I am going to order a roll cage sometime this week and i am wandering which is better chromoly or mild steel? I noticed chromoly cages are way more exspensive. aRE they stronger and lighter? or is there no real differance?

PLEASE HELP!!!!!!!!!!!!!!!!!!!!

 

Yes, stronger. I think they are usually spec'ed with the same wall thickness (NHRA rules), so they'd weigh the same.
I personally don't think that extra strength is needed, i've never heard of a roll cage collapsing during a crash, ie, not from welds, but tubing that buckled - they're pretty crazy strong as is. Your call though - what's your life worth I guess eh?

 

chromoly cages are thinner and therefore lighter. They also must be TIG welded instead of regular mild steel which can be MIG'd.

 

Chromoly cages are lighter and thinner material. They are usually .083 thickness compaired to mild steel of .120. Due to a stiuation a few years ago. Most people who sell a mild steel cage that is going to be used for drag racing use .125 DOM mild steel which usually measures .131 or so.

Chromoly does require tig welding and much better fitment when building the cage. If your doing a home job and do not have the correct tool I would highly suggest mild steel. You can get away with more of a gap prior to welding it in the car.

99% of the time I put chromoly cages in cars but then I do not mig weld cages in cars that I have built.

 

For the typical person wanting to put a cage/bar in their car, the weight saving of CM over MS doesn't justify the added cost even if they have access to a TIG machine. Normally when weight is becoming an issue, you're running quicker than 8.0 in the 1/4 mile.

That's not saying a 10-11 second car shouldn't have a CM cage. If the person wants to spend the extra money to save a few pounds then they can.

Tubing size will depend on exactly what you're getting. If you're only buying a roll bar, it doesn't include a halo and a-pillar bars, all the tubes will be 1-3/4" diameter. If you're getting a full cage, most of the bars will be a maximum of 1-5/8" diameter and a bunch of the other bars are only 1-1/2" diameter. Although you'll have more tubes, the weight of a full cage can be only a little more than a simple roll bar.