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Cobb front swaybar failure...


fatbastard

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Yeah the shaft collars are pretty common as can be seen in this link: http://rallitek.com/rafrswbar20w.html where Rallitek supplies them with the bar. For the Cobb bar it is even more important than the stocker since it is slightly shorter. This difference in length creates a larger angle to the endlink even if completely centered, so if it shifts it is likely you will exceed the max angle they can sustain.
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This is an unusual and unfortunate event which we have not seen this failure at all with our sway bars.

 

I noticed you put on some collars right before the break. We don't suggest anyone puts collars on the bars since they do need some movement play around, and by having those their you're creating a major stress point.

 

We stand behind our products and if there's ever an issue we resolve it in a timely matter but we can not guarantee that our products will perform if they've been tampered with. We offered the customer to sell him a brand new FSB less then cost for us; since the bar is indeed out of warranty and now looks like the failure point can lead to those collars.

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We stand behind our products and if there's ever an issue we resolve it in a timely matter but we can not guarantee that our products will perform if they've been tampered with. We offered the customer to sell him a brand new FSB less then cost for us; since the bar is indeed out of warranty and now looks like the failure point can lead to those collars.

 

My two cents...

 

Cobb is proposing a reasonable solution by offering partial credit on a part out-of-warranty.

 

Perhaps the OP should consider bars that are shipped with lateral locks by the manufacturer... Whiteline, for example? Lateral locks should not cause any sort of torsional failure.

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You may have offered a discounted price but I highly doubt it is less than your cost. If that were true there would be no margin for you or other vendors to make any money selling these and I am sure you do not do this for charity.

 

First the collars have been on since the bar was installed about a year and half ago so they are not new. Second they were not installed such that the bar could not move laterally, it just limited this movement. Third, if the collars were the failure mode then there would be tons of bars with this same failure. As I posted above Rallitek SUPPLIES you with these collars and from what I remember there were other bars that had a feature welded onto the bar to limit movement. While I currently have nothing to back this up; I think it has more to do with the way the hollow bar is formed. As I mentioned in my email to you, the shape of the Cobb bar is very similar to other bars out there so that in and of itself is not likely to be a problem. But I am concerned about how the bar is formed and since it is hollow the internal stresses will be quite different than a solid bar. As I mentioned when I get a chance to get the broken piece off I will sit down with other engineers in house and inspect the fracture lines to try to determine a root cause.

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so if you use collars the warranty is void, if you dont use collars you get too much movement and risk the bar falling out or breaking your endlinks.

 

hrmm.. yea.. not buying that.. or buying this product.

 

thanks for the response tho.

"The penalty good men pay for indifference to public affairs is to be ruled by evil men." - Plato
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I'm really surprised at the level of animosity in this thread towards Cobb. It's a really odd failure, one that has never been seen before, and the compounding factor was collars. It failed 1" away from a collar.....on a 3 foot long bar.

 

I'm not an engineer, but I'm betting most on here aren't either. Those collars might protect the endlinks, but at what cost? Maybe collars aren't a good idea with hollow bars due to the stress they create? Do any of us know. Probably not.

 

I started a thread awhile back on my Cobb sway bars having a problem. When I got around to resolving it, it was clearly an installation issue on my part. Re-tightened, they worked great. The cobb supplied parts were perfect for the job, and well-made.

 

Another member had a rear sway bar break off the mounting point....but he hadn't installed the cobb reinforcement plate and bracket for that mounting point.

 

Others have had clunking....but I haven't seen alot of resolution as to whether or not they re-tightened every bolt. Some have had resolution by replacing worn-out bushings. Cobb's bushing straps have a zerk fitting for regular greasing.

 

I'm not saying Cobb is perfect or that all their products are gold or that this one wasn't a failure due to a forming technique or manufacturing defect. I'm just saying: We've got complicating issues here and the thread has turned somewhat toxic towards a good vendor.

 

Their front sway bar retails for $165. Personally, I think Cobb should've offered to replace it free of charge if not for the collars....if they offered to replace it for ~$100 or less considering the collars, that's probably a pretty sweet deal.

