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View Full Version : Offroad sway bar writeup *pics*



ELLLLLIOTTTTT
03-09-2007, 02:57 PM
I've been wanting to do this for awhile and after plenty of research I think this is a pretty effective way to get a stable ride on the highway and the trail yet still allow for plenty of suspension travel. Just as a little history, I was running a stock swaybar with JKS disconnects in my ZJ which worked great. When I got a daily driver I decided swaybars weren't that important so I ditched them altogether. After a few trail rides and extended periods on the road, I knew that running no swaybars, longarms, and soft shocks was not going to work. So I looked into this.

There are a few different brands of swaybars like this. Teraflex makes one, Currie produces their popular anti-rock, and a relatively low-key company "Rock Equipment" makes one as well. Considering price and quality I chose the rock equipment swaybar kit.

http://i14.photobucket.com/albums/a349/Puma297/swawybar/swaybarLarge.jpg

I got the 36" bar kit that comes with threaded rod, nylon locknuts, heim joint rod ends, bushings, and stainless arms (pictured black), and tubing inserts to hold the bar. It was a little bit cheaper than the Currie anti-rock and essentially the same thing.

Time to get started.

Here is the swaybar and arms all put together. Pretty bling and top notch quality.

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000320.jpg

Now since my front axle is stretched about 3" the arms are way too long to fit without rubbing on the springs. The only solution to this was mill the arms down to make them a more managable size, OR move the swaybar mounts forward about 5". Since I don't want to bash this thing on every rock at Tellico I chose to cut down the arms. Doing this also makes it easy to add some extra holes for ride stiffness adjustability.

BEFORE

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000323.jpg

AFTER

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000324.jpg

Now that everything was sized up right it was time to make brackets. The tubing is 1.75" HREW .120 wall and the plate is just some hacked up 1/4" link brackets. The tubing's ID matches the bushings OD.

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000328.jpg

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000330.jpg

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000334.jpg

Now to get everything up on the "frame". Not a perfect fit but a little plate and alot of welding wire will fix that problem.

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000339.jpg

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000342.jpg

Now to assemble the linkage while the brackets are cooling. You have to cut the threaded rod down to your desired length, thread the lock nuts on, mock up the swaybar, and decide how long you want them.

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000322.jpg

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000338.jpg

The angle of the swaybar is pretty important in terms of its effectiveness, so we put it at around 11*. Now everything is ready to go together.

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000343.jpg

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000344.jpg

http://i14.photobucket.com/albums/a349/Puma297/swawybar/S5000345.jpg

On the road I was pretty stoked. It's MUCH better than not running a swaybar, especially on those windy days. As with any lifted vehicle there is still some body roll present but with this upgrade its no more than what you would have with a stock swaybar. I am looking forward to getting it out on the trail and seeing what it does for those off-camber situations.

I see this topic pop up every so often around here so I hope this helps someone out. As always if you have anything to contribute please go ahead. Thanks for looking!

-Elliott

Krash80
03-09-2007, 03:23 PM
Ellllllll-iot-

Bitchin' setup.
Nice to see you're being more useful than a Torx Bolt these days.

One thing I've always wondered is why this style of swaybar works offroad and a stock style swaybar does not. Other than the joints on the swaybar links (which get changed w/ JKS or RE or whatever), I really don't see all that much difference.
I'd like to know since my rig obviously needs some sort of anti-body-roll device on the trail..

ILikeMud
03-09-2007, 03:29 PM
Very nice Elliot.

Skyline
03-09-2007, 04:21 PM
Ellllllll-iot-

Bitchin' setup.
Nice to see you're being more useful than a Torx Bolt these days.

One thing I've always wondered is why this style of swaybar works offroad and a stock style swaybar does not. Other than the joints on the swaybar links (which get changed w/ JKS or RE or whatever), I really don't see all that much difference.
I'd like to know since my rig obviously needs some sort of anti-body-roll device on the trail..

I don't think this swaybay will work any better off-road than a stock bar. Some of the other set ups like this have devices that give you the ability to vary the amount the amount of roll stiffness. That way you can drive on the street with full stiffness, and swap to something like 1/3 stiffness on the trail. Also, by shortening the end bars, Elliot added additional roll stiffness. Sure looks cool though, and very nice handiwork.

I think a better solution for a ZJ would be one of these for the rear, and adding discos instead of the end links in the front.

ELLLLLIOTTTTT
03-09-2007, 04:29 PM
Thats why I punched the holes out, to vary the amount of stiffness.

Skyline
03-09-2007, 05:08 PM
Thats why I punched the holes out, to vary the amount of stiffness.
True, but the closer you move the link to the pivot point of the bar, the stiffer the bar will become.

Think of it this way:

Let's say you have a fastener that is really tight. So tight you can hardly turn it with a ratchet. So you get out your two foot breaker bar, and can exert that same twisting force with ease. Same deal with the sway bar.

So if it feels pretty decent on the road set at the last hole in your arms, (as shown in your pics) it will be progressively stiffer if you move the end link attachment closer to the pivot. Chances are the setting that's good for the street will be way too stiff for the trail and will limit flex significantly.

Just in case you doubt this, the formula for sway bar stiffness is:

Where Sway Bar Stiffness = K

K = 500,000(D)(D)(D)D)
_________________
0.4244(A)(A)(B)+0.2264(C)(C)(C)

Where
A= one end link length
B= bar center section length
C= other end link length
D= bar thickness

This formula is only really valid for a solid round bar, and does not account for rubber mounting that can flex either. But it is clear to see that lowering the "moment arm" of your end links increases stiffness.

