Do I need bigger torsion bars? SB to BB

[Moms68]

I am in the planning process to swap out a 318/ 904 to a 440/ 727 in a '68 B body. The 440 will have aluminum heads and intake as well as tubular headers. The car has its original suspension. Will it be necessary to change out the bars or will an adjustment help with the added weight?

Thank you.

 

[pnora]

Maybe. Maybe not. All depends on what bars are in the car and how good they are. Plan on changing them in your budget. Then get it all together and see how they react.

 

[dfrazz]

It is not "necessary" but bigger bars always help.

 

[lewtot184]

I would use a .92 bar like 440's came with. I have .92 bars with a 1 1/8" firm feel sway bar on one of my cars with a 440 and aluminum heads/ intake, and it works nicely.

 

[TorRed]

If it's a 1/4 mile car only I'd keep the lighter bars, if you want it to handle at all I'd definitely plan on upgraded larger T-bars and sway bars. Plan for the 383 Roadrunner is .96 T-bars, XHD rear leaf springs, 1 1/8" Front sway bar and .75" rear. If it handles anywhere near as good as the 72 Fury II ex-cop car I had in college, I'll love it!

 

[Don67Satellite]

My '67 was a 318LA car and now has a 440/727. I found the original bars were quite "wallowy" (if that's a word) in even mild cornering. Now, the shocks were definitely garbage too. When I had all the ball joints & bushings done, I added Hotchkis 1.03" bars and some new shocks. A far more enjoyable driving experience now. The car corners much better, although I may still add a sway bar in the future, undecided.

 

[Moms68]

Thanks for the advice. I will start researching the best source for bars and sway bars. I'd assume this is a much easier job when the motor and transmission are out of the car?

 

[Don Frelier]

It's an easy job, even with the engine/trans in the car. Depends on the purpose of the car, what type of driving you'll do, and the roads. Roads ? Yes, roads. If the roads are nasty where you are, the thicker bars will exhibit a teeth-rattling ride. Call PST.

I have the PST bars on my Charger and no teeth rattling even with KYB shocks.
Much more nimble and I like the ride feel.

 

[Don67Satellite]

No teeth rattles here either, and our roads are not the best. Also running KYB (Kill Your Back) shocks. Could have likely done better there.

 

[Don67Satellite]

Thanks for the advice. I will start researching the best source for bars and sway bars. I'd assume this is a much easier job when the motor and transmission are out of the car?

Search the forums or go on YouTube, lots of info how to do this quite easily and no need whatsoever to remove engine or trans.

 

[Kern Dog]

It's an easy job, even with the engine/trans in the car. Depends on the purpose of the car, what type of driving you'll do, and the roads. Roads ? Yes, roads. If the roads are nasty where you are, the thicker bars will exhibit a teeth-rattling ride. Call PST.

This is not always true.

No teeth rattles here either, and our roads are not the best. Also running KYB (Kill Your Back) shocks. Could have likely done better there.

There is where the problems often lie, cheap shocks.
I have used stock .88, aftermarket 1.0 and 1.15" torsion bars in cars and the quality of the ride is directly related to the shocks. I currently have the 1.15s in a car with 40 series tires and the car rides firm but nor harsh in any way. The shocks will determine the harshness.
To the original point, the stock torsion bars will be okay but handling will be better by stepping them up in size. The 1.03 bars are a popular upgrade from stock and the FBBO site sponsor PST does offer them. Torsion bars are not cheap though like coil springs are.
Traditionally, Ma Mopar equipped these cars with smaller torsion bars (with less spring rate) than much of the competition. What I mean is, they were softer riding than the GM and Fords of the era so a swap to a larger size will be a good move for you.

 

[Don67Satellite]

the quality of the ride is directly related to the shocks.

100% true. I cheaped out on the shocks, but they are still better than the garbage that was in the car.

Eventually I'll change them to good shocks like the Bilsteins or Koni.

With that said, the bigger bars just make the car feel more sturdy, especially in corners, as it feels like I hardly get any body "lean" now.

 

[Kern Dog]

No teeth rattles here either, and our roads are not the best. Also running KYB (Kill Your Back) shocks. Could have likely done better there.

Therein lies the problem, bad shocks.
I had 1.0 torsion bars and KYB shocks for several years and blamed the firm ride on the torsion bars. In 2015 I swapped in a set of 1.15" bars and Bilstein shocks. The car rides better now than it did with much smaller bars and crappy shocks. I know one guy with .96s in a Challenger, a guy with .96s in a 69 Coronet and another with similar sizes in a Satellite and all three rode great.

