Roll cage advise

[funky_monkey58]

Read the links posted and know the facts. Chromoly is downright DANGEROUS if not properly welded (and the risk of this is very very high, if they're having issues on top fuel dragsters, you think you're going to have your cage done perfect?).

As in the link I posted since you fools don't know how to click

The wall thickness spec is higher on mild steel and it's going to be heavier. Nowhere did I say anything about "made exactly the same."

Reading comprehension owns another one.

Also conviently missed my first link...

I saw your link.

You assume that nobody knows how to weld chromoly.

Why don't you do some more bench top racing there buddy.

 

[gaboonviper85]

Read the links posted and know the facts. Chromoly is downright DANGEROUS if not properly welded (and the risk of this is very very high, if they're having issues on top fuel dragsters, you think you're going to have your cage done perfect?).

As in the link I posted since you fools don't know how to click

The wall thickness spec is higher on mild steel and it's going to be heavier. Nowhere did I say anything about "made exactly the same."

Reading comprehension owns another one.

Also conviently missed my first link...

no poodles....you said "mild is just as good!".....chrom is lighter, stronger, and simply better!...yes it may be hard too weld but that's where money comes too play here!

All aspects say chrom is better...in the hands of a pro welder chrom is a superior choice in safety, weight, strength! You've posted one damn link that defends you're ideas but seriously YOU ARE WRONG! That is it...accept it....

Btw chrom is not hard too weld...it's all the wannabe welders who fuck up and it backfires as chrom is less forgiving...this does not mean chrom is unsafe but instead means that assholes need too put the welder away and pay a pro!

 

[gaboonviper85]

Poo...I'm sure I can find a link that says poop is the best choice...you are very smart poo but metal work is not your field nor does it look like it ever will be! Spouting off garbage like this as fact generally is an infractable offence here as you know...obviously fabrication is not a topic you have experience in unlike myself or funky...I have my machinist handbook ($250 book that changes every few years) becide me that proves you full of shit so please stop talking! As in my eyes you are abusing your mod status as misinformation is an offence!

 

[Slow66]

And the MS vs. CM war continues to wage....if I could count how many times I've seen this arguement on different forums. They each have their place IMO. Nascar uses MS with alot of success. A 3500lb car going 200mph into a concrete barrier is alot of energy, and drivers can walk away from those. Youtube "Mike McDowell crash" for evidence... There is also a reason 300+mph fuel cars use CM. Youtube "Daniel Wilkerson crash" for that evidence.

Bottom line is ANY cage can fail if done improperly, and each material has their place in the racing world. $$ should not be a deciding factor in the material under any circumstance IMO.

 

[Poodles]

Knock the insults off.

No I do not assume nobody knows how to weld it, but if you read up on how it's used in other applications and know how difficult it is, I wouldn't put my life in the hands of "I think he got it right."

Cracks in chromoly welds aren't visible on the surface of the weld, that's why they pass inspection but still fail. Mild steel or DOM doesn't have the same issues. The only reason chromoly is better is it's weight (also why it was used in early aircraft before aluminum).

Also of note is that NASCAR does NOT use chromoly...

 

[gaboonviper85]

^^^^

indeed!

My argument is against one saying mild is "as good" as chrom...it is not true...steel works well no argument there at all!

In reguards too slow66

there is much more racing than NASCAR poo...that isn't saying a whole lot...get with it..

And if "reading comprehension owns another" isn't an insult then what is....hi pot meet kettle! Fallow your own advice!!!!!

 

[Poodles]

If you look there is still a lot of arguement about if the chromoly spec in NHRA is smart. Chromoly sounds great, but has issues with becoming too brittle and failing from vibration.

Also, don't think the weight savings is that much, it's minor.

 

[gaboonviper85]

Here poo...as obviously you think I'm stupid..

Molybdenum 41xx...modulus of elasticity (10 six power, psi)=48.....shear modulus (10 six power, psi)=17

steel, cold-rolled...29.5....11.5

you get it yet?

 

[gaboonviper85]

30+ pounds isn't minor

 

[Poodles]

Never said you're stupid. Chromoly is more brittle than mild steel but has higher tensile strength.

SCCA also banned chromoly for the exact reasons I've stated.

40lbs is .05 in the quarter, and if you're that competative you can find other ways of dropping weight...

 

[Neodeuccio]

OK, so I've read all of this stuff, but it's a bit complicated, and doesn't seem to be getting us closer to a consensus. Can someone answer this question for me without interjecting opinion?


