Torsion Bar Question

[Josecuda]

Does anyone know what is the difference, besides the age & price, between new +$300 torsion bars and used torsion bars? I will like to know if torsion bars get "tired" through time and if there is a noticeable difference between using new or used bars. Thanks for reading !

 

[Johnny Dart]

Torsion bars use to be around $150.00 for a set. Then they got rediciously priced,something about the price of steel.

I have no problem using a used set of bars. Just make sure there in good shape and not all gouged up. Gouges can lead to rust,which can lead to weaker bars.

Also make sure you have them on the right sides. Thats about it.

 

[Josecuda]

I asked this cause I heard someone saying that torsion bars, due to the fact that they do the "same" function as coil springs, they become tired. Thanks.

 

[n00blike]

I would think new bars would work better due to the stress the bars are put through after long use (even if that is what they are made for). By how much better and if it would be noticeable i don't know. Most buy new bars to get bigger diameter bars to improve handling.

lets see what others think, im still learning :read2:

 

[67limecrazy]

My guess would be that the newer ones would be stiffer than the older ones. Bouncing of the front end would be less. Better handling. This is my 2 cents.

 

[C130 Chief]

A spring will only return to 99.9% of it's original length after being compressed. So torsion bars will "twist" after time, much like a coil or leaf will settle. However the spring rate will remain constant (they don't get softer). So we have an advantage with the adjuster, we can compensate for "wear".

As said before, used torsion bars are fine, make sure you have a left and right of similar diameter and most importantly, make sure they have not been damaged.

 

[dartley]

All springs wear with time. All things being equal, new bars are better springs. But all things are not equal - you have to factor in how abused the old springs have been vs the quality of the new springs, at the very least. Then, as mentioned there are spring rates. If all you want to do is replace with as near identical rates as original that factor is off the table. As mentioned many/most? upgrade the rate. Then there are cases where worn springs and shocks are (or used to be, at least) preferable for drag-only because the weight transfer is better. That factor goes away on a street driven vehicle ... or at least, for safeties sake it should ;-)

 

[Josecuda]

So we have an advantage with the adjuster, we can compensate for "wear".

Here's the thing. In my '72 /6 Duster I have the torsion bars (stock) equally adjusted, according to the number of turns made to the adj, bolt. While driving the car the drivers side seems a bit lower than the passengers side. Even, in specific situations, to the point where the drivers side front tire rubs a bit with the inner fender. Maybe I'll have to adjust more one side than the other one or this is not correct? Similar past experiences anyone?

 

[dartley]

There is a lot not mentioned here. The first question, ahem, is ... how heavy are you? Sorry, no insult intended, but it is a factor.

Two, /6 bars are very soft (softer on Plym I think than Dodge - could be wrong there) ... but they are soft. And if they are orig, then they are softer.

Three, The adjustment is a height adj, not a #turns adj. You'd need to see a manual on how to do this; but likely someone else will give specifics.

 

[Dan201]

I have two dart both DD's for the last 35 years unless you ramp the car or hit a hard bump fast it shouldn't bottom out unless the height is too low the factory repair manual will give you a ride height for the front end that you can simply measure from the front bumper on level ground you may just have the car a little low and whatever you do don't buy heavy duty shocks like I did if they're the ones with the coil over they make the car so stiff that it destroys the beautiful ride the car has and feels like driving a brick with no suspension over railroad tracks.

 

[Johnny Dart]

Here's the thing. In my '72 /6 Duster I have the torsion bars (stock) equally adjusted, according to the number of turns made to the adj, bolt. While driving the car the drivers side seems a bit lower than the passengers side. Even, in specific situations, to the point where the drivers side front tire rubs a bit with the inner fender. Maybe I'll have to adjust more one side than the other one or this is not correct? Similar past experiences anyone?

Get a factory service manual or something close,and it will give you the stock height to adjust your car.

An old school trick fort the street/track was to adjust the height with the driver in the car.

Theres is no exact science to the height. Some like the front a little lower than stock,some like it higher.Dealers choice. However,raising it or lowering it can affect your alignment. So sometimes after adjusting it an alignment may be in order.

 

[72bluNblu]

Most new torsion bars are a larger diameter, and therefore have a higher spring rate, than the stockers. The old bars do wear, and will sag. If you've got a /6 car, you have the weakest bars that mopar made. As I've pointed out before, most mopars were undersprung in the front from the factory, a new set of bars can help address this and improve handling substantially.

Also, beware of buying used bars. The steel is old and quite possibly very worn, and its unlikely you'll know anything about the history of the car you're getting them from. Why spend any money on a set of springs that could have hundreds of thousands of miles on them? Pay special attention to any gouges in the bars, torsion bars are just springs. Gouges can lead to cracks, and torsion bars CAN FAIL if they develop any cracks. This can lead to a rather spectacular failing of the bar, since they are under quite a bit of tension that gets unloaded all at once in case of a failure.

