Preventing Tubular K-Member Failure?
#1
Preventing Tubular K-Member Failure?
I've got a 383 LS6 in a 2002 Z28. When I had the motor out, I was pleased to find I came in ~$1000 under what I had budgeted for the build. In celebration, I blew it on front end suspension goodies: Tubular BMR K-member, adjustable UMI lower A-Arms, and some urethane bushings for the sway bar. After everything was back in the car, I discovered a few threads on here talking about tubular K-member failure.
https://ls1tech.com/forums/suspensio...really-do.html
https://ls1tech.com/forums/suspensio...-k-member.html
It doesn't seem common, but it got me worried since this car sees mostly DD service. Next to replacing it with stock, what else can I do to prevent breakage?
I posted in the STB thread a few days back without much success... would a STB help to compensate for the lower lateral rigidity of the tubular K-member? Anyone have any information on the subject? UMI? BMR? Founders?
https://ls1tech.com/forums/suspensio...really-do.html
https://ls1tech.com/forums/suspensio...-k-member.html
It doesn't seem common, but it got me worried since this car sees mostly DD service. Next to replacing it with stock, what else can I do to prevent breakage?
I posted in the STB thread a few days back without much success... would a STB help to compensate for the lower lateral rigidity of the tubular K-member? Anyone have any information on the subject? UMI? BMR? Founders?
#2
Hey mealonwheels.
We have hundreds of K-members out there and have never had a customer complaint concerning failure on their daily driver. The main benefit is decreased front end weight. As other threads have mentioned, the stock K-member is the strongest but when something is over-strong (such as the factory) it leaves room for us in the aftermarket to make something completely suitable at a lower weight.
As a side note, Ryan (UMI President) heard from a customer that one of our K-members plowed a groove in a dragstrip when the front end came down too hard. The only damage was chipped paint.
As for a strut tower brace, since that thread is pages and pages long, my two cents is they are an easy upgrade and I choose them on all my vehicles. Quantitative data or not.
We have hundreds of K-members out there and have never had a customer complaint concerning failure on their daily driver. The main benefit is decreased front end weight. As other threads have mentioned, the stock K-member is the strongest but when something is over-strong (such as the factory) it leaves room for us in the aftermarket to make something completely suitable at a lower weight.
As a side note, Ryan (UMI President) heard from a customer that one of our K-members plowed a groove in a dragstrip when the front end came down too hard. The only damage was chipped paint.
As for a strut tower brace, since that thread is pages and pages long, my two cents is they are an easy upgrade and I choose them on all my vehicles. Quantitative data or not.
#3
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We sell anywhere between 400-500 K-Members a year and we seldom, if ever, have customers call us up and tell us theirs is broken. So, if it were a real concern, I would expect at least a call every month...or every other month...or every year. Not really the case. Just a seldom isolated incident here and there. We did, however, have some issues with our first design, but not with our new design that was changed about 5/6 years ago.
You should be just fine!
You should be just fine!
#4
Hey mealonwheels.
We have hundreds of K-members out there and have never had a customer complaint concerning failure on their daily driver. The main benefit is decreased front end weight. As other threads have mentioned, the stock K-member is the strongest but when something is over-strong (such as the factory) it leaves room for us in the aftermarket to make something completely suitable at a lower weight.
As a side note, Ryan (UMI President) heard from a customer that one of our K-members plowed a groove in a dragstrip when the front end came down too hard. The only damage was chipped paint.
As for a strut tower brace, since that thread is pages and pages long, my two cents is they are an easy upgrade and I choose them on all my vehicles. Quantitative data or not.
We have hundreds of K-members out there and have never had a customer complaint concerning failure on their daily driver. The main benefit is decreased front end weight. As other threads have mentioned, the stock K-member is the strongest but when something is over-strong (such as the factory) it leaves room for us in the aftermarket to make something completely suitable at a lower weight.
As a side note, Ryan (UMI President) heard from a customer that one of our K-members plowed a groove in a dragstrip when the front end came down too hard. The only damage was chipped paint.
As for a strut tower brace, since that thread is pages and pages long, my two cents is they are an easy upgrade and I choose them on all my vehicles. Quantitative data or not.
On the strut bar, I'm still not convinced. The main mode of failure of tubular K-members appears to be in DD applications on the center bar between the two sides. I'm not a mechanical engineer, but it just seems like this is indicative of side-to-side stress, more pronounced in a DD/road race application where turns are much more common (hopefully) than at a drag strip. And since the STB adds 7lbs, it negates some of the benefit of the K-member. So, if it's a real failure mitigation piece for tubular K-members, I would sacrifice the 7lbs for an overall weight loss of ~18bs. So, any data?
