Roll bar material: Chromoly or Steel?
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From: Around, VA, USA
Roll bar material: Chromoly or Steel?
I was looking at purchasing a roll bar for my car and was wondering which would be a better material to go with for the street. Steel or Chromoly? I know the chomoly is lighter but is it also stronger or are they the same? thanks
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From: Hudson, NH, 03051
Re: Roll bar material: Chromoly or Steel? (Infinity_Racer)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Infinity_Racer »</TD></TR><TR><TD CLASS="quote">I was looking at purchasing a roll bar for my car and was wondering which would be a better material to go with for the street. Steel or Chromoly? I know the chomoly is lighter but is it also stronger or are they the same? thanks</TD></TR></TABLE>
Rubber would be the best material unless your going to wear your helmet every day.But if your going to do it mild steel would be fine.
Rubber would be the best material unless your going to wear your helmet every day.But if your going to do it mild steel would be fine.
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From: cincinnati, ohio, u.s.
Re: Roll bar material: Chromoly or Steel? (NJIN BUILDR)
from what i know wich isnt much they both weigh the same. but cm is stronger and you can use a thinner diameter pipe and achieve the same result. in a car that once wrecked its easier to buy a new shell then fix the wrecked car just use mild steel.
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From: retired 2/13/10
Re: Roll bar material: Chromoly or Steel? (mrbh22)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrbh22 »</TD></TR><TR><TD CLASS="quote">from what i know wich isnt much they both weigh the same. but cm is stronger and you can use a thinner diameter pipe and achieve the same result. in a car that once wrecked its easier to buy a new shell then fix the wrecked car just use mild steel.</TD></TR></TABLE>
this is correct. until sometime last year i didnt know that chromoly was the same weight as mild. as mrbh22 said you are allowed to use a thinner material when using chromoly making the cage lighter than if you had the equivalent mild.
this is correct. until sometime last year i didnt know that chromoly was the same weight as mild. as mrbh22 said you are allowed to use a thinner material when using chromoly making the cage lighter than if you had the equivalent mild.
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From: chambersburg, PA, usa
Re: Roll bar material: Chromoly or Steel? (1 2 NV)
chromoly does have a higher tensile strength than mild steel. but it is also alot more brittle. i myself would use the steel
the steel will bend before snap as the chromoly will snap before bend.
really your choice. actual car that use chromoly for a cage or frame setup should have the piece heated and brought back down by slow temps. beleive its called aneilling or something like that. mucho expensive, but most people dont do it that way anyway, unless your a big company
the steel will bend before snap as the chromoly will snap before bend.
really your choice. actual car that use chromoly for a cage or frame setup should have the piece heated and brought back down by slow temps. beleive its called aneilling or something like that. mucho expensive, but most people dont do it that way anyway, unless your a big company
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From: Macon, Ga
Re: Roll bar material: Chromoly or Steel? (postman)
CM is stronger, hence less chassis flex, so it will make a difference on a auto-x course or drag strip. You also have to weld it a certain way(TIG). The material is approx twice as much.
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From: CT
Re: Roll bar material: Chromoly or Steel? (postman)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">actual car that use chromoly for a cage or frame setup should have the piece heated and brought back down by slow temps. beleive its called aneilling or something like that. mucho expensive, but most people dont do it that way anyway, unless your a big company</TD></TR></TABLE>
That is all incorrect. For the thickness that you use in a cage (0.083 wall) you do not need to heat treat before or after the weld.
Don't spread incorrect info like that.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">the steel will bend before snap as the chromoly will snap before bend.
</TD></TR></TABLE>
Also another incorrect statement....
That is all incorrect. For the thickness that you use in a cage (0.083 wall) you do not need to heat treat before or after the weld.
Don't spread incorrect info like that.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">the steel will bend before snap as the chromoly will snap before bend.
</TD></TR></TABLE>
Also another incorrect statement....
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From: Portland, OR
Re: Roll bar material: Chromoly or Steel? (Infinity_Racer)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Infinity_Racer »</TD></TR><TR><TD CLASS="quote">I was looking at purchasing a roll bar for my car and was wondering which would be a better material to go with for the street. Steel or Chromoly? I know the chomoly is lighter but is it also stronger or are they the same? thanks</TD></TR></TABLE>
Like others said. They weigh the same if the tube is the same diameter and thickness. CM is stronger so you can use a thinner tube, thus its lighter. If you're planning on tracking the car (or even if you're not) I'd look into the rules for the sanctioning club that you're running with to be sure that what you're getting will pass their specs. The SCCA and NASA both allow CM and Mild steel, but the mild MUST be DOM, not ERW.
