ERW or Seemless (DOM) tubing for wishbones

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Hello, I am having trouble finding out information on whether ERW tubing would be correct to use for upper wishbones on a race car build.  I have built many race cars in the past etc but I have always been given the wishbones to bolt to chassis.  I use rectangular welded tubing for the chassis with ERW round tubing for braces.  All 4130 for roll cages etc.If I use ERW round tube in the size on the spec sheet 1.5" with a 1/8" wall, for the wishbones is this correct?  Round tubing is all that is listed on the drawings, no steel spec or type.  The regulations for touring car racing say nothing about material for wishbones and I need make a call on this yesterday.  I always understood wishbones to be breakable so in the event of an accident the chassis would not be wrecked.BTW this is for the upper wishbones on a 2000lbs touring car.
Reply:Either one would work, DOM would be marginally stronger. Most DOM starts out as welded tube and then is drawn over a mandrel which sets the wall thickness and final dimensions as well as rolls the seam out so you can't see it. It's biggest advantage is that there are no stress risers within the tube. If this is something that if it were to fail would cause some serious safety issues, spend the money and get DOM as well as an engineered drawing and welding procedure. It's all about how much liability you are willing to accept.
Reply:@ v12 guy - interesting topic. Certain you've read Zap's sticky at http://weldingweb.com/vbb/showthread.php...ght=Roll+cages.  Been reading a bit on the applications for 1018 and 4130.  Always impressed by the wizards who fab n fuse these cages of perfection. Another solid reference on mechanical properties for these materials is at www.emjmetals.com.  Their hard-copy volumes of "matl/tech resources" are excellent."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:I think DOM is typically a different alloy too, not just a different process.Welding/Fab Pics: www.UtahWeld.com
Reply:Some reading on the subjecthttp://www.chopperhandbook.com/tubing.htmDave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:I thought Drawn Over Mandrel was a shaping process whereby some tube is subjected to additional forming once it is rolled and welded to form a  tube. ERW is a welding process whereby nearly all tube and/or pipe is welded together once it is rolled into the circular shape. The two phrases aren't necessarily exclusive of each other. Seamless is generally a misnomer. Any pipe or tube that has been welded together has a seam, they merely go the extra step of removing the raised 'flash' left from the welding process on some tubing or pipe."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Lots of info, thanks for the link Dave.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Originally Posted by SandySeamless is generally a misnomer. Any pipe or tube that has been welded together has a seam, they merely go the extra step of removing the raised 'flash' left from the welding process on some tubing or pipe.
Reply:I would think you'd want to ask car builders, not welders.  I realize that some people here might have some experience in that regard, but this seems to be in the realm of a serious engineering question, not a welding technique question.  That doesn't mean that I don't want to know the answer you come up with, just that your question has pretty serious ramifications, where "guessing" or armchair conjecture is not good enough.  Also, are you building this for someone else?  If so, I'd think that if the material is not stated on the drawing, that it's their responsibility to do the research and tell YOU, as the fabricator, what they need.  Otherwise, you're acting as an engineer, as well as a fabricator.  That's not a big deal when making a fence, bench, or probably even a set of metal stairs.  Something with incredible dynamic forces playing on it, and eeeehhhhh, that's a little scary.  Let us know how it all goes!Miller Dynasty 200 DXMiller CP-300 with 30A feederHypertherm Powermax 900Oxy-fuel w/Harris torchesScotchman Glide-in bandsawMonarch 10EE latheEmi-Mec Autoturn latheDeckel FP2NC milling machinePro-Tools 105 Bender