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Sway Bar Adjustment

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Old Jul 5, 2011 | 08:55 PM
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iLuveketchup's Avatar
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Default Sway Bar Adjustment

Sorry for the dumb question.... Is it safe to adjust a FSB to a middle setting on one end & a stiffer setting on the other? My car pushes at full stiff & rotates too much on the middle setting. I need to get the car somewhere in between the two.

Saner bar w/ adjustable endlinks
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Old Jul 5, 2011 | 09:30 PM
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Originally Posted by iLuveketchup
Sorry for the dumb question.... Is it safe to adjust a FSB to a middle setting on one end & a stiffer setting on the other? My car pushes at full stiff & rotates too much on the middle setting. I need to get the car somewhere in between the two.

Saner bar w/ adjustable endlinks
Yeah, definitely. 3-way adjustable (3 holes) are actually 9? 3x3.
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Old Jul 7, 2011 | 09:58 AM
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I never heard it that way but it makes sense. It wouldn't have a tendency to make left stiffer than right? or vice versa?
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Old Jul 8, 2011 | 11:49 AM
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The side with the link mounted further from the pivot axis will see a SOFTER sway bar, the side with the link mounted closer to the pivot axis will see a STIFFER sway bar.

You will ALSO load up one side vs. the other in a straight line under straight-line braking, acceleration, and over undulations.

Bad bad idea IMO...
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Old Jul 8, 2011 | 12:53 PM
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Originally Posted by ZDan
The side with the link mounted further from the pivot axis will see a SOFTER sway bar, the side with the link mounted closer to the pivot axis will see a STIFFER sway bar.

You will ALSO load up one side vs. the other in a straight line under straight-line braking, acceleration, and over undulations.

Bad bad idea IMO...
I disagree with the first part.


The stiffness is a combination of the 2 arms. It will be very close to the same in both directions.

"You will ALSO load up one side vs. the other in a straight line under straight-line braking, acceleration, and over undulations."

I will agree that this could be a problem.

On my Gendron I often run with 1 hole difference on the arms. I would not go more than 1 hole difference.

Some people that know their stuff think it's bad, for the reasons SDan pointed out but I have never had any problems doing it.
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Old Jul 8, 2011 | 01:29 PM
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Originally Posted by rjones
I disagree with the first part.

The stiffness is a combination of the 2 arms. It will be very close to the same in both directions.
Push up on the link on the effectively shorter-arm side while holding the link on the effectively longer-arm side static and the spring rate you see will be much stiffer than if you push up on the long-arm side holding the short-arm side static. And the effective stiffness varies with the square of the lengths of the arms. I.e., if the effective length on the short side is 7/8 that of the long side, the short side effective sway bar stiffness will be (8/7)^2, 1.3x as stiff.


On my Gendron I often run with 1 hole difference on the arms. I would not go more than 1 hole difference.

Some people that know their stuff think it's bad, for the reasons SDan pointed out but I have never had any problems doing it.
I think that unless you are intentionally doing an asymmetric setup for a course where the nature of left handers is very different from right-handers, it's not ideal.
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Old Jul 8, 2011 | 01:45 PM
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Originally Posted by ZDan
Push up on the link on the effectively shorter-arm side while holding the link on the effectively longer-arm side static and the spring rate you see will be much stiffer than if you push up on the long-arm side holding the short-arm side static. And the effective stiffness varies with the square of the lengths of the arms. I.e., if the effective length on the short side is 7/8 that of the long side, the short side effective sway bar stiffness will be (8/7)^2, 1.3x as stiff.


Have you done that test? I have not so you could be correct, but it does not work that way in my head.
.

If you are correct, I cannot tell driving, but I seldom have 2 corners that are the same just left and right.

OP take any thing I say with a grain of salt. It may be worth what you paid for it

I would test it in a safe place and see if it works for you.

I do it often but YMMV.
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Old Jul 8, 2011 | 02:17 PM
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ZDan could be correct. The math for this is way over my head. It's easy until you try and include the twist of the bar.

I think if you assume the bar twist, then my way of thinking makes sense. If you assume the bar does not twist then I think ZDan would be correct.
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Old Jul 8, 2011 | 02:28 PM
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The bar does twist, but you still get the big effective stiffness difference, varying with the square of the relative lengths.

I actually just ran a quick/dirty fea to confirm. With one bar end twice the length of the other, I get 4x the displacement pushing with 100 lb. on the long side holding the short side static vs. pushing up on the short side holding the long side static (1.2" vs. .3" for a 3/4" bar, 40" span, one 10" arm and one 5" arm, 100 lb up load).

When you push up on the short side, you have less mechanical advantage over the bar, you're putting less torsion in it. And the other side, having greater mechanical advantage against twisting, doesn't want to budge.
When you push up on the long side with the same force, you get greater torsion in the bar, and the short-arm side doesn't have as much resistance against it.
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Old Jul 8, 2011 | 02:46 PM
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I think you are correct ZDan.

Looks like I need to stop using the 1/2 steps. Thanks ZDan.
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