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View Full Version : chromoly tubing, where to buy?


NOT A TA
08-29-2008, 08:37 PM
I'm having a shop install a 10 point cage in my Firebird and dropped it off at the fab shop a couple days ago. After the shop owner talked to the sanctioning body I want to run the car in about whats required they decided on .095 1-5/8 chromoly for most of the cage.

His regular suppliers don't have tubing any in stock so he asked me to check around and see if I could locate it. Anyone have any ideas? We're in New England.

B Schein
08-29-2008, 10:41 PM
There is an airplane supply place in Pennsylvania where Bought some chromoly tubing when I used to live up in the norther part of Maryland But i can't remember there name I know John Parsons knows who it is because he is the one who told me about them. It the closest thing to New England that I know of.

chicane
08-29-2008, 11:16 PM
Any real reason to why you want ChroMo other than to say its made of ChroMo ??

What kind of events are you considering and which sanctioning body are your rules from ??

I only ask because there is no benifit to using ChroMo unless you heat treat the finished product... and in the fashion of a tubular cage... that would mean that you would have to heat treat the entire chassis, which... isnt going to be done. Not to mention that unless you properly preheat the material before weldment and normalize the material after... there is absolutely no benifit to using ChroMo. The extra expense in material cost yields you zero...

A bit of advise ?? I would pick up a copy of Carroll Smith's "Engineer to Win" and then make your determination on what material you should purchase. In fact... if you are going to be doing any kind of motorsport... I would highly recommend that you purchase his whole line of books... trust me, after you read them... you will look at things in a whole 'nother light. >> Click here << (http://www.carrollsmith.com/books/)

I believe... that you would be much better off with using 1018 or 1020 DOM. Especially considering inch and five eighths... o-nine five. That is considered to be the absolute bare minimum size/dia in chassis weights under 3000 to 3200 lbs. Not to forget to mention... in the science of safety... the majority of sanc bodies are making the move towards DOM over that of ChroMo in a unitized chassis. Just the mere fact of 4130/N weld embrittlement would make me run the other way.

Im not saying that ChroMo doesnt have its place, because it sure does and I like to use it myself... but definately not in a unitized chassis. If you built the entire chassis out of ChroMo and had the entire chassis heat treated... I would be all over that !! But... the truth of the matter is, that it is not going to happen.

Educate yourself now... before you make a possible mistake. :thumbsup:


Aircraft Spruce, Industrial Metal Supply, Metals Depot, All Metals Inc, Online Metals... all of which can ship or source the materials you need and in some instances, even locally to you.

Tig Man
08-30-2008, 04:23 AM
aedmotorsports.com

They have the best prices most of the time!

Musclerodz
08-30-2008, 10:02 AM
There is an airplane supply place in Pennsylvania where Bought some chromoly tubing when I used to live up in the norther part of Maryland But i can't remember there name I know John Parsons knows who it is because he is the one who told me about them. It the closest thing to New England that I know of.
Dillsburg Aeroworks or something like that.

B Schein
08-30-2008, 04:18 PM
Dillsburg Aeroworks or something like that.

That sound like it.

NOT A TA
08-30-2008, 08:09 PM
Thanks guys!

Chicane, First let me say thanks for helping knuckleheads like me on these forums. Having read a lot of your posts here and elsewhere it's obvious you're knowledgable and just want to help. Seems like you're an honest to goodness nice guy with no hidden agendas. It'd be a pleasure to meet ya someday.

I don't really care what what the cage is made out of as long as it helps save me should the need arise. Balsa wood would be OK with me if it saved my butt!

Car is a 70 Firebird. Weighs about 3500 lbs (may go on a diet at some point)I have been using the car at NHRA tracks, NASA HPDE events at road courses, and the ECTA. The NHRA tech guys at a couple tracks made it clear that they didn't like my harness setup (Schroths but a little to much angle)and wanted me to have at least a roll bar with a harness bar. The NASA tech guys made it clear that I was kinda going too fast at Road Atlanta for no bar. The ECTA won't let me run over 135 MPH.

Like a lot of folks I was trying to avoid spending the loot and I really liked my interior the way I did it. I have used the car for vacations etc. sometimes driving thousands of miles and the idea of a Kirkey seat, no sun visors, and 5 or 6 point Harnesses on a 12-14 hour drive didn't appeal to me. However the car is slowly evolving into a limited street use car so now's the time! I'm thankfull I never had a mishap at speeds up to 150 and know I should have done these things before.

So I'm on a safety mission and promised myself I won't make the car any faster or run it anywhere till I get few things done so I might live to run again should something go wrong even if the cars totaled. Full cage, Fire system,elec fuel pump shutoff by oil pressure switch,better helmet (got an Arai), fire suit(thinking alpine stars).

