Torsion bars

[69furyIII]

Hello, I was wondering how to tell if torsio bars wear out, mine are the originals. Just not sure how long they will last for.

 

[mr. fix it]

unless they snap in half they are good for life...

 

[69furyIII]

That sounds good to me, what about the front sway bar, in sure the bushings need replacing , after all there 48 years old,lol

 

[MrMoparCHP]

That sounds good to me, what about the front sway bar, in sure the bushings need replacing , after all there 48 years old,lol

At that point you are in for a full rebuild, ball joints, tie rod ends etc.
The lower control arm bushings (torsion bar) are first in last out.
As for the sway bar bushing, those can be done independently of the rest.


Alan

 

[mr. fix it]

Rubber bits are a different story.
there are vendors selling polymer bushing kits but I don't have that on hand.
I'm sure others will chime in soon.

 

[mr. fix it]

At that point you are in for a full rebuild, ball joints, tie rod ends etc.
The lower control arm bushings (torsion bar) are first in last out.
As for the sway bar bushing, those can be done independently of the rest.


Alan

Hi Alan,
Aren't the torsion bars first out and last in?

 

[MrMoparCHP]

Hi Alan,
Aren't the torsion bars first out and last in?

Not necessarily, you need to put the control arms in first, then the bars so the bars come out first but it is everything else that needs to come off before the control arms
Installation sequence for me:
1. Lower control arms
2. Upper control arms
3. Upper ball joint
4. Shock
5. Spindle
6. Lower ball joint
7. Bump stops
8. Torsion bars
9. Steering assembly

I often don't take the bars out till I have everything else off.
Disassembly
1. Tie rod ends
2. Loosen bars
3. Pop ball joints
4. Remove spindle/lower baljoint
5. Remove upper ball joint (with arm still in car)
6. Remove Upper control arm
7. Remove lower control arm


So if you need to do the lower control arm bushing you are into everything.


Alan

 

[Davea Lux]

unless they snap in half they are good for life...

They don't generally wear out, the only reason to change them is if you wanted to go to a different spring rate, usually stiffer. Might also want to change them if you upgrading from a small block to a big block.

Dave

 

[Davea Lux]

If you are planning to pull your torsion bars, be sure to put an index mark on them so that they go back in as they came out. If you change the rotation on a torsion bar, that is why they will break. It moves the tension to a different part of the bar.

Dave

 

[polara71]

Nobody ever told me that. I know mine are not installed as I took them out

 

[Davea Lux]

Nobody ever told me that. I know mine are not installed as I took them out

In that case, look at the back of the torsion bar, it has a stamping on it. Now go to the FSM, that shows how the factory should have installed them. Most of the time, the factory got it right so if you put them back to the factory specs you should be ok.
Ran across some over the years that were installed to other than factory specs which is why I now always index them.

Dave

 

[MrMoparCHP]

In that case, look at the back of the torsion bar, it has a stamping on it. Now go to the FSM, that shows how the factory should have installed them. Most of the time, the factory got it right so if you put them back to the factory specs you should be ok.
Ran across some over the years that were installed to other than factory specs which is why I now always index them.

Dave

Interesting, nothing in my 67 or 69 factory service manuals.


Alan

 

[MrMoparCHP]

The bars don't know and don't care what their rotation is, all they do is twist.


Alan

 

[Davea Lux]

The bars don't know and don't care what their rotation is, all they do is twist.


Alan

That is true with new ones. Used ones get a memory within the cell structure of the metal. If you change that you are asking for trouble.

Dave

 

[MrMoparCHP]

That is true with new ones. Used ones get a memory within the cell structure of the metal. If you change that you are asking for trouble.

Dave

Whereas that may be true, the clocking will not make a difference in the operation, twist is twist the world around.

Now I would never swap sides of the car with a used bar, that is where that may be an issue.


Alan

 

[Davea Lux]

Whereas that may be true, the clocking will not make a difference in the operation, twist is twist the world around.

Now I would never swap sides of the car with a used bar, that is where that may be an issue.


Alan

Agreed, the twist ratio is the same. But remember that the twist ratio is not uniform across the load bearing portion of the bar. In simple English, one side or the other has more stress. This was built into the design. That is why you can not move a right to the left etc. To better explain this, if you twist a piece of round spring steel, it will start to bow in the center under full load. That section will be loaded and unloaded repeatedly as the vehicle bounces up and down going down the road. This imparts a cellular "memory", The strand of metal conforms to a certain pattern of loading. That means that the parts of the metal structure that are loaded have a "string" shaped structure to them. The parts that can not string break off. That all works fine unless the rotation is changed. Then parts that should string are already broken from the previous rotation. This leaves the part in a weakened state.

Dave

 

[CBODY67]

As I recall, there are "Right" and "Left" bars. Seems like they are marked that way?

The bars might weaken a little with age and duty cycles, BUT unlike coil and leaf springs that will do the same thing, the torsion bars can be adjusted with a little more pre-load on the adjusting bolt to re-level things out.

The diameter of the bars will vary from front to rear, which allows the special factory tool to clamp around them for removal and installation (rather than using Channel-lock pliers or vice grips!) to work. The diameter (where the official diameter measuring location might be) determines the load and ride rate. Putting a little more pre-load into the bar stiffens the ride rate, just as reducing the pre-load will lower the front end and decrease the ride rate.

In ANY front end rebuild, don't forget the rubber pivot shaft bushing in the lower control arm. With time, it'll settle-out as it's a load-bearing bushing, which can affect getting the alignment correct. A press will be needed, usually.

CBODY67

 

[Davea Lux]

The bars don't know and don't care what their rotation is, all they do is twist.


Alan

Interesting, nothing in my 67 or 69 factory service manuals.


Alan

Alan:

At the Mopar dealership, I worked on on mostly police vehicles. They were in a lot for suspension related issues. That was our protocol per the factory rep and general repairs I seem to remember that the factory specs in the FSM always showed the markings on the rear of the torsion bars as being readable from the "right side up". "Left" or "Right" should be upright. Never know though, our shop manager was ex-military and always stickler for detail.

Dave

 

[FK3 Sport Fury]

Thought I'd share these pics I just took of a Dart parts car that was sitting on the driver side snubber.I pulled the back of the bar out and saw the break pattern which was interesting.

 

[polara71]

.... that's interesting