Cost may also be an issue, is the savings in weight worth the extra money?
Like others said. They weigh the same if the tube is the same diameter and thickness. CM is stronger so you can use a thinner tube, thus its lighter. If you're planning on tracking the car (or even if you're not) I'd look into the rules for the sanctioning club that you're running with to be sure that what you're getting will pass their specs. The SCCA and NASA both allow CM and Mild steel, but the mild MUST be DOM, not ERW.
Cost may also be an issue, is the savings in weight worth the extra money?
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From: Cincinnati, Ohio, USA
Re: Roll bar material: Chromoly or Steel? (tepid1)
[QUOTE=tepid1]That is all incorrect. For the thickness that you use in a cage (0.083 wall) you do not need to heat treat before or after the weld.
Don't spread incorrect info like that.
Before you start telling people wrong information because of an opinion of your own back up some of your information with facts from reliable sources. You are REQUIRED to heat treat Chromoly because it will become brittle at the weld joint and crack in the event of an accident. This site pisses me off because one person said that you don't need to do something and the whole site swings from his nuts and takes his opinions and restates them. I have seen thin wall chromoly crack first hand because the idiots that built the frame didn't stress relieve the welds. Go read some books by Carroll Smith. He is a well known race car builder that has been in every venue from nascar to F1. He will tell you everything you need to know about engineering things to make it through a race.
As for the original question just use mild steel you are not saving very much weight, and without the proper treatment and welding procedures of a chromoly cage will not benefit you in a roll over.
Don't spread incorrect info like that.
Before you start telling people wrong information because of an opinion of your own back up some of your information with facts from reliable sources. You are REQUIRED to heat treat Chromoly because it will become brittle at the weld joint and crack in the event of an accident. This site pisses me off because one person said that you don't need to do something and the whole site swings from his nuts and takes his opinions and restates them. I have seen thin wall chromoly crack first hand because the idiots that built the frame didn't stress relieve the welds. Go read some books by Carroll Smith. He is a well known race car builder that has been in every venue from nascar to F1. He will tell you everything you need to know about engineering things to make it through a race.
As for the original question just use mild steel you are not saving very much weight, and without the proper treatment and welding procedures of a chromoly cage will not benefit you in a roll over.
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From: ca
Re: Roll bar material: Chromoly or Steel? (Electron_LS-Vtec)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Electron_LS-Vtec »</TD></TR><TR><TD CLASS="quote">[QUOTE=tepid1]This site pisses me off because one person said that you don't need to do something and the whole site swings from his nuts and takes his opinions and restates them.</TD></TR></TABLE>
you dont expect us to swing on your nuts, do you?
Modified by Lamchop0000 at 12:53 AM 1/31/2007
you dont expect us to swing on your nuts, do you?
Modified by Lamchop0000 at 12:53 AM 1/31/2007
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From: CT
Re: Roll bar material: Chromoly or Steel? (Electron_LS-Vtec)
Here is some good info that you should go by. This is from a race car fabricator....
Q. Can I weld 4130 using the TIG process?
A. Yes, 4130 Chrome-Moly has been TIG welded in the aerospace and aircraft industries for years. As with all welding, proper procedures and techniques must be followed.
Q. Do I need to pre-heat?
A. Thin wall tubing (< 0.120" wall) applications do not typically require the normal 300ºF to 400ºF pre-heat to obtain acceptable results. However, tubing should be at room temperature (70ºF) or above before welding.
Q. What filler material do I use?
A. Although there are several good filler materials, ER80S-D2, is one you should consider. This filler material is capable of producing welds that approximate the strength of 4130. ER-70S-2 is an acceptable alternative to ER80S-D2, as is ER70S-6, although the weld strength will be slightly lower.
Q. When I use ER70S-2 filler material, do I give up strength for elongation?
A. Yes. The filler material, when diluted with the parent material, will typically undermatch the 4130. However, with the proper joint design (such as cluster or gusset, for example), the cross-sectional area and linear inches of weld can compensate for the reduced weld deposit strength.
Q. Why is 4130 filler metal not recommended?
A. 4130 filler typically is used for applications where the weld will be heat treated. Due to its higher hardness and reduced elongation, it is not recommended for sporting applications such as experimental airplanes, race car frames, roll cages, etc.
Q. Can I weld 4130 using any other filler metals?
A. Some fabricators prefer to use austenitic stainless steel fillers to weld 4130 tubing. This is acceptable provided 310 or 312 stainless steel fillers are used. Other stainless steel fillers can cause cracking. Stainless filler material is typically more expensive.
