rollcage suggestions

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The MT cage is real nice. It's a good option to use for FJ40 owners. However, I am a big supporter of local business, so I say you go to Stan or M&M Offroad to have a cage built and installed. They are both expert metal fabricators and will use the welding technique that is best for how they build the cage. The MIG vs TIG debate doesn't really matter if you aren't welding the cage in yourself.

Long story short:
- decide on the type of cage you want and how you want it to look
- bring your truck and some pictures / ideas to your selected fabricator
- leave your truck and some $$
- wait some time, then pick up your truck with its newly installed, professionally welded, roll cage.
- add some high density foam around the head area for both driver, passenger and rear passengers
- wheel the crap out of it :D
 
Now, when talking about roll cage design, we're talking about people's safety, so everything has to be considered, from the vehicle's gross loaded weight to the anticipated speeds of said vehicle, to the terrain that you intend to use it in.

For example, if your vehicle weighs 3000# and speeds around a track at 160mph, then you're going to want to ensure that if you roll at high speed and the high-speed momentum of that vehicle comes down at the peak of the A-pillar, then it needs to be as rigid as possible to disperse that weight. The momentum of that crash is likely to be greater than the momentum of a low-speed rollover for a 5000# vehicle, which is likely why there is this new requirement that the a-pillar bar can only have one bend in it.

In addition, the necessary diameter and wall thickness of selected tube for a 4500# FJ40 might not be appropriate for a 6000# FJ60 or 6500# FZJ80. The overall design has to change not only for the different design of the interior but also because the weight distribution for a wagon is different than that of a 40. Let's not even talk about how light those mini-truck things are :D

As for the roll-cage design with regards to terrain, I've seen some pretty open-top roll cage designs in open-top vehicles. If I owned a FJ40 with an open top and wheeled it like that, I'd be worried about a rock coming in from the top of the cage ( while upside down ) and knocking me in the head. Uwharrie has some pretty loose and jagged rock formations, and then obviously lots of trees + tree stumps, which all pose a head injury risk. If I had an open-top vehicle, I'd put more bars spanning the main side hoops to better protect the head. Better yet, skin the top with 14 gauge or better steel and put some speed holes in there. Take a look at this picture and then envision a pointy rock or tree stump sticking in through the head area of the cage and giving you a concussion ( pilfered from http://metaltech4x4.com )

10_1_.jpg


Real-world testing is the next best thing to CAD testing. 4xinnovations did a great series of tests that show the effectiveness of their cage. It would better represent a Land Cruiser weight range if they welded a bunch of steel plates to the floor.



One last thing to consider is that no rollover is perfect, nor is every rollover the same. Imagine a situation where you are in a rollover and instead of rolling down the mountain, you roll over twice and then into a huge oak tree. Is your roll cage designed to protect in event of a side-impact? Take a look at this video:




Overall, there are a TON of things to consider when improving the safety of your custom vehicle, not just your average rollover. I haven't decided if I want to put a fully-triangulated cage in my truck yet because in order for it to do what I want it to do, I'd need a bunch more tube than your average cage.
 
Very well stated Johnny. Things like a harness bar with angle bracing are a must as far as I am concerned. Access to the rear is secondary, I want cross bracing, triangles are your friend :) Not everyone feels the same and are willing to give up something like a door bar or harness bar bracing for better access to space.

As I have stated above, if someone came to me for a cage in a 40 I would reccomend the MT full cage, hip bars, tie in kits front and rear as a base. More bracing, harness bars etc to owners specs for specific uses. It would be far cheaper for the cutomer than starting from scratch with an already proven base design.
 
GLTHFJ60 said:
The momentum of that crash is likely to be greater than the momentum of a low-speed rollover for a 5000# vehicle, which is likely why there is this new requirement that the a-pillar bar can only have one bend in it. .
Click to expand...

I agree and very good points but one thing I would add is to take into consideration if the truck is going to be daily driven or just trailered to events. I designed my FJ40 cage for freeway use, not just a soft roll off road at low speeds. It was braced up with a shoulder bar and cross bars like you'd see in a race car and the seats were on a cradle.

Here is my point:

I sold that FJ40 to a guy who rolled it on the freeway at 70 MPH with his 16 year old son in the truck. They rolled many times at speed because a wheel came off after they did some maintenance and left something loose.

Both walked away un scathed thanks to the cage and Diest belts (and a big dose of good luck). The truck was a total loss and the cops were amazed they were OK. I think the shoulder bar placement was key in them not hitting their heads and keeping them in their seats.

So you have to build the cage for on road too unless you trailer it. You can't just say it's good for off road and leave it at that if you drive on the street and value your life.

On your 60 series the challenge would be building a cage where you head is not going to hit it with out a helmet on. This subject comes up again and again with street driven race cars. There is less headroom in a 60 than in a 40. The implication here is that you may hit your head on the cage in a mild accident where you don't roll and be worse off having the cage than not. Again a subject that has beat to death on many forums.
 
That's one thing I didn't touch on in my post above, multi-purpose vehicles. That's part of the reason why I haven't decided on a design for my 60 at this point.

Do you have any pictures of what the roll cage in your 40 looked like? Sounds like exactly the amount of protection I'm looking for.
 
I do, you can dig through my photo album of pre-digital printed photos - yes I am old - when I move in. No after the crash pics as that happened before the digital age.
 
What were the original crash rating specs on a 60?? That is also something to take into consideration on a multipurpose vehicle, if they were really good like the 80's are then the less beefy of a cage you will need. There are some crazy crash threads in the 80 series sections that you can't believe no one was seriously hurt from. The one where the guy passed out at the wheel and crashed at 60+ mph into a giant earth mover was unreal. I don't think my truck will ever get an interior crane as I don't think it needs any more passenger protection. I'd do an exo just for the sake of saving the sheet metal as much as possible in a roll over.

Now a 40 is a different matter altogether not to get too far off topic.


Personally if I had the big white beast that johnny has i'd do an exo on it. :)
 
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