 

Just my .02

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I've had the Cobb bars (f/r) on for 2 1/2 years without collars. I've autox'd the car numerous times. Even with Swift springs and stock links, no problems at all. And the car handles great even with the stock shocks. Neutral and a blast in the snow.

 

I've recently learned just how easy it is to break the rear end loose on wet cold pavement. I entered into a wide open intersection making a 90 degree turn (no other cars in sight) and floored it in first. The rear end swung about 150 degrees and then snapped back inline when I let off. :)

 

Joe

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That may be. I do not regard Cobb as a poor quality company or anything.. However the sheer number of people that have had various problems with their cobb suspension products lead me to the conclusion that unless I plan to retire my LGT as a weekend fun car.. I should not buy their suspension products due to the seemingly very high potential for failure or problems. If my car breaks down because a sway bar falls out or breaks off or what ever.. I will have to miss work and/or rent a car just to get around.

 

For those of us who daily drive, it is my opinion that there are too many problems associated with this product to keep it in consideration.

 

Cobb is the first place I turn when I think of performance products for my car, and the sway bars have been something on my list for some time now because it would be an easy not-noticeable mod that I could do and stil be able to do that would improve daily handling in the surprisingly twisty back roads of suburban Atlanta. But I cant afford to risk reduced reliability in the name of performance enhancements. If maybe 1 person out of every 10,000 or so had a small issue I would understand, but it seems SOMETHING comes up about a cobb swaybar every couple of months on these forums.

 

I dont know if maybe the suspension in our car is very dynamic and therefore hard to make a product for or what.. but I know the jdm bars from what I have heard are thicker and have no issues, and other brands have not had major issues.. so.. its simply the natural conclusion I come to.

"The penalty good men pay for indifference to public affairs is to be ruled by evil men." - Plato
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Darkfox - As someone who read everything I could find before, during, and after I bought and installed my cobb sway bars, could you tell me the failures?

 

I've seen a fair number of threads on broken stock sway bar links. This is a known weakpoint when upgrading sways, and I decided that to me it was ok given it's my wife's daily driver, we won't be thrashing the car, and we won't be using super sticky tires.

 

I've seen clunking....in fact, I had clunking....turned out it was improper tightening of the sway bar endlink bolts on my part. Other clunking primarily involves failed bushings.

 

Have you seen a sway bar actually fail in any other way? I'm seriously asking, cause I don't remember any.

 

Joe

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the biggest one I remember was someone with an outback. I dont erally know the details or resolution of that case, but his kinda.. fell out on the side of the road on one end. I beleive the site now says (to their defense) that the bar does not fit the outback.

 

I had read about the end links breaking as well.

 

please dont get me wrong, I'm not trying to muddy Cobb's name. I apologize to Cobb and to everyone here if thats the impression you get from me.

 

Perhaps we hear more of people breaking mounts endlinks and weird issues like this one for the cobb bar beacuse more people have them? My initial thought was quality and reliability but thats another factor I had not thought of.

"The penalty good men pay for indifference to public affairs is to be ruled by evil men." - Plato
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After I installed my Cobb Sway bars, I drove my car into a giant compactor. It couldn't crush my car! Now that's stiff!

 

:)

 

I hope the op finds some resolution. I kinda think of this like the transmission/clutch on these cars.....the clutch is the weak point (kinda like the stock end-link). Change the stress points (sway bar collars), and other things might break.

 

Shame, cause I like the idea of the collars. Maybe on solid bars it's the best option.

 

Joe

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I've recently learned just how easy it is to break the rear end loose on wet cold pavement. I entered into a wide open intersection making a 90 degree turn (no other cars in sight) and floored it in first. The rear end swung about 150 degrees and then snapped back inline when I let off. :)

 

Joe

 

I had a wonderful 4 wheel drift once when I was entering a road, had to turn about 120 degrees and misjudged oncoming traffic's speed. Gunned it in first while turning across the near lane to get into the far lane and all 4 wheels were drifting. In the dry. Whoopeee! :lol:

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Before anyone gets too crazy here....I did not start this thread to bash Cobb. I posted because I know I am not the only one running these bars and I am fairly confident I am not the only person who added shaft collars. So that means there is a possibility this could happen to someone else. I consider myself lucky that this happened at low speed, things could have been much worse.

