Tubular control arm failure
March 28th, 2015, 11:01 AM
#1
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Tubular control arm failure
My left front lower tubular control arm just failed catastrophically. Thankfully in a parking lot.
Can't post pictures from my phone, will update you later.
Can't post pictures from my phone, will update you later.
March 28th, 2015, 12:57 PM
#8
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I was backing out of a parking space, 2 MPH tops. My guess is that it's been a long time underway.
The reassuring thing to me is that, looking at the UMI website, their current tubular control arms are reinforced in exactly that spot. I've yet to hear from them, and don't expect to until Monday.
The reassuring thing to me is that, looking at the UMI website, their current tubular control arms are reinforced in exactly that spot. I've yet to hear from them, and don't expect to until Monday.
March 28th, 2015, 02:03 PM
#14
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Eric & Eric: Agreed, I puckered up when I realized how lucky I was. These cars aren't made for crashing.
I've contacted UMI, we'll see what they say. Judging from this picture ( http://umiperformance.com/catalog/im...031aaa_LRG.jpg ) they reinforce that same area in their current production, so it's something they know would happen eventually.
Which brings me to '69442ragtop: If they offer the same product with no improvements; no way. Then I'll ask for a reimbursement. But if the product is better, I'll accept it.
I've contacted UMI, we'll see what they say. Judging from this picture ( http://umiperformance.com/catalog/im...031aaa_LRG.jpg ) they reinforce that same area in their current production, so it's something they know would happen eventually.
Which brings me to '69442ragtop: If they offer the same product with no improvements; no way. Then I'll ask for a reimbursement. But if the product is better, I'll accept it.
March 29th, 2015, 09:33 AM
#22
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Good to see your Ok Seff, that just turned me away from tubular arms. I was thinking about swapping them in my 76. Well (Global west arms) I'm going to reconsider now.
As Eric mentioned buy a round for the angels, they save you from gaining another stair to the above world.
Eric
As Eric mentioned buy a round for the angels, they save you from gaining another stair to the above world.
Eric
March 29th, 2015, 09:51 AM
#23
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Seeing that turns my stomach thinking of how many of those control arms the company has sold that have not failed yet. And! And!, how lucky they are to not have any fatal complaints!
I would love to personally return them back to the manufacture so they would NEVER sell that thin walled crap again...Sorry had to get that off my chest. Glad your OK!
Sean
I would love to personally return them back to the manufacture so they would NEVER sell that thin walled crap again...Sorry had to get that off my chest. Glad your OK!
Sean
March 29th, 2015, 10:55 AM
#25
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that seems like a bad place to skimp on steel. There is thicker tubing, if you as the manufacturer ask for it. That looks like exhaust pipe tubing. I am not impressed. Again, NOT BETTER than factory parts.
Please elaborate on the advantages gained with these fragile items. Are we SURE these gains are not just a warm fuzzy feeling, or perhaps attributable to other coincident modifications such as new/ better shocks, stiffer [new] bushings, stiffer springs, new ball joints, etc. ?? Because, I noticed a HUGE improvement in the handling of my '68 442 when I rebuilt the front end with all new wear parts, using factory equivalents.
From an engineering perspective, that part has to do 1 or 2 things. Withstand tensile and compressive axial forces [FAIL], and rotate a bit at the end joints. Oh and the bottom one has the suspension spring mounted to it so it carries the weight of the front corner with a huge bending moment added to the part. It theoretically never gets twisted in operation. That's why the factory part has the shape that it has, and is not tubular. Tubular shapes are great for resisting torsion, far more so than flat or open [C or U] shapes. Readers are advised to do the paper towel tube experiment w/o, then with, a slit down the side if you are unclear how an enclosed tubular member resists torque better.
The factory part also has a reinforcing lip where yours is broken, which extends out oh 6-10mm, which adds quite a lot of strength to that attaching point.
Turns out, it's not all that easy to do better than factory engineering. Different is not equal to better.
Please elaborate on the advantages gained with these fragile items. Are we SURE these gains are not just a warm fuzzy feeling, or perhaps attributable to other coincident modifications such as new/ better shocks, stiffer [new] bushings, stiffer springs, new ball joints, etc. ?? Because, I noticed a HUGE improvement in the handling of my '68 442 when I rebuilt the front end with all new wear parts, using factory equivalents.
From an engineering perspective, that part has to do 1 or 2 things. Withstand tensile and compressive axial forces [FAIL], and rotate a bit at the end joints. Oh and the bottom one has the suspension spring mounted to it so it carries the weight of the front corner with a huge bending moment added to the part. It theoretically never gets twisted in operation. That's why the factory part has the shape that it has, and is not tubular. Tubular shapes are great for resisting torsion, far more so than flat or open [C or U] shapes. Readers are advised to do the paper towel tube experiment w/o, then with, a slit down the side if you are unclear how an enclosed tubular member resists torque better.
The factory part also has a reinforcing lip where yours is broken, which extends out oh 6-10mm, which adds quite a lot of strength to that attaching point.
Turns out, it's not all that easy to do better than factory engineering. Different is not equal to better.
Last edited by Octania; March 29th, 2015 at 11:00 AM.
March 29th, 2015, 11:41 AM
#26
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My friend has a 70 el camino with UMI control arms, my 69 Chevelle has eBay chinesium tubular control arms. We compared the 2 and sorry to say, but in this case chinesium was much better quality, better welds, thicker steel and cheaper.
Last edited by 70cutty; March 29th, 2015 at 11:55 AM.
March 29th, 2015, 12:27 PM
#27
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China CAN make good product.
Witness the Dewalt brushless impact tool.
