Roll bars - Chrome moly vs mild steel

[Skinny]

First off, the things everyone knows: chrome moly IS lighter (about 25lbs on a 6pt bar) and cost about twice as much. Chrome moly is a stronger material.

Now, why would one choose a steel bar over a CM one? Money of course for one. Here's another reason I may be passing on the CM bar... Chrome moly tubing is obviously much stronger than the mild steel tubing, but in effect, that makes it more brittle. On a street driven car (my daily driver), I'm worried that a CM bar, being less resistant to the flex which would have to occur in driving around every day on the streets, would eventually crack. The mild steel bar on the other hand, would be much more apt to absorb the flex and not weaken the bar.

Anyone else have any thoughts on this?

[WishIHad$$$]

I'd play it safe and get the steel. Not only is it cheaper, it's obviously stronger. 25 Pounds won't be that big of a deal. [img]smile.gif[/img]

[StudlyCamaro]

the body flex wont crack a chromemoly cage, if you look at the torsional rigidity and compression loads that it can take before failure you will know what im talking about

and on a side note : i used to work on a formula SAE race car team with my university and i'd guess overr 90% of all the cars that enter the annual event use chromemoly tubing for their whole car. our car pulled over 1.2 G's... the stuff isnt going to crack ;)

[Jerriko]

Originally posted by StudlyCamaro:
the body flex wont crack a chromemoly cage, if you look at the torsional rigidity and compression loads that it can take before failure you will know what im talking about

and on a side note : i used to work on a formula SAE race car team with my university and i'd guess overr 90% of all the cars that enter the annual event use chromemoly tubing for their whole car. our car pulled over 1.2 G's... the stuff isnt going to crack ;)

Yeah, no kidding. Chrome moly isn't going to crack. If you need to save money, buy the steel but don't buy the steel over cm because of misinformation.

[Timbo1969]

Chrome Moly is the way to go.

[WickEdSix9838]

my dads CM tube chassis car has 1000's of low-high 8 second passes on it and none of the tubing has cracked...

[Wicked 3800 V6]

Go CM if you can afford it. Sucks to slice out a steel cage a year later to put in a CM!

[12secondv6]

Skinny has a VERY good point.

This is why I did NOT get a chrome moly k member and a arms.

Yes it is lighter.
Yes it is MORE $$$$
Yes it is stronger.

BUT!

For a STREET car, it is NOT the way to go.

If it is a car that ONLY see's smooth race track set up's then chrome moly is perfect.

If the vehicle see's TRUE street duty where pot holes, uneven roadway's, and sudden shocks to the suspension can occur w/o will then STEEL is the way to go.

Steel will flex, chrome moly is LESS forgiving.

Chrome moly CAN shatter on a STREET car that see's STREET duty.

VERY good point.

My k member and a arms are mild steel.

When I get around to a cage I am still debating but will probably get chrome moly because I don't drive the car much at all anymore.

[StudlyCamaro]

our race car saw lots of time on the street and in not very smooth parking lots, a cage isnt gonna break from a pothole, i can understand not wanting chromemoly a-arms on a street car kind of.. but for a cage it will be fine

[67-03 RIP]

Keep in mind that not every Tom,Dick and Harry can weld CM either (I believe it has to be TIG welded).

As far as potholes, etc making it crack, you can't convince me your (our) daily driver cars hitting a pot hole is going to be tougher on CM than a Top Fuel or Funny Car with 6000 +HP and running 330mph. Watch a TF car sometime - it flexes WAY more than you think.

[mrbako]

can the CM be welded as easily as steel? or will it require special welding..even more $$$?

either wasy i say go w/ the CM, but i don't know what a budget is.

[67-03 RIP]

can the CM be welded as easily as steel? or will it require special welding..even more $$$?

1. No
2. Yes

[Magnus]

Definately get the CM if your wallet can afford it.

I spent about $150 more on a CM cage bacause I know I'll be keeping the car and look for every ounce of performance I can get.. that weight savings is worth it. Saving 30lbs or so for $150 isn't bad at all.