The teeth rattle reference is as original as the neighbor that sees you washing your car and says Hey, you missed a spot ! It is neither original nor correct.
My car rides no more firm than the Wife's 2015 Challenger. The car doesn't rattle. It has exhaust noise and wind noise but I'm not tightening up loose bolts due to a stiff ride. I have short sidewalls too, a factor that would really highlight any ride deficiencies if they actually existed.

 

[Kern Dog]

Here are a few examples of my (admittedly ) unscientific experiences....
I have a 67 Dart with a 360 and 1.03 bars. It rides pretty good for a crappy looking car. My red Charger rides firm but is comparable to a new Challenger or Mustang. If you consider that "teeth rattling" then that is an opinion, not a fact.
My other Charger has stock .88 bars and cheap KYB shocks. Oddly, it does wallow around a bit but also transmits vibrations through the chassis that doesn't bother me now, but would if I actually drove it for very long. I threw the car together 3 years ago with a lot of stuff I already had here.
Years ago, XV motorsports built a chassis jig to test deflection and spring rates on classic Mopars. They found that all the classics could benefit from more spring rate up front while many times, the rate at the rear was fine. Torsion bar rates in these cars has always been softer than other brands. I'm not advocating a leap to the 1.24 size but if someone were to take your advice to avoid teeth rattling, they would stay with bars that don't allow the car to perform up to it's potential.

 

[Don67Satellite]

 

[WileE]

I deleted my posts, since I prefer to not condescend another poster. Please provide a reputable source that says stiffer springs do not affect ride quality.

 

[Cranky]

THIS is what you get from someone that has no direct experience with high performance suspensions.
Too many people respond to these questions with comments that they heard from a buddy. This is likely the case here.

Sounds like someone got up on the wrong side of the bed this morning.....or didn't even go to bed?

 

[Durandal25]

I've done a 383 to 440 drop with the .92 bars.....the only thing I noted.....initially was a slight pull to the left when driving. Odd for sure......but I just relaxed the torsion and went back and checked the ride height on both fenders. Once I was happy with it...it ironed out perfect. I'll note that torsion bars are pretty easy to swap out once an engine is removed....and you can service all those pesky boots and repack grease ect.

 

[Cranky]

I am in the planning process to swap out a 318/ 904 to a 440/ 727 in a '68 B body. The 440 will have aluminum heads and intake as well as tubular headers. The car has its original suspension. Will it be necessary to change out the bars or will an adjustment help with the added weight?

Thank you.

It would be good if you could figure up what the weight difference is between the teen and the 'aluminized' 440 is. I know that a big block wedge head is about 40 lbs complete. Did the car come with AC? The factory compressor is fairly heavy too and if it isn't there anymore, that's another consideration. What would I do.....? I'd inspect the old bars to assess their condition. Did the car look like it was abused when you got it? Measure the diameter of the old bars and see what you have. Usually cars that were loaded up had a bit larger bar than one that was plain Jane.

 

[Kern Dog]

In 2001 when I pulled the 318 and swapped in a 440, the car weight went up by 90 lbs.
The 318 had A/C and was all iron. The 440 had an aluminum intake, aluminum radiator and no A/C. I thought the weight difference would have been greater. I went from stock torsion bars to the Mopar Performance 1.0" set. Yes, the car rode stiffer. Common sense tells anyone with it that a stiffer spring would deliver a stiffer ride. I didn't know how crucial the choice of shock absorber would be, I went with what was cheap and widely available. For many years, I drove lowered vehicles that rode stiff so maybe the standard of what is acceptable is different for me.
Never have I experienced a "teeth rattling" ride in any car, even the lowered ones. That description that some people use has never been what I would use.
Torsion bars have not evolved much over the years but shock absorbers have.
You can have a shock that, for the lack of a better term, tames the frequencies of the spring rate.
When I changed to the 1.15" bars, I changed to Bilstein shocks at the same time. I expected a firmer ride but much to my surprise, it was similar but smoother. There was less lean, less brake dive but fewer shakes and rattles. I won't state that the 1.0" bars and KYB shocks delivered a "teeth rattling" ride but it was not smooth. The bigger bars were a better match for the car because of the shocks. If I had kept the 1.0 bars but changed the shocks, I may have felt that the front needed more spring rate. Good handling has been my primary goal since I first started driving.
My limits of ride tolerance may be higher than the guys that grew up where it was popular to raise cars up. In the 80s, we lowered our cars and trucks. A firm ride was what we were used to feeling.