Q. Do I need to heat treat (stress relieve) 4130 after welding?
A. Thin wall tubing normally does not require stress relief. For parts thicker than .120", stress-relieving is recommended and 1,100ºF is the optimum temperature for tubing applications. An Oxy/Acetylene torch with neutral flame can be used. It should be oscillated to avoid hot spots.
Q. Do I have to pre-clean 4130 material?
A. Remove surface scale and oils with mild abrasives and acetone. Wipe to remove all oils and lubricants. All burrs should be removed with a hand scraper or de-burring tool. Better welding results with clean materials.
Q. Do I need to back-purge 4130 material?
A. Backpurging is not normally necessary, although some fabricators do. It will not hurt the weld and may improve the root pass of some welds.
Q. Should I quench the metal after I finish welding?
A. ABSOLUTELY NOT! Rapid quenching of the metal will create problems such as cracking and lamellar tearing. Always allow the weld to slow cool.
Here are some cooling rates to go by for thin wall material....
Tube = .0625 in wall; V (volts) = 10; I (amps) = 90; travel = 11 ipm
Using thin plate equation:
-2*3.1416*0.024*0.29*0.11= -.00481
Hnet = 2.33
(h/Hnet)2 = 0.000718
(Tc-To)3 = 1.07*109
Rc = -3700 deg F / min = - 62 deg F / sec
Tube = .093 in wall; V (volts) = 10; I (amps) = 110; travel = 9 ipm
Using thin plate equation:
-2*3.1416*0.024*0.29*0.11= -.00481
Hnet = 3.48
(h/Hnet)2 = 0.000713
(Tc-To)3 = 1.07*109
Rc = -3671 deg F / min = - 61 deg F / sec
More good info can be found here....
http://www.netwelding.com/4130...s.htm
http://www.netwelding.com/Welding%204130.htm
You have to do it right. You can't cut corners and you have to be an experienced welder. If you can follow the cooling rates above you have a good chance that it will not be brittle and it will be just a strong as MS.
So before you try to act like you know something, put on your big boy pants first.
Q. Can I weld 4130 using the TIG process?
A. Yes, 4130 Chrome-Moly has been TIG welded in the aerospace and aircraft industries for years. As with all welding, proper procedures and techniques must be followed.
Q. Do I need to pre-heat?
A. Thin wall tubing (< 0.120" wall) applications do not typically require the normal 300ºF to 400ºF pre-heat to obtain acceptable results. However, tubing should be at room temperature (70ºF) or above before welding.
Q. What filler material do I use?
A. Although there are several good filler materials, ER80S-D2, is one you should consider. This filler material is capable of producing welds that approximate the strength of 4130. ER-70S-2 is an acceptable alternative to ER80S-D2, as is ER70S-6, although the weld strength will be slightly lower.
Q. When I use ER70S-2 filler material, do I give up strength for elongation?
A. Yes. The filler material, when diluted with the parent material, will typically undermatch the 4130. However, with the proper joint design (such as cluster or gusset, for example), the cross-sectional area and linear inches of weld can compensate for the reduced weld deposit strength.
Q. Why is 4130 filler metal not recommended?
A. 4130 filler typically is used for applications where the weld will be heat treated. Due to its higher hardness and reduced elongation, it is not recommended for sporting applications such as experimental airplanes, race car frames, roll cages, etc.
Q. Can I weld 4130 using any other filler metals?
A. Some fabricators prefer to use austenitic stainless steel fillers to weld 4130 tubing. This is acceptable provided 310 or 312 stainless steel fillers are used. Other stainless steel fillers can cause cracking. Stainless filler material is typically more expensive.
Q. Do I need to heat treat (stress relieve) 4130 after welding?
A. Thin wall tubing normally does not require stress relief. For parts thicker than .120", stress-relieving is recommended and 1,100ºF is the optimum temperature for tubing applications. An Oxy/Acetylene torch with neutral flame can be used. It should be oscillated to avoid hot spots.
Q. Do I have to pre-clean 4130 material?
A. Remove surface scale and oils with mild abrasives and acetone. Wipe to remove all oils and lubricants. All burrs should be removed with a hand scraper or de-burring tool. Better welding results with clean materials.
Q. Do I need to back-purge 4130 material?
A. Backpurging is not normally necessary, although some fabricators do. It will not hurt the weld and may improve the root pass of some welds.
Q. Should I quench the metal after I finish welding?
A. ABSOLUTELY NOT! Rapid quenching of the metal will create problems such as cracking and lamellar tearing. Always allow the weld to slow cool.
Here are some cooling rates to go by for thin wall material....
