Okay say you want to fab up an anti rock type sway bar.
Any idea on what dia bar to get is there a formula or is it just hit and miss?
I was thinking a 7/8" or 1" bar but having never done such a thing I'm really clueless if that would be too stiff or not strong enough to do anything?
Do you use wieght of vehicle taking in amount of lift or what, any ideas?

Thanks

I use one on the rear, think it's great.
Did some research to make my own,but think it's cheaper/better to buy the Currie unit.
Thiers is .750x36" 4130.

http://www.stockcarproducts.com/

id like to know the same thing....these guys have the parts, and i think i can piece it together for cheaper than 300 from currie.
anyone that knows how to figure out the diameter you should use, let me know.
~John

Originally posted by JohnBuuu
http://www.stockcarproducts.com/

id like to know the same thing....these guys have the parts, and i think i can piece it together for cheaper than 300 from currie.
anyone that knows how to figure out the diameter you should use, let me know.
~John

If you want your rig to articulate like a stock car, go for it.
Let me know how it works.;)

haha...ill keep you posted:flipoff2: :flipoff2: :flipoff2:

on a serious note, they have same, bigger, and smaller bar diameters, and all sorts of arms and mounting hardware..i hope itll work

Stiffness of a swaybar is diameter^4. So you can see how drastic the changes are between relatively small diameters.

The swaybar diameter for your vehicle depends on many things so there is no easy method that I'm aware of. However, what I did on my old Jeep was got a swaybar that was overly thick and ran it. I did this because I needed a baseline and I figured since I would be getting two I might as well get a real stiff one so that I could put it on if I wanted to do a lot of road driving. It limited my articulation to the point that I think I was only getting 12" of articulation and I wanted 20", so what I did was I used some math to figure out the swaybar needed. So my 2nd try was dead on. You really need some type of baseline to figure things out from.

I can't say enough about the quality of the Stock Car Products parts. I'm really lucky that they are located about 15 minutes from my house, I stop in fairly regularly picking up odds and ends. The swaybar stuff is definately very trick and you'll be pleased. Custom lengths are available but it takes some time.

Now that I'm thinking....let's say you get 15" of articulation out of a 7/8" swaybar and your wanting 20". You would need a swaybar that was 1/3 less stiff. (Because (20-15)/15 = 1/3)

Initial Swaybar Stiffness
1) 7/8" ^ 4 = .58618
Percent Difference between Required Swaybar (Your new swaybar needs to be 1/3 less stiff or 2/3 as stiff)
2) .58618 * 2/3 = .39078
Determining Diameter of Required Swaybar
3) x ^ 4 = .39078
4th Root of .39078 = .79065
4) Closest Swaybar Diameter to .79 is 3/4"

That will get you the articulation your looking for, and a bit more at that since .75 is less than .79. Be sure that you don't change lengths because that will screw everything up. I can say that 3/4 - 7/8" is probably what most people are going to benefit from, it doesn't take much.

I'm sure there are other methods but this is one approach that worked for me. It made the Jeep work so much better on and especially off-road.

Good luck,
CJ

Another thought, in my scenario I was looking to add as much resistance to my rear suspension as possible without sacrificing articulation if all you want to do is give it a little resistance I'd get the softest you can get and add it to whichever suspension on your rig(front or rear)is working the most to help equal them out.(And in the case of the other thread, help with body roll)

CJ

I have had this similar discussion with many people, including JR and CJ Lagos. It is pretty much a guess, or at least start with what works for similar vehicles. The currie bar seems to work for most people, it is 36" long and .700 od, the arms are about 16" long, the length of the arms also makes a big difference to the roll rate, and it's easy to adjust. I dont know what the stock car products and speedway bars are made of and heat treated to but the are designed for a circle track car with 6" of travel and may not hold up to the angles imposed but your mass articulation vehicles. I know that the currie bar is made from 4340 and heatreated to RC 46-48, which is about the hardest you want to take 4340, if you need a higher allowable stress you will need 300M. I wouldnt waste time and money using 4130 because it doesn't heat treat like 4340, and the material cost is negligable at this point so you may as well use 4340. When all is said and done, the currie bar is the best bar if it fits your chassis.

I'm using a 1.25 hollow bar at .095 wall. The end links are 15" c/c and the spring rate is 57 lbs. This is almost the softest sway bar of the circle track/nascar type bars.

