Synergy Suspension 4 link Or Rock Krawler 3 link whats better?

[94xjstud]

Then dont make radically different UCA and LCA lengths. Only Teraflex does that with their "long arm" kit.

I agree. That's why I will be cutting into the floor to get good separation and have the arms as close as possible to the same length.

 

[Gaius]

On know it's on the TJ, but I finally got around to building the 3rd link on my midarm over the past couple days. Been running a 5 link midarm for a few years now. Need to raise up the axle side LCA mounts a bit to get even separation.

Actually reused the only good part of an old RK 3 link: the solid arm.

Something similar is very doable to do on an XJ, and will be doing the wife's XJ next. Tired of the ride on short arms with 4 inches of lift.

 

[94xjstud]

Is that single shear on the upper arm?

 

[Gaius]

Sure is, and only 5 or so tack welds. I think it'll hold.


edit: It's single shear on my track bar, too. Oh noes!



Look at the 3rd pic, it's all welded. I'll be finishing it up tomorrow, and get some finished pics.

More mock up:

 

[BenDiesel]

redrider kit? Never heard of them you have a link?

As for the numbers they mean alot to me. I'm a machinist and understand how steel works..

well maybe you can explane them to me cuse its a bunch of mumbo jumbo. and i was a machinest for a while to.

 

[nochance9]

well maybe you can explane them to me cuse its a bunch of mumbo jumbo. and i was a machinest for a while to.

What I got from the numbers war was that tubing as used in most control arms, is stronger than the solid hex stock used in the red rider kit. But that the hex stock will sort of bend without braking, while tubing, once it has a dent in it, will fold upon itself easier...

Someone correct me if I'm wrong. And by correct, I mean do it without bashing one side or another. I tried to keep my personal bias out so the facts are equally represented...

I think this is an interesting debate.

 

[brianglawson]

Redrider: Will you Long Arm brackets, 3 link or 4 link work with say a DetoursUSA frame stiffener/rock rail package?

 

[redrider2911]

Ben Diesel made his work with I believe RuffStuff Frame stiffeners. He had to lengthen the notches for the 6 bolts that mount the belly pan to the frame brackets if I remember right... If you need it customized for your setup regardless of what it is I can always do it.

Just so everyone knows. I still have no doubt in my mind that the 1-1/4 hex is a great material for my setup. But, through reading what alot of a peoply have said I have decided that my customer base would actually grow if I gave the guys what they wanted. If you want heavier arms and 1.25 heims on your LCAs. Well now I will be offering it in my setup with 12L14 1.75 hex. The cost will go up atleast 150-200 dollars but I believe many will see that my kit is worth it. Then no one will have a reason to say the arms are not strong enough...

 

[ktm racer 419]

Not to mention your link geometry all messed up from the deformation.

how much will link geometry be messed up from a lower control arm being slightly bowed anyway?

ok, i will answer my own question

i played with my link calculator and changed link lengths in every which way by 1/4" and my antisquatters stayed within one percent.

its a pretty silly argument

 

[redrider2911]

Sorry KTM. I did not see the question when I read through everything the other day in a hurry during break. Your right, there is not very much difference in antisquat numbers, well actually it would be antidive since we are talking abou the front. I do know that your pinion and caster angles will change enough to throw your alignment out of wack. And who wants to constantly adjust their alighnment? on a dedicated trail rig this might now be a concern. But on our daily driver/weekend wheelers, I know I dont want my vehicle to start pulling to the left on the freeway because my left control arm is bent even a little.

Answer your question? I never said anything about antisquat numbers. Just link geometry.

 

[XJLI]

Sorry KTM. I did not see the question when I read through everything the other day in a hurry during break. Your right, there is not very much difference in antisquat numbers, well actually it would be antidive since we are talking abou the front. I do know that your pinion and caster angles will change enough to throw your alignment out of wack. And who wants to constantly adjust their alighnment? on a dedicated trail rig this might now be a concern. But on our daily driver/weekend wheelers, I know I dont want my vehicle to start pulling to the left on the freeway because my left control arm is bent even a little.

Answer your question? I never said anything about antisquat numbers. Just link geometry.

1/4" isn't gonna throw your front end into space, regardless of where its added or subracted from.

 

[ktm racer 419]

1/4" isn't gonna throw your front end into space, regardless of where its added or subracted from.

x2.

a radius arm design has less desirable chartacteristics than a 3 or 4 link with a bowed link.

and a billiondy people run radius arms and are happy

 

[XJLI]

x2.

a radius arm design has less desirable chartacteristics than a 3 or 4 link with a bowed link.

and a billiondy people run radius arms and are happy

exactly. a radius arm constantly changes caster/pinion angle throughout travel.

 

[vetteboy]

Finally had time to think about this...

Link to a simple calculators for everyone

http://www.engineersedge.com/section_properties_menu.shtml

1.25 hex: .23438

Let's use .20313 instead. Worst case, ya know?

Now lets talk about. Yield strength. People dont want their arms looking like bananas right?

1018, what MOST companies use
http://www.pmtsco.com/1018CD.HTM
tensile strength, 64000 PSI. Yield strength, 54000 PSI

12L14, What I use
http://www.pmtsco.com/12L14CD.HTMtensile strength, 78000 PSI. Yield strength, 60,000 PSI

Or what *a lot of* people use, ASTM A513 DOM. Which is also what I've bent in the 2" OD x .25 wall flavor.

Tensile strength, 87,000 PSI, Yield strength, 72,000 PSI.

Back where I used to work as an engineer we would use 1-1/4 hex for gear shafts. They dont come perfectly strait of course like anything. We would take the 4 foot long shafts under our 4 ton press to straiten them to tolerance. In order to take a .003 bow out of this material you would have to bend it atleast 8 inches in the opposite direction.