The fabricator is familiar with mostly drag car stuff so I got him in touch with Joe Timney of the ECTA. I had spoken with Joe previously about requirements up to about 200 MPH. He'd mentioned door nets etc. as well as some of the requirements most of which went over my head since I'm not a metalurgist, fabricator, or welder. So I thought the fab guys could chat and figure out what I would need to run up near 200 later on. It was after they talked that my fab guy asked about the 095 chromoly and said my other option was the 1020 DOM. I'd be very interested to learn about these things but right now I just want the experts to tell me what needs to be done and someone with the correct skills to do it so I can concentrate on other things. I've built my cars by myself and it 's killing me to let someone else work on it but know someone else can build a safer cage than I can.

I'm going to continue to work up through the NASA groups (I'm in 2 now) and think the TT's would be fun but no side by side racing in this car. I'll be going back to the ECTA probably a couple times a year. I'm planning a west coast trip (trailered) for fall 2009 hoping to run the Silver State classic and/or possibly Bonniville and maybe hit a track day or two at road courses in California. I'm not trying to "win" anything just go out and have fun driving different events. Eventually once the safety stuff is in place I'd like to work on the aerodynamics and add power till I can safely hit 200 MPH.

John

chicane
08-30-2008, 11:08 PM
Hey when you come out for SSC... let me know !!



Wow... do I know what your dealing with.

I too am building a 67 f-body... that has to meet the rule's of three different sanctioning bodies. Please allow me to offer this advise... get all the rule books from the different sanctioning bodies you plan to deal with, and find out what works with what. It will save you tons of headache when dealing with the cats in tech. For instance... its a great idea to "taco" the a-pillar bar to the body and part of the halo to the roof line... and it works for one sanc body... but its illegal in another !! So before you do anything... read up !! Because I am sure you don't want to do things twice... just to make one of them happy.

Food for thought. I am going to use 1 3/4 x .120" for the main structure (the cockpit four point) and then you can use 1 5/8 for the support structures to keep the weight down... without sacrificing strength where it needs to be.

FWIW... I do technical inspection for SCTA/BNI... so I am in the midst of the issues in the 'science of safety' and am actively involved in the direction of making it safer and hopefully setting standards across the board. More specifically, I specialize in dealing with fire suppression systems, roll cage structures, restraints, seats (with emphasis on lateral head restraints), roof flap systems, drive-line (obviously) and at Bonneville this year... fuel systems. So yeah... I know where your going on you safety mission. Keep it up man... learning as much as you can is the right way to do it !!

In specific relation to roll cage structures and the ECTA (which actually follows the majority of the SCTA/BNI rule book)... the ringer statement is, "Vehicles in classes where the existing record exceeds 175MPH must use the larger tube minimum requirements." I can pretty much bet that you will be classified in "Classic Gas Coupe"... and depending on your power plant I think you will most likely be classified in "Gas Coupe." If you swapped in an LSx or something other than was a factory offering, it will depend on where it will place you in the "Production" or the "Modified" category.

The good thing with the seat issue... as I myself use to drive long distances, constantly, with the same idea of comfort... but the new seats, are so damn comfortable... who knows. But in all actuallity... you will only need to bolt in the "Kirkey" for the events you run... and you can always run your regular seats until the required weekend.

As you can see, I have just gotten the chassis to the point where I can get the 108 ft of 1018N tube installed... and had to get the seat in my hands to get its position down to where I can now configure the tubes around me, the driver. I think ya gotta know just how much room you have or don't have to really figure out where critical tube placement needs to be so it doesn't end up to be a jungle gym.

http://i90.photobucket.com/albums/k270/chicane67/IMG_1415.jpg



Ahh yes... the illusive 2. Rules also limit you to what you can and/or cant do in terms of aero modifications. But... I do know... it will take you about 650 to 700 HP to get into the 2's in a second Gen !!

Other notes...

Suit. You are gonna need to get a minimum of a 15... boots and gloves, minimum of 5... for any work 175 MPH and up. For comfort, I would get a two piece suit. If it were me I'd get a 20 two piece, 15 boots and gloves. You are the most important part of the equation... don't skip on PPE. In this arena... if you go over the minimum, your covered in all other sanctioning bodies.

Helmet. I would get something that has top or side feed air. For the super cheap... you can get helmet forced air systems for not only the fresh air requirement of some rules... but it makes a HUGE difference in comfort. Why sweat when there are cold air systems, or you can even make you own, really really cheap. I'm installing a Cool Shirt Pro system with both air to the helmet and water to the suit... just because if you have ever spent anytime in a suit and especially waiting in any kind of line to take the course... its all worth it in terms of fatigue.

Anyway... enough of my rambling... keep me up on your project. It sound like a fun build.

:cheers:

Musclerodz
08-31-2008, 10:55 AM
Any real reason to why you want ChroMo other than to say its made of ChroMo ??

