chromoly tubing for cage ?

[ProdigyCustoms]

I love these sites. I am able to give advice and share my experiance and make a living doing this. How cool is that.

Know what is even more cool? When a thread like this comes up and really makes me think. Making me think enough that we may change our views on a important decison we are about to make on Project Unfairs cage.

Up until this thread got me really doing some math, we had it in our heads we would use Chrome Moly. But when I do the math, best I can figure we will save 40LBs to 50LBS at best by using .95 Wall Chrome Moly (1.679 lbs per foot) VS .120 Wall DOM (2.089 lbs per foot). Now it is 40LB to 50LBS of which about 2/3 the weight is above the COG. But best I can figure in fast math with out litterly measuring everything the net weight above the COG , deducting the offset weight of the cage material that is below the COG may only be 20LBS different! And while we are watching our weight we are really watching our COG as much as anything.

Like Rodger said. A few trips to the Gym and a little chicken instead of pasta would probably be easier and better for me.

[Vegas69]

Frank, that reminds me of when I picked up my ZL-1 block at Randy Walkers shop in So Cal. He runs pro-street in the PSCA and was contimplating spending 3,4,5 grand to shed 30lbs off the car. He decided to lose the weight.

[Vince@Meanstreets]

Originally Posted by ProdigyCustoms

I love these sites. I am able to give advice and share my experiance and make a living doing this. How cool is that.

Know what is even more cool? When a thread like this comes up and really makes me think. Making me think enough that we may change our views on a important decison we are about to make on Project Unfairs cage.

Up until this thread got me really doing some math, we had it in our heads we would use Chrome Moly. But when I do the math, best I can figure we will save 40LBs to 50LBS at best by using .95 Wall Chrome Moly (1.679 lbs per foot) VS .120 Wall DOM (2.089 lbs per foot). Now it is 40LB to 50LBS of which about 2/3 the weight is above the COG. But best I can figure in fast math with out litterly measuring everything the net weight above the COG , deducting the offset weight of the cage material that is below the COG may only be 20LBS different! And while we are watching our weight we are really watching our COG as much as anything.

Like Rodger said. A few trips to the Gym and a little chicken instead of pasta would probably be easier and better for me.

or let the stig drive it. LOL


That metal supply shop on the corner of Davis and Doolittle can get it. I usually buy my stuff at Alstons if you don't mind a Sacremento trip. Its not cheap. Just go with the DOM. 1 3/4" will keep you safe in most sanctions.


Vince

[mfain]

I found out the hard way that it is far better to build the cage "by the book" the first time than it is to replace bars after the fact. Note also that some of the sanctioning bodies have upcoming rule changes (2011) that mandate two (vice one) doorbar. I also spent a lot of time moving my battery cut-off switch and adding an aluminum firewall between the fuel cell and passenger compartment of my plastic car to conform to rule changes. Another hint is that the sooner you get your car certified by one (any) sanctioning body, the sooner it is "grandfathered" for future rule changes, and you can usually race in other series with an SCCA or NASA certification.

Pappy

[chicane]

Read these two threads about materials selection:

This one

And this one

[toddshotrods]

This is an awesome thread! Very timely for me to find it now, as I will need to do a cage for my race rod eventually, and would have been really tempted to fall into the "moly" trap. I was doing it to save weight, but had assumed the savings would be more than thy really are. After reading this thread, and since my main rails are mild steel, it seems logical now to do the cage in mild steel.

One question: Is there any problem with TIG welding mild steel? What filler rod is recommended? Anything special that needs/should be done?

[coolwelder62]

The use of 4130 over mild steel is for wt.# saving's.1.75X.095 4130 weighs the same per foot as 1.75x.095 mild steel tubing.4130 is about 60% stronger than mild steel so you can use a thinner wall thickness than mild steel to abtain the same amount of strenght in your roll cage or chassis.Most of the drag race chassis builder's I've seen use a gas lense as Greg say's and never post heat the tube joint anymore.They just hold the torch over the weld puddle after finishing the weld and let the post flow cool it down.If you keep the ambiant tempure down you should not have any weld joint failure.You will know when your weld temp is right your weld on 4130 will a rainbow of gold to blue.To hot and the weld will turn out all grey & will see small stress cracks if you use a mag. glass.

[toddshotrods]

Thanks coolwelder, but those are moly tips. What about TIG on mild steel? Any issues.

I was going to use moly, but my weight savings would be even less than ProdigyCustoms because of the size of my cage and vehicle. I am seriously thinking about just using DOM and chasing the weight away somewhere else.