Tube = .0625 in wall; V (volts) = 10; I (amps) = 90; travel = 11 ipm
Using thin plate equation:
-2*3.1416*0.024*0.29*0.11= -.00481
Hnet = 2.33
(h/Hnet)2 = 0.000718
(Tc-To)3 = 1.07*109
Rc = -3700 deg F / min = - 62 deg F / sec
Tube = .093 in wall; V (volts) = 10; I (amps) = 110; travel = 9 ipm
Using thin plate equation:
-2*3.1416*0.024*0.29*0.11= -.00481
Hnet = 3.48
(h/Hnet)2 = 0.000713
(Tc-To)3 = 1.07*109
Rc = -3671 deg F / min = - 61 deg F / sec
More good info can be found here....
http://www.netwelding.com/4130...s.htm
http://www.netwelding.com/Welding%204130.htm
You have to do it right. You can't cut corners and you have to be an experienced welder. If you can follow the cooling rates above you have a good chance that it will not be brittle and it will be just a strong as MS.
So before you try to act like you know something, put on your big boy pants first.
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From: chambersburg, PA, usa
Re: Roll bar material: Chromoly or Steel? (tepid1)
u my friend no nothing. regardless if your a race car fabricator or not. hell my little brother calls himself that and hes 12. and the snap before bend sit. doesnt mean always. but a good chance.
and the heating process isnt for the welds its for the entire project. like a garage size oven.
so before you start talking **** get the dick out your mouth
also i have a degree for chassis fabrication, i dont build chassis everyday but i know what i know. but since im not a showboat like you i forgot to mention that earlier.
i said good day!!!
and the heating process isnt for the welds its for the entire project. like a garage size oven.
so before you start talking **** get the dick out your mouth
also i have a degree for chassis fabrication, i dont build chassis everyday but i know what i know. but since im not a showboat like you i forgot to mention that earlier.
i said good day!!!
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From: CT
Re: Roll bar material: Chromoly or Steel? (postman)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">the steel will bend before snap as the chromoly will snap before bend.
</TD></TR></TABLE>
So basically you are saying that you can't bend cromoly or it will snap....
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">u my friend no nothing.
</TD></TR></TABLE>
Hmmm I think you might want to reconcider what you wrote and apply it to yourself.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">also i have a degree for chassis fabrication, i dont build chassis everyday but i know what i know. but since im not a showboat like you i forgot to mention that earlier.
</TD></TR></TABLE>
So please educate us all. I am curious what for YEARS people have been building cages and not heat treating them. So you are effectively telling me that everyone has been doing it wrong.... please.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">so before you start talking **** get the dick out your mouth
</TD></TR></TABLE>
First off that just doesn't make sense.... you just showed your maturity with that sentence. If you can even call what you write a sentence.... go back to school homie.
</TD></TR></TABLE>
So basically you are saying that you can't bend cromoly or it will snap....
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">u my friend no nothing.
</TD></TR></TABLE>
Hmmm I think you might want to reconcider what you wrote and apply it to yourself.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">also i have a degree for chassis fabrication, i dont build chassis everyday but i know what i know. but since im not a showboat like you i forgot to mention that earlier.
</TD></TR></TABLE>
So please educate us all. I am curious what for YEARS people have been building cages and not heat treating them. So you are effectively telling me that everyone has been doing it wrong.... please.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">so before you start talking **** get the dick out your mouth
</TD></TR></TABLE>
First off that just doesn't make sense.... you just showed your maturity with that sentence. If you can even call what you write a sentence....
go back to school homie.
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Joined: Sep 2003
Posts: 8,357
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From: CT
Re: Roll bar material: Chromoly or Steel? (postman)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">ur a waste of space.
</TD></TR></TABLE>
I know you are, but what am I?
</TD></TR></TABLE>
I know you are, but what am I?
B*a*n*n*e*d
Joined: Jan 2002
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From: retired 2/13/10
Re: Roll bar material: Chromoly or Steel? (tepid1)
ive read the same thing about not annealing chromoly if its under a certain thickness and .083 falls under that. no annealing needed IMO.
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From: Dallas, TX, USA
Re: Roll bar material: Chromoly or Steel? (1 2 NV)
Don't you think chromoly cages would not be legal if they were as unsafe as some of you people make it seem?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">u my friend no nothing</TD></TR></TABLE>
Just wanted to quote that, though it was pretty funny. The intelligence behind it just slaps you in the face! lol
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">u my friend no nothing</TD></TR></TABLE>
Just wanted to quote that, though it was pretty funny. The intelligence behind it just slaps you in the face! lol
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From: madison, south dakota, u.s.a.
