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Roll cage design recommendations with pictures

bp71k5 said:
I think Chris mentioned not to try and tie the windshield frame into the cage. What are the issues in doing that? My hardtop ties into the same spot so it "seems" like it would be ok. I don't mind being wrong though.
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Brian,

I think the only arguement against tying the cage to the windshield frame is that unless the cage is connected to the frame (and the body mounts are effectively eliminated) the front cowl will still want to move and twist relative to the cage. Tying them together is just going to create tearing further down in the cowl area as the two "systems" fight each other.

FWIW, I am planning to tie my cage to the a-pillars but I'm also doing a lot of other structural cagework under the dash and through the firewall into the engine compartment, as well as from the cage down to the frame underneath.

I suppose that a compromise solution might involve some sort of tab gussets with a flexible bushing that allows you to connect from windshield to cage, but at that point I'm not sure what real benefit you'd get.

The cage looks good. I especially like the aesthetics of the long overhead bars that run from the a-pillar all the way back to the c-pillar area. Using a b-pillar hoop and trying to connect everything to that always seems a bit awkward-looking, and the overhead bars with that sort of design always end up a lot closer to the driver's (and front passengers) head

For your "Moab mode", I'd think a bit more about a removeable "X" brace that installs vertically at the very back of the cage in the c-pillar area...or perhaps something directly behind the rear passenger seat (again vertically) to protect those occupants from the "parallelogram effect" if there was a rollover.

My hydro-bender parts just arrived yesterday, so I'm probably about 1 month behind you on my own cage work... I'll be watching your progress with great curiousity and interest! :D :thumb:


:usaflag:
 
I dig these cage discussions, even if they have been talked about many times before. there is allways good that comes out of them. Although some of us may disagree on some things it's still a learning lesson for alot of members and non members alike. Good job fella's :waytogo: Keep the comments & ideas coming.
 
miniwally said:
I think that all things should be made from DOM.
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I would have gotton flammed for this comment :D but I agree. HREW is WAY WAY better then nothing at all. IF I could not afford DOM Sure as hell I would be using HREW in a red hot second. But I personally will allways use DOM for a cage, atleast it's my first choice in material. Sure it's insanly pricy compared to HREW but whatever. To me it's worth the added strength vs cost.
 
A long time ago Bell helmets had a magazine ad with the tag line:

"If you've got a $10 head, wear a $10 helmet..."


I guess that always sort of summed things up for me relative to safety equipment. My noggin and other body parts are worth the extra $$$ that DOM costs. All other factors being equal in a cage design, the DOM cage will be substantially stronger.


:usaflag:
 
I have seen many cases where a HREW tube was smashed with what I would call a minor hit.

I have seen even more cases where a DOM tube took a major hit and came away with a minor dent.

The simple fact is that DOM is better than HREW which is better than nothing at all.

Another thing to remember is that in an engineering sense the welds are there to hold a joint together only. The fit of the tube agianst the other tube or tubes is where the strength comes from. This is purely in an engineering sense and a perfect world.

In the real world we are humans and can't make a perfect cope for every tube and really can't in situations which require cutting a tube a bit short to fit into a totally captured spot. This is where weld strength comes into play.

I for one can weld well enough to get the job done but when it comes to the welds around my head I fit everything then have one of the welders from the shop do the welding for me.
 
Found this in my files jsut now. Not mine but I think a members rig who sold it about a year ago. I really like this design but I know many of you will say it needs more x-bracing but it does have a lot of the tube gussets that look great. It's what I'd do if I could.

