Weight diff. between chromoly and mild steel
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LBC,
I don't know about the cost of roll cages, but I do know a little about steel. CrMo alloys are heavier than an equal volume of lower grade steel, like 1018 for example. However, the weight differential is very slight, but you asked. The beauty of CrMo alloys is that is can be much stronger than 1010 or 1018 alloys, so the cross sections can be thinner, thus lighter. Tubular sections of CrMo are very strong, since the alloy has a very high tensile, compressive, and prehensile strength.
You'll find that CrMo steel alloys are stronger (pound for pound) than the 700/7 (T-graded) aircraft aluminum alloys. That's why compettition bicycles use CrMo tubing instead of aluminum alloys or composites. The Tour de France was won on a stock, off the shelf Trek bike made of CrMo tubing (and one *** -kicking American cyclist, too!)
If the price is prohibitive, get some 3" tubing of your choice from your local steel supplier, a MIG welder, some plates, and start cutting.
------------------
Later,
Vader
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Justice and Freedom will Prevail
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I don't know about the cost of roll cages, but I do know a little about steel. CrMo alloys are heavier than an equal volume of lower grade steel, like 1018 for example. However, the weight differential is very slight, but you asked. The beauty of CrMo alloys is that is can be much stronger than 1010 or 1018 alloys, so the cross sections can be thinner, thus lighter. Tubular sections of CrMo are very strong, since the alloy has a very high tensile, compressive, and prehensile strength.
You'll find that CrMo steel alloys are stronger (pound for pound) than the 700/7 (T-graded) aircraft aluminum alloys. That's why compettition bicycles use CrMo tubing instead of aluminum alloys or composites. The Tour de France was won on a stock, off the shelf Trek bike made of CrMo tubing (and one *** -kicking American cyclist, too!)
If the price is prohibitive, get some 3" tubing of your choice from your local steel supplier, a MIG welder, some plates, and start cutting.
------------------
Later,
Vader
------------------
Justice and Freedom will Prevail
Adobe Acrobat Reader
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From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Mild steel roll cages/bars can be mig welded. Chrme Moly roll cages/bars must be tig welded to pass a tech inspection.
3" is a little large. A 6 point bar only needs 1 3/4" x .118 mild steel or 1 3/4" x .083 of 4130 chrome moly tubing.
A full cage from scratch can use smaller tubing. See an NHRA or IHRA rulebook for all the specifications.
The main reason for using mild steel is the reduced cost. Chrome Moly is used because thinner material can be used to get the same strength as mild steel. Since the material is thinner, the advantage is the weight saving.
My 6 point mild steel roll bar weighs 70 pounds.
------------------
Follow my racing progress on Stephen's racing page
and check out the race car
87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block (times are for the current engine)
Best ET on a time slip: 11.447 altitude corrected to 10.99
Best MPH on a time slip: 119.42 altitude corrected to 124.86
Altitude corrected rear wheel HP: 493
Best 60 foot: 1.586
Racing at 3500 feet elevation with a typical race day over 5000 feet density altitude!
Member of the Calgary Drag Racing Association
87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley
3" is a little large. A 6 point bar only needs 1 3/4" x .118 mild steel or 1 3/4" x .083 of 4130 chrome moly tubing.
A full cage from scratch can use smaller tubing. See an NHRA or IHRA rulebook for all the specifications.
The main reason for using mild steel is the reduced cost. Chrome Moly is used because thinner material can be used to get the same strength as mild steel. Since the material is thinner, the advantage is the weight saving.
My 6 point mild steel roll bar weighs 70 pounds.
------------------
Follow my racing progress on Stephen's racing page
and check out the race car
87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block (times are for the current engine)
Best ET on a time slip: 11.447 altitude corrected to 10.99
Best MPH on a time slip: 119.42 altitude corrected to 124.86
Altitude corrected rear wheel HP: 493
Best 60 foot: 1.586
Racing at 3500 feet elevation with a typical race day over 5000 feet density altitude!
Member of the Calgary Drag Racing Association
87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley
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