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Sorry mods, figured if I post here it might get more answers..
Looking at picking up a 8pt, S&W cage for the Lexus. The mild cage runs about half the price of the Chromoly. The car is a street car and is heavy, not looking at making it too much heavier, but weight is not life or death.. What should I go with? Thank you -Brett
 

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Chromoly DEFINATELY. To me that's like saying "Carbon Fiber or plastic?"

Brian
 

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The cost benefit of using chromoly is definately worth it. As long as you have somebody reputable to weld the chomoly you should go with it. Chromoly and Mild Steel weigh exactly the same. The chromoly ends up being lightter b/c its .083 wall vs .125 wall. a 6+ Chromoly cage in my car weighs 62lbs. Definately look into who will weld it before you make the decision.
 

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Not true. Chromoly is more brittle than mild steel, a will wear out sooner. Chromoly can flex, resulting in fatigue, but it takes the torque of a of a high powered engine to cause this flexing. A chromoly cage or roll bar (when properly installed) should last the life of the race car.
 

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PM-Performance said:
something to think about. Tons of people say mild steel is safer if you end up in an accident
This is very true. Mild steel deforms better in a crash, chromoly is more likely to break. Nascar requires their roll cages to be mild steel if you need proof.

Not saying i'd go mild steel over chromoly, but mild steel might be safer since they make you go thick enough to make up the difference in strength.
 

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You can patch a cromoly cage if you crash it. A mild steel cage is toast if it gets bent. Factor that into cost.
 

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I dont know about nascar but the latest NHRA certs require chro mo for the chassis on the faster cars. In the end it is your call but do it once and be done chro mo
 

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All you have to do is compare the tensile streth of both metals weather you're gonna go with TIG or MIG. My roll cage is made of DOM mild steel, one of the strongest mild steel. I also have chromoly "x" braces in the rear. All mouths were MIG's..

Cost is a lot..but be safe..I wish I had gone all chromolly.
 

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toyman1987 said:
I can not say how much the mild steel weighs, but my S&W 8pt chrome moly weighs 65lbs.
5 pt mild steel roll cage they put in my car today weighed 35 lbs. Actually guess that was a 4 pt, didn't include the swing out door bar.
 

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RichGT said:
How does tensile strength in the welds not apply here?
tensile strenght is one direction, a chassis is pushed/pulled in several diff directions(ie; launch, steep driveway, pothole, etc...)
From my understanding, to be legal, all moly has to be tig welded. To me it comes down to cost and weight. Nascar says mild steel, NHRA says chromally on its fastest cars(I didnt know this??). Neither would mandate something they feel is the lower quality.
If you have the money to go moly, do it. If you need a lighter cage to hit a certain weight, do it. If your on a budget, go mild steel. If weight isnt an issue, go mild. Either choice is better than no cage
 

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I have very little faith in NHRA's 'research' into this subject. Most likely, they just mandated chromoly because it's the strongest and never researched it. Only time rules seem to change over there is when someone dies.

Also, Chromoly has to be tig welded. From my understanding if you Mig weld it it weakens it considerably because it gets the steel too hot. Chromoly almost always breaks about an inch or two from the weld because of the heat zone being the weakest point and with Mig it'll be way worse (IE weaker).
 
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