Best torsion bar upgrade when swapping small block to big block

[A3404bbl]

I have a 74 Challenger with a 340, that I am swapping out for a 512 stroker (440 block). While the motor is out I want to upgrade the torsion bars and wanted to know what brand and diameter people are running. My car will be a cruiser that may see a little action between lights, but won’t see any track time.

 

[Montclaire]

Many years ago I upgraded my 73 440 Challenger to Mopar Hemi bars (.92 maybe?) paired with the HD rear leafs from ESPO. This stiffened up things pretty well, and I found that it rode best with a soft shock like a Monroe-matic.

I also added a rear sway bar but I didn’t think that it was really necessary. I was running 235/60s and 275/60s so the rake combined with the stiff leafs may have negated the bar. Front bar was upgraded to over 1”, company was called SuperTuff Performance but I don’t think they sell to the public anymore.

If you are going with aluminum heads, water pump, etc., I would figure out total weight and compare to what the factory weights were and stay one step above. If you end up closer to 383 territory, go with the factory 440 bars and non-HD leafs. Everything needs to work together.

I would NOT box your LCAs, but I WOULD buy oversized, non-adjustable strut rods. Just Suspension used to sell them. Try to find old stock bushings, the new ones are all crap.

 

[A3404bbl]

Thanks! I’m running 225/60 and 255/60. Upgraded to rear HD springs when one of the originals broke a few years back. Goal is to upgrade the torsion bars to support the extra weight of the big block, and stiffen up the ride a little. Not hitting the bump stops, but can get a bit floaty on rough roads.

 

[Montclaire]

Yeah, I know the feeling. You will see a pretty big difference. Like I said though you want a soft shock.

Originally I had KYBs but with the stiff bars and leafs the suspension couldn’t do its job. The softer shocks allowed for more travel and the car felt more comfortable and predictable. BIG difference in feel.

 

[1972CudaV21]

You could also just install a used set...

 

[Montclaire]

Believe it or not, they do wear out.

 

[Chryco Psycho]

All depends on what kind of feel you like original or more modern ?
For a more modern feel you can easily go over 1" diameter , or to stiffen it up .96 will work
Shocks make a huge difference & KYB are the worst , using a T bar over 1" with a good shock such as QA1 or Bilstein or even an double adjustable can give an awesome ride .
I Like to corner so bigger sway bars are a great addition , You can go to Hotchkiss & get a very balanced pkg for front & rear using lighter weight hollow swaybars although I prefer the stock type for the rear that hangs on the frame & links down to the diff for less unsprung weight .

 

[1972CudaV21]

Believe it or not, they do wear out.

Yes, but some used ones could be an option.

 

[Ralph]

I ordered a .94 bar from firm feel for my 383 - 71 challenger. Will be an big upgrade from the worn bars that the car has now.

 

[Montclaire]

This thread got me thinking, I looked up the biggest pass car bar that Chrysler put out. So far the winner is a whopping 1.06” bar for 70-74 C-body with 440 and HD suspension.

At some point its probably too much of a good thing but .94 should be fine.

 

[70chall440]

I have 1.14 on my Cuda, they are STIFF... lol

 

[Montclaire]

Is it too stiff for the street? That answer will depend a lot on personal preference, but for me if the suspension is too stiff it hurts feedback and that can make a car uncomfortable to drive. On a muscle car you want a little lean in the corners.

 

[Chryco Psycho]

The C body bar is longer so it will seem softer at the same diameter .
The biggest possible 1.24" with the factory sockets .
1,14 should be a very nice ride with good shocks .

 

[Mopar Mitch]

Montclaire -- Starting back in the early 80's, I've tried and run many progressive different sizes of TBs. Conclusion ... don't be afraid of larger size TBs. the factory sizes were pathetically small and weak, even the largest E-body TBs at 0.92 (same for all T/A, AAR 4406 and Hemi.. they all used the same size).

For a nose-heavy BB, I recommend nothing less than about 1.12... a better choice would be ~1.18 from Firm Feel. Regardless of whatever size you choose, for whatever your intentions will be, plan to get some better quality shocks... rule-of-thumb for shocks is... you pay for what you get. The recent influx of double-adjustable shocks (Viking, QA1, etc) are a great choice to fine-tune your ride.

I settled on 1.24" diameter TBs... with my T/A used for AX, HPDE, HSAX... and still very drivable on the roads (avoid bumpy roads with pot-holes, frequent RR crossings, etc... is the norm).

Your tire pressures and profiles will make notable difference in ride quality... shorter sidewalls = harsher ride.. but better transient handling response.

The larger diameter TBs also reduce unwanted front lift and dive.... better handling overall.

Take it from me... and those who have gone with larger TBs... as soon as you make a change to be lager diameter from factory sizes, ... you will notice them difference.. and then say to your self... that its not that big a difference... and you should've gone larger yet. A BB... 1.12 minimum.. 1.18 better... 1.20-1.22-1.24 are all not as stiff as you'd think. Firm Feel will make the 1.24 bars upon request and probably have a few within their inventory.

I'd never go less for my driving than 1.24 on my own cars.

 

[elnielsen]

I just did this and I chose the Swayaway 1.08 and this is an original 318. I was going to go with the 1.20 just to back of a smidge from the 1.24 maximum offered. Then they kept urging me down based on me hot rodding on a windy mountain pass and not wanting to skid over bumps in the road. I went to 1.14, then kneejerk changed on shipping to 1.08. Still way better than the stock 0.89s I had? But, I really wish I had gone with stiffer. I think Mopar Mitch does autocrossing on flat ground, where stiffest works great for that. I had previous very stiff cars that did skid over bumpy road, but yea should have went 1.14.

Swayaway has slightly different numbers offset from Firm Feel (& FF maxes at 1.18), the rods are powdercoated red, so you see them when the hood is open. Might as well look at those since the 318 isn't interesting..

 

[70chall440]

When I built my Cuda I went down to Firm Feel and talked to Dick (the owner). He talked me into the 1.14 at the time and I can say the car is stiff but not in a bad way if you want it to handle. In the 71 Charger I am building now I am thinking of going to 1.18 or perhaps 1.20.

With all this said, you have to remember that this is a "system" and it needs to be thought of that way. The TBs are just one part/component and the rest of the system needs to be equally good. When I built my 70 Challenger I used KYB shocks but when I did the Cuda I used Bilstein; man what a difference! So much so I changed out the ones on the Challenger. You need quality tie rods, pitman arm, idler arm, steering box, control arm bushings, sway bar thickness and bushings, as well as the wheels and tires. Lastly, you need the right alignment to allow everything work correctly.

I'd be remiss if I didn't mention the brakes; need good brakes to compliment the good suspension.