What kind of events are you considering and which sanctioning body are your rules from ??

I only ask because there is no benifit to using ChroMo unless you heat treat the finished product... and in the fashion of a tubular cage... that would mean that you would have to heat treat the entire chassis, which... isnt going to be done. Not to mention that unless you properly preheat the material before weldment and normalize the material after... there is absolutely no benifit to using ChroMo. The extra expense in material cost yields you zero...

A bit of advise ?? I would pick up a copy of Carroll Smith's "Engineer to Win" and then make your determination on what material you should purchase. In fact... if you are going to be doing any kind of motorsport... I would highly recommend that you purchase his whole line of books... trust me, after you read them... you will look at things in a whole 'nother light. >> Click here << (http://www.carrollsmith.com/books/)

I believe... that you would be much better off with using 1018 or 1020 DOM. Especially considering inch and five eighths... o-nine five. That is considered to be the absolute bare minimum size/dia in chassis weights under 3000 to 3200 lbs. Not to forget to mention... in the science of safety... the majority of sanc bodies are making the move towards DOM over that of ChroMo in a unitized chassis. Just the mere fact of 4130/N weld embrittlement would make me run the other way.

Im not saying that ChroMo doesnt have its place, because it sure does and I like to use it myself... but definately not in a unitized chassis. If you built the entire chassis out of ChroMo and had the entire chassis heat treated... I would be all over that !! But... the truth of the matter is, that it is not going to happen.

Educate yourself now... before you make a possible mistake. :thumbsup:


Aircraft Spruce, Industrial Metal Supply, Metals Depot, All Metals Inc, Online Metals... all of which can ship or source the materials you need and in some instances, even locally to you.
You don't need to heat treat 4130/N. The problem is people TIG it and don't pre-heat and post heat to normalize the weld. The heat is so concentrated in MIG and TIG, the welded area is heat treated and needs to be normalized to prevent failure right next to the weld. I have been welding 4130/N for years on vintage airplanes and only gas weld it to prevent embrittlement. It becomes much harder to gas weld large tubing and keep the heat in it so TIG works much better. However extra steps in pre and post heat have to be taken to prevent the embrittlement.

The only real gain to using 4130 is weight savings. Due to its higher strength than DOM, you can run lighter wall tubing. If you are just running a 4 point, I don't think it is worth it, but if you are building an entire cage, I would go the extra to use 4130.

chicane
08-31-2008, 03:10 PM
Ok... with all the talk about ChroMo being stronger than mild steel... lets clear up the real questions to what is behind it all.

For one to just drop the 4130 tag into a discussion is somewhat futile. To specify which 4130 material to use would be respectable. And to suggest the heat treatment of the stated 4130 would be down right noble. You cant just throw the 4130 tag around like its cool... without explaining the difference to your audience... because they might not know any better. In consideration to what is relevant, this response will only deal with 4130A (the typical 4130 material used; hot worked and annealed, and not recommended), 4130N (what should be specified and used for almost everything you would make any worthy part from), and of course... 1018 and 1020 carbon steel. All materials have an 'ultimate tensile strength' and a coinciding value to which they "yield." So, with this, all of the following numeric values will be in psi.

For cold rolled 1018/1020 the number is 82,000 and yield at 70,000
For 4130A the number is 85,000 and yield at 65,000
For 4130N the number is 97,000 and yield at 85,000

By the numbers, metallurgically... there is not that much of a difference... especially when looking at the yield values, which is where we need to concentrate our focus on, for the individual, material strength.

Since 1018 and 1020 don't respond to heat treat, they will be left out of this. But 4130N on the other hand... when heat treated to a C scale of 25 to 30... the heat treat will increase the yield value to somewhere near 130,000 to 135,000+ psi. THAT... is a considerable difference and increase in strength. It almost doubles that of CR 1018/1020 and it does double that of 4130A.

So basically, if you don't heat treat 4130N... all you end up with is an expensive part with the same strength as 1020... and brittle weld areas.

4130 is often considered to be the ideal material for high strength and stress applications... but it really isn't. I keep hearing... "since 4130 is so much stronger than 1018/1020, you can get away with a thinner wall and save some weight." Well... that just isn't true. Unless you heat treat the 4130N material. With the yield strengths being as close as they are with like material diameters and wall thickness'... if you were to actually listen to those who would say this and go to a thinner wall... you would end up with a roll cage structure that would be measurably weaker than that of using 1018/1020.

If you dont heat treat the entire 4130N component... you will end up with embrittlement issues just outside of the weldment because of the martensite appearent just outside of the pearlitic structure formed by localization and not treating the entire structure. I brought up your same arguement a couple of years ago at work... and it went over the same way. I learned not to question the super genius' from that point on. But, at least I got an education out of it... :lol:

Musclerodz
08-31-2008, 04:55 PM
I have never dealt with 4130"A", always 4130"N" in repairing vintage aircraft structures.

