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Discussion Starter #1 (Edited)
Had a new cage done at shop in Peoria, AZ. Gravity Motorsports owner and fabricator is Dean Harper. Built me a bullet proof cage because i ride hard and don't want to injury any of my passengers. He can do bling bling work but i just wanted it extremely strong and he made it happen.
 

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Wow, I like that one! The radius cages just don't do it for me, they look like a rockin chair turned upside down:rofl3:

Dwight
 

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Discussion Starter #3
exactly i dont know why people like that look but it is what it is but the radius actually makes it 30% weaker
 

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exactly i dont know why people like that look but it is what it is but the radius actually makes it 30% weaker
This is a false statement. In many cases a radius makes the tube more rigid, thus stronger. Now this does not make a flat roof design a weak design, just the fact that you are stating a radius is weaker and using a percentage is false. Kreger Fab was one of the first to design a radius into their off-road race chassis. Now it is norm for most of the industry. One big factor in strength is what material are you using and what wall thickness.

And in order for a cage to even be considered "bullet proof" you will need to have some diagonal tubes between the B pillar or in a 4 seat chassis behind the C pillar. Ideally in the 4 seater you would want a diagonal in the B pillar to support the whole cage, but the Polaris RZR platform is not the most ideal design to be making a truly proper cage.
 

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Not a huge fan of the design but to each their own. Although im sure its an upgrade over the stock cage its far from bulletproof. Like mentioned above some diagnal bars would add a lot. Also notice that you still have the oem mounts in the front. A cage is only as strong as its weakest link and im sure thats it... depending ofcouse on how they secured it to the chassis in the B and C pillars. Its a good start but if you really want bulletproof id address a few of the issues.
 

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The roof bracing does not support the A, B & C pillars. The roof bracing helps keep the roof of the cage from twisting & from large objects from entering in a roll over. But the roof bracing does nothing from keeping the cage from rocking over in a roll or compressing. What I am talking about when saying compressing, is if I dropped the car on it roof the B & C pillars would most likely bend more at the bends as there is nothing to support them. If you look in the 3rd picture you will see a tube that supports the C pillar at the bend and ties it to the rear down tubes. Also they have added small tubes on the B pillars to help support them.


The first 2 pictures show examples of diagonal or X bracing. Like I said the ideal design on a 4 seater would be to have a single diagonal tube, a V like in the picture or a X brace like the picture on the B pillar. This would support the cage in the middle. But being where the B pillar mounts to the chassis and where the seats mount it is not really possible to do. So at least a diagonal in the rear will help. Even the stock cage had a diagonal V at the C pillar.

Now regarding the V in the front window, it will help a little bit, but that is more of an intrusion bar then a true cage support. In a race car that V would tie into other tubes making it structural. All 3 weld points are what you would call dead end tubes. They dont tie into any other tubes to transfer load and make the chassis more rigid.

Dont take what I am saying as a bad thing against your cage. It is a very nice cage for what it is. It is better then what comes from Polaris. I am assuming you cage is 1.75 X .095 Mild Steel?





 

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Rzrxp7 please don't take what these guys are saying as bashing, they are trying to help. Everyone of us had to learn somewhere and these guys are just trying to pass on the knowledge. What they are saying about gussets and some triangulation bracing on the C pillar loop are correct. Your cage is nice but it is missing some basic components to make it safer.

http://www.therangerstation.com/tech_library/rollcage.htm

The article above is a good how to with basics explained. As far a curves or bends are concerned, in general bends reduce the capacity of a bar to carry compression loads unless they are braced. However as stated above curved or "arched" cages done correctly have many strength advantages and also maximize passenger compartment room. If you look at many of the top trophy truck and class 1 race cars they incorporate curved tubing into their designs.

Again please take the info presented as constructive criticism. If you really do "run hard" then you may want to take your cage back to your builder and have him add in the rear bracing and gussets suggested.

Have fun and be safe,

Chris


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Rzrxp7 please don't take what these guys are saying as bashing, they are trying to help. Everyone of us had to learn somewhere and these guys are just trying to pass on the knowledge. What they are saying about gussets and some triangulation bracing on the C pillar loop are correct. Your cage is nice but it is missing some basic components to make it safer.

Building A Roll Cage For Your Ford Ranger/Bronco II

The article above is a good how to with basics explained. As far a curves or bends are concerned, in general bends reduce the capacity of a bar to carry compression loads unless they are braced. However as stated above curved or "arched" cages done correctly have many strength advantages and also maximize passenger compartment room. If you look at many of the top trophy truck and class 1 race cars they incorporate curved tubing into there designs.

Again please take the info presented as constructive criticism. If you really do "run hard" then you may want to take your cage back to your builder and have him add in the rear bracing and gussets suggested.

Have fun and be safe,

Chris


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Nice article. You are correct. I built late model dirt track chassis and the support above or below any radius bends is a must if you are looking for the strongest cage you can possibly build. It is crazy how many extra bars go into a late model dirt track car just to support another bar some where else. I am getting ready to my RZR4 900 with a custom cage. It is taking me a while to figure out what to build because it will be my own custom cage.
 
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