I'm about to get a roll bar put in my car, and I'm trying to decide if its worth the extra $$$ to go with chromoly. For a 5 or 6 point roll bar, can anyone give me an idea of how much lighter the chromoly roll bar will be?

I've been doing some research, and it seems that the chromoly is not lighter itself; its just stronger. This allows you to use smaller tubes, which are lighter. I don't know the weight differences between the 2 different sizes of pipes or how much piping a roll bar takes, so I can't make a final calculation.

I've read that a full SCCA-approved cage weighs 8-12 lbs less with the chromoly. I've also heard that a 6-point roll bar will weigh 35 lbs less with chromoly. Which sounds more accurate? Or perhaps there's a middle ground? I'm trying to decide if its worth the extra $$$ and time it will take to get the chromoly roll bar in. The shop I've elected to do the install can't get the chromoly bar done in time for my final race of the season (IDRC on sept. 7th)

 

I say go chromoly! We need to save all the weight we can... Its not like we drive torque monsters

I can't exacly recal the exact weight difference but it is something like 1/3rd the weight of mild steel....Plus its strong as ****!

 

http://www.oceanstreetvideo.co...l.htm

Any thoughts?

 

Chromoly is 30% lighter than the mild steet. I run a chromoly cage in my car and love it. The welds look awesome as well since chromoly has to me TIG welded where as mild steel only MIGed...not to mention TIG welding is an *** load stronger than MIG.

-Ryan

 

Everyone, check this out: (I found it with a simple google search), it is whats was in the link I posted initially

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Many people keep getting the impression that Chromoly is lighter than mild steel roll bars. not true! The only reason that myth got started is because chromoly is actually stronger than mild steel it allows you to use a lighter guage or thinner wall tubing. That is where the weight savings comes in. If you were to use a .120 wall Chromoly tubing vs. a .120 wall Mild Steel tubing...there would be no weight savings. The difference in weight comes from being able to use .095 Chromoly vs. .120 wall Mild steel because of the strength characteristics of Chromoly. This is factual and anyone who has constructed roll cages and chassis will tell you the same thing. Another thing to keep in mind is that Chromoly characteristics change when welded and the chassis should be annealed (heat treated) so the integrity of the chassis is sound. Chromoly is very strong but the welding along creates weak points outside the welds where it often cracks under continuous stress. Mild Steel, on the otherhand, is more forgiving and not as brittle. Many circle track racers have used Mild Steel tubing for years which when braced properly can give you just as much good protection. If you are building a roll cage...and are concerned with overall car weight..use the lighter wall chromoly. If you are just looking for safety and it is a street car...use Mild Steel. You will be just as safe and it will cost you a lot less for a little difference in weight. This comes from personal experience so just take it as food for thought. Rick M Phoenix Rick M </TD></TR></TABLE>

I am trying to get an idea of the magnitude of the weight differences for the roll bar constructed of the small tubing, since all the research that I've done says that the weight of 2 equally sized bars (crhomoly vs mild steel) is the same!

 

not to change subjects. Is there anyway to tell by just looking if your cage is chromoly or mild steel? thanks.

 

I read that. All I am saying is that there is a 30% weight savings available...so if you go witht the smaller chromoly bars you will save weight. There is really no point in having a cage made out of the bigger chromoly when you can just have it made out of the mild steel for cheaper. I think it all comesdown to how much you want to spend. The difference in price for my chromoly cage was $400.

-Ryan

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by autoEXturbo &raquo;</TD></TR><TR><TD CLASS="quote">not to change subjects. Is there anyway to tell by just looking if your cage is chromoly or mild steel? thanks.</TD></TR></TABLE>

Look at the welds.

 

you have any pics of the difference between a mig and tig weld?

 

Not in front of me...MIG welds tend to be larger in size. (Like what an exhaust shop would do) While TIG welds are more compact and precise looking. (I hope that makes sense)

-Ryan
This is a TIG weld

Picture courtesy of rev210

This is a MIG weld

Picture courtesy of racinskittle


Modified by Kwuaymaikrup at 2:00 PM 8/22/2003

 

before I graduated college....my instructor talked about cages with us. he's an old can an, trans am, indy, nascar, bonnevile, world outlaw racer....

he said that chromoly was the devil. it's strenght is almost TOO much. It doesn't bend...and when in a wreck with it...it can hurt more than help.

They used to say in indy...this is when they first started using CM, that....when there was a wreck you'd replace the body and the driver...and not mess with the frame.

 

with teh tubing size we use for roll cages and roll bars, the mild steel weighs about 3lbs a foot and the CM weighs about 2lbs a foot. A civic would need about 30ft to make a roll bar.

do the math and you get

mild steel- 90 lbs
CM- 60 lbs

 

I hope that top weld is not TIG

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stierhund &raquo;</TD></TR><TR><TD CLASS="quote">I hope that top weld is not TIG</TD></TR></TABLE> Got a better one for ya...that other hardly did TIG any justIce. Just the first one I came across.

-Ryan

 

thanks for the pick kwuamaikrup, now I can check to make sure mine is chromoly.