Re: Roll bar material: Chromoly or Steel? (tony1)
the last race car frame we purchased(2002 moulder late model, from iowa) was for NMRA sanction, fastest full bodied dirt cars in our area 355 alcohol motors, unlimited suspension options, except for the udtra hava-tampa series or whatever it's called now, but anyways it was chromoly and it was mig welded? i dont know much about welding but i know enough to know that it was not tigged and i know it was chromoly
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From: CT
Re: Roll bar material: Chromoly or Steel? (tony1)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 »</TD></TR><TR><TD CLASS="quote">The intelligence behind it just slaps you in the face! lol</TD></TR></TABLE>
His intelligence just radiates from his comments.... Glad it wasn't just me that noticed that....
His intelligence just radiates from his comments.... Glad it wasn't just me that noticed that....
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From: Catching Rivers on Fire TWICE
Re: Roll bar material: Chromoly or Steel? (tepid1)
just to be a devils advocate<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tepid1 »</TD></TR><TR><TD CLASS="quote">
Hmmm I think you might want to reconcider what you wrote and apply it to yourself.</TD></TR></TABLE>
reconsider , but i still think you're more cool
Hmmm I think you might want to reconcider what you wrote and apply it to yourself.</TD></TR></TABLE>
reconsider
, but i still think you're more cool
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From: CT
Re: Roll bar material: Chromoly or Steel? (Soccerking3000)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Soccerking3000 »</TD></TR><TR><TD CLASS="quote">
reconsider , but i still think you're more cool</TD></TR></TABLE>
lol good catch
reconsider
, but i still think you're more cool</TD></TR></TABLE>lol good catch
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From: Houston, Texas, USA
Re: Roll bar material: Chromoly or Steel? (postman)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman »</TD></TR><TR><TD CLASS="quote">chromoly does have a higher tensile strength than mild steel. but it is also alot more brittle. i myself would use the steel
the steel will bend before snap as the chromoly will snap before bend.
really your choice. actual car that use chromoly for a cage or frame setup should have the piece heated and brought back down by slow temps. beleive its called aneilling or something like that. mucho expensive, but most people dont do it that way anyway, unless your a big company</TD></TR></TABLE>
Thats crazy because I bend it with my tube bender all the time, never once had it snap
-James
the steel will bend before snap as the chromoly will snap before bend.
really your choice. actual car that use chromoly for a cage or frame setup should have the piece heated and brought back down by slow temps. beleive its called aneilling or something like that. mucho expensive, but most people dont do it that way anyway, unless your a big company</TD></TR></TABLE>
Thats crazy because I bend it with my tube bender all the time, never once had it snap
-James
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Joined: Dec 2006
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From: Calgary, Alberta, Canada
Re: Roll bar material: Chromoly or Steel? (nateg)
"the last race car frame we purchased(2002 moulder late model, from iowa) was for NMRA sanction, fastest full bodied dirt cars in our area 355 alcohol motors, unlimited suspension options, except for the udtra hava-tampa series or whatever it's called now, but anyways it was chromoly and it was mig welded? i dont know much about welding but i know enough to know that it was not tigged and i know it was chromoly."
This is bad. The world will keep turning, but I wouldn't want that protecting me. NHRA etc. spec GTAW for a reason. The main reason is so they can see
the weld quality. Any hack can run a downhand mig on a cage, and it can be very pretty and be only surface fusion, or even cold-lapped.
Another reason is the amount of heat input.
This is bad. The world will keep turning, but I wouldn't want that protecting me. NHRA etc. spec GTAW for a reason. The main reason is so they can see
the weld quality. Any hack can run a downhand mig on a cage, and it can be very pretty and be only surface fusion, or even cold-lapped.
Another reason is the amount of heat input.
Screw you guys, I'm... going... home.
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From: lovely Raleigh, NC
Re: Roll bar material: Chromoly or Steel? (jjspec)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jjspec »</TD></TR><TR><TD CLASS="quote">CM is stronger, hence less chassis flex, so it will make a difference on a auto-x course or drag strip. </TD></TR></TABLE> Actually the stiffness or "spring" constant of both materials is almost identical. The difference is that you can bend the CM "spring" farther (i.e. apply more stress) before it yields, but so long as you are staying within the elastic limits of the materials (i.e. not hitting a tree) the chassis/roll cage flex will be the same. Just an FYI.
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From: madison, south dakota, u.s.a.
Re: Roll bar material: Chromoly or Steel? (9bells)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 9bells »</TD></TR><TR><TD CLASS="quote"> NHRA etc. spec GTAW for a reason. </TD></TR></TABLE>true but in our sanction they dont require that, if they suspect somthing bad they drill a hole and measure thickness of the material, or cut a small area of weld. and when you buy a car from a reputable builder around here you know you get quality parts and service