All right, Rice701 and I have been at eachother's throats this evening on the subject of frame tie-ins for cages. We need some input from those who are in the know.

My position is that a triangular, boxed, gussetted mount (just like the stock body mount plates) with a poly bushing on top of it (again, like stock with a boat roller, hockey puck, etc) through bolted and washered with beefy Grade 8 hardware is the way to go. This allows for strength, some torsional flex (with the frame), and isolates the cage from some vibration.

Rice's position is that the poly busing won't take the stress and will fold in critical situations. Instead he proposes that PBM's design with NO bushing and minimal shock absorbtion is superior:


Now I'm not knocking PBM's design, because I know it was purpose built for relieving stress on a fiberglass frame, it was easy to fab for the given space, and let's face it, the man has BEEN there first hand. But it would seem to me that under stress from off-angle this would fold faster than the stock body-mount design.

So let's get the guru's to weigh-in on this one. What's the best way to tie in the feet of a full cage to the frame?

'83 CJ-7 nothing original but the tub and axle tubes

Well, I aint gonna say it's the best way (I think it is, but who am I ) is to make them just like you say!! That's the way I've built the 5-6 cages I've done and 2 of them have rolled hard and held up fine..Least where they were supposed to anyway!!

It's as close to a 1ton as it can get and still be a jeep!!! Gotta love it!!

Going to the frame with the body mount idea, or outrigger with or without isolation will be stronger in certain situtations due to the angle of forces. The reason I did it this way on the CJ7 is the cage style that comes down behind the seat lends itself to a weird mount either way, & I have the cage tied in at eight points, these are the only two that are at an angle. I didn't isolate them from the body or anything, they are rigid from frame to cage, body twists, fatigue, vibrations, and cracking aren't that important to me, strong cage is. I think either way you go you are fine, just make sure it is strong and attached well.

<font color=purple>pbm</font color=purple>
<font color=red>There is a difference between being Educated and Intelligent!</font color=red>

My cage has both. The front and main hoops attach to the frame like you had described with the outriggers similiar to the body mounts. The rear section of the cage where it attaches to the fenders has bent pipe attached to the frame.

Rick
80 CJ7

I'm not replying to hurt anybodys feelings, but whatever way you do it, do not trust welds that look like that. They look like they were done with an underpowered mig machine using flux core wire. Not enough heat, no pentration, and poor sheilding. Even if you ground them down to make them look pretty, I'd bet the penetration is poor. When building a cage, safety is #1, That means in the design, and in construction technique. IMO, a weld like that is not good enough for a SAFETY cage.

CTjeepnut

You had to do what to fit those little tires?
I'm sure glad I own a CJ!

Paul-
You are absolutely correct & the the first person to mention that, I did screw that one & a rear one up royally & I HAVE removed and re-did them after looking and constantly doubting their strength. I ran out of gas on my large mig, and tried using a smaller one w/o gas and this is how it turned out. It actually penetrated somewhat (not good enough though)after cutting it apart. Your description of the machine is right on, great eye and thanks for the concern. One of those fun things of being impatient not wanting to wait to get gas and use the right machine, so I ended up spending more time, cutting it off, grinding and redoing it all, than waiting til morning and getting gas. The rest of the cage is great, and my welds have saved me and a couple others before, this was just a momentary lapse of thinking/patience which is what you don't want building the cage and glad Paul brought it up for people to see.


<font color=purple>pbm</font color=purple>
<font color=red>There is a difference between being Educated and Intelligent!</font color=red>

here is my thoughts.. however you tie it to the frame great.. make it solid.. and as for under the mounting plate of the roll cage.. use a slightly larger plate.. say the cage sits on a 4"x4" square plate.. use a 4.5"x4.5" square plate for under the body.. and in between the bottom one and the body.. put a piece of old tire.. (thick dense rubber 1/2" thick) that way.. it isolates from vibration.. and doesnt colapse... best of both worlds in my eyes.. i also put a piece of realy thin rubber under the roll cage plate.. just for vibrations..

http://www.jeepgod.net


<font color=orange>If you are allergic to lead, it is best to avoid a war zone</font color=orange>

my tie ins were just like the ones in the pic (way better welds though..LOL) and they held great for my recent roll, and it wasnt a slow roll either

~~Elusive~~
everything good in life is round, breasts, halos, and headlights
http://www.jeepgod.net

Slow rolls can be as bad as fast rolls. It's distance dependant to the first blow, like down a hill. This of course factors in time and magnifies the force via the gravity of the situtation.

So which is best?

IMNO the best is tied as stiff as you can get it tied to the frame mounts....no chushion no nothing. That presents a problem where the body has to flex around the roll bar mounts. If the mount ain't cushioned... the body can't flex and that can be a warp problem for both Metal and Fiberglass bodies.

Then there's anohter question of what to do with the seats. They sure can pull loose as the tub attemts to rip off the frame mounts (or punch through the frame mounts in the case of a Fiberglass body incorrectly installed) and kill the driver. Again, IMHO, it's best to put a little more thought into the cage and weld a few more bars for seat mounting to hardend the system.

We all remember this very sad picture of a several hunderd yard roll down a Colorado mountian (at slow speed) about 2 years ago...



God forbid it will happen again, but I'm sure it will. Here's a case of you may not have the chance to do it right the second time, so you'd best do it right the first time.

Think of the worst roll you'll ever be in, it's forces, it's vectors and plan for it and then work your plan by building the cage an saving your own life.

What thickness/diamiter tube would everyone suggest?