#5
We sell anywhere between 400-500 K-Members a year and we seldom, if ever, have customers call us up and tell us theirs is broken. So, if it were a real concern, I would expect at least a call every month...or every other month...or every year. Not really the case. Just a seldom isolated incident here and there. We did, however, have some issues with our first design, but not with our new design that was changed about 5/6 years ago.
You should be just fine!
You should be just fine!
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#8
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The picture below is customers car that Ramey was referring too. He is running a best 60-foot time of 1.27. The car has popped up twice and startled him and came back down and hit the ground. Our K-member has smacked the ground twice, once leaving a deep divot in the track. Neither time has effected the K-member other than the powder coat.
#10
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No scientific data here, but my UMI road race kmember doesnt show any wear from crappy PA roads. I went with the road race one due to the extra bracing on it just for piece of mind. I can jack it from the front just like the stock k member with no issues either. Like I said not scientific, but just my experiences with it.
#11
No scientific data here, but my UMI road race kmember doesnt show any wear from crappy PA roads. I went with the road race one due to the extra bracing on it just for piece of mind. I can jack it from the front just like the stock k member with no issues either. Like I said not scientific, but just my experiences with it.
To be honest, I'm not sure if it will though. I bought the Founders' piece, and though I was pleasantly surprised with the lightweight yet beefy nature of it, the mounting surfaces were slotted in the way the force would be applied. I torqued down the strut nuts, but if force were applied in the lateral direction in the magnitude that would cause K-member failure, I would think the STB would give first due to the lateral slots in the mounting surface... I guess time will tell?
#13
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From folks who regularly abuse their cars ... these guys crack stock K-Members!
http://www.frrax.com/rrforum/index.php?showtopic=13841
http://www.frrax.com/rrforum/index.php?showtopic=8071
I wouldn't even consider anything but a UMI unit.
http://www.frrax.com/rrforum/index.php?showtopic=13841
http://www.frrax.com/rrforum/index.php?showtopic=8071
I wouldn't even consider anything but a UMI unit.
#16
From folks who regularly abuse their cars ... these guys crack stock K-Members!
http://www.frrax.com/rrforum/index.php?showtopic=13841
http://www.frrax.com/rrforum/index.php?showtopic=8071
I wouldn't even consider anything but a UMI unit.
http://www.frrax.com/rrforum/index.php?showtopic=13841
http://www.frrax.com/rrforum/index.php?showtopic=8071
I wouldn't even consider anything but a UMI unit.
#17
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I'm not saying the STB would complicate any issues with using a tubular K-member, I'm asking if adding a STB may mitigate any structural compromises (if there are any) with lateral forces in a tubular k-member scenario. Basically, IF a tubular k-member fails laterally due to less rigidity side-to-side than a stock k-member (again, that's IF), then would the additional lateral support at the shock tower help solve some of this additional flex in the k-member? I have a feeling this won't be resolved technically, but I've got a STB on now and hopefully some peace of mind someday
Not arguing which unit to use, I've already got a BMR unit in there (Thanks BMR!) And though the links do not work for me, it appears to be to a road race site. I don't road race, but I had heard of tubular k-members breaking in daily driven applications.
Not arguing which unit to use, I've already got a BMR unit in there (Thanks BMR!) And though the links do not work for me, it appears to be to a road race site. I don't road race, but I had heard of tubular k-members breaking in daily driven applications.
As for the broken stock K-Member...if you break a stock K-member, you're going to break anything. A factory A-arm, a factory hard mounting point, a wheel, etc. This is not the norm, and it shouldn't deter anyone from buying an aftermarket K-member, IMO.
#18
Even though we're in friendly competition as suspension manufacturers, I agree with Kevin. We have customers on standard and road race K-members and most use STB's, and a few don't. Failures are statistically non-existent.
ramey
ramey
#19
Understandable concern. But, like I said, we hardly are presented with a failed K-Member to begin with. As a matter of fact, we just looked into it and we have not been presented with a single failure with our second generation K-member that we have been building for the past 6 years. Talk about assurance in a product! Adding a STB on there would only serve to strengthen the connection as the forces would have more area to spread.
As for the broken stock K-Member...if you break a stock K-member, you're going to break anything. A factory A-arm, a factory hard mounting point, a wheel, etc. This is not the norm, and it shouldn't deter anyone from buying an aftermarket K-member, IMO.
As for the broken stock K-Member...if you break a stock K-member, you're going to break anything. A factory A-arm, a factory hard mounting point, a wheel, etc. This is not the norm, and it shouldn't deter anyone from buying an aftermarket K-member, IMO.
Wow, great! To hear of virtually no failures nowadays is very reassuring, thanks for the feedback guys
#20
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Glad I saw this thread! I'm planning on swapping my kmember soon but recently I've been reluctant. I saw some posts on here about the aftermarket kmembers breaking. Glad to read that its very isolated. This will be going on my daily driver.