its cold outside... aint climbed more than three degrees above the big goose egg for almost a week! ! ! anyhow, now that i have gotten done complaining what is the recomended/required/desired wall thickness for the 1 3/4" diameter roll bar hoop and braces? do these things need to be made of chromoly or can we use mild steel? reason i ask, a guy i work with told me his brother has a pile of s**** length 1 3/4" round mild steel, .120 wall (under 8' pieces is what this dude calls "s****" . . . wonder what the **** he makes? ? ? ) im going to snag up all he has obviously... hell even if all i do is make fence post out of the ****, or sell it to the s****yard for expedited shipping to china so it can build some bridge or something, what the hell it was FREE !!!
According to the NHRA. Mild steel .118 wall or .058 C/M..DOM (drawn over mandrel) tube is the best to use. best consisdentcy(spl) on the wall thickness for M/S. But course Moly is the best material, But it has to be Heli-arc welded.
Thingy is right but, the guy probably has Electric welded tubing. If you put in more bars in the right places, I think it will be fine for the speeds you're going. It wil be hevier though.
gotcha. . . as i say, im takin all he has either way... it'll find a use someplace so DOM is the safest way to go.,.. exactly what i needed to know thanks fellers
The following is just my opinion: In an enclosed car there is some protection provided by the sheetmetal of the body, so using the minimum thickness tubing allowed does not seem all that unreasonable. In an open car the roll bar tubing will have to take the brunt force of any inpack. I for one did not want to suffer an unnecessary injury that when looking back could have been prevented by running a little thicker tubing...or even an extra bar here and there. Pick out something that you feel will keep you safe. Talk to the guys at the metal yard and get their recommendations. I have found the DOM tubing to be pretty good and not too hard to bend. It is easily welded and comes in a wide variety of sizes and tubing thickness. It is not real cheap...but it might be a smart investment.
Fiddy, I used .130 wall tubing on mine. It may be a little heavier, but I figure if something does go wrong, my *** may be a little more protected. At times, I have to laugh at all of this. I used to drag race bikes and all that was required was a helmet, gloves and a leather suit. I was running 8.50 in the quarter at 160 mph. Now I'm having to figure all of this roll over protection and such and I'll hopefullly be running mid to low 13's at 100 mph.
Like Rand Man said - he's probably got HREW tubing (Hot Rolled Electric Welded) - while there was major strength concerns over this type of tube in the "old days" most of the modern produced tubing is nearing the strength of DOM. I wouldn't hesitate to use it to build an HA/GR frame - yeah it'll be a little heavier but it will definately be plenty to hold up to a wreck or roll when built properly, and best of all - it's FREE! It's the best for the budget minded racer, but if you're going for max effiort (lowest ET) then get the molly tubing tack it together with the mig, then have it tig'd together - that will be the lightest weight setup.
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