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Roll cage design


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When i have been looking through my pics of different challenge events i have seen a few different

cage designs, most of them have the same kind of design for the front hoop.

Sorry Jim

looking at jims (gigglepin) truck the design for his truck looks as if it would be a better idea for my truck

seems as if the bar over the windscreen is separate the the main front hoop


I have always thought the front hoop needs to be 1 complete bar.

If the way jims truck is done is fine that would save me a lot of bother with my truck.


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There is no set rule for roll cage design,

to be honest it boils down to this.

If you feel competent to design and build a LIFE SUPPORTING structure on your vehicle then you probably know the answer to your question your self. (not meaning any offense what so ever, I don't know your background)

There are several conflicting ideas toward roll cages and it all depends on what your intended use is.

Possibilities are.

a. To protect the occupants, = Strong design with no or few weak points and tubes triangulated as much as possible, strong tube but deformable without fracture in severe impacts.

b. To protect the vehicle, = Strong design with no or few weak points and tubes triangulated as much as possible, as strong tube as possible.

c. To look cool, = lots of rolled bends and fancy stuff.

d. To be part of the supporting structure to add strength or be part of the chassis, = Strong design with no or few weak points and tubes triangulated as much as possible, as strong tube as possible.

e. Do all of the above (except c cos that's for the yanks :P ) with as little weight as possible. = Intelligent use of materials and good design.

Jim's cage was designed to do a purpose, and does that to the level he is satisfied with, In order to answer your question you would first need to know what criteria Jim or the manufacturers had in mind when it was designed and built. Maybe it is just a fancy light bar? or maybe the whole cage is made from special hi tec Ti-xyz-ium?


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There is no set rule for roll cage design,

Apart from the designs approved by the MSA/FIA where the rules and regulations are very specific and Jim's design doesn't meet any of them :)

Only a problem if you want to compete in an MSA event that requires a roll cage of course.

The single piece front hoop thing comes from the ALRC whose designs were incorporated into the MSA regs rather sharpish when it was realised that all their cages were about to be "illegal" for MSA use :)

My cage doesn't meet full MSA regs either as far as I can tell but it's designed to do a job, as you point out.

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The original MSA / FIA regs all required a separate section over the windscreen with the front 'legs' extending back to the main hoop. But as Dave says, this was changed to allow the ALRC type front hoop (one piece front legs and accross windscreen).

The most critical thing is that the main hoop (behind the driver) is in one piece, chassis mounted and triangulated. Everything else is secondary.

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To be honest, the MSA rules for roll cages give you an awful lot of leeway! they are a "minimum" guide for MSA run events but are only there to guide you to what they see as safe enough, they are certainly not blueprints for success.

Again though, depends on the cages ultimate intended use. Most Landrover ones are there to protect the vehicle as much as the occupants.


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As to if you NEED MSA Cage spec or not thats one thing...

But - Do bear in mind that the MSA Styles of cage design etc have been er, how shall we say...

er...been "Lovingly Pre- Tested" by many which we as new cage owners can take the benefit of, so if we

ever do, we should again benefit from those who went before us :lol:

Again, IMVHO - A Big "Eeeeeeeeeek Feeeeeeeeeeeeeeeeeeeeeerkkingell" moment

.....is not the time to be testing your 'design' of cage :)


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The reason that idea would be better is i have a rear mounted rad and have a cooling duct above the windscreen

same kind of idea as a tomcat etc

The way jims cage is the bar across the top of the screen will miss the duct

If anyone has any other ideas fell free to fire them over.


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Bent backstays are the work of the devil. Proper triangulation is the way forward. The shape of the main hoop, with the bend coming back onto itself is a rather bad way of doing things. I know it is in the arc rules, and nearly all cages are like that, but having seen FEA analysis on that, its a bad solution.


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I agree in principal but again you really must include the full intended purpose when you judge,

For strength triangulation is obviously the most important consideration.

For safety, sometimes it is not!

Some people build a weak point into their design as in a "crush" zone, some people brag about FEA designed cages and then remove bars in silly places and the driving compartment turns into the crush zone! all sorts of things come into play. This is growing into a sport where at the top level you are going to use your cage! and probably for more than one purpose. We need to consider this!

Jim's cage may or may not be your cup of tea, for sure in a big roll it will deform, maybe he wants that? I for one would want the cage to bend rather than my brain (if I had one) get turned to mush. How much the deformation and at what load is down to the designer and the person paying the bill.

Not everyone needs or wants a Sherman tank!

Horses for courses!


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All cages are a compromise between ultimate safety and practicality. Whilst some designs aren't the ideal they can make for a much more practical vehicle if you need a multi-purpose vehicle. When I had my cage built I had a choice between storage and practicality or going for a full MSA spec. In the end I went for the former simply because I'd spent too many years struggling around an MSA design that screwed up everything I wanted to do with my vehicle.

My current design gives maximum storage for camping gear, food, clothing, spares and allows me to easily slot an Ifor Williams or crew cab soft top on the back if I need more storage for long distance touring. My comp motor even gets to tow the caravan sometimes !

We're not competing in high speed events and I've triangulated the rear stays to give the main hoop further support and there is also triangulation form the front hoop to resist the cage going into "shear".

Having said all that a close look at my main hoop will also reveal lugs for fitting by the book MSA spec rear stays should I need to at some point in the future !

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I would argue that whay you have done is perfectly acceptable Carl - the doubled up box section braces effectlvely extend the chassis and form a good rigid node for your tubework to connect to.

Agree the MSA may not like it, but I think it looks safe. :)

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Russ, If you need any more photos or info i can post them on here,


Fell free to post your pics up mate

Be nice to see your a overall view of your truck!

Its mainly the front hoop thats causing problems with the cooling duct

Found this pic and petal has the same kind of idea for the duct as mine but still has the front hoop

made out of 1 bar.


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Russ, my advice on the cage is take a big stack of paper and a pen and start sketching as many different designs as you can and then, as Jez said, remove as many bits of tube as possible that do little for the strength of the cage - basically just keep at it until you think you're done then leave it for a week and have another go. If you end up with something that has good triangulation of the cab and minimal bends you'll have a cage that'll do as it's designed.

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