Rustys Long Arms - another breakage

[XJoachim]

these arms are meant to twist/articulate at the threaded section. Users who choose to add jam nuts are stopping the rotation of the arm, and in a limited range of motion, something has GOT TO GIVE. If you stop the arm from rotating, flex will cause fatigue. Rusty never intended for users to stop this rotation with jam nuts. He is not surprised that this would happen. Rusty also instructs users to run BOTH uppers. He cannot honor warranty claims for users that run ONE arm.

When it is understood that the arm may have failed because it was forced into a range of motion that exceeds the bushings ability to give, failure is guaranteed.

interesting.........

Beezil, the suspension was tested without any springs or shocks to be bind free. The jam nuts are there because i was too lazy to remove them but they have not been bolted up. There are also RE SF joints at the frame side of the long arms. Now tell me what extra force is applied on the lower arms if i run just one upper? Show me the math that proves that the bushing had to give because of that fact.

Everybody is talking about the fact that i just hav one upper arm that caused the lower to fail but no one has an explanation why the force on the lowers is greater if i remove an upper arm. Come on, this is basic math, it's impossible that 2 lowers fail before 1 upper arm gives. :rtm: If the upper would have failed you would never have seen anyy posting from me about that. But the single upper could take the load that 2 lowers couldn't.

Before you start argueing about my suspension design do some math and you will realize that the upper should be the part to fail, not the lowers. Removing the second arm eliminated all the bind in my suspension. I maxed out the shocks and when i remove the shocks i can raise the chassis enough that i can remove the springs without removing the 3" longer bumpstops that i use to prevent the springs from falling out. And i hold every bet that the RE joints i welded in instead of the broken metal will withstand every abuse.

OK, some other companies tried to go with a single upper and they failed. My design works, there is just a piece of sheet metal that was not strong enough because it was overheated during welding that caused structural fatigue. That's the point that caused this thing to fail and it will not fail a second time. I'm more than happy with the front suspension design and i will not change it because it works. I'm sure the time i ran 2 uppers did the damage to the bushings because i had so much bind that i ripped of the axle mounts of one upper arm a few times. The 60 housing does not give so the bind was transferred to the suspension linkage.

Do what you want to do, buy Rustys stuff or don't, i just posted this failure to show people what can happen and they should be careful. I always check my rig after a trail run because i had so much different failures. The last failure before this one was a broken steering box output shaft. Maybe i wheel my rig hard, maybe i put too much stress on it. I don't care, i beef it up and see what gives next.

But i'm sure i will not break any Rusty part a second time. :nono:

 

[Beezil]

Beez....from an engineering perspective, (which neither one of us are) which has the better ability to withstand repetative torsional loading, a set of threads or a joint like we've discussed?

I'm no engineer, thats for sure!

but imho, i think a johnny type joint is a good solution.

 

[wilsmick]

The upper arm(s) prevents the axle from rotating and the lowers have to transfer the power from the axle to the frame. If the (single) upper arm would have broke or would have ripped off the mount from the axle - my fault. If the lower arm cannot transfer the momentum of the axle to the frame that a stock, tired 180.000 mile 4.0 sixbanger produces - also my fault?

Do you have a clear understanding of what control arms do? Even with all four in there, it's just a bit more complicated than uppers prevent axle rotation and lowers transfer power from the axle to the frame. There are SO many things that have to be taken into consideration here. Now - removing a link creates an entirely different set of reactions for any given situation. This is just way too complicated to get into here. And your sixbanger isn't the only thing creating momentum on your axle and the loads on your LCA's. How about bouncing around on those rocks? You can still bounce around in neutral right? What about during braking? I'm just trying to illustrate that loads you subject your control arms to are extremely complicated. Both the uppers and lowers will see tension and compression. The magnitudes and directions will vary GREATLY depending on a huge array of factors. And taking a link out has a simply HUGE effect on the loads that all of the remaining links will see. You can't just take out an UCA and assume that the remaining upper is doing the same job as the previous two. I just find your summation completely inadequate.

There is no bind in my front suspension so this also could not be the reason for this (bind and something has to give).

Intended purpose - repeated compression and tension. no torsion. looks like you had this part right. so no jam nuts, right?

you eliminated the bind, mission accomplished.
but you totally redesigned your suspension system by taking out that UCA. you gotta realize that.

 

[wilsmick]

Come on, this is basic math, it's impossible that 2 lowers fail before 1 upper arm gives. :rtm: If the upper would have failed you would never have seen anyy posting from me about that. But the single upper could take the load that 2 lowers couldn't.

Before you start argueing about my suspension design do some math and you will realize that the upper should be the part to fail, not the lowers.