As far as one side being higer than the other, driver's weight, the alignment of the car, and just good old plain wear and sag of the suspension (and the frame of the car) can cause the need for slightly different settings to get a level ride height.

 

[RedFish]

Raw materials are not what they once were in quality grade or price.
Where a coil spring looses some stand heigth a torsion bar bows.
Used bars that are not straight are fatigued and used bars with scars are subject to cracks and breaking. There are plenty of good used OEM bars still around today. I dont expect to find good used aftermarket bars 25 years from now. Inspect any used bars closely.

 

[C130 Chief]

X2 on the factory manual for setting ride height. You park on a FLAT surface and measure down from the inner and outer tie rod ends.

As far as springs getting softer with wear, I'll march a whole parade of BS flags on that one. If the heat treat of the steel is not changed, the rate will remain constant. If you think you can prove me wrong, try. And by that I mean you'll need sound metallurgical evidence, and then use it to disprove Hooke's Law. Yes, the ride height will decrease in time, but this can be compensated for with the adjusters.

 

[green1]

A spring will only return to 99.9% of it's original length after being compressed. So torsion bars will "twist" after time, much like a coil or leaf will settle. However the spring rate will remain constant (they don't get softer). So we have an advantage with the adjuster, we can compensate for "wear".

As said before, used torsion bars are fine, make sure you have a left and right of similar diameter and most importantly, make sure they have not been damaged.

yep.

 

[green1]

Here's the thing. In my '72 /6 Duster I have the torsion bars (stock) equally adjusted, according to the number of turns made to the adj, bolt. While driving the car the drivers side seems a bit lower than the passengers side. Even, in specific situations, to the point where the drivers side front tire rubs a bit with the inner fender. Maybe I'll have to adjust more one side than the other one or this is not correct? Similar past experiences anyone?

You adjust the ride height, not number of turns.
The engine is offset.

 

[green1]

Measure both sides; from the lower balljoint, to the lower control arm bottom, right under the torsion bar.
Adjust both the same, it doesn't matter,the factory height. but give the lower bumper at least 1 inch clearance.
Now get it aligned.

 

[RedFish]

You adjust the ride height, not number of turns.
The engine is offset.

Thats right.
A slight diffence in the rear leaf springs will alter the front stance also. If right rear goes down a little , left front goes up a little.

 

[Josecuda]

Thats right.
A slight diffence in the rear leaf springs will alter the front stance also. If right rear goes down a little , left front goes up a little.

Right. With all this I've read it seems the driver's weight will influence a lot (the car looks terribly low when a 300 pound friend is sitting on the car). Besides, if there are stiffer leaf springs, the same stock bars and a difference of an inch or so in the rear vs. front tires (225/60/15 front 275/60/15 rear) there might be other relevant point for the height issue. I think I'll start by re-adjusting the bars following the instructions listed previously. Seems I was doing something wrong :angry7:.

 

[twofosho]

Don't forget to take the car's weight off the torsion bars by jacking it up, before trying to run the adjusters in or out. Running the car back and forth after lowering it back to the ground will take the bind out of the suspension, then pushing down on a fender to bounce the car will help get an accurate measurement. It may take more than a couple of times playing with the adjustment to get it where you want it.

Adjusting the front ride height to at least make the car sit level from front to rear, and not dumped in front, will help save whatever caster the car is capable of.

I normally check ride height at the front and rear of the rockers, and match all four corners. Because the wheel opening lips are approximately the same height from the ground front and rear, I cheated on my Duster, and measured to the bottom edge of the top of the opening.

Even the softest six cylinder bars should be capable of adjusting high enough to give adequate ride height. The resistance to roll won't be helped by jacking the car up or down, however, no matter what the static ride height is. Only by increasing torsion bar rate (bigger diameter bar for any given length) or adding a stabilizer bar(s) can you improve it.

 

[autoxcuda]

X2 on the factory manual for setting ride height. You park on a FLAT surface and measure down from the inner and outer tie rod ends.

As far as springs getting softer with wear, I'll march a whole parade of BS flags on that one. If the heat treat of the steel is not changed, the rate will remain constant. If you think you can prove me wrong, try. And by that I mean you'll need sound metallurgical evidence, and then use it to disprove Hooke's Law. Yes, the ride height will decrease in time, but this can be compensated for with the adjusters.

Over time the rate will go down. How much? You really need to put them on a Spring Rater, rather than guess. He have a Longacre Spring Rater for our Coil and Leaf Spring on the Circle Track team I crew on. The coils and leaf will reduce. Not a ton. Like a 750 tested spring might turn into a 738 over a season or two. To us, that is a big deal. But on a street car I don't think your are going to notice.

A spring is getting worked over time. Hooke's Law is a perfect case scenario that doesn't address that.