You have two identical cars, one has a moly cage, the other has a mild steel cage. The cage designs are identical, except the dimensions, per the NHRA. Assuming you use the measurements listed in the link that Pood put up (1.75" OD x .118" for mild steel; 1.25" OD x .083" for moly), ignoring the weight difference, which cage is better and why?

 

[Poodles]

Chromoly must be inspected often for cracks. On a 1/4 mile car that doesn't see much use that's acceptable, but any other type of racing or a street car it's just another thing to go wrong. If you want to race your car in other types of racing, some have banned chromoly so you'll be SOL.

Design is more important than the material as well, and if you know the weaknesses of the material it's easy to work around.

 

[figgie]

folks

enough of the childish crap......
I like this thread.

This is not technical but I might move it there and you guys can duke it out.

 

[funky_monkey58]

OK, so I've read all of this stuff, but it's a bit complicated, and doesn't seem to be getting us closer to a consensus. Can someone answer this question for me without interjecting opinion?


You have two identical cars, one has a moly cage, the other has a mild steel cage. The cage designs are identical, except the dimensions, per the NHRA. Assuming you use the measurements listed in the link that Pood put up (1.75" OD x .118" for mild steel; 1.25" OD x .083" for moly), ignoring the weight difference, which cage is better and why?

For your application, go with a DOM mild steel.


And figgie you going to respond to the callout thread?

 

[dbsupra90]

i didnt mean to make such a fuss.

regardless of what material is used, it has to be properly designed, installed, and welded. i've seen so many poorly put together cages (not that i am an expert inspector) that i wouldnt trust in a crash.

 

[Poodles]

Not a problem, I love a good debate :rofl:

Honestly, it's like heim joints and aftermarket aluminum suspension arms. They're race items that need to be inspected often and have no place on a street car IMHO. This also includes road course racing (SCCA banned chromoly).

Another interesting thing I found is that IF a chromoly cage is properly constructed and welded, it's still weak where it's welded to the normal steel chassis and is usually a point of failure. That's not an issue on a top fuel dragster that's made completely out of chromoly.

For a fast street car, I'd run a mild steel or DOM cage. It also has to be padded where your head might impact (best to pad the entire thing, there are kits to do it and they also have stitch up sleeves to go over it so it looks clean).

Also, you're going to have to decide on a few things. How integral to the car do you want the cage? The cages that go through the dash and hug the A pillar tend to give better visability than the ones that don't go through the dash.

Also, do yourself a favor and buy the current rule book from NHRA. There are certain specs not covered (like how some of the bars can be bent, ect) that will help you build your cage.

 

[dbsupra90]

thru the dash is def nice. i'm not fast enough to require that yet. just an 8pt works fine, and the 12pt could be added later. in fact, the OP might be able to use a 6pt and be ok.

screw padding. wrapped in razor wire is where it's at. gives that industrial i mean business look.

speaking of legality, i dont know of anyone that will allow a bolt in. and different bodies sometimes require different things. i only drag, so thats all i care about.

one last thing i'd like to add- it stiffens up the chassis way more than any strut tower brace!

 

[VooDoo]

Boy this took off. Well Ill just be running the 8-point for now. Like said earlier, I can add on in needed. Will probably run the dom. Also will be using the approved swinging door bars.

 

[NashMan]

http://www.youtube.com/watch?v=9AKAh_7gb6A




fuck that i gonna make mine out of oak

 

[MDCmotorsports]

Poodles.

4130 is used for a reason. Its stronger pound for pound than any other ferrous steel out there. It also retains memory. Once bent to shape, it has a "spring" effect in that it wants to return to its original position and shape.

Ask this guy if he would rather have mild steel or 4130?

http://www.youtube.com/watch?v=69G0ay8kSkI

And then ask this guy how much he likes his mild steel, electronically seam welded cage:

http://www.youtube.com/watch?v=HlxnDJ1wQbI

Yes DOM and Mild Steel (Seam welded) cages can be made strong. They can be made to do the job. At the end of the day, properly welded vs properly welded, the 4130 is going to win hands down every time.

As for quoting NHRA - you're playing with fire there. These are the same ass holes who said that top fuel rail and funny car chassis were to be HEAT TREATED after welding.

WOW. Just wow. That's giving your drivers a coffin @ 300mph. As John Force how well he likes his heat treated 4130 chassis.

Now, if you'd like to continue to argue, please show me how many 200mph dragsters you've welded on and list all the midget / sprint cars frames that have flipped out of the ball park with the driver walking away - that you've welded on or designed.