be a while before I can comment to how my TB choice handles, but sure am looking forward to it. Hopefully the 2nd half of 2021 will be productive and I can have the car on the road sometime in 2022! @72bluNblu ... look forward to some future questions on wheel/tire combos from me. You seem to have that all figured out. Ha!
 
273 said:
It's an old SA book, forget the name it's in my storage locker, It's all old school torsion bar and leaf spring setups.
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One of these?

D78A839D-5AF7-45A3-9AD7-468505FF3E81.jpeg
 
autoxcuda said:
For all the info you put out in this thread, that seems like a good starting point for what your are after and your background.

I could see you even going/trying/testing more bar.
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Getting some 1.03's monday!
 
Good choice. I have 1" bars on the car in my avatar ('70 Duster), definitely at looking to go up to 1.14"-ish. I'd recommend running 1" bars on anything mostly stock with 14" or 15" wheels and fat-sidewall tires but when you want to get serious it's not nearly enough. After I put on the current wheel and tire setup and lowered my car (less than an inch in the front, about 2" in the back to make it level as it used to have a rake) the increase in grip was so much that the level of body roll in hard cornering is almost as bad as it used to be with my old tires/wheels before I added sway bars. I can get around a track much faster now but I need to stiffen up the suspension more to get the most out of the tires. Also need to do upper A-arms, I get plenty of caster with offset upper bushings in the stock arms but they're like 9 years old at this point.

For reference my car has the 1" t-bars, offset UCA bushings, poly LCA bushings, boxed LCAs, adjustable strut rods, front and rear Hellwig sway bars and Hotchkiss rear leaf springs. Shocks are lame OE replacements, some nice adjustables might be next on my list but it's a toss-up between shocks and bars honestly. I noticed @BergmanAutoCraft recently started carrying tuned adjustable Fox shocks hmm (!!)
 
MopaR&D said:
Good choice. I have 1" bars on the car in my avatar ('70 Duster), definitely at looking to go up to 1.14"-ish. I'd recommend running 1" bars on anything mostly stock with 14" or 15" wheels and fat-sidewall tires but when you want to get serious it's not nearly enough. After I put on the current wheel and tire setup and lowered my car (less than an inch in the front, about 2" in the back to make it level as it used to have a rake) the increase in grip was so much that the level of body roll in hard cornering is almost as bad as it used to be with my old tires/wheels before I added sway bars. I can get around a track much faster now but I need to stiffen up the suspension more to get the most out of the tires. Also need to do upper A-arms, I get plenty of caster with offset upper bushings in the stock arms but they're like 9 years old at this point.

For reference my car has the 1" t-bars, offset UCA bushings, poly LCA bushings, boxed LCAs, adjustable strut rods, front and rear Hellwig sway bars and Hotchkiss rear leaf springs. Shocks are lame OE replacements, some nice adjustables might be next on my list but it's a toss-up between shocks and bars honestly. I noticed @BergmanAutoCraft recently started carrying tuned adjustable Fox shocks hmm (!!)
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I ran same setup in my barracuda from 1993 to 2010. Daily driver from ‘93 to ‘03. And commuter from 97-03. 225/60/15, 225/50/15, 245/50/15 tires.

I mostly ran used KYB shocks. Cycled through a few front sets every few years. Had some old used front konis, got a couple years out of them.

But did run some new 3 way adjustable Herb Adams VSE front shocks. Blew those out in a few years.

Had a used set of front QA1 1-way adjustable’s. Those lasted. Still good. Just got replaced with RCD’s with a complete hotchkis setup.
 
MopaR&D said:
Good choice. I have 1" bars on the car in my avatar ('70 Duster), definitely at looking to go up to 1.14"-ish. I'd recommend running 1" bars on anything mostly stock with 14" or 15" wheels and fat-sidewall tires but when you want to get serious it's not nearly enough. After I put on the current wheel and tire setup and lowered my car (less than an inch in the front, about 2" in the back to make it level as it used to have a rake) the increase in grip was so much that the level of body roll in hard cornering is almost as bad as it used to be with my old tires/wheels before I added sway bars. I can get around a track much faster now but I need to stiffen up the suspension more to get the most out of the tires. Also need to do upper A-arms, I get plenty of caster with offset upper bushings in the stock arms but they're like 9 years old at this point.

For reference my car has the 1" t-bars, offset UCA bushings, poly LCA bushings, boxed LCAs, adjustable strut rods, front and rear Hellwig sway bars and Hotchkiss rear leaf springs. Shocks are lame OE replacements, some nice adjustables might be next on my list but it's a toss-up between shocks and bars honestly. I noticed @BergmanAutoCraft recently started carrying tuned adjustable Fox shocks hmm (!!)
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One of the reasons for your increased roll when you lowered the suspension is the lengthening of the moment arm. You’ve moved the roll center further away from the center of gravity. Using the taller FMJ spindles in this situation will reduce body roll. You can also achieve the same thing by using a taller ball joint.
 
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