Blazer cage pic 5.jpg

Blazer cage pic 4.jpg

Blazer cage pic 3.jpg

Blazere cage pic 1.jpg

Blazer cage pic 2.jpg

Blazer cage pic 5.jpg

Blazer cage pic 4.jpg

Blazer cage pic 3.jpg

Blazere cage pic 1.jpg

Blazer cage pic 2.jpg
 
[FONT=Arial, Helvetica, sans-serif]Hot Rolled ERW (HREW)[/FONT]
[FONT=Arial, Helvetica, sans-serif]HREW is rolled into a tube at elevated temperatures, usually way above room temperature. This produces a tubing that is more malleable and therefore easier to form but that is also not as strong, is supplied covered with scale, and not as uniform in dimension as cold rolled. It is also quite a bit cheaper than cold rolled. [/FONT]
[FONT=Arial, Helvetica, sans-serif]Cold Rolled ERW (CREW)[/FONT]
[FONT=Arial, Helvetica, sans-serif]CREW is manufactured by a process in which a steel bar is rolled into a tube and the seam welded, usually at room temperature. Compared to hot rolled, CREW is stronger - (greater yield strength) - because of the improvement in the crystal lattice structure from improved grain size, shape, and orientation imparted by being worked at cold (room) temperatures), straighter, has a much smoother and more uniform surface finish, and is made to much tighter, more consistent dimensions. It is the best economical choice for tube work, and because of the better surface finish and tighter dimensional tolerances it is much nicer to work with than HREW.[/FONT]
​
[FONT=Arial, Helvetica, sans-serif]Drawn Over Mandrel (DOM)[/FONT]
[FONT=Arial, Helvetica, sans-serif]Strong and well-finished DOM is an electric resistance welded tube tested for soundness of weld and drawn through a die and over a mandrel. This process imparts significantly improved mechanical properties to the tube, due to the cold working process. It is considered a high quality tube, and is normally constructed from SAE 1020 or 1026 steel. Note that, technically DOM refers to the process by which the tube is finished after having started as an ERW tube. Technically, DOM is not a type of steel tube, but rather a process. As so often happen though - in common use the term has become accepted to mean a specific type of tubing rather than a process. In this case, when people say "DOM" they normally mean an ERW tube drawn over a mandrel at (close to) room temperature and made from SAE 1020 steel. It is normally drawn to O.D. and I.D. dimensions. Here is what the Steel Tube Institute of North America has to say about DOM:[/FONT]
[FONT=Arial, Helvetica, sans-serif]The DOM Manufacturing Process [/FONT]
[FONT=Arial, Helvetica, sans-serif]The manufacturing process for DOM tubing begins with coils of steel, which are slit to the proper width for the desired tube size. The strip is cold formed and passed through an electric resistance welder which joins the edges together, under pressure, to complete the tubular shape. After testing the weld's integrity, the tubing is cut to length for further processing.[/FONT]
[FONT=Arial, Helvetica, sans-serif]The cold-drawing process creates a uniform, precision product with substantially improved tolerances, surface finish and tensile strength, increased hardness and good machinability. In this process, the tube is cleaned and annealed, and one end of each length is squeezed to a point so it can be gripped by the drawing mechanism. The tube is then drawn through one or more dies and over mandrels. This reduces the diameter of the tube and thins its walls to the required dimensions in a controlled fashion to provide the qualities desired in the finished product. Metallurgically, drawing improves the tube's concentricity, tensile strength, hardness and machinability. Close dimensional accuracy is achieved through tight control of both outside and inside diameters.[10][/FONT]
​
[FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif]Directly from this Bilivista: Quote:[/FONT][/FONT]
[FONT=Arial, Helvetica, sans-serif][FONT=Arial, Helvetica, sans-serif][/FONT][/FONT]
[FONT=Arial, Helvetica, sans-serif]<B>[FONT=Arial, Helvetica, sans-serif]My personal mantra on the subject of steel tubing choice for 4x4s and rock crawler's is:[/FONT]
[FONT=Arial, Helvetica, sans-serif]"You can't go wrong with 1020 DOM!" [/FONT]
​
</B>
[/FONT]
 
no post info didn't show up correctly damnit.
 
but I know many of you will say it needs more x-bracing
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I actually think fewer could have been just as strong and looked better. A couple of those gussets seem redundant. For example, is there really an advantage to gussest both front and back of the B pillar and tie the rear gusset down with that diagonal? I think he could have got the same strength shape without the small gusset on the rear side of the B pillar. I suppose every gusset you add helps, but I'm doubtful there is a significant difference in strength from that.

I actually just looked at Hoby's cage again and it does look almost identical. I don't suppose you've had a chance to "test" it yet? ;)
 
I suppose that a compromise solution might involve some sort of tab gussets with a flexible bushing that allows you to connect from windshield to cage, but at that point I'm not sure what real benefit you'd get.
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I get it now. The only real reason I had for doing it, is to keep the door gaps large enough when the body is twisted up a bit. Whenever I was getting out on stops on the trail, I'd have to pry the door open to get out. I suppose the real solution is to stiffen up the rocker area a bit to prevent that since the windshield isn't the strongest area to do that.

