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Who is interested in roll cage and sub frame connectors twice as strong as 4140?


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I am a believer in building a car to what you intend to use it. 50% or deaths in crashes happen below 35 mph just saw that on the net today and the net does not lie, lol.
Not joking. I worked with Swedish Steel to use their materials in automotive and farm equipment designs to make stronger and lighter.
I am working with Swedish Steel to see if they are willing to make inch sizes in tubing or just metric. The current SCCA rules call for roll bars to be 1.5" .120" thickness tube for roll bars on cars over 1,500 lbs. or 1.75" .095" wall.
I am working with as mfg of tube benders and they currently do not support the millimeter sizes. The Domex material that Swedish Steel makes is twice the strength of 4140 and 4 times the strength of current sub frame connectors so a big gain is out there.
I am going to make the investment to build my cars using the new materials that are way better. There are no weld issues because the Swedish Steel Domex does not depend on high carbon to gain the strength. There are no weld issues like with 4140.
Give me your thoughts. Would anyone want to buy a cage or sub frame connector way ahead of any made today? I am going to do for my track days car and the Q code vert. Not going to have a car without bars with those capabilities. The track days car will be to the Kar Kraft specs plus some.

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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I have a MS in engineering mechanics and worked as a structural engineer for many years. I have worked with some fairly exotic materials in the aerospace industry. 4140 is crap steel and I cannot think of a single area where it would be used except in tooling (great for that). MIL-HDBK-5 has been replaced with a SAE document that I can't recall. Problem is we don't do much welding on high strength steels. Fty of 4140 is around 60 ksi (yield strength above which the material yields but does not fail, i.e. it takes a permanent set where the material does not return to quite same shape). Many good aluminum alloys are 70-75 ksi however aluminum is about 1/3 the stiffness and weight of steel. If the material you are talking about can be hobbyist welded then it is a good choice. For a reference I used steel that was 220-280 ksi (PH13-8 up to AERMET 100). Any of these steels would likely require special inspection techniques after weldment. There are some very special techniques required for welding these types of steel.

Edited by cwalker509
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Wisdom, knowledge and intelligence are three very different things.

1971 convertible, H-code, Ram Air

1971 Mach I, M-code, Ram Air

1972 Mexican GT-351

1988 Bronco II

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The welding of this material was never an issue and the program we use on was awarded the Swedish Steel best use for that year. It is way better than anything out there and way easier to weld. Why knock it?

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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Not knocking the swede steel at all. If it is hobbyist weldable then it is an excellent choice. I can look into alternatives that are not proprietary that may be easier to source and less expensive. 4140 is great foe so many applications because it is cheap and easy to work with 

Wisdom, knowledge and intelligence are three very different things.

1971 convertible, H-code, Ram Air

1971 Mach I, M-code, Ram Air

1972 Mexican GT-351

1988 Bronco II

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The cost is not the issue. My customers always looked at cost. They would not have used it it was not cost effective. If you want the best cost has little influence. Ether best or junk.

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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11 minutes ago, Horsin' Around said:

What is the reason no one makes a "bolt in" subframe connector? A pre-welded one piece X or Ladder style that snugs right up to the floor would be great. 

It's hard to insert through the door or windshield, don't you think?

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I think someone did not read the information. The reason for the Swedish Steel being better is there are no weld issue. BTW has anything you worked on been given the most innovative use of there steel before, mine has. Their steel is way ahead of others. This is way ahead of anything being used in sub frame connectors or roll bars currently. If not so please publish the information.

 

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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I pulled the brochure on domex. It comes in various grades from around 52 ksi to 100ksi. From what I remember it seems like where domex may shine is that it is easily cold formed. It also offers some improvement in weld strength characteristics particularly hydrogen embrottlement. It did mention that MAG (metal active gas) seems to be preferred. Anyone certified for wlding like this? I am not in any way shape or form. All this being said....what is the underlying rationale for doing this? Is it stiffening the structure? Does yield strength even play into it? I do not know. Many things are designed with deflections in mind as opposed to failure strength. I have designed for both. For instance residential floor joist spacing is designed by deflection and not failure strength. Someone would need to analyze the loads and stress in something like this. Just food for thought. Stronger is not necessarily better if you never approach the yield strength. I am just trying to give a perspective of how I would approach designing something like this. That is why 4140 is used in tooling. It is stiffness designed rather than strength designed so it is good enough.

