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Race car tubing?

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Hey guys I am going to need to buy some roll bar tubing for the 1973 celica soon to do the roll cage and tube front end. To run Hot laps and track events etc what should I be buying and welding into the car in terms of size and thickness etc.? What else do I need to consider before buying that I am not aware of? Thanks in advance.

 

ps if someone has a tube bender they are willing to lend me for that would be awesome :)

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1.5" x 0.120 wall DOM covers everything.

Make sure you are using a bender that has the correct bend radii and ovalling requirements and follow FIA spec 253 for your tube layout.

If you are going to do it, might as well do it as if you are going racing...cuz ya never know!!

Edited by nopistons

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Hey, so because this is a topic that can create some good, informative discussion - and as NoPistons mentioned "just in case you go racing", you really should do the footwork now so your cage is correct the first time, and built for the intended end-use of the car, IE: "maybe i'll go rallying one day?" Well, that's a different set of roll cage rules. There are different materials that are approved, but as mentioned, DOM is the standard. :) Before you build your own cage, talk to the local club Tech Inspector. Look a the rule book and look at a couple cars. Requirements are changing more recently than ever before and because this is a primary structure, it is not to be taken lightly.

Why DOM? no seams, its stronger. The FIA in Europe/Asia has a list of "Approved Builders", these builders have fabricated and destructively tested (iaw FIA test procedures) a sample cage and have been deemed worthy, in fact they are so worthy, that the FIA will let them build a cage with weaker, seamed tubing, but you and i can't. And also because we are largely removed from the FIA, we have a local sanctioning body (WCMA) that is largely responsible for the technical specs like roll cages. There is no "approved builder" list in North America, so there are no options, DOM or 4130 it shall be, but 4130 is another discussion...

FIA 253 and 256 should be required reading when preparing a door car for competition.

Many sanctioning bodies have a slightly different but similar requirements for the construction of a roll cage, the primary tubing diameter and thickness are like mentioned above, 1.5" x .120" for your vehicle as it will be under a certain weight, 2500-3000lbs usually for 1.5". WCMA, SCCA, NASA, HSR all have there own, even a WCMA club, the SCCBC has there own roll cage rules in addition to the WCMA rules...the list is long, special events like the Silver State Classic Challenge and the Pikes Peak Hill climb have their own roll cage requirements as well (and they will let you build a cage from Aluminum!). Drag racing is a different animal, so is Rally - all different cages. So, talk to the WSCC technical representative and look at the latest updates to cage design and you will be on the right track.

matt

PS: i have rented a mandrel bender in the past from Campbell North rentals, not sure if they are still around but it was a good bender, under 2% ovality.

PPS: i have a UT tester for verifying wall thickness thinning at bends. Wall thickness tends to thin out at .0015" per inch of bend radius used. So a 10" bend rad can expect .015" reduction of wall thickness, or .120" becomes .105" at the outside apex of a 90 degree bend with a 10" rad.

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True, and if he does go rally racing, the extra bars can easily be added to the standard FIA bar layout.

There are a couple folks who regularly run in Gimli with "rally" cages for the inevitable "someday".

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2017 WCMA stipulations for ovality is 8%

 

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Out of curiousity anyone off hand know what Targa Newfoundland would require? Asking just incase someday happened. 

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Yes, and they have there own regs as well, you will notice they cut and pasted FIA 253 illustrations and some text here and there. If you ever wanted to know about running there, talk to Dyrk, he's ran it 3 times and can answer questions with first hand experience.

http://targanfld.com/wp-content/uploads/2016/02/Volume-2c-Rollcage-Construction-Installation-4.pdf

from page 4:

"(íi) Material All roll cage shall be manufactured from cold drawn seamless ERW or DOM mild steel tubing.

Gross vehicle weight under 2000 lbs (910 kgs) MILD STEEL 1.50 x .120

Gross vehicle weight over 2000 lbs (910 kgs) MILD STEEL 1.75 x .120

These figures represent the minimal allowed. In selecting the steel, attention must be paid to obtaining good elongation properties and adequate weld ability. An inspection hole of at least 4.5 mm diameter must be drilled in a non-critical area of the main hoop to facilitate verification of wall thickness."

This does not reflect the WCMA mandate of DOM only OR the same weight breaks for tube specs. These special events all have a different take on this. and I may be wrong, but i think your car has to be approved at the local level before you take it anywhere else - maybe somebody with more experience can chime in on that? i could see that stipulation being a road block if, for example, you build a cage to the Targa specs above with ERW and it fails WCMA tech, but is acceptable at the Targa...but you cant run there because your car isn't certified locally...

Edited by mcorrie

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If it was easy, everyone would do it...

http://www.wcma.ca/new/wp-content/uploads/2018/02/2018-WCMA-Technical-Regulations-02012018.pdf

https://www.fia.com/file/73846/download/20691?token=-HU9nfAD - appendix J of article 253

https://www.fia.com/sites/default/files/regulation/file/253 (2015).pdf - article 253

Reading the FIA stuff can be a pain in the ass. Lots of cross referencing other documents/sections. Appendix J of 253 has the diagrams and most of the technical details of what you should build.

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