So are you saying I am completely wrong on my math and material choice?

I dunno. For that arrangement, looked at as a simply-supported beam:

Max bending moment: (8000)(48)/4 = 96,000 in-lbs

Bending stress: M/s = 96,000/.20313 = 472,603 PSI

Hmm...maybe deflection:

y = [(W)(L^3)]/[(48)(E)(I)]

y = [(8000)(48^3)]/[(48)(29,000,000)(.14648)]

y = 4.339 inches

Which is irrelevant anyway, because you've completely blown past elastic deformation at that point. (see figure for bending stress)

So I'm confused. What were you trying to get at here?

 

[brianglawson]

RedRider: in all legitimacy, how does your 3 link handle the street? my jeep is a DD, and even with 6.5 inch of lift, drives very nice with short arms and drop brackets.... how would your 3 link compare?

 

[redrider2911]

OK

Fact. I never once said that my links were as strong or stronger than any other manufacturer.

You guys are trying to rip me apart like I did.

Yes. I have ran variations of the same setup for over 5 years now and I havent had a single issue with bending links. Granted I might not wheel on the same terrain that some of you do or even treat my rig the way I have seen others treat theirs but many guys around my area can attest that I have done some crazy things coming down on my Jeep extremely hard be it on the links, the uniframe, the crossmember, axle, or tires. I have broken many other parts but have not had a problem with my links. I also have many customers all running my products on all different types of terrain with different wheelin habits and yetI havent had a complaint about their links bending either. That is all I am stating and claiming.

Yes, I am a small time business hoping to grow but I know I am not running with the "big guys" YET... I still have things to learn like anybody. One Thing I am learning right now is that if the customer or maybe/hopefully future customer has concerns about my product, give them what they want. So now I am offering the heavier lower arms and joints. End of story. There's no argument.

I am proud to be a sponsor of and I will be for many years. I will be one of the many supporters that help keep this site alive year after year. Many of you will go to your chapter events and some of you will be lucky enough to win a raffle prize, maybe even one of my products. All I ask is that if you dont appreciate the time, hard work, effort, and thought that I put into a product that you might win. Please hand it on to someone that will...

 

[redrider2911]

KTM. Yes a 1/4 inch isnt much in length change over a long scale. After going through some sketches and doing some math a 1/4 inch change in a lower link would change the caster on an axle with standard CA mount locations and seperation about 2.5 degrees or so. Not too much but I am the kind of person that bothers and I would definitely be fixing it, being doing a whole front end alignment how it is or trying to straiten the link the best I could then realign everything. Bending a link could cause a front end to pull the left a little, how much, I havent bent a link so I dont know. I dont know if it would really be measurable honestly. I do know that the difference from -7 caster to -5 caster does change the way a vehicle feels and handles. Steering feels a little "grabby" and i dont like it at all, especially on a vehicle lifted above 6 inches on 35 inch tires.

Is a link bent up to a 1/4 inch shorter really gonna make a difference to you? Thats up to you. I know alot of people dont like a new product to start looking like bananas that they paid good money for. Thats it. Go on cosmetics then. lol

 

[redrider2911]

Brian. I love the way the 3 link feels, on and off the road. The change in arm length and angle makes a difference during daily driving, hitting pot holes, pulling into parking lots, or whatever. Either way the over all ride will be nicer. The heims will also feel more secure and the front handling will seem to be more rigid. In return, you feel more of the cracks in the road because of the solid joints. Thats why I offer poly joints on one end of my lower control arms. Of course the cracks arent going to almost disapear like with the stock rubber bushings but it will definitely help. It really depends on you and your needs. For a daily driver I would suggest running the poly joints on 1 end. I can tell you that you wont regret going to a long arm if thats what you choose to do.

 

[vetteboy]

That is all I am stating and claiming.

While I truly appreciate your sponsorship here, and what you're trying to do.

If you're going to throw out technical stuff - suspension geometry, strength of materials, etc - back it up.

I know I've been a bit of a hardass on the numbers and the suspension stuff, and I'd like nothing more than to have a legitimate discussion on all those things. But, if you can't back up your claims with real numbers or research, that's all I have a problem with. Because without that, it really looks like you're just trying to sell stuff based on fluff instead of actual facts. And to be perfectly honest - you haven't responded to the few questions I've raised. Both here and in the other thread.

I admire the fact that you're gonna offer larger link sizes to appease the masses, but at the same time, I can't help but think that says that the smaller size was only because of the cost, not the strength. There's a reason that links aren't generally made with such a small section modulus, and while I admit I beat on my junk harder than most people here, I'll also gladly show why the stuff I run fails the way it did.

Anyone reading this that isn't comfortable with the numbers, post up, and I'll gladly explain any part of what's been posted thus far.

 

[brianglawson]

Brian. I love the way the 3 link feels, on and off the road. The change in arm length and angle makes a difference during daily driving, hitting pot holes, pulling into parking lots, or whatever. Either way the over all ride will be nicer. The heims will also feel more secure and the front handling will seem to be more rigid. In return, you feel more of the cracks in the road because of the solid joints. Thats why I offer poly joints on one end of my lower control arms. Of course the cracks arent going to almost disapear like with the stock rubber bushings but it will definitely help. It really depends on you and your needs. For a daily driver I would suggest running the poly joints on 1 end. I can tell you that you wont regret going to a long arm if thats what you choose to do.

THank you very much!!! Im running drop brackets now with solid lower control arms and stock uppers.... Do you think your 3 link with poly bushings would ride basicallyas smooth or smoother?