Wisdom, knowledge and intelligence are three very different things.

1971 convertible, H-code, Ram Air

1971 Mach I, M-code, Ram Air

1972 Mexican GT-351

1988 Bronco II

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Well gents, I know squat about types of steels beyond the basics. My background includes machining and as such, have only used 4140 in tooling, it's also known as Pre-Treat. I recently found out that apparently some cheapo leaf spring manufacturers also use 4140 for springs. Really! Springs!

Why I chimed in here is simply this, what does NASCA or other racing organizations specify? If it's good enough for racing at 200mph and drivers survive horrible looking crashes, why the need for some other exotic steel? Just asking the question, not to start a war. 

Edited by Stanglover
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Geoff.

 I learn something new every day!

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I believe the tubing used in racecars is 4130 or commonly called chromoly. 

4140 is oil hard tool steel. 

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[align=left]Jeff T.

 

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passengers. [/align]

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I like the idea of using steel that is both stronger and weld friendly. However, just because a steel is stronger (generally shown by tensile and yield strengths) a good steel also has to have toughness, ductility, and weldability. In other words reduced fatigue cracking and work hardening (embrittlement) and hardening from welding. Railroad rails are a good example of a steel that has both strength and ductility but welding requires a certain process to prevent brittleness.

So in other words I would need to see the specs on it and I definitely have an open mind for trying something rather than 4140. And one other thing, it needs to be compatible with welding to the subframes in our cars. To me a bolt-in subframe connector wouldn't be that effective.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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I'm now wondering if David miswrote by saying 4140. Did he mean 4130 which I also believe is Chromoly. That would make more sense.

Geoff.

 I learn something new every day!

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You'd have to buy a f-ton of tubing to get someone to make you a special size. 

I can't believe that tube bending equipment suppliers are not supporting metric sizes, it's not 1955 any more. You can order mandrels, dies and wipers in any size you need, as long as the equipment supports it and it'll form properly. If you're going to form these components, you're running the tubing through a mandrel bender, and there are far more tube forming equipment manufacturers in "metric" countries than there are in the US. 

The market will never support anything more costly than 4130 in any volume. We sell 100 mild steel cage kits and hoops to one 4130 kit sold. 

IMAG3114.jpg

IMAG3013.jpg

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8 hours ago, Hemikiller said:

You'd have to buy a f-ton of tubing to get someone to make you a special size. 

I can't believe that tube bending equipment suppliers are not supporting metric sizes, it's not 1955 any more. You can order mandrels, dies and wipers in any size you need, as long as the equipment supports it and it'll form properly. If you're going to form these components, you're running the tubing through a mandrel bender, and there are far more tube forming equipment manufacturers in "metric" countries than there are in the US. 

The market will never support anything more costly than 4130 in any volume. We sell 100 mild steel cage kits and hoops to one 4130 kit sold. 

IMAG3114.jpg

IMAG3013.jpg

Something like this for the metric bending is what we use

https://www.swagelok.com/downloads/webcatalogs/en/MS-01-179.pdf

 

 

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Strength is also as much about the design of the structure as the material. Most if not all racing sanctions will sonic check the tubing thickness based on the material used. To introduce a new material and get sanctioning bodies to accept it may be a challenge too. That said, I've seen some very scary stuff at the track. 

I may not be smart enough to be scared but I don't like the look of a roll bar in a convertible. Not in mine anyway. 

[align=left]Jeff T.

 

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passengers. [/align]

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From what I gathered from David's post, the strength trade off is lighter weight. If you can make your cage/subframe lighter, but just as strong, then you have a performance improvement. But how much lighter?

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By making it lighter you are also making it less stiff. I am uncertain if roll cages are primarily for safety (i.e. roll over) or for stiffness. I lean towards the former so make it out of the strongest material available. High quality 7000 series aluminum is stronger than most "basic steels". It is roughly 1/3 the density and stiffness of steel. Look at some of the alloys used in F1 and get out your checkbook. There are lots of options but "value" of going a specific way is subjective so long as it meets requirements 

Wisdom, knowledge and intelligence are three very different things.

