is it ok to adjust torsion bars to change my cars stance.

[hughesboysvaliant]

Ive got a 67 valiant and I would like to change the stance of the car so that the rear is a little higher than the front. A friend said that you could adjust on the front side torsion bar bolts and lower the front, without damaging anything. I would just need to realign the front end. Is this OK ???

 

[71dusterdan]

it does reduce the amount of front end travel....meaning you will most likely bottom it out on bad bumps! You will definetly need to realign after the drop. There are also drop front spindles available from several sources, Magnum Force would be my 1st choice, unless Firm Feel has released something since I last looked!:burnout:

 

[mtandrews]

I used the TB's to lower the front before (1 inch) no adverse affects at all. Now I'm quite sure if you go overboard something bad is probably gonna happen...

 

[Jim Lusk]

The worst that will happen is that you will bottom out the suspension and this can cause problems in certain driving conditions, but generally only a harsher ride. Leave about an inch between the Lower Control Arm bumper and framerail and you'll be fine.

 

[goldfish65]

Once you get the height you want, re-aim your headlights.

 

[hughesboysvaliant]

Thanks for the info Ill give it a try. I,ll also look into the drop spindles Im looking at a disc break kit that has new wheel hubs with it (large lug hole pattern) , and replacing all the front suspension rubber. this would be the time to add drop spindles if possible.

 

[yellowdartdave]

Remember that raising or lowering the torsion bar changes the spring rate, ride height and the caster and camber.

 

[CUDA69]

No it doesn't change the spring rate, not even the preload. You would need a different torsion bar to change the spring rate. The same weight will be on the torsion bar, the car will just be at a different height. Caster, camber and toe will change.

 

[yellowdartdave]

When the car is sitting on the bump stops, what is the spring rate compared to having the bars cranked up all the way ?

 

[72bluNblu]

When the car is sitting on the bump stops, what is the spring rate compared to having the bars cranked up all the way ?

If its sitting on the bumpstops, the spring rate is infinite, because the springs are completely out of the equation. But otherwise, changing the height does ABSOLUTELY NOTHING to change the spring rate. The torsion bar adjusters control only the angle of the lower control arm, and do nothing to the bar itself.

As far as lowering a car using the torsion bar adjusters, there's no problem with this at all, especially if you're only looking for about 1". As others have already mentioned, it will reduce your suspension travel. But, as long as you don't lower the car drastically, this shouldn't be a big problem. Stiffer torsion bars would also help keep the car from bottoming out.

You will need a new alignment. As you lower the car, the suspension geometry changes. If its only a minor drop, then the car should have no issues being adjusted back to spec. But again, if you lower the car significantly, say more than 1", you may not be able to get the alignment back in order without offset bushings.

Drop spindles are a quick way to lower the car, I have a set on my Challenger. But, also know that drop spindles change the geometry of the front end also. Not alignment type stuff, but they will raise the roll center of the car, and increase bump steer slightly. If you can lower the car with just the torsion bars, this will give you a better overall geometry than drop spindles will. But, you may need stiffer bars and offset bushings, so there's a trade off.

 

[ProStreetDuster]

The worst that will happen is that you will bottom out the suspension and this can cause problems in certain driving conditions, but generally only a harsher ride. Leave about an inch between the Lower Control Arm bumper and framerail and you'll be fine.

^^^^^^^^^
What he said.
I've always adjusted the torsion bars of every mopar I've ever bought until I get the right stance, then it's off for an alignment.
Chevy guys used to hate us in high school because of how easy it was to raise or lower the front end LOL.

 

[yellowdartdave]

OK...put it up to factory ride height and go for a ride.
Then crank them all the way up and go for a ride.
Then tell me the ride is the same.

Or set it to correct ride height and jump on the bumper
Then crank it up all the way and jump on it again.
Bet you don't move it.
The farther you pre-load the bars, the harder it rides.... you have changed the spring rates.. just like air shocks or air bags.

 

[72bluNblu]

OK...put it up to factory ride height and go for a ride.
Then crank them all the way up and go for a ride.

Then tell me the ride is the same.
The farther you pre-load the bars, the harder it rides.... you have changed the spring rates.. just like air shocks or air bags.

This is 100%, absolutely false.

