Torsion Bar ?

[randy73]

Getting new bars and am wondering what size to get, I have a 73 340/ with aluminum heads and intake, but I also added hideaways. So I think when all is said and done I lost about 20-25lbs off the nose. So do I get the .88 or the .94 bars?

[303 Mopar]

Biggest bars you can find. Hotchkis, Firmfeel, PST all have good sizes.  Our cars were severally undersprung so bigger bars helps the ride.   

[green69rt]

I'd go with the 0.94 or even a little more.  Modern shocks will help make up for the added stiffness and the increased spring rate will make the car seem more stable.  How's the rest of the front suspension look?  Got a front sway bar?  The 20-25# loss doesn't make that much diff unless you're racing, then every pound helps.  Lots of folks take off 20-25 then add it back as unsprung weight with wheels and tires.

[randy73]

Yes, went with a bigger sway bar upfront and rear. Rest of the suspension has been rebuilt.

[randy73]

Well talking to Firm Feel tech rep, I went with 1.06, as I already have oversized front and rear swaybars. Will let you know how it turns out.

[Nacho-RT74]

I'm happy with the 1.06"  but I think 1" could have being enough really

[Kern Dog]

I have 1.15s in my 70 Charger with a stroked 440 and aluminum stuff. It still rides no worse than the Wife's 2015 Challenger R/T.

[Bronzedodge]

Wow, 1.15.  Where did you get those, KD?

[green69rt]

Well talking to Firm Feel tech rep, I went with 1.06, as I already have oversized front and rear swaybars. Will let you know how it turns out.

Sounds like you are in good hands.

[randy73]

He kept talking about the 1.12's, but I told him I did not think a 50+ yr old man would be doing any road racing. LOL

I also got their leaf springs, was a little worried because they have an extra leaf and I did not want the rear to be sticking up, as I would like the car to have a slightly lower stance than stock, but the tech reassured me the springs would sit at the stock level. We will see.

[Nacho-RT74]

I will be adding an extra leaf in mines too, but just for stiffness, not for height.

In my experience and as I told, the 1" could be enough. I'm also running 1.06" from FF on my BB car. Adjuster bolts are really leaving out a lot from LCA, but is truth that I used the last hex face on adjuster. I will reindex it soon.

I'm a bit lower than stock ride height.

Thicker sway bar accomplishing the new T Bar could make a better job than a thicker T bar and stock sway bar for handling

[randy73]

Well, I hope going with 1.06 that I do not make the ride harsh and I can corner a lot better than before.

[Kern Dog]

Wow, 1.15.  Where did you get those, KD?

Bergman Auto Craft. Peter bought the leftover stock when XV racing was on its way out. Somehow, the company later reorganized and is back in business. Peter Bergman had other sizes too.

[Nacho-RT74]

Well, I hope going with 1.06 that I do not make the ride harsh and I can corner a lot better than before.

will be fine

[68CoronetRT]

1.1" Hotchkis here. Love them!

Had to ding my brand new TTi headers in 1 spot to make them fit. 

[HPP]

Don't forget that 73+ years have longer bars, so a 1.06 is only slightly more rate than a pre '72 1.0 (208# vs 176#).  Typically, a 50# difference in rate can only be noticed by the stop watch and not the butt dyno. A 32# difference is basically non-existent for serious differences.

[randy73]

Think you mean pre 73 and 73 b-bodies with 440's and police cars got .98 diameter torsion bars, 340's and HD 318's got .96 diameter bars, rest of 318's got .94 and 225 got .92, so I went up .10 in diameter.

Up to 72, torsion bars were .925 for 440's and hemi's, rest of BB and 340 got .90, HD 318 .88, rest of 318's and slant 6's got .86

See the difference between 73-74 and older b-bodies.

as for rate, my stock bars have a rate of 100#, not sure what Firm feels are.

Not only are the bars longer for 73-74 (2.6"), but they are setup differently, so you really cannot compare them to 72 and older chargers.

And so endsxhausts my knowledge of torsion bars.

[HPP]

The best way to compare rates among different cars, suspension types, and spring methods is to use the wheel rates. This is because most cars mount the spring somewhere inboard on the control arm and this position will reduce the effective rate of the spring. For example, in a 2nd gen Camaro, a 400# spring only produces 200# of wheel rate. In a Mopar, the torsion bar is mounted at the pivot point, so all of its spring rate is applied to the wheel, hence a 200# torsion bar produces 200# of wheel rate.

These days with more focus on handling and corner performance, 1.0"  for pre 73 cars is generally considered the baseline for anything nearing the feel of a later model vehicle, which typically have 30% more wheel rate than muscle era cars. For anyone getting into autocross or serious handling performance, the mopar t-bars actually are at a disadvantage  compared to other makes because of their limit in size. High performance handling in GMs usually are around the 300-400# wheel rates, which are at the extreme high end of whats available for a mopar. Our saving grace is we can step up sway bar sizes as well to create a greater roll rate to keep up, plus the trend over the last decade has been towards softer spring set ups with much more advanced shock control, but that is getting us into racing level technology with prices that will run a couple hundred+ per shock.

[Lennard]

HPP, I want to thank you for sharing all your knowledge here on the forum.  I've learned a lot from your replies over the years.  

[HPP]

My pleasure!