1971 convertible, H-code, Ram Air

1971 Mach I, M-code, Ram Air

1972 Mexican GT-351

1988 Bronco II

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The suppliers of DOM tube now have the Domex and is in stock. As far as a metric bender they do make. The one I was looking at getting is strictly for someone like me just doing their own work. I was looking at the Pro-  Tools 105 bender if I remember right goes to 2 1/2" dia. I did send them an email and they do support metric round but not square or rectangle at this time. The dies come in different versions some to to 180 deg. bends. I would never need that capability.
Another material I have never understood why it did not take off is Tegris. It was developed by Milliken in Spartanburg, S.C. They have a strictly R&D area with 12 separate labs working on pure research. The Tegris was used in the front splitters on the NASCAR racers it looks like the cheap tarps but is stronger than carbon fiber and lighter than aluminum. One of the huge issues with carbon fiber in a race car is when you crash it makes thousands of sharp pieces like needles so lots of clean up or lots of flat tires.
When I was working they came to our plant since were were just miles away and wanted to know if we would be interested in helping them develop uses in the automotive world.
They have a walk of fame at their facility. One of the items using the Tegris was kayaks you could pick up with one finger and way stronger than fiberglass or plastic.
So this was 10 years ago now. I took an old draw die we had with nitrogen system that could be adjusted to any force up to about 30 tons. We had an old LDH, Limiting Dome Height test machine. It has a standard die with draw beads and you have a die that cuts the blanks. The machine draws a cup up to the point of splitting and records the data. So with Aluminum being used more and more we did layered aluminum and Tegris. Milliken did all the research in the adhesive and how it was laminated. I rebuilt the draw die to simulate like the ribs in a pick up truck bed.
Using the LDH machine for testing samples they settled on what mix of type aluminum, layers of Tegris and type of adhesive. 3-M was involved there a lot. We could form a part that was stronger that steel or just aluminum but was lighter than just aluminum. About the time I get fed up with the politics in mfg. and retired early at 62.
I went to their site and it has made it's way into tires, hoses and other items in cars. At one time the Indianapolis racing series was going to require it to be use in the bodies to get the carbon fiber off the tracks.
Here is link to their web site. Would be great for spoilers and such. https://textiles.milliken.com/products/tegris
One of my jobs in the past I had to page through all the new patents issue to see if there was anything we might be interested ir or something we would make better and work around the patents. This was about 1985 and at that time its was like 93% of all products that got patents were never made. Most companies do not patent items unless chemical or electrical too easy to build something better if a mechanical item.
What sucks now is I hurt my back about two weeks ago putting door on the Q vert. I have done nothing for two weeks and gave up and went to Dr. yesterday and he is going to do a round of Prednizone to see if pain will ease off but I doubt it. I can hardly turn my head or lift my arms or pain is unbearable. So I might be out of the car hobby soon.

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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I hope the Dr can help to find you relief from the pain. 

[align=left]Jeff T.

 

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passengers. [/align]

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The Dr's. here never give pain pills. If Ibuprofen doesn't do it you just bite your lip. When I had surgery back in fall they did not even give any pain meds. My discs are herniated and pushed out. Yes if you are in traction it pulls the bone off the nerve for temp. pain relief. They say screws and plates will be only long term relief.
I lived and worked in China for 17 months. While there the government had started to discourage citizens from doing acupuncture. They had specials on TV with info.
Prednisone is only meds he has me on to calm down the nerve irritation some. At least I can turn my head now and not cringe. I do wish I had a hot tube to soak in. A good friend has on on her back porch but she is in medical and we are staying apart due to Covid.

 

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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2 hours ago, Carolina_Mountain_Mustangs said:

The Dr's. here never give pain pills. If Ibuprofen doesn't do it you just bite your lip. When I had surgery back in fall they did not even give any pain meds. My discs are herniated and pushed out. Yes if you are in traction it pulls the bone off the nerve for temp. pain relief. They say screws and plates will be only long term relief.
I lived and worked in China for 17 months. While there the government had started to discourage citizens from doing acupuncture. They had specials on TV with info.
Prednisone is only meds he has me on to calm down the nerve irritation some. At least I can turn my head now and not cringe. I do wish I had a hot tube to soak in. A good friend has on on her back porch but she is in medical and we are staying apart due to Covid.

 

 Ah I see. It is unfortunately worse than I'd hope for you. Muscle spasms, pinched nerves, pulled or strained muscles are one thing, herniated discs are another. I hope you find relief moving forward, so wishing you all the best.

Geoff.

 I learn something new every day!

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