torsion bar ride quality vs coil spring

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ChryslerCruiser

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I am interested to hear opinions and perspectives on the benefits of the torsion bar suspension. I come to the FMJ cars because I like Mopar's engineering background, and I've had dodge trucks since the 1990's.

That being said, I am not clear as to why Mopar decided to use a torsion bar front suspension. I am sure they had good reason, and interested to hear any opinions or experiences you may have had.
 
Having owned vehicles similar size with the different suspension setups I've never noticed any sort of difference that you could tell what suspension it had by feel. Torsion bar might be a bit more firm in feel and handling.
One big advantage is adjustability. Springs wear out and they're done. Torsion bars are adjustable. Down side is less aftermarket.
Don't forget it's not just mopar. GM and Ford trucks have also used torsion bars.
 
Torsion bars take less room than a coil front suspension and the whole suspension is lighter in weight. They also create better handling but do tend to ride stiffer. Unlike a coil, a torsion bar doesn't rebound as much which means a softer shock can be used than with coils to sort of offset the firmer ride of t-bars. Without shocks, coils will bounce for days where torsion bars won't keep bouncing as much. Coils and t-bars each have their pros and cons. The old FWD Eldorado and Toronado had t-bars, VW Beetles had 4 wheel bars, and IIRC Packard had a four wheel t-bar suspension for a couple years in the 1950's and there were others also. Just call me Mr. Useless Trivia guy, :rolleyes:
 
In a traditional coil spring suspension the weight of the spring is unsprung weight, carried in the suspension, where as the torsion bars are carried in the chassis, and are sprung weight. The suspension is lower profile in the chassis, allowing more engine room. Torsion bars are not subject to the "wave" harmonics that coil springs are. The traditional Mopar torsion bars allowed a lighter front structure, since the "spring load" was in the center of the car.
 
A torsion bar is a straightened out coil spring, or if you prefer, a coil spring is a torsion bar wound into a spiral.....
OK it's not quite that simple, but not far off.
Production costs and chassis design are the main factors in deciding which layout to use.
Other systems used have been rubber cones - the original British Mini, Hydropneumatic suspension - Citroen for many years, air bags - popular on big trucks, and tried by Cadillac over half a century ago.
they all have pros and cons, but it seems the steel coil spring has prevailed for passenger cars.

Roger.
 
Great discussion, I am enjoying the responses and perspectives shared.

I did not know that Ford or Chevy used a torsion bar suspension on their trucks.

I have seen that some mid 50's tanks used them...
 
A lot of tank designs use them, due to the way that they need to package a lot of independent springs (each set of wheels or wheel bogies gets a spring) in a relatively small vertical space. Most famously, the Russian T-34 (aguably the best tank of World War II) used a torsion bar suspension that was designed by a US engineer.
 
One thing not mentioned is torsion bars are a lot safer to work on.
Relieve the tension from torsion bar system and no worries.
Use a spring compressor on a coil spring and it is like passing a live un-pinned hand grenade from person to person to person. There are countless number of technicians who has been injured, maimed or killed when working with a coil spring suspension system.
BudW
 
BudW said:
One thing not mentioned is torsion bars are a lot safer to work on.
Relieve the tension from torsion bar system and no worries.
Use a spring compressor on a coil spring and it is like passing a live un-pinned hand grenade from person to person to person. There are countless number of technicians who has been injured, maimed or killed when working with a coil spring suspension system.
BudW
Click to expand...
At work we refer to a compressed coil spring as a loaded bomb. Even with the correct compressor for the type of job, it still always makes me nervous.

An advantage of the FMJ transverse bar setup is, the entire suspension and steering are on one modular assembly and it's both lighter and more compact than it would be if they'd have gone with a coil spring suspension. The transverse t-bars seem to get a bad rap from the Mopar snobs but I have never found any problem with them. OK, one problem, the tendency for the upper control are towers to flex but a simple repair with the factory (or homemade) shims fixes it right up. Seems like it bends to a certain point but never gets any worse, provided rust isn't a factor.
 
All great points describing the benefits of the torsion bar system.

As a further comparison, Uncle Tony did a quick segment on Ford musclecar spring setups. Most GM at the time put the spring between the lower A-arm and the frame. Ford put it from the upper A-arm to the shock/spring tower, really cramping the engine compartment badly. Compare the engine bay of a 1968 Cougar, for example, to a similar year Chevelle or Charger.
 
Mikes5thAve said:
Having owned vehicles similar size with the different suspension setups I've never noticed any sort of difference that you could tell what suspension it had by feel. Torsion bar might be a bit more firm in feel and handling.
One big advantage is adjustability. Springs wear out and they're done. Torsion bars are adjustable. Down side is less aftermarket.
Don't forget it's not just mopar. GM and Ford trucks have also used torsion bars.
Click to expand...
[Waving hand in air] International Harvester!
 
At least in my experience ride quality in a tbar car goes to pot when you start increasing spring rates. You can make up for it with lots of sidewall on the tire. 300# on a 235-60-15 was great. Go to a modern size tire and you'll rattle your teeth out. Has to be a reason no modern production cars uses tbar suspension.
 
The vast majority of this stuff that makes you scratch your head comes down to unions or accountants. If something can be made cheaper and faster, that's what they will do. They don't care about the guy who has to fix the car 3 years after it's built (or 3 weeks). That's why they do things like plastic A/C lines or sheetmetal sunshells in automatic transmissions. It doesn't have to be better. They want to build more cars. They want to build them cheaper, and they want you to make payments the rest of your life and pay interest. They don't want the car to last. And it won't.
 
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