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PostPosted: Tue Aug 26, 2008 8:10 am 
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JPaul wrote:
maybe I just have a complete inability to grasp your description, or something, but it doesn't make any sense.

What would be the point of preventing a wheel from lifting if it does not also act on the chassis/body in some way? It seems that the opposite of what you are saying would be true. if the rear sway bar is only meant to keep the wheel from lifting off the ground, wouldn't the only way to do that be by acting on the body in an opposite direction of force from the lean generated by the turn?

The axle doesn't need a bar to keep the wheel from lifting, if anything the bar will encourage the wheel to lift. If the bar wasn't there then there would be nothing to prevent the wheel from lifting and you'd lose a rear spring on the kj in a sharp enough turn with enough body roll. My understanding is that the whole point of a sway bar is to try and keep the wheels on an even plane with the chassis/body of the vehicle. When a car enters a curve it wants to lean toward the outside of the curve. In order to prevent this from being unsafe and excessive, the only tools you have are the spring for the suspension on the outside of the curve and your sway bar.

The spring can only exert so much force on the vehicle to keep it upright. past that point the body will lean to the outside of the curve and continue to do so until the forces overcome the balance of the vehicle and it goes rolling off in a semi tangent line from the curve.

The sway bar comes into effect by tying the two sides of the axle together. As the car enters the curve, the outer wheel gets stuffed while the inner wheel hangs loose. With the sway bar connecting the two sides, the force generated by the lean of the body acts not only on the outside spring, but the inside spring as well, effectively doubling (or less, depending on the spring rate of the bar itself) the spring rate of the outer spring. That is what really prevents the body roll, since the lean is only counteracted by the outer springs and nothing else, with out a sway bar that is.

So when you disconnect your sway bar, whether it is attached to the body or not, you now only have one spring to counteract the force of the lean in a curve.

With the bar connected, you now can use the springs on both sides of the vehicle to counter act the lean.


Otherwise, with the way you explained it, what the heck is the point of having the bar there? To keep my wheels on the ground while the body leans as it pleases? I doubt the engineers would have done that on a high center of gravity vehicle prone to roll overs. It just opens the doors for a massive class action lawsuit for all the rolls overs the vehicle would enjoy.
Maybe this will help you.

The front KJ swaybar has 4 connection points so the bar only does a torsional force.The rear bar has only 2 points of contact,which lets the bar have torsional and up/down force.That up/down movement from having only 2 points of contact will not control and body lean.


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PostPosted: Tue Aug 26, 2008 8:40 am 
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I could argue this all day long, but why bother? You're right and I'm clearly wrong and that's how it's gonig to stay because you have more experience and knowledge than I do, so why bother listening to me?

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PostPosted: Tue Aug 26, 2008 8:46 am 
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JPaul wrote:
I could argue this all day long, but why bother? You're right and I'm clearly wrong and that's how it's gonig to stay because you have more experience and knowledge than I do, so why bother listening to me?
You've explained perfectly the operation of the front swaybar,just not so much the rear bar.


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PostPosted: Tue Aug 26, 2008 11:00 am 
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You said shaft.

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PostPosted: Tue Aug 26, 2008 11:25 am 
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If it makes you feel any better, I used to believe the rear sway bar was also a very functional piece of equipment on the KJ.

Then

I crawled under the KJ and to my amazement I saw what appeared to be a bar. Bolted to the control arms that wasn't connected to the body of the vehicle. If the control arms are connected to a steel tube (the axle) and that tube is forced to the road with the springs, what is the true function of that sway bar? Any rolling moment from side sway is only counter acted by the spring. The sway bar may help a tiny bit but only on the wheel that is on the indside track of the turn. Most of the roll control in the rear suspension is handled by the outside spring and that spring alone.

I think this was one of the reasons for the change in the rear suspension geometry on the KK... They wanted to make the rear end a little more functional.

I also think this is one of the major reasons lifted (spring lifts) KJs enjoy more ride control... The STRONGER rear springs.

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PostPosted: Tue Aug 26, 2008 10:23 pm 
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I had mine off about a year, put it back on with the 6" lift hasn't impaired the articulation a bit far as I can see.