WOW, are you serious? OMFG!!! this is NOT basic math. your talking about comparing two different linkages !!!!

try saying "3 dimensional kinematic analysis" :doh:

I'm not doin your "simple math" for you..... but if your interested in doin your own, try taking a kinematics class (right after all the prerequisites, hehe) you might need more than "basic math"

as for the kinetics end of it (including loads) here's my best attempt to explain.

there will be a worst-case loading scenario for each member of the each linkage design. its entirely resonable that a loading scenario that breaks an UCA in one design might actually break a LCA in a different design (same loads), or i might not break anything.

also, the results of each analysis would depend HIGHLY on the location, direction and magnitude of the loads applied. in other words the link that you break might be different than link that i break because we typically apply different loads - i drive with a heavier foot than you, or i ride in different terrain, who knows.

my point is that there is no "simple math" involved, we're talking about suspensions systems. they're called systems because they include components that effect the behavior and response of each other. change one and you change them all. because of that, i don't think you should complain about breaking a component that was intended for a different system. if you like the way it articulates now, then just keep redesigning the weak links (like you are) to handle the new set of forces that will be applied to them and you should be fine.

bottom line - its entirely possible to design a suspension system for articulation and then estimate the stresses in each component during expected usage of that system. but removing a link makes a different system and therefore must be expect to have a different set of resulting stresses.

i tried not to tear into you too much here, you just have no idea what you're talking about.

 

[XJoachim]

I too have no idea what you're talking about. :roll: You and many others here at this board including Rusty have no clue what my front end suspension looks like. You don't even know what end is connected and which not or what type of upper arm i run and how it's connected. Instead of that you want to tell me that i don't know what i'm doing and instead of getting the next darwin award i try to put all the shit to the manufacturer.

And your sixbanger isn't the only thing creating momentum on your axle and the loads on your LCA's. How about bouncing around on those rocks? You can still bounce around in neutral right? What about during braking? I'm just trying to illustrate that loads you subject your control arms to are extremely complicated. Both the uppers and lowers will see tension and compression. The magnitudes and directions will vary GREATLY depending on a huge array of factors.

So what are you trying to say? What is my application and why did the 2 lower arms break? You're so great an expert, please enlighten me :worship: :worship: and besides that tellme which side is connected to the axle and how :worship:

You don't have any clue what you're talking about and you try to tell me that i don't know what i'm saying? :roflmao:

 

[bheit4x4]

i think your an asshat. all everyone is trying to say is that you took one system and modified it to your likeings and it broke. and you posted on here like look at what happened rustys stuff is junk. just fix it or buy new whatever. big tires/axles break things period end of story something eventually has to give and thats what did

and since you know sow much about front suspention and the geometry of it all I will be looking for you to design a kit, mass produce it, and warranty it in the near future

 

[ChuckD]

WOW, are you serious? OMFG!!! this is NOT basic math. your talking about comparing two different linkages !!!!

try saying "3 dimensional kinematic analysis" :doh:

Did Rusty take that class? Or even a welding class?

 

[XJoachim]

Improving the ride, great handling, increasing wheel travel, performance and durability are what you will expect from a suspension kit or suspension products from Rusty's. Even using the highest in quality components, a Rusty's product is a superior value delivered at a reasonable price. Designed and manufactured to perform in the toughest conditions

As we use these hard core Jeeps, flexing and twisting them, weld fatigue happens, causing the cracking problem. But not with Rusty's long travel kit.

These quotes are taken from the web site. Do i need to say more?

@bheit4x4
I don't know where you came from, what do you know about suspensions? You don't know nothing about my application and you're calling me an asshat? Go back where you came from, i don't whine about braking anything, i'm sure i destroyed more parts than your complete XJ is worth. I just wanted to know everybody about a weak link. The fact that Rusty doesn't warrantee it is a thing between Rusty and me and is not your business. :moon:

 

[wilsmick]

So what are you trying to say? What is my application and why did the 2 lower arms break? You're so great an expert, please enlighten me :worship: :worship: and besides that tellme which side is connected to the axle and how :worship:

Look, you totally missed my point. I'm not an expert and I never claimed that.

It's unnecessary for me to know which side is still connected or how. there were 2 UCA's, now theres 1. thats all i need. you now have a different linkage - end of story. there is no simple way to relate one to the other. your linkage has the advantage of not having inherent binding when the axle twists. so if you like it, beef your busted parts and go with it.

i'v had bad luck with rusty's stuff too actually, (he's just always warrenteed mine) but in this case, i'm not for or against rusty's products, i was just pointing out that your reasoning was off, and then that "this is basic math" comment you made really got me goin. so wrong.

 

[XJoachim]

Sorry, but there are so many "experts" chiming in :wave1: Sure it is my suspension design and sure i will beef it up an go on. I only wanted to show people that this stuff is not bombproof nor is it bulletproof. It has its design failures and i wanted everybody to know what they're dealin' with.

I build my own stuff and i redesign the suspension to my needs. If somethings breaks i beef it up and go on. Just don't want someone to get killed by a "built-in failure by design". That's it. :wave1:

 

[bheit4x4]

well you know what you made it evreybodys buisness to talk about discuss coment or whatever when you posted it on here and i'd bet you that he would fix it or replace it if you were useing it for its applied application or close to it because he fixed my upper on my long arm when I broke it

and as far as not knowing your application I think I can picture taking rustys long arm kit removing 1 upper arm and stuffing a big ass 60 in there with 39 inch tires on it

 

[Gil BullyKatz]

The fact that Rusty doesn't warrantee it is a thing between Rusty and me and is not your business. :moon:

...interesting thread

...not an engineer, nor a hater, but I do find the above quote contradicting. Consider the fact that you're commenting on a product YOU purchased and modified... It failed. Why? Maybe the material, maybe the welding technique, maybe the modifications to it, maybe the use you subjected it to, maybe a temporal butterfly in Mongolia flapped it's wings too hard...