ELLLLLIOTTTTT
03-09-2007, 05:39 PM
Skyline,

First of all, thanks for the explanation, very well written. I have tried the swaybar on at the different mounting positions and you are right, the closer I move it to the pivot point the stiffer it gets. I would try to explain this in terms of torque arm and moment of inertia but, hell, I'm on spring break. :D Either way, with the arm adjusted all the way back (as shown in pics) it allows more flex and has marginally noticeable increased body roll. Since my rig doesn't see alot of street time I think this will be the best setting. If it were on the street more I would move it up a few notches.

IMO, it probably won't allow as much ACTUAL FLEX as running no swaybar but it will help CONTROL FLEX drastically. It will take some trail time to tune in the suspension exactly so I will update this when that happens.

ArloGuthroJeep
03-09-2007, 05:42 PM
Also just an FYI, moving it in closer will also increase the SB angle additionally making it even more difficult to flex.

redzj
03-10-2007, 12:10 AM
I have been considering something similar for offroad more than anything. I would like to control my flex a little more, besides RTI ramps are gay. Nice job by the way.

ATL ZJ
03-10-2007, 12:40 AM
Looks really good. What are you running for limit straps?

ELLLLLIOTTTTT
03-10-2007, 12:51 AM
Looks really good. What are you running for limit straps?

I've got limit straps on order with my 12" Bilstein 5100's. That should finish up my suspension work at least for a little while.

mudforblood
03-10-2007, 09:19 AM
Looks good! Just keep an eye on the end link mount on the axle. If it is still the stock bracket it will bend towards the center. The passenger side will bend all the way over to the trackbar bracket.

If I leave mine connected and go on a quick trail the brackets bend. I would gusset the bracket before trying it offroad.

I have JKS quicker disconnects on mine. I think because it has ball and socket type joints it doesnt provide any lateral support for the pins or studs that bolt to the bracket or swaybar. It allows the pin to bend down easier than an endlink with bushings.

Does any of that make sense?

Sudz
03-10-2007, 10:11 AM
True, but the closer you move the link to the pivot point of the bar, the stiffer the bar will become.

Think of it this way:

Let's say you have a fastener that is really tight. So tight you can hardly turn it with a ratchet. So you get out your two foot breaker bar, and can exert that same twisting force with ease. Same deal with the sway bar.

So if it feels pretty decent on the road set at the last hole in your arms, (as shown in your pics) it will be progressively stiffer if you move the end link attachment closer to the pivot. Chances are the setting that's good for the street will be way too stiff for the trail and will limit flex significantly.

Just in case you doubt this, the formula for sway bar stiffness is:

Where Sway Bar Stiffness = K

K = 500,000(D)(D)(D)D)
_________________
0.4244(A)(A)(B)+0.2264(C)(C)(C)

Where
A= one end link length
B= bar center section length
C= other end link length
D= bar thickness

This formula is only really valid for a solid round bar, and does not account for rubber mounting that can flex either. But it is clear to see that lowering the "moment arm" of your end links increases stiffness.

the 'stiffness' of the ride is a direct result from changing the geometry of the setup (end link relationship to bushing pivot point) - has nothing to do with torsion (twisting) of the sway bar rod or 'twisting' of the complete assembly

do a fbd and take a close look at what you are proposing - the bar does not become 'stiffer' - it's all about the pivot point geometry - i agree that there is a minimal amount of sway bar twist, but not enough to soften the ride - if that were the case, metal fatigue and failure would just be a matter of time

:best:

Skyline
03-10-2007, 11:52 AM
the 'stiffness' of the ride is a direct result from changing the geometry of the setup (end link relationship to bushing pivot point) - has nothing to do with torsion (twisting) of the sway bar rod or 'twisting' of the complete assembly

do a fbd and take a close look at what you are proposing - the bar does not become 'stiffer' - it's all about the pivot point geometry - i agree that there is a minimal amount of sway bar twist, but not enough to soften the ride - if that were the case, metal fatigue and failure would just be a matter of time

:best:

By stiffness, I was not talking about the stiffness of the ride. By "stiffness", I was talking about the ability of the bar to resist the twisting effort placed on the bar.

A sway bar does very little to effect ride stiffness. Nor does the geometry effect ride stiffness. They effect roll stiffness, and the two are very different things. This is primarily the reason that a stiffer sway bar will do little to detract from ride quality on road, (unlike stiffer springs, for example). This is because if both tires hit a bump at the same time, the sway bar will not twist at all...it will pivot. On the other hand, if one tire hits a bump, and the other does not, the sway bar WILL twist, resisting the upward motion of the wheel and pulling the other side wheel up with it, (a great thing on the road, but you may not want that other wheel lifting up off-road.) In this case, the sway bar IS acting like a spring. This works to resist body lean when cornering.

I do agree that it is all about pivot point geometry, and the equation I listed makes that point. But the sway bar is constantly twisting. Every time you turn it twists. And yes, metal fatigue does eventually set in, but just like a coil spring might sag over a long term period, a sway bar will become less effective as well. It just takes a really long time.

And the twisting of the bar is critical here. A thicker bar (of the same material) will twist less. If Elliot finds that rear most hole on the arms is too stiff for off road, since he has no room for longer arms, he might be able to obtain a somewhat thinner center section of the bar, and get the range of adjustment he needs.

Roadhouse
03-19-2007, 10:21 AM
Puma297 thanks for the info. The Rock Equipement kit is about $50 less than Curries..thanks