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PostPosted: Wed Aug 27, 2008 8:36 pm 
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Ok, everyone has an excellent prespective on the function of a sway bar, If it did not have a purpose well....... here is the run down,

Stabilizer bars are part of a car's suspension system. They are sometimes also called anti-sway bars or anti-roll bars. Their purpose in life is to try to keep the car's body from "rolling" in a sharp turn.
Think about what happens to a car in a sharp turn. If you are inside the car, you know that your body gets pulled toward the outside of the turn. The same thing is happening to all the parts of the car. So the part of the car on the outside of the turn gets pushed down toward the road and the part of the car on the inside of the turn rises up. In other words, the body of the car "rolls" 10 or 20 or 30 degrees toward the outside of the turn. If you take a turn fast enough, the tires on the inside of the turn actually rise off the road and the car flips over.

Roll is bad. It tends to put more weight on the outside tires and less weigh on the inside tires, reducing traction. It also messes up steering. What you would like is for the body of the car to remain flat through a turn so that the weight stays distributed evenly on all four tires.

A stabilizer bar tries to keep the car's body flat by moving force from one side of the body to another. To picture how a stabilizer bar works, imagine a metal rod that is an inch or two (2 to 5 cm) in diameter. If your front tires are 5 feet (1.6 meters) apart, make the rod about 4 feet long. Attach the rod to the frame of the car in front of the front tires, but attach it with bushings in such a way that it can rotate. Now attach arms from the rod to the front suspension member on both sides.

When you go into a turn now, the front suspension member of the outside of the turn gets pushed upward. The arm of the sway bar gets pushed upward, and this applies torsion to the rod. The torsion them moves the arm at the other end of the rod, and this causes the suspension on the other side of the car to compress as well. The car's body tends to stay flat in the turn.

If you don't have a stabilizer bar, you tend to have a lot of trouble with body roll in a turn. If you have too much stabilizer bar, you tend to lose independence between the suspension members on both sides of the car. When one wheel hits a bump, the stabilizer bar transmits the bump to the other side of the car as well, which is not what you want. The ideal is to find a setting that reduces body roll but does not hurt the independence of the tires.

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PostPosted: Wed Aug 27, 2008 8:44 pm 
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LIV42DY wrote:
Ok, everyone has an excellent prespective on the function of a sway bar, If it did not have a purpose well....... here is the run down,

Stabilizer bars are part of a car's suspension system. They are sometimes also called anti-sway bars or anti-roll bars. Their purpose in life is to try to keep the car's body from "rolling" in a sharp turn.
Think about what happens to a car in a sharp turn. If you are inside the car, you know that your body gets pulled toward the outside of the turn. The same thing is happening to all the parts of the car. So the part of the car on the outside of the turn gets pushed down toward the road and the part of the car on the inside of the turn rises up. In other words, the body of the car "rolls" 10 or 20 or 30 degrees toward the outside of the turn. If you take a turn fast enough, the tires on the inside of the turn actually rise off the road and the car flips over.

Roll is bad. It tends to put more weight on the outside tires and less weigh on the inside tires, reducing traction. It also messes up steering. What you would like is for the body of the car to remain flat through a turn so that the weight stays distributed evenly on all four tires.

A stabilizer bar tries to keep the car's body flat by moving force from one side of the body to another. To picture how a stabilizer bar works, imagine a metal rod that is an inch or two (2 to 5 cm) in diameter. If your front tires are 5 feet (1.6 meters) apart, make the rod about 4 feet long. Attach the rod to the frame of the car in front of the front tires, but attach it with bushings in such a way that it can rotate. Now attach arms from the rod to the front suspension member on both sides.

When you go into a turn now, the front suspension member of the outside of the turn gets pushed upward. The arm of the sway bar gets pushed upward, and this applies torsion to the rod. The torsion them moves the arm at the other end of the rod, and this causes the suspension on the other side of the car to compress as well. The car's body tends to stay flat in the turn.

If you don't have a stabilizer bar, you tend to have a lot of trouble with body roll in a turn. If you have too much stabilizer bar, you tend to lose independence between the suspension members on both sides of the car. When one wheel hits a bump, the stabilizer bar transmits the bump to the other side of the car as well, which is not what you want. The ideal is to find a setting that reduces body roll but does not hurt the independence of the tires.
Again a good explination of how the front swaybar works with 4 anchor points,does not apply to the rear bar with only 2 anchor points.


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PostPosted: Wed Aug 27, 2008 8:51 pm 
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Joe Jeeper wrote:
I had mine off about a year, put it back on with the 6" lift hasn't impaired the articulation a bit far as I can see.

Curious... Why did you decide to put it back on?