For your "Moab mode", I'd think a bit more about a removeable "X" brace that installs vertically at the very back of the cage in the c-pillar area...or perhaps something directly behind the rear passenger seat (again vertically) to protect those occupants from the "parallelogram effect" if there was a rollover.
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That was my original concern with adding in something like the green bars. Since it could be removable I wouldn't mind the extra bracing. I'll have to keep looking at that.

My hydro-bender parts just arrived yesterday, so I'm probably about 1 month behind you on my own cage work
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You're probably a month ahead of me. I won't have any tube until late January at the earliest. I think Scott and I have a -potential- future plan for trading some bender time for materials.
 
bp71k5 said:
I actually think fewer could have been just as strong and looked better. A couple of those gussets seem redundant. For example, is there really an advantage to gussest both front and back of the B pillar and tie the rear gusset down with that diagonal? I think he could have got the same strength shape without the small gusset on the rear side of the B pillar.
Click to expand...


I think the only advantage was to make the coping easier for the tube from the back that is tied into that joint. It adds some strength but I think your right, not a huge amount. I would have just coped the tube on both sides for the 90 deg corner. Maybe added the front gusset only. I guess is adds some symetry to the look of it.
 
So here's a couple of ideas on additional green colored "moab mode" bracing. I like the first option better since it allows eaiser access to space in the back. Is the second option going to be significantly better?

I suppose I could also just add permanent bracing in the C Pillar like Chris suggested. Picture #3 is a nice balance of rear visibility and strength. That gusset is about 8" down from the top of the vertical portion of the C pillar.

cage_4.jpg

cage_5.jpg

cage_6.jpg
 
How is your rear seat going to mount, factory floor or cage mount? I assume cage. The problem with tube mounting it is it raises it too high for my taste. I don't want passenger head clearence to be an issue. I am in the process of fabricating a rear mount for my bench Mastercraft. I'm using a 3/16 steel plate that fits between the wheel wells and is about four to six inches wider then the seat front to back.

It will be tied into the cage with tube. The seat will be removable and the floor will be flat once the seat is removed. Only the plate thickness will be there.
 
The seat will likely be mounted to the floor. It doesn't fold, flip, or slide so it just bolts down to the bed. I may try adding in some kind of quick release mounting method that makes it easier to remove for the times when I need to haul around big stuff.
 
In the pics above the first option will ofcourse be the strongest but the third pic is the most user friendly, which I like the most. I will have a removable X brace of some type. When it's only two people I will pull the rear seat out.
 
I mounted my rear bench seat to the cage by running a hoop in front of and behind with tabs coming forward to attach the seat. It is cage mounted but still sitting on the floor.
gabe
 
Brian,

Here's a potentially cool idea:

Do an "X" brace that mounts directly behind the passenger seat.....BUT instead of welding it in place, use two bushings at the two upper corners where it mounts. The floor mounts could be either some sort of strong pins or tube clamps that could be disconnected easily. When not in "Moab Mode", imagine swinging the entire X-brace up to the overhead bar area and locking it in place there instead.

The effect would almost be like a solid garage door.....down is Moab Mode, and giving good triangulation of the B/C pillar area. Up is creating a less useful but unobtrusive X-brace across the overhead tubing in the rear of the truck. :thinking:

I'm not sure dimensionally how all that would work (too long? too short?) but it might be worth fooling around with a bit. I like the idea of not having to wrestle around with a large, heavy X-brace to remove it. My guess is that it would get old in a hurry....and it's going to be bulky and awkward to carry and store it.


:usaflag:
 
Greg72 said:
A long time ago Bell helmets had a magazine ad with the tag line:

"If you've got a $10 head, wear a $10 helmet..."


I guess that always sort of summed things up for me relative to safety equipment. My noggin and other body parts are worth the extra $$$ that DOM costs. All other factors being equal in a cage design, the DOM cage will be substantially stronger.

:usaflag:
Click to expand...

....speaking of helmets: a steel cage is harder that a skull... depending how tight you're strapped in, contact of the head with a cage is a concern, particularly in an accident on the highway...

I see more and more of the buggy types wear helmets on the trail...
 
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