certified roll cage

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mopar4406bbl

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Can a roll cage that is stick welded get certified?
I went to tech first time out with car,and tech guy said nothing about being stick welded just to add X brace to the 2 bars going through were back seat was .Then said to add a bar across between pillar bars. and last said to replace the swing out bar beside driver. I have purchased cm tubing to make him happy,I know they have to be tig welded.I have been told nhra won't pass a stick welded cage,is this true?
 
Well I called NHRA chassis tech guy tonight,and everything track tech guy said is wrong.track guy saidI needed a bar between " A " pillars and it couldn't be bent.NHRA guy says not needed with a stock fire wall. track guy says I need a X bar between rear bars going through rear seat NHRA guy says not needed if bars are 1 5/8". track guy says swing out bar has to go at 9.99 et, NHRA guy says it is ok to 8.50 et.
 
general nhra regs for full bodied cars that are 8.50 and slower just need a basic cage. chromoly must be tig, mild steel mig or tig. the bar across the drivers door is a minimum of 1 5/8" mild steal .118"thick. NHRA doesnt call for an x brace as long as the tube is at least 1 5/8".
 
I was going to say, I dont have a general rule book, but I recall it stating chromoly must be Tig and everthign else must be Mig or Tig, with no grinding welds.
 
My guess is it's much more common for amatuers to own stick welders, and they had seena bunch of unsafe welding done. Most of the rules are reactive... There must have been a reason.
 
NHRA wants moly tigged.

The reason is the heat affected zone is much smaller when using a tig as you can control heat input better. Moly tends to crystalize when heated and you want to keep that area to a minumum if you can't bring the temp down slowly.

You can mig moly, done it plenty of times.

I know of a few certified moly cages that had multiple welds done with a mig. go figure.

In these pics of a friends work, you can see the outer ring. That's the HAZ area. It would probably be another 50-100% wider using a mig to get adequate penetration.
zt3.jpg

zt2.jpg

zt1.jpg
 
i have walked through the tech lines at maplegrove and there are some cages that ive seen that are like you will go down the track and feel safe with it. but they passed tech so they must be good. i know that welding isnt the easiest but some times it just better to pay for the safety aspect.
 
71produster said:
You can stick welded the cage but you must be very dam good at it!!!
Mild steel only!!!
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The NHRA tech guy told me that a stick welded cage is not suppose to pass certifaction, but You can go over stick welds with tig or mig weld.I can live with that. What suprised me most, was everything track tech told me about cage was wrong.The NHRA tech guy is going to be at local track in 3 weeks,hope to have welds gone over by then and see what happens.
 
mopar4406bbl said:
The NHRA tech guy told me that a stick welded cage is not suppose to pass certifaction, but You can go over stick welds with tig or mig weld.I can live with that. What suprised me most, was everything track tech told me about cage was wrong.The NHRA tech guy is going to be at local track in 3 weeks,hope to have welds gone over by then and see what happens.
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Yes,there are some people teching in cars that should NOT be doing it..i had some genius try to tell me my helmet had expired 2 years ago at the time the helmet was 2 years old,and is approved til 2017...:angry7:
 
how exactly do they check the welds on the 200$ bolt together roll bars on all those 11 sec imports at the track is what i wanna know....
 
Well had NHRA tech guy look cage over and with 1 exception cage is fine.Everyone here may already know this, if you butt weld any bars on your cage you have to put a sleave at least 6" long inside. 2 1/2" on each side of weld you have to drill a 3/8 hole & weld it so you can see the sleave inside.weld around hole to weld bar to sleave, but not a plug weld, inspecter has to be able to see the sleave is long enough. Make sure all bars are fitted correctly an welded all the way around.
 
I know this isn't cage related, but the worse I saw years ago was a front-engine fueler with the engine mounts hose clamped to the chassis rails! Talk about scary.
 
mopar4406bbl said:
The NHRA tech guy told me that a stick welded cage is not suppose to pass certifaction, but You can go over stick welds with tig or mig weld.I can live with that. What suprised me most, was everything track tech told me about cage was wrong.The NHRA tech guy is going to be at local track in 3 weeks,hope to have welds gone over by then and see what happens.
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While going over the welds might make them look kosher, the heat sinking will only be made worse. Chrome-moly has a higher carbon content than mild steel, and at high temperature the carbon migrates and localizes at the weld, making it brittle. Repeated heating will worsen this effect, increasing the chance of cracking at the welds.

As mentioned above, TIG welding limits the area exposed to heat, reducing the amount of carbon that can be pulled into the weld. If you only expose a quarter inch of metal to high temps, then only the carbon in that quarter inch can migrate. Expose an inch of metal, all the carbon in that inch can migrate to the weld. And if you expose the same metal to high temps several times, you will end up with migration each time, resulting in more of the carbon getting closer to the joint.
 
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