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post #1 of (permalink) Old 08-21-2000, 11:58 AM
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Is this rollbar too beefy?

There may br no such thing as too much roll bar? I am concerned about weight. I do not want to add weight that is not needed to the Jeep. especially above the center of gravity.

I have attached a .jpg of my latest roll bar idea. I am thinking 2" .125 wall seemless tubing. This design is considerabley more beefy than the one I was originally considering. The past few posts of roll overs has scared the crap out of me. The yellow tubing on the picture is the original rollbar. Do any of you roll bar experts see any of these tubes as unneccessary weight? The body (which is very solid) will be sandwiched between the main roll bar section base, and the frame tie-in base. The frame tie-in will be welded directly to the frame. The body will be sandwiched with grade 8 bolts (4 per plate). The 4 points surrounding the front seats will be attached to the frame. The rear mounts will be to the body only. I do not run a back seat.

I am building this roll bar for a slow roll. But better safe than dead.

Jesse

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post #2 of (permalink) Old 08-21-2000, 12:40 PM
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Re: Is this rollbar too beefy?

WOW!!!!
How'd you do that, what program did you use. Is that horizontal bar paralell to the top of the stock bar going to be used for a 3 or 4 point harness? All that diagional bracing couldn't hurt. Remember to make your "sandwich" plates different sizes so you don't end up with a cookie cutter effect.

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post #3 of (permalink) Old 08-21-2000, 12:45 PM
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Re: Is this rollbar too beefy?

It appears in the pic (great drawing BTW, CAD?), that the front hoops go outward a little before the top bar, is this correct or is it an illusion? If so, the top bar will want to compress at the bends and flatten out under impact.

The tubing you're looking into using will weigh approximately 3 pounds per foot, but I don't think it's excessive at all. I would put the side braces from the stock roll bar further down though, to maximize the strength. I'd also add gussets at all the connections, made out of 1/4", so help strengthen the welds and avoid folding. 1/4" steel weighs 10.2 pounds per square foot.

I would like to add I have only built one roll cage, but have rolled and seen countless other cages "in action" so to speak. I have also never seen one fail, but all were well built. All of the rollovers were also slow speed with no more than one complete roll.

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post #4 of (permalink) Old 08-21-2000, 12:52 PM
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Re: Is this rollbar too beefy?

Thanks for the info on the plates. It makes perfect sense.... I overlooked that. I will probably make the upper plate larger than the lower plate, just for room's sake.

I used pro-engineer a 3d CAD software program to make it. It is like a 6K softweare package with virtually unbreakable copywrite protection. Luckily my work has several seats of pro-e, so I made the bar off- and -on over the past few months on lunch breaks.

The parallel bar will eventually hold harnesses. The exact height placement of that bar will be determined by myself sitting in the vehicle, but the cage will have the same basic geometry.

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post #5 of (permalink) Old 08-21-2000, 12:59 PM
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Re: Is this rollbar too beefy?

Thanks for the info JEEPN.

The fron hoop doesn't flare out as much as the lower section of it comes inward to allow for the attachment of steel doors. I think the amount that it is coming in is exagerated by the picture. I am also considering taking the 2 outer spreader bars (from front hoop to original hoop) outward a little, so they are located in the center of the corner arcs of the hoops. Then the X shaped spreader bars will have a slight upward angle to them. I will make the adjustments and attach a picture ina few minutes.

Jesse

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post #6 of (permalink) Old 08-21-2000, 01:01 PM
 
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Re: Is this rollbar too beefy?

No comments on the cage, don't want to get anything started again.

What program did you draw that graphic with??
I really like that graphic!

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post #7 of (permalink) Old 08-21-2000, 01:22 PM
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Re: Is this rollbar too beefy?

Here is the latest roll-bar with what might be an improvement. I left the old spreader bar design in there it is sort of a transparent color. The new bar design is in red. What do you guys think. Is it better to widden the spreaders, and take the x shaped spreaders up at an angle, where they meet at a point?

Jesse

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post #8 of (permalink) Old 08-21-2000, 01:46 PM
 
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Re: Is this rollbar too beefy?

I would think about the placement of the bar behind your head and bars above. In roll cages by stockcar rules I believe its supposed to be two inches above the drivers shoulder blade for safety standards. This is what I was told at Rosner Racing in eastern Mass. I built mine to that spec, and when you start putting it all together it should be custom to you. From the main hoop I have a cross bar that angles back stightly on both sides so that my seat can go back a little. gusset every 90 you can, Mark is right there. Itll add gobs of strength. Everytime I put a bar up top, I sat in the rig and put my hands crossed on my chest as if I where rolling and thought "where is my head going" and re positioned the bars accordingly. It looks simply fantastic on paper, I love what youve done, just dont expect it to translate to real application so easily. Try to be open to variation when you build it, so as not to comprimise safety on the inside as well. Food for thought. I can send you a picture of mine as well if youd like. I used ERW tubing at .95 thickness @ 2" in diam. its the same as the local stock car racing around here. Strong for my sammi but im not a pro to comment as to how it would work on your jeep. The plates are a smart move, have mine to the frame in six places and it disperses weight very well. good luck, Max

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post #9 of (permalink) Old 08-21-2000, 04:53 PM
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Re: Is this rollbar too beefy?

Yeah the way I figure it will work, is that I am going to take the pictures I have made with me and sit down with the welder and decide what will work best. He has made several SCCA car roll bars and several have been tested for real, and passed.

I am pretty confident that he will do a bang-up job. I am going to be there with him, and if when we are fabbing, something looks better in a different place, then I will toss it there.

The welder is fabbing up the bar in trade for a contour SVT motor I got for his SCCA Contour. I am not sure how much he wants to do for the motor, I will have to play it by ear. The gussetting might have to wait a while.

Hopefully it all goes in this weekend as planned.... I am scheduled for the maiden voyage of all the new "winter projects" on labor day weekend. Yeah, the winter projects took a little longer than expected... as usual.

Jesse

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post #10 of (permalink) Old 08-21-2000, 05:09 PM
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Re: Is this rollbar too beefy?

I suppose it depends on the use of your jeep, daily driver or strictly off-road, but you will begin to hate the outside bar between the front hoop and the rear hoop if you get it too low...it'll remind you how hard steel is everytime you get in you jeep and when you do a quick look into the mirror. Mine is about where your original drawing is and it still reminds me!!

My thoughts.

Looks great though!!

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