But the manufacturer/ buyer here has to tell them exactly how, then watch them like a hawk and insist that what was requested be delivered as specified.
I see thin wall tubing where it most needs strength. That is an engineering failure, even with the best of manufacturing ability.
Witness the Dewalt brushless impact tool.
But the manufacturer/ buyer here has to tell them exactly how, then watch them like a hawk and insist that what was requested be delivered as specified.
I see thin wall tubing where it most needs strength. That is an engineering failure, even with the best of manufacturing ability.
March 29th, 2015, 01:01 PM
#28
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It will be interesting to see how they handle this. I plan on going tubular when I rebuild the 71. When I rebuilt the front end I just did the stock components with but was very tempted with the Chinese arms. I didn't like you couldnt get parts to rbuilt them if they wore out and no one really new the quality of the metal/welds. Glad you were only in the parking lot.
March 29th, 2015, 04:58 PM
#30
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Hi Mark.
Thanks for the reply.
My plan is to put an order in tomorrow morning for a new set for you. We will get them out to you asap. Also, I'll send you a tag so you can return the old ones for our inspection.
thanks/sorry
Thanks for the reply.
My plan is to put an order in tomorrow morning for a new set for you. We will get them out to you asap. Also, I'll send you a tag so you can return the old ones for our inspection.
thanks/sorry
Octania: The gain in handling is due to the taller ball joints. The lowers have no real advantage apart from that. The upper arms also have taller ball joints and allow for more caster. The deal with tubulars, generically, is more rigidity. We agree that theoretically there shouldn't be any torque that a tubular construction could withstand better than the factory design.
I can show you the stress fracture I found in my original control arm if you want, though. They're certainly not perfect either, especially not seeing as they have 40+ years of wear. I wasn't going to patch them up, and went with the tubulars instead.
Eric: Good. Means the replacements I'll get are reinforced too.
March 29th, 2015, 05:16 PM
#32
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You mean the uppers?
EDIT: looking at the website, they make both adjustable and non-adjustable uppers. I have the latter.
If the car can't come to me, I'll come to the car
https://i.imgur.com/qZfMNlJ.jpg
People kept coming over to chat
https://i.imgur.com/JVM0t9D.jpg
Fracture
https://i.imgur.com/sNcxxmu.jpg
https://i.imgur.com/oeja7Rl.jpg
Missing nut meant I had to leave her like this
https://i.imgur.com/Cfe5g91.jpg
EDIT: looking at the website, they make both adjustable and non-adjustable uppers. I have the latter.
If the car can't come to me, I'll come to the car
https://i.imgur.com/qZfMNlJ.jpg
People kept coming over to chat
https://i.imgur.com/JVM0t9D.jpg
Fracture
https://i.imgur.com/sNcxxmu.jpg
https://i.imgur.com/oeja7Rl.jpg
Missing nut meant I had to leave her like this
https://i.imgur.com/Cfe5g91.jpg
Last edited by Seff; March 29th, 2015 at 05:33 PM.
March 29th, 2015, 06:05 PM
#33
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I had an issue with my first generation UMI roto joints because they didn't use positive locking mechanisms to keep the bushing retainer nuts from backing out. I found it when I pulled my rear end to do other work and started finding massive lateral play in the joint. I likely wouldn't have found it otherwise until I started having a serious issue, probably while driving.
They took care of me without question and updated both joints without cost, but I was always a bit suspicious/irked that they don't "recall" or notify users of their products when they find a significant design defect (and that sufficient field testing isn't performed for fatigue type failures prior to selling product). I understand that aftermarket parts don't come with the same level of rigor and testing that most OEM parts come with, and they have no legal responsibility to notify users... however, it would bother me knowing I had design defects out in operation that could cause harm to people or cars. I switched my parts out to another manufacturer with a better design after that, even though it cost significantly more.
It was a wakeup call to me... get your car on jackstands at least once a year, pull the wheels off, and inspect everything. Wiggle ball joints, check for play in the suspension, look for signs of wear/tear. Factory parts break too (early A-body lower arms aren't known for their strength).
They took care of me without question and updated both joints without cost, but I was always a bit suspicious/irked that they don't "recall" or notify users of their products when they find a significant design defect (and that sufficient field testing isn't performed for fatigue type failures prior to selling product). I understand that aftermarket parts don't come with the same level of rigor and testing that most OEM parts come with, and they have no legal responsibility to notify users... however, it would bother me knowing I had design defects out in operation that could cause harm to people or cars. I switched my parts out to another manufacturer with a better design after that, even though it cost significantly more.
It was a wakeup call to me... get your car on jackstands at least once a year, pull the wheels off, and inspect everything. Wiggle ball joints, check for play in the suspension, look for signs of wear/tear. Factory parts break too (early A-body lower arms aren't known for their strength).
March 29th, 2015, 06:15 PM
#34
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March 30th, 2015, 01:38 AM
#35
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Looks like it. To my mind a tear like that is more due to a bad weld than due to me driving with my head up my butt - it's been splitting for a while, after all.
When I told them I live in Denmark they said they'd have to live with detailed pictures. Offered to cut the offending piece off the control arm and send it to them.
When I told them I live in Denmark they said they'd have to live with detailed pictures. Offered to cut the offending piece off the control arm and send it to them.
Last edited by Seff; March 30th, 2015 at 01:43 AM.
April 7th, 2015, 11:37 AM
#38
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Update: Replacement arms have been sent from the US, no charge. The suggestion on their part was not to over-tighten the bolt, and to remember to grease the bushings, since these failures are typically caused by bind. I greased the bushings a year ago, so I doubt that's the problem.