Why is there a need to heat treat 4130"N", when you can remove the embrittlement by pre-heating and post heating the weld when TIG or MIG welding it? I never suggested a huge savings over DOM or even 1020. It is a marginal gain for the cost increase.

I think we are in agreement, just coming at it from different directions. And the day I quit learning will be the day I die. :thumbsup:

chicane
08-31-2008, 08:58 PM
Yea Mike... I think/know that we are both in agreement. :yes:

In my opinion, heat treating any material and in specific terms with this thread and 4130 material... goes beyond the mere attribute of embrittlement. Way beyond. But in a short summation, heat treatment can make metals not only harder, but, stronger and tougher. And depending on the material and the 'how and why' you are heat treating it... you can also make metal softer and more ductile.

If you made a part and spent $1000 on it with the ability to yield a certain value of strength... and then had the ability to make the same part but with a 75% increase in strength and fatigue resistance by simply heat treating it... would you not do it ?? I'll even throw that into the specific respect to airframe materials. I am sure if one were to look at the engineering drawings for any given aircraft part... that it will specify a specific heat treatment.

Really my statement was more to point out that the idea of running 4130x and that one could get away with a thinner wall thickness and have the same strength... isn't necessarily true. When looking at the yield number from my last post, without any heat treatment... all you will end up with is an expensive part with the same, and in most cases, less strength than that of 1018/1020. Now if you were to heat treat it... the numbers would go the other way and yield more favorable results.

I believe that if you don't heat treat 4130x... your wasting valuable time and money. Most of the time it is at your customers expense...

When it comes to putting all of this into a unitized chassis... the 1018/1020 material is better suited for this application... without braking the bank.

NOT A TA
09-01-2008, 07:11 PM
So it seems I'll have to meet the specs for at least 4 types of "racing" so to speak. dragstrips, road course, top speed, and open road.

The drag thing isn't a problem because without being a dedicated drag car it won't run quick enough to require more cage than it will have to satisfy the top speed guys.

The road course activities will be limited to HPDE events and there's minimal tech requirements there because it's not door to door racing.

So I really only need to find out what sizes and materials as well as configuration and installation methods will satisfy both the Top speed and open road tech guys while keeping me safe.

I'll order a new tech book from the ECTA and get one from the open road guys.

Thanks for all the info

NOT A TA
09-01-2008, 07:22 PM
For those who stumble on this thread one day doing a search for chromoly and wonder what the car looks like here it is.

http://i240.photobucket.com/albums/ff292/NOTATA/PopHotRodcover-1.jpg

http://i240.photobucket.com/albums/ff292/NOTATA/IMG_0198.jpg

Tom.A
09-02-2008, 10:28 PM
John,

I just went through this same process about 2 months back. I had some telling me do 4130 and others DOM and some shops out there are just using mild steel. When I tried to research rules it seemed like there was no standard. Also it seemed like I read if your floor and firewall are modified or not original that could push into another class. It was all over my head and I think Chicane's advice is good. I am a nobody when it comes to this stuff but his points are things I discovered. The whole post heat treat kinda scared me. When I started my car it was just gonna be a cruiser and by most points still will be just that however the street/track car is appealing more to me. Perhaps in my case starting with a heavier A-Body was not the desired vehicle but it is what is. I also hope to be at the Silver State Classic next fall (Maybe be two years) or Pony Express, Gamblers Run etc. It appears that (I could be wrong) if you show up with a car that has a cage that does not look like a backyard job you will be OK in the lower classes. I believe there are many production cars running in the lower classes. In the SSC the lowest class is 95 MPH avg over the 90 miles you cover. In my case with no driving credentials the max class a rookie can run is 110 MPH avg with a tech speed of 124 MPH.....still sounds like a blast to me. Return trips will with a good staying in the rules record will likely yield an elevated class. I like you don't expect to win anything and in reality my car will only see open track days on road coarse and hopefully some auto x. So in the end I also elected to with 1-3/4" 120 wall DOM. I still have to ad a few things to cage but am happy with the way it came out. You can see pics here http://ls3-chevelle.com/Current_Updates.php , And here is some more reading if you still are pondering 4130. A friend put me in contact with John Parsons and John suggested this link for some reading http://www.netwelding.com/Welding%204130.htm
Good luck on the project and I like the gumballs I got mine in the mail the other day. And if the stars align for SSC maybe will see you out there.

NOT A TA
09-03-2008, 07:19 PM
Tom_a, Your car looks like it's coming out nice! Thanks for the welding link, It backs up what Chicane was getting at as well as Mikes experiences on planes. Looks like the 1 3/4 .120 DOM will be the material of choice for the main hoops. No heat treating worries, embrittlement, etc. I'll wait till I get the SCTA/BNI info to compare with the SSCC requirements before final design is determined.