First: Pre-load and spring rate are not the same thing. Once a spring is made, its spring rate does not change. If it is a "progressive" spring, like some coil springs now, it has a rate that changes with compression. But at a given level of compression, the spring rate is always the same. If it is a "linear" spring, the spring rate remains constant regardless of twist or compression. Torsion bars are linear springs. Wind them up all you like, the spring rate will never change. This is a simple fact of physics.

Second: Changing the torsion bar adjuster does not twist the torsion bar. It does not change the pre-load in any way whatsoever. Torsion bar preload is set by the offset of the bar, in the case of factory bars, 30 degrees. If you look at the construction of an LCA, this becomes clear. The torsion bar cup, spindle, and adjuster lever all rotate together. The adjuster therefore does not twist the bar!!! It simply controls the angle of the lower control arm with relation to the torsion bar.

So, changing the adjusters does not change pre-load. Even if it did, changing the pre load does not change the spring rate.

If the car rides differently afterward, its because either 1. The alignment is off, or 2. It been lowered to the point where you're hitting, or even riding on, the bumpstops, or 3. You've lowered it to the point that your shocks are no longer the correct length, and are not working properly.

Also keep in mind that the car will handle better if you lower it. Lowering the center of gravity even 1" makes a huge difference in the handling ability of the car, even with no other changes. This will also effect how the car "feels".

 

[yellowdartdave]

When you twist the front end and the rear of the bar is still in the same place, you are loading the bar. And the farther you twist it, the more it resists.
Like I said, twist it up all the way and take it down a potholed New York street and see how it reacts. Make sure your seat belts are tight.

And the different sized bars.. /6, LA, BB, Hemis (just like coils) just have a different spring rate starting point.

 

[mopar340dave]

Look, you're not getting it. When you tighten the torsion bar adjustment bolt you are rotating the control arm, not the torsion bar. That is why it rides higher. You have not changed pre-load (there is none) or spring rate.
I think you are speaking in extremes? as in cranking it way up and driving it?

 

[ElFin]

To change the spring rate, you need to temper the bar.

 

[Jim Lusk]

As stated, you cannot change the spring rate or even the rate at rest of the bar. Torsion bars do resist twist more as they are twisted, but the adjuster bolt does not change any angle of the bar, just the LCA. You may need to take a loose arm to see the relationship between the torsion bar socket and the arm, but these are the facts.

 

[caferacerx]

think of it this way, when you put the car on jack stands, then raise the jack stands one notch, the car still weighs the same, it is higher but the weight on the jack stand hasn't changed, same thing happens when you raise or lower the torsion bars, you are not "twisting" the torsion bars, you are "rotating" them because they are moving the same amount front and back

 

[twofosho]

If its sitting on the bumpstops, the spring rate is infinite, because the springs are completely out of the equation. But otherwise, changing the height does ABSOLUTELY NOTHING to change the spring rate. The torsion bar adjusters control only the angle of the lower control arm, and do nothing to the bar itself.

As far as lowering a car using the torsion bar adjusters, there's no problem with this at all, especially if you're only looking for about 1". As others have already mentioned, it will reduce your suspension travel. But, as long as you don't lower the car drastically, this shouldn't be a big problem. Stiffer torsion bars would also help keep the car from bottoming out.

You will need a new alignment. As you lower the car, the suspension geometry changes. If its only a minor drop, then the car should have no issues being adjusted back to spec. But again, if you lower the car significantly, say more than 1", you may not be able to get the alignment back in order without offset bushings.

Drop spindles are a quick way to lower the car, I have a set on my Challenger. But, also know that drop spindles change the geometry of the front end also. Not alignment type stuff, but they will raise the roll center of the car, and increase bump steer slightly. If you can lower the car with just the torsion bars, this will give you a better overall geometry than drop spindles will. But, you may need stiffer bars and offset bushings, so there's a trade off.

Raising the spindle hub axis relative to the ball joints (dropped spindles) will NOT have an effect on the roll center or change bump steer. Raising the tire contact patch relative to the kingpin axis with a drop spindle WILL change the amount of scrub by moving the kingpin axis intersection with the ground plane inboard.

Lowering the front of the car relative to the rear WILL reduce the effective amount of caster.

 

[Jim Lusk]

think of it this way, when you put the car on jack stands, then raise the jack stands one notch, the car still weighs the same, it is higher but the weight on the jack stand hasn't changed, same thing happens when you raise or lower the torsion bars, you are not "twisting" the torsion bars, you are "rotating" them because they are moving the same amount front and back

You aren't rotating the torsion bars at all, you are rotating the LCA.....

