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Discussion Starter · #1 ·
well the frame part of my build is done now i need is the roll cage. i was going with a chromoly but i keep hearing it has to be heat treated due to the carbon thats in the metal. so ill just go with dom steel which isnt a problem. but my question is how are you guys mounting the roll cage to the floor boards? i would just like to see some pics to get an idea. i plan to run a 10 pointer but with 2 extra rear runner bars that are x'ed for more support due to the new rear frame. well lets see those pics thanks in advance.
 

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i was going with a chromoly but i keep hearing it has to be heat treated due to the carbon thats in the metal.
You mean due to the EXTRA carbon? Unless you're planning to run in the low 7's at over 250MPH, I think you'll be OK without a heat treated CM roll cage, as long as you use the right rod for the welds.

but my question is how are you guys mounting the roll cage to the floor boards?
I haven't done this, but if you're going bolt in, then you're supposed to weld the tubing to a plate that gets bolted to the body. You'll also need more bars. If drag racing is your intended purpose, then get the NHRA rule book as it will answer all your questions.
 

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Discussion Starter · #3 ·
Well I figured I was gonna go with cm but it has to be done by someone that really knows how so ill stick with dom. And I have the rulebook but it says on SUBframe cars you weld and bolt together r 1/8th plates that are 6x6 inches does that apply do full frame cars?
 

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Yes, CM must be done properly, and it's a good call to go DOM if you can't have CM done by a professional.

You don't have to follow the rules for Sub frame cars IF you weld to the frame. Do you need the ability to remove the cage? If not, then just weld to the frame instead. It's stronger overall and will make the car stiffer too. You'll want a good angle die grinder with a cutoff wheel to cut the holes in the floor pan. It'll be easier than a sawzall in certain places. I use a hand held belt sander to make the fish mouths, and make them as perfect a fit as you can. When welding in the car, use a heat shield pad (you can make your own) to protect the roof pad etc.
 

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Minor note:

"DOM" translates to "Drawn Over Mandrel" and is an indication of how the tubing/pipe was formed - not an indication of what type of 'steel' it is. What you want to know is the 'ASTM' number or 'trade name' of the material, which will lead you to the properties of the material.

"Chrome-Moly" indicates only that the 'steel' contains both chromium and molybdenum - the materials composition (and thereby properties, i.e. 'strength') vary with the 'SAE' number.

Some (limited) good info here: http://www.ryerson.com/stocklist/l-2310-Data-Steel.html

If you have any question about what you intend to use, PM me - 'steel' is what I do for a living.

HTH
 

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Discussion Starter · #6 ·
Yes, CM must be done properly, and it's a good call to go DOM if you can't have CM done by a professional.

You don't have to follow the rules for Sub frame cars IF you weld to the frame. Do you need the ability to remove the cage? If not, then just weld to the frame instead. It's stronger overall and will make the car stiffer too. You'll want a good angle die grinder with a cutoff wheel to cut the holes in the floor pan. It'll be easier than a sawzall in certain places. I use a hand held belt sander to make the fish mouths, and make them as perfect a fit as you can. When welding in the car, use a heat shield pad (you can make your own) to protect the roof pad etc.
no the cage cant be removeable i dont plan on driving it in the street. and i guess my real question should have been can i just weld the roll cage tubing to the frame directly? i have the nhra book in front of me i either aint reading it right or the info isnt there lol. and thanks for the tips we have a angle grinder with the cutwheel and a sawzall left over from the back half.

Minor note:



If you have any question about what you intend to use, PM me - 'steel' is what I do for a living.

HTH
will do thanks!
 

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A certified welder can weld it to the frame and it's not going to break. don't forget to add bracing at your contact points or most NHRA inspectors will fail it for that. Check your tube wall so it's correct. You can go CM for an 8.5 cert.

That was the sticking points I remember when I did my car.
 

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Discussion Starter · #8 · (Edited)
Cool nice to know jeff. And you mean gussetts correct?


Btw sorry everyone for the noobieness I want to get the info right. Since I want to do this once and the right way.
 

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Gussets aren't required if you can weld all the way around the bar. That's where a good welder comes in handy. I don't have a single gusset on my cage.
 

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Discussion Starter · #10 ·
That's also good to know. Thanks glen.


Also for the main hoop since the frame isn't fully boxed in like there the front and the rear part is how do I do about welding it to the frame?
 

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That's also good to know. Thanks glen.


Also for the main hoop since the frame isn't fully boxed in like there the front and the rear part is how do I do about welding it to the frame?
You weld in a reinforcing plate, which you can get from any chassis shop or possibly Chris Alston, to box it in at the point where the cage meets the frame.

I also highly recommend swing out door kits, because working on the car otherwise is a royal pain in the A**! http://www.cachassisworks.com/c-165-side-bar-clevis-sets.aspx
 

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If you plan on having the cage certified by a NHRA/IHRA tech, a DOM cage can be MIG welded but a CM cage must be TIG welded. This was info I learned yrs ago and I'm guessing its still true.

From my so called memory, full frame cars must have the cage welded to the frame and not the body. My 85 Monte was welded this way.
 

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Yes Gussets. If you want the cage to hug the roof lines you will not be able to weld all the way around, special if you plan to keep the roof liner.

If it's just a race car then it's much easier. My car is all stock stuff but 8.5 certifed. I can't even get the 4L60E out of the car anymore without pulling the engine because of the certified shield on the tranny so this safety stuff is a real pain unless your just wanting a race car. You can also use swing outs so you don't have to crawl over the bars to get in. Our full frames allow us to do a lot of things most cars can not so make sure you read up on full frames.
 

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Yes Gussets. If you want the cage to hug the roof lines you will not be able to weld all the way around, special if you plan to keep the roof liner.

If it's just a race car then it's much easier. My car is all stock stuff but 8.5 certifed. I can't even get the 4L60E out of the car anymore without pulling the engine because of the certified shield on the tranny so this safety stuff is a real pain unless your just wanting a race car. You can also use swing outs so you don't have to crawl over the bars to get in. Our full frames allow us to do a lot of things most cars can not so make sure you read up on full frames.
i do them all the time without gussets. takes more time,but it can be done. removing the front glass helps a ton.
 
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