Here's the problem. It's perfect on the street or in my case fast in the dirt, but it's still to stiff at full flex.

The bar that Currie has deleloped is more linier in spring rate where as mine and the others like this style are too progressive.
Currie's bar for example is 60 lbs first inch but is only 90 lbs at the 4 inch mark. My bar is 55 lbs first inch but 220 lbs at the 4 inch mark. (hope I explained this ok)

That doesn't mean mine doesn't work only that right now Currie's bar works better.

It was difficult to come up with a bar spec that a manufacturer could build production units for me but I'm close. The last bar I got was 80% what I wanted and what I think everyone wants.

If anyone has used hollow bars, please post your thoughts here.

thanks,

tony k

One more thing. Sway a way makes the bar for Currie but doesn't sell the bar or anything like it 1 at a time. They don't do hollow bars. And with SAW being so bad at building parts on time, I can't give them this project.

tony k

Hey Goat,

Good to see you chimed in. The Stock Car Products bars are "4140 and heat treated". There are at least 3 of me and my good buddys using their swaybars without issue. Especially my two friends who have been using theirs for 2 years of wheeling with no probelms.

What do you think about 4140, this is way out of my area of knowledge. Any specific questions I can ask them, I'm planning on stopping in tomorrow and can ask the machinist who makes them.

CJ

Why go to the trouble to make a sway bar, don't you usually discon it when you hit the trail?

I got rid of both of mine and haven't noticed any negatives.

Do the rear leafs make you want to keep the sway bar connected? Or is this a potential product?

Bob

Any idea on what dia bar to get is there a formula or is it just hit and miss?
There is a formula and it is the angle of twist for the bar. It is dependent on the torque on the bar, the length of the bar, the type of material, and the diameter. It would also be a real pain to measure all the loads that are needed to design the right swaybar. My suggestion to you is to use a bar that is similar to others out there. The posts mention 4340 and 4140 which would both work. If the bar was 1" or 1.25" that should be enough. When you make it you should make the attachment point on horns of the bar adjustable so that you can vary the stiffness of the swaybar. That way you can tune your suspension to get the right amount of flex on road and off road. The easiest way to make it adjustable is to either use a sliding attachment on a round horn or use a square bar and drill multiple holes. If you use the multiple hole method it is easy to disconnect on the trail. Hope this helps

Originally posted by CJ Lagos
Hey Goat,

Good to see you chimed in. The Stock Car Products bars are "4140 and heat treated". There are at least 3 of me and my good buddys using their swaybars without issue. Especially my two friends who have been using theirs for 2 years of wheeling with no probelms.

What do you think about 4140, this is way out of my area of knowledge. Any specific questions I can ask them, I'm planning on stopping in tomorrow and can ask the machinist who makes them.

CJ

I had been thiking about swaybars for a while after doing the leafs out back on the TJ. And yesterday I got a new Stockcar catalog hence the question about swaybars.
I think I know the two fellas yor talking about we had achance to trail with them last year at Winchester I got to see first hand how the swaybars can really help a coilover rig, plus it does look cool with the rear one up in the back of the tub for all to see :)
Thanks for all the info I appreciate it if I do the swaybar I'll make sure to post if it's the bomb or a bust.

Do the Currie swaybars come with the brackets and bushings to mount it, or do I have to fab up my own? Any idea how long they are? What I want to do is run one through the stock shackle holes in the frame for the rear suspension. Are they long enough for that?

Originally posted by TJBob
Why go to the trouble to make a sway bar, don't you usually discon it when you hit the trail?

I got rid of both of mine and haven't noticed any negatives.

Do the rear leafs make you want to keep the sway bar connected? Or is this a potential product?

Bob

It is just a thought right now with the rear leafs the jeep feels 100% more stable I was just thinking about tinkering with the front coils that's all.

CJ, 4140 is a good choice for making a swaybar, but it all depends on what it is designed for, in the case of stock car products, it works fine because the bars in stock cars do not see much deflection, and if it works for you, than it's good enough. 4340 or 300M ( and heat treated properly!) will allow the bar take more angle before exceeding the allowable stess.

The diameter and length of the bar also determines how much angle the bar can take, as well as the torsional rate. A longer, smaller od bar will be able to twist more than a shorter fatter bar. Also some one mentioned how the material affects the spring rate of the bar, this material property is the torsional modulus of elasticity "G" and is the same for all steels, no matter what alloy or what heat treating is done.