 

[caferacerx]

You aren't rotating the torsion bars at all, you are rotating the LCA.....

doh!

now why is the adjuster at the back of the torsion bar in my mind? it's not that way on my car, oh well my brain likes to play tricks on me sometimes I guess

 

[oldkimmer]

........When ur adj the T bar ur rotating the mount in the lca, which in fact rotates the lca cause there 1 of the same,u r infact twisting the T bar, thats y u should always loosen the thru bolt on the K frame, adj then tighten it back up........otherwise u have put it in a binding situation.........thats what accelerates wear on the lca bushing.......there is only so much designed in parameters, once u go beyond that point u have problems.........u can only put so much strain on a bushing.............kim.........

 

[CUDA69]

OK...put it up to factory ride height and go for a ride.
Then crank them all the way up and go for a ride.
Then tell me the ride is the same.

Or set it to correct ride height and jump on the bumper
Then crank it up all the way and jump on it again.
Bet you don't move it.
The farther you pre-load the bars, the harder it rides.... you have changed the spring rates.. just like air shocks or air bags.

After sleeping on this I have to admit that yellowdartdave has a point here. Experience may trump basic theory sometimes. Even though the "rotational" spring rate has not changed the practical one may have. Here's my thinking on this: (An extreme example just to make the math easy)

If you start out with the lower control arm horizontal to the ground, and it was 12 inches long, and you put 1000 pounds on it, then it would transfers 1000 FtLbs to the torsion bar. Then you crank it up so the LCA is now 30 degrees to the ground. Even though you still have the same 1000 pounds on it, the torsion bar would only see 866 FtLbs because the force is only vertical, not tangential like when using a wrench.
As far as the driver is concerned, the perceived spring rate has increased 16%.

OK, so the LCA does't move that much, but even a 10% increase is very noticable. What do you think?

 

[Jim Lusk]

........When ur adj the T bar ur rotating the mount in the lca, which in fact rotates the lca cause there 1 of the same,u r infact twisting the T bar, thats y u should always loosen the thru bolt on the K frame, adj then tighten it back up........otherwise u have put it in a binding situation.........thats what accelerates wear on the lca bushing.......there is only so much designed in parameters, once u go beyond that point u have problems.........u can only put so much strain on a bushing.............kim.........

Kim, I used to think the same thing, but think about it. Once ride height is set (and yes the pin should be loose the first time) you will not be rotating the bushing anymore.

 

[72bluNblu]

Raising the spindle hub axis relative to the ball joints (dropped spindles) will NOT have an effect on the roll center or change bump steer. Raising the tire contact patch relative to the kingpin axis with a drop spindle WILL change the amount of scrub by moving the kingpin axis intersection with the ground plane inboard.

Lowering the front of the car relative to the rear WILL reduce the effective amount of caster.

The roll center is changed, as well as the bump steer. The roll center changes because the angle of the control arms change relative to the height, and CoG, of the car. It changes the relationship between the ball joints and the control arm mounting points at a given height, which changes the roll center.

The bump steer changes because the steering arms postion changes with regard to the spindle location, by the full 2".

There was a pretty extensive discussion on this over at Cuda-Challenger, by guys that understand suspension better than me. Complete with computer analysis (page 5)

http://www.cuda-challenger.com/cc/index.php?topic=72437.0

After sleeping on this I have to admit that yellowdartdave has a point here. Experience may trump basic theory sometimes. Even though the "rotational" spring rate has not changed the practical one may have. Here's my thinking on this: (An extreme example just to make the math easy)

If you start out with the lower control arm horizontal to the ground, and it was 12 inches long, and you put 1000 pounds on it, then it would transfers 1000 FtLbs to the torsion bar. Then you crank it up so the LCA is now 30 degrees to the ground. Even though you still have the same 1000 pounds on it, the torsion bar would only see 866 FtLbs because the force is only vertical, not tangential like when using a wrench.
As far as the driver is concerned, the perceived spring rate has increased 16%.

OK, so the LCA does't move that much, but even a 10% increase is very noticable. What do you think?

I can see how you might think this, but your physics is a little off. The lower control arm does not change in length, and the force applied does not change. The ground being parallel is of little consequence, because the force is applied on a rotation. Your frame of reference isn't the ground, its the torsion bar.

Think of it this way...Does the angle of the handle of your socket wrench change the amount of force you apply to the bolt?