1. How do you verify that a roll bar is chromoly versus mild steel?
2. You can't mix and match Chromoly and mild steel (e.g. adding steel bars to chromoly bar), right?
Just wargaming a little on the Street "Ruster" Duster ChumpCar idea...
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| Author: | Rob Simmons [ Thu Oct 11, 2012 10:09 am ] |
| Post subject: | How to verify Chromoly roll bar..? |
1. How do you verify that a roll bar is chromoly versus mild steel? 2. You can't mix and match Chromoly and mild steel (e.g. adding steel bars to chromoly bar), right? Just wargaming a little on the Street "Ruster" Duster ChumpCar idea...
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| Author: | slantzilla [ Thu Oct 11, 2012 10:27 am ] |
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If it is Mig welded it will almost definitely be mild steel. CM pretty much has to be Tig welded, and CM that is Mig welded won't pass tech. (Well, not a any track that actually does tech anyway) Some places Tig mild steel too, so that is not a sure tell. CM will be thinner wall, but if you can't see an end on any pipe you won't be able to tell. 
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| Author: | Rob Simmons [ Thu Oct 11, 2012 11:38 am ] |
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Thank you so much for your help...  Ben SAID it was chromoly... So, how do tech inspectors tell the difference then? Do they have some whiz bang thickness checker er sumthin'..? I'll git my weldin' buddy over thar ta give it a look see... 
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| Author: | Fopar [ Thu Oct 11, 2012 12:54 pm ] |
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If it hasn't been painted you should be able to see the printed the full length of tube, both O.D. and wall thickness. At least it is on my CM tubing. Richard |
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| Author: | Rob Simmons [ Fri Oct 12, 2012 4:19 am ] |
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It's been painted. I looked at the welds and to my uninformed eye it looks like TIG...
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| Author: | slantzilla [ Fri Oct 12, 2012 6:16 am ] |
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Mig will look a lot like stick weld, Tig will have a lower bead and be a lot smoother. Yes, if you have a car fast enough to need certed, the NHRA/IHRA will have a sonic checker for wall thickness. |
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| Author: | CNC-Dude [ Fri Oct 12, 2012 9:55 am ] |
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Most people are misinformed about the correct terminology of things in general, and hear the term "Chrome Moly" when guys talk about race cars and either intentionally or unintentionally call all race car roll bars and chassis Chrome Moly not knowing there is a difference between that and mild steel. Its also done a lot with aluminum when people call even the cheapest grades of it "aircraft grade", when only just a few really are. They also make thin wall mild steel, so make sure that someone wasn't trying to get by with lighter weight tubing in an attempt to save weight or money, but failing to realize they sacrificed strength and safety. |
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| Author: | Exner Geek [ Fri Oct 12, 2012 1:49 pm ] |
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There must be some way they determine if a tube is 4130 or not. My old friend Dean Schoers told me it make different color sparks when you hit it with a grinder. It might sound different if you ring it also but I don't know if that works in the car. If all else fails Lou has the spectrometer. |
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| Author: | Dart270 [ Fri Oct 12, 2012 9:08 pm ] |
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Um, uh, yeah. You could do some sort of elemental analysis to see how much Cr and Mo are in there. The different color sparks might tell you this too. IIRC, Mo should make a more reddish color? I'll have to review this... Lou |
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| Author: | Rick Covalt [ Sat Oct 13, 2012 5:10 am ] |
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Rob, You could make friends with someone who works for a Natural gas pipeline company. They all have ultrasonic thickness equipment. Ask me how I know. If you bring your car to Mason Dixon I will have a tester there to check it for you! Rick |
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| Author: | Rob Simmons [ Sat Oct 13, 2012 5:51 am ] |
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Quote: If you bring your car to Mason Dixon I will have a tester there to check it for you!
I a pershee-ate that offer Rick, but this here car prolly ain't gonna be movin' fer a little while. I dun yanked all the suspension off it fer yet another hairbrained idea I got goin'... Rick Once I got the K member out of the way I could really tell how bad the front framerail was. I think one of those Auto Rust Technicians "Safe T Caps" will work fine. I can tell the frame is nice & solid, 'cuz when I put it up on blocks it would "three point" real good. I'll post some pictures of the carnage here shortly...  I'll do a little here & a little there as time and resources allow and eventually we'll have ourselves a "Ruster Duster ChumpCar"! Anybody that wants to play, just let me know.
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