Regardless here are the facts we have right now:

1) The front bar failed in what looks to be the passenger side bushing or maybe to the inboard side.

2) The shaft collars were installed with the bars about 1.5 years ago. The collars have a 1" or 25.4mm bore, the Cobb bar is quoted as 25mm. With that said I do not believe there is a way I could have compressed the bar to deform it or cause any internal stresses. This can and will be confirmed when I take the bar off.

3) Cobb has offered to work with me on replacing the bar even though it is not under warranty. The original price quoted was high, but this was because internally they had a miscommunication as to which bar had failed. They have since made another offer which is fair.

While the offer Cobb made is fair; I will not make a decision on what I do until I am comfortable with the failure mode. As mentioned above I consider myself to be lucky; if this was not an isolated manufacturing issue or related to something I can change I do not want to take further risks by running their bar reagardless of the price. When I get the bar off I will sit down with other engineers at work to try to determine the root cause of the failure by looking at the way the bar fractured.

As I have posted earlier, I do not see how a shaft collar that does not deform the bar could change the stress on the bar. My understanding of these bars and how they work is by resisting motion on one side vs the other by twisting the bar. A shaft collar could not change the way the bar is loaded unless it was fixed and could not move. While I did not see any signs that the collar was locked to the bushing or to the chassis I will not know for sure until I get the bar off.

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Fatbastard- My very short .02 cents on an issue above my head.

 

"My understanding of these bars and how they work is by resisting motion on one side vs the other by twisting the bar." "A shaft collar could not change the way the bar is loaded unless it was fixed and could not move."

 

Isn't the point of a shaft collar to prevent sway bar movement through the bushing? By default then, by limiting the transfer of forces, would the collar then shift the way the bar is loaded? Honestly, I would think the bushing strap would take the brunt from no longer allowing the sway bar to shift through it....instead of the thick steel. But I'm no structural/mechanical engineer :)

 

Joe

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The collars keep the bar from moving side to side...the bar is not supposed to move side to side. When it does it increases the angle on teh endlinks which will cause a failure.

 

The swaybar works by transferring vertical motions in either end of teh bar into a twisting motion of the center of the bar. To better understand what I am describing; take your right and left thumbs and put them together so one hand forms an L and the other a backwards L. Now when the car goes around a corner one side of the car dives and the other raises, because the car rotates about its center. So as you raise one index finger and lower the other you'll notice that your thumbs are rotating. This is the torsion the the center of the bar tries to resist. Now if you put a ring on your thumb and did the same thing you thumbs would still rotate. The only way this ring could change the forces is if the ring was stuck to your thumb and to something that can't move.

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Do you know approximately how many miles you had with the bar installed? I've actually heard of a few other companies having this issue with hollow bars (on a lot of different cars) just because that thin sidewall will fatigue over time. We just picked up a new private label customer for this very reason and he is switching his product from hollow to solid.

 

It's definately not because of your collars but at the same time it is out of warranty. I don't think Cobbs stance is out of line at all. I don't expect to see this happen a lot but out of warranty is out of warranty, at least they offered you some help...

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The collars keep the bar from moving side to side...the bar is not supposed to move side to side. When it does it increases the angle on teh endlinks which will cause a failure.

 

The swaybar works by transferring vertical motions in either end of teh bar into a twisting motion of the center of the bar. To better understand what I am describing; take your right and left thumbs and put them together so one hand forms an L and the other a backwards L. Now when the car goes around a corner one side of the car dives and the other raises, because the car rotates about its center. So as you raise one index finger and lower the other you'll notice that your thumbs are rotating. This is the torsion the the center of the bar tries to resist. Now if you put a ring on your thumb and did the same thing you thumbs would still rotate. The only way this ring could change the forces is if the ring was stuck to your thumb and to something that can't move.

 

Crap. Of course the bar moves side to side. As load is transferred from one suspension side, the bar will be loaded by the link. The first motion will be lateral and once it can't move anymore laterally, the bar will twist, supplying the resistance to roll. If it wasn't diesigned to slide, ALL sway bars would have a built in collar to resist such movement.

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