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PostPosted: Wed Aug 27, 2008 8:58 pm 
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I stand corrected 2 vs 4 you are absolutly right. But let me thro this at you; in a situation when you needed to disconect the SB since the front end will be the first point of contact I would want the front to disconect, more flex in the front end=more surface contact(depending on the situation) the rear would just follow, my point is that is there really and advantage to disregard the rear SB? On the KJ.

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PostPosted: Wed Aug 27, 2008 9:27 pm 
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Actually the rear bar does have 4 mounting points - they're just indirect.
i.e. it mounts to the control arms - the control arms are mounted to the body and to the axle - so any compression on one side is transmitted though the bar to the other side. Just like any other sway bar.
It's not very effective - because rear sway bars aren't too effective - you'd notice the difference if you ran an autocross slalom and you might notice it towing a trailer in crosswinds.
But you'd probably have to do an immediate before and after comparison.

rear sway bars are only really significant on front wheel drive cars and then the rear sway bar had to be big, bigger than the front.

sway bars in general are a compromise - they allow reasonable handling with softer springs so you have a softer ride - best handling is with stiffer springs - they allow each wheel to respond independently.

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PostPosted: Sat Aug 30, 2008 10:44 am 
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I found this info on allpar.com

"A linkless rear stabilizer bar bolted directly to the lower control arms eliminates a noise transmission path into the body structure"


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PostPosted: Sat Aug 30, 2008 11:26 am 
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wait for it...

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PostPosted: Sat Aug 30, 2008 10:03 pm 
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tjkj2002 wrote:
The added benifit from removing the rear bar is you get slightly more rear flex and the rear will flex alot easier without that bar there.


So with the slightly more rear flex, is it worth it?

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PostPosted: Sat Aug 30, 2008 11:02 pm 
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dieselenthusiast wrote:
tjkj2002 wrote:
The added benifit from removing the rear bar is you get slightly more rear flex and the rear will flex alot easier without that bar there.


So with the slightly more rear flex, is it worth it?


Mine has been off forever, I don't miss it on road. If I was towing, I might put it back on there.

The quality of the travel in the rear is much improved without it. It does not travel much more, per say-- but it travels and tracks much better. It just responds quicker and you spend less time spinning the wheels. Actually, the same goes for disconnecting the front off-road (especially stock when you have so little travel).


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PostPosted: Sun Aug 31, 2008 12:52 pm 
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I never noticed any difference to the handling on the road with out the rear swaybar. The better articulation off road is well worth the 10 minutes under the jeep to pull it off.

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PostPosted: Sun Aug 31, 2008 1:29 pm 
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daspes wrote:
I never noticed any difference to the handling on the road with out the rear swaybar. The better articulation off road is well worth the 10 minutes under the jeep to pull it off.


Sounds good, looks like mine will be coming off! :D

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PostPosted: Sun Aug 31, 2008 2:34 pm 
ATXKJ wrote:
Actually the rear bar does have 4 mounting points - they're just indirect.
i.e. it mounts to the control arms - the control arms are mounted to the body and to the axle - so any compression on one side is transmitted though the bar to the other side. Just like any other sway bar.
It's not very effective - because rear sway bars aren't too effective - you'd notice the difference if you ran an autocross slalom and you might notice it towing a trailer in crosswinds.
But you'd probably have to do an immediate before and after comparison.

rear sway bars are only really significant on front wheel drive cars and then the rear sway bar had to be big, bigger than the front.

sway bars in general are a compromise - they allow reasonable handling with softer springs so you have a softer ride - best handling is with stiffer springs - they allow each wheel to respond independently.


I was going to say that. I can see how the control arms would be kept in check with eachother since they are connected through the swaybar. However only the torsional rigidity of the sway bar is what keeps them in check since while it is bolted in 4 places the actual object that transfers the forces from one side to the other is the bar itself. Since the force of the vehicle in motion is much greater than the sway bar's rigidity it easily allows for independent flexing. Perhaps DC wanted it this way to allow for greater flex in the rear.


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PostPosted: Wed Jan 28, 2009 9:15 pm 
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With an OTT lift - the dead struts on the front would have much more effect than the rear sway bar. :D






okay - you probably won't notice any difference unless you're towing trailer in crosswinds.

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PostPosted: Wed Jan 28, 2009 9:45 pm 
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I took mine off 5 years ago after driving around lifted for about 6 months with it on. I have yet to detect any difference. I think it is a cover your booty feel good part without making any measurable difference.

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