...Make a better product at THAT price, offer a full waranty and you'll be selling them like beer at spring break.

The point: Sucks that it broke... get over it, make it better

p.s. post on a public forum and it's no longer just "between Rusty and me and is not your business"

 

[Darky]

I too have no idea what you're talking about. :roll: You and many others here at this board including Rusty have no clue what my front end suspension looks like. You don't even know what end is connected and which not or what type of upper arm i run and how it's connected. Instead of that you want to tell me that i don't know what i'm doing and instead of getting the next darwin award i try to put all the shit to the manufacturer.



So what are you trying to say? What is my application and why did the 2 lower arms break? You're so great an expert, please enlighten me :worship: :worship: and besides that tellme which side is connected to the axle and how :worship:

You don't have any clue what you're talking about and you try to tell me that i don't know what i'm saying? :roflmao:

He's not telling you what your suspension is doing. He's telling you that by changing one part of the system, you're changing the entire system. Its not that difficult of a thought here. If I make a house of cards and remove one of the cards, from anywhere, without knowing which one it was, you would tell me that it fell down because I removed a card. And you'd be right. He doesn't need to know what part was removed to kow that its different than how it was designed. And I, personally, don't see how if other manufacturers have tried running one UCA and realized it just wasn't sturdy enough for them to sell, you can say that they were all too stupid to figure it out but I have. Your approach seems to be one of I will modify this part to make it perform better, and now such and such broke, so its time to beef that up. And repeat process breaking and beefing. That's a good process because you will eventually end up with a highly capable and nearly bulletproof vehicle. You just have to be willing to break a few things along the way.

 

[old_man]

I have a question. Did anyone else notice that picture of the broken arm has it mounted with the short arm bracket in the down position. Why?

I am and engineer and I agree that if you have the jamb nuts tight and flex the vehicle, since it only has poly bushings, something has to give. Yes SuperFlex joints would help, but you paid for poly, not SuperFlex joints. If you wanted SuperFlex joints, either you should have gotten a product with them or you should have added them yourself. As an engineer, I can tell you that a three link system puts significantly more stress on portions of the suspension during certain types of flexing.

The first rule of wheeling is that equipment breaks. Get used to it. Wheel for a while and you will see the effects of flex. The body will start to seperate.

My personal opinion is that Rusty provides a reasonable product for a reasonable price. It isn't perfect, none is, but if it were, you couldn't afford it. Life is a series of tradeoffs. You picked quick, easy, and cheap. No one held a gun to your head to buy it. You got what you paid for so quit your whining. If you think you can build a better product for the same price, go for it. Talk is cheap.

 

[RCP Phx]

I have a question. Did anyone else notice that picture of the broken arm has it mounted with the short arm bracket in the down position. Why?

I dont see what your refering to?

 

[OT]

I dont see what your refering to?

Look at the orientation of the break on the axle. Then look at where the break is on the long arm pic. The upper arm mount is hanging to the bottom (appearantly)

This pic:

And this pic:

 

[RCP Phx]

He just put it back on that way to get home some and it wouldnt be as likely to fall off!!Notice the strapping keeping it in place!

 

[old_man]

Things are so muddy I have a hard time telling what is what, but the bracket shown in the first pix appears to be a lower bracket. I see light in the upper right hand corner. Is the first picture up side down, I dont think so. The break is on the same side as the bracket and in the first picture, the break is at the bottom, which puts the bracket at the bottom. If the bracket is truly the upper bracket, then what is the long arm doing on the upper bracket and how the heck did the axle get rotated that far.

You can rule out the arm being flipped to keep it from dropping because if you look at the bushing and the sleeve, they are oriented correctly with respect to each other, unless the bushing was flipped as well as the arm which I highly doubt due to the mud and rust on the bushing.

When I built my long arms, I found that the junction of the bushing sleeve and the arm had to be at an angle for the arm to reach the mount without excessive side loading of the bushing. If the arm is run upside down, it would be putting a tremendous amount of side loading on the bushing unless the arms were swapped side to side. An excessive amount of side loading could easily cause the sleeve to effectively tear during flex. The failure shown is a tear failure.

 

[RCP Phx]

When I built my long arms, I found that the junction of the bushing sleeve and the arm had to be at an angle for the arm to reach the mount without excessive side loading of the bushing. If the arm is run upside down, it would be putting a tremendous amount of side loading on the bushing unless the arms were swapped side to side. An excessive amount of side loading could easily cause the sleeve to effectively tear during flex. The failure shown is a tear failure.

I agree completely on this,I had to do the same and theres no way mine are interchangable.I dont know how Rusty build his but RE also has a left/right arm!

 

[MaXJohnson]

when the newbie's are in the house, the sig lines flow like water