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Body roll

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Old Apr 15, 2015 | 09:35 AM
  #31  
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Originally Posted by TaylarsJK
But for now I'll just get longer rear links and see what difference that makes
My front swaybar & links are pretty much dead on at 90 degrees. The rear sway bar is angling down probably about 10 degrees. There is a little body roll going on but I only notice it if I'm taking a fast/sharp 90 degree turn. Hasn't been much of a problem otherwise.

If you're also dealing with bump-steer and front end wobble then yeah, that's a whole different thread. It's tough when you're trying to swap out components from a previous install and rolling the dice hoping things will work.

Good luck!
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Old Apr 15, 2015 | 10:02 AM
  #32  
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Originally Posted by 14Sport
Now the end link may have to work harder to move the bar 30* when less than perpendicular, but the bar still moves 30* regardless.
Yeah I believe that's a true statement but even though it may move 30*, the Torque created is still much less and thus the torsional resistance is less. Because the torsional resistance is less, then there's less body roll that is being countered.

At 45* you're cutting the magnitude of force along the x-axis by exactly half. Because of that, you're also cutting the Torque in half. So there is half as much "twist" going into the swaybar to counter body roll.
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Old Apr 15, 2015 | 10:46 AM
  #33  
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Okay I think I got it. Even though the resultant torsional force is the same the up force on the INBOARD side of the axle is reduced since it is not starting at perpendicular.

Thanks, Professor DJ.
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Old Apr 15, 2015 | 05:59 PM
  #34  
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Originally Posted by DJ1
At 45* you're cutting the magnitude of force along the x-axis by exactly half. Because of that, you're also cutting the Torque in half. So there is half as much "twist" going into the swaybar to counter body roll.
Exactly!!!!!! That's what I've been saying. If your sway bar ain't twisting - the body ain't rolling right?
You're basically saying you would get half as much body roll if your bar was pointed at a 45* to the links as opposed to it being at 90* It's the same effect as running a stiffer bar that rotates less with the same force applied.

Last edited by sea bass; Apr 15, 2015 at 06:09 PM.
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Old Apr 15, 2015 | 10:58 PM
  #35  
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Originally Posted by sea bass
Exactly!!!!!! That's what I've been saying. If your sway bar ain't twisting - the body ain't rolling right?
You're basically saying you would get half as much body roll if your bar was pointed at a 45* to the links as opposed to it being at 90* It's the same effect as running a stiffer bar that rotates less with the same force applied.
THE BODY ROLLS REGARDLESS in a turn. The only thing countering that body roll is torsional resistance. That is the swaybar's only function = to counter body roll. It is at optimum performance when the LINKS ARE PERPENDICULAR TO THE SWAYBAR = 90 DEGREES.

If the vehicle is just driving straight on a flat road, there's no body roll to counter so the sway bar isn't twisting.

Last edited by DJ1; Apr 15, 2015 at 11:14 PM.
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Old Apr 15, 2015 | 11:25 PM
  #36  
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you stated...

so....the torque in the pics is what's essentially causing the sway bar to twist allowing the body to roll correct?
The Torque that is being applied to the swaybar creates the torsional resistance needed to COUNTER the body roll in a turn. Body roll is created by the body/weight of the vehicle as it gets slung from side to side. The swaybar DOES NOT CREATE BODY ROLL. It's also why it's called a stabilizer bar. It's there to stabilize not create chaos.

The steeper the angle, the less torque is created using the same force which would mean less twisting of the swaybar.
That is correct...


If you're not twisting the sway bar as much, then you're getting less body roll.
No, if the torsional resistance is less because you're not torqing the sway bar as much, the sway bar is only stopping a portion of the body roll force.

Links disconnected = 0 twist of the stabilizer bar. 0 torsional twist in the stabilizer bar = allows full body roll = sayonara!

Links connected at 90* = maximum twist. Max twist = full torsional resistance to stop body roll = ideally little to no body roll.


Then a level sway bar will cause more body roll then one angled.


Am I nuts? I very well could be :-)
Yes, I'm beginning to think you're nuts

Last edited by DJ1; Apr 15, 2015 at 11:33 PM.
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Old Apr 15, 2015 | 11:42 PM
  #37  
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Hmmmmm for some reason I thought of this lol
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Old Apr 16, 2015 | 06:43 AM
  #38  
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Originally Posted by DJ1
. No, if the torsional resistance is less because you're not torqing the sway bar as much, the sway bar is only stopping a portion of the body roll force. Links disconnected = 0 twist of the stabilizer bar. 0 torsional twist in the stabilizer bar = allows full body roll = sayonara! Links connected at 90* = maximum twist. Max twist = full torsional resistance to stop body roll = ideally little to no body roll.

This is the part you keep saying that I don't agree with. (Not the part about removing links - that's a no brainer)

The more your sway bar is twisting, then the more your body is rolling assuming your tires are on flat ground. Twisting of the sway is a direct reaction to body lean. Your axle and body (frame) are directly connected to each other by the swaybar and links so this must happen.

Are you saying if you ran a solid swaybar (too stiff to twist) than you would have more body roll because the sway bar isn't twisting?
The more angle you run, the shorter the "lever" applying rotational torque to your sway bar essentially, which would give your sway bar a stiffer effect.

Otherwise, I agree with what you're saying :-).

I do think our jeeps should run the swaybar at or close to 90. I'm sure that's the proper rate and was designed that way. Anything pointing down, I would worry about it inverting.

Rear swaybars have a lot less effect than the front. Running a longer link is not going to cure then OP body lean, but I would still run a longer one to keep it from twisting backwards if he somehow had both wheels droop at the same time.

Where's dirtman or planman? We need a third party ruling :-)
Or we can agree to disagree - I'm fine with that as well

I don't have all the cool emoticons on my iPad app :-(
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Old Apr 16, 2015 | 08:07 AM
  #39  
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Run your vehicle through a slalom strip. Once with your swaybar pointed 45 degrees downward, the second time with your swaybar parallel to the ground / links perpendicular. See how fast you get through the course for each case. Video record it looking at the vehicle straight on.

You're telling me that 45 degrees is stiffer and because of that will stop body roll better than at 90*. So if that's the case you'll post faster slalom times with the sway at 45* and you'll be beating the laws of physics.

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Old Apr 16, 2015 | 08:18 AM
  #40  
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Originally Posted by DJ1
Run your vehicle through a slalom strip. Once with your swaybar pointed 45 degrees downward, the second time with your swaybar parallel to the ground / links perpendicular. See how fast you get through the course for each case. Video record it looking at the vehicle straight on.

You're telling me that 45 degrees is stiffer and because of that will stop body roll better than at 90*. So if that's the case you'll post faster slalom times with the sway at 45* and you'll be beating the laws of physics.

Run both sets front & rear @ 45*. Then both at 90*...
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