Roll cage tubing size ???
12-09-2007, 11:18 AM
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Roll cage tubing size ??? I know NHRA requires a 10 pt cage to have a minimum of 1 5/8 .118" wall DOM. A road race friend of mine told me that 1 3/4 .095" wall DOM is lighter and stronger than the 1 5/8 stuff. Is this true? And would a 10 pt cage from 1 3/4 .095" wall be NHRA legal?
12-09-2007, 11:50 AM
#2
You must have at least .118 thickness in a mild steel tubing, the lightest and strongest version to meet that minimum requirement is 1 5/8 .120 wall DOM
Electric welded steel 1 5/8 .134 wall is not stronger than the DOM, it has a lower yield point than the DOM is even though it is slightly thicker.
NHRA only requires that the cage be 1 5/8 .083 wall c-moly.
If light weight and strength are your number one consideration I would use c-moly. In 1 5/8 .083 it will be lighter than the DOM mild steel, or you can build it with 1 5/8 .095 wall c-moly to make it stronger and they even make 1 5/8 .120 wall c-moly, but as the thickness goes up so does the price.
If you are looking to make something as strong as possible and light I would consider building a c-moly cage with x door bars and an x on the roof bar and gusseting the main cage bars.
It really depends on what you are trying to do, you could make an entire 25.2 cage, but it just depends on how crazy you want to go.
What are your speed goals or ET goal or type of racing you are going to be doing?
To answer your question tube diameter has a great effect on strength than thickness, but thickness would be second in this factor.
To give you an example a 1" .083 = X amount of strength, so you want it stronger and say you use 1" .120 wall for the same thing, you just increased weight 40% for a 30% increase in strength.
Now you take the 1" x .083 which = x strength and use a 1.125 tubing which is only 1/8" bigger in diameter with the same thickness and you increased weight only 13% but increased strength 48%.
So yes in theory your friend's point is correct but NO it is not legal in mild steel. It must be a minimum of .118 even if the tube is bigger diameter.
12-09-2007, 11:59 AM
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You must have at least .118 thickness in a mild steel tubing, the lightest and strongest version to meet that minimum requirement is 1 5/8 .120 wall DOM
Electric welded steel 1 5/8 .134 wall is not stronger than the DOM, it has a lower yield point than the DOM is even though it is slightly thicker.
NHRA only requires that the cage be 1 5/8 .083 wall c-moly.
If light weight and strength are your number one consideration I would use c-moly. In 1 5/8 .083 it will be lighter than the DOM mild steel, or you can build it with 1 5/8 .095 wall c-moly to make it stronger and they even make 1 5/8 .120 wall c-moly, but as the thickness goes up so does the price.
If you are looking to make something as strong as possible and light I would consider building a c-moly cage with x door bars and an x on the roof bar and gusseting the main cage bars.
It really depends on what you are trying to do, you could make an entire 25.2 cage, but it just depends on how crazy you want to go.
What are your speed goals or ET goal or type of racing you are going to be doing?
To answer your question tube diameter has a great effect on strength than thickness, but thickness would be second in this factor.
To give you an example a 1" .083 = X amount of strength, so you want it stronger and say you use 1" .120 wall for the same thing, you just increased weight 40% for a 30% increase in strength.
Now you take the 1" x .083 which = x strength and use a 1.125 tubing which is only 1/8" bigger in diameter with the same thickness and you increased weight only 13% but increased strength 48%.
So yes in theory your friend's point is correct but NO it is not legal in mild steel. It must be a minimum of .118 even if the tube is bigger diameter.
Electric welded steel 1 5/8 .134 wall is not stronger than the DOM, it has a lower yield point than the DOM is even though it is slightly thicker.
NHRA only requires that the cage be 1 5/8 .083 wall c-moly.
If light weight and strength are your number one consideration I would use c-moly. In 1 5/8 .083 it will be lighter than the DOM mild steel, or you can build it with 1 5/8 .095 wall c-moly to make it stronger and they even make 1 5/8 .120 wall c-moly, but as the thickness goes up so does the price.
If you are looking to make something as strong as possible and light I would consider building a c-moly cage with x door bars and an x on the roof bar and gusseting the main cage bars.
It really depends on what you are trying to do, you could make an entire 25.2 cage, but it just depends on how crazy you want to go.
What are your speed goals or ET goal or type of racing you are going to be doing?
To answer your question tube diameter has a great effect on strength than thickness, but thickness would be second in this factor.
To give you an example a 1" .083 = X amount of strength, so you want it stronger and say you use 1" .120 wall for the same thing, you just increased weight 40% for a 30% increase in strength.
Now you take the 1" x .083 which = x strength and use a 1.125 tubing which is only 1/8" bigger in diameter with the same thickness and you increased weight only 13% but increased strength 48%.
So yes in theory your friend's point is correct but NO it is not legal in mild steel. It must be a minimum of .118 even if the tube is bigger diameter.
My car is a street car 90% of the time, so I just want the minimum to get by NHRA tech. I'm also not concerned too much about weight. The only reason I ask is because while buiding my cage, we are also building one for my freinds BMW, and he wanted to use the 1 3/4 .095" wall because it is lighter. This means along with buying a tubing bender, we have to buy two sets of dies at $250 a set.
12-09-2007, 04:02 PM
#4
My car is a street car 90% of the time, so I just want the minimum to get by NHRA tech. I'm also not concerned too much about weight. The only reason I ask is because while buiding my cage, we are also building one for my freinds BMW, and he wanted to use the 1 3/4 .095" wall because it is lighter. This means along with buying a tubing bender, we have to buy two sets of dies at $250 a set.
Yes a 1 3/4 tube would be stronger but .095 wall won't pass tech.
Either way 1 5/8 .134 EWS or .120 DOM is more than strong enough for what you guys are doing.
