88 XJ Improvements

[NXJ]

I never understand why you guys don't build the cage tighter to the roof construction, especially the A-pillars, I'd have a little difficulties getting in and out of the driver seat in a hurry. I guess you look at it as exercise? :laugh3:

Anyway, why not route the front tubes through the dashboard? That's what I'll do on another (even smaller) vehicle.

 

[8Mud]

I never understand why you guys don't build the cage tighter to the roof construction, especially the A-pillars, I'd have a little difficulties getting in and out of the driver seat in a hurry. I guess you look at it as exercise? :laugh3:

Anyway, why not route the front tubes through the dashboard? That's what I'll do on another (even smaller) vehicle.

The fewer bends the better. When a cage does crush, it has a tendancy to fold at the bends. Curves are better than bends and bends are stronger facing out than in. Triangles are the strongest shape, in many directions.
You can plan around the likely directions of crush. But it's doubtfull, a person can forsee all the stresses involved, without a lot of trial and error.
I'd plan for strength first, then directions of crush in a likely crash scenario, then for comfort.
I tend to think of the cage as an extension of the exisiting body, not as an independant structure. And try to make it strong, where the body is weak.
The last cage I built, actually folded the front tires under the drivers seat and spit the motor, tranny and transfer underneaath and out the rear. Not good planing, more luck than anything else. You hit a five ton rock at 50+ MPH and something is gonna give.

 

[8Mud]

I never understand why you guys don't build the cage tighter to the roof construction, especially the A-pillars, I'd have a little difficulties getting in and out of the driver seat in a hurry. I guess you look at it as exercise? :laugh3:

Anyway, why not route the front tubes through the dashboard? That's what I'll do on another (even smaller) vehicle.

The fewer bends the better. When a cage does crush, it has a tendancy to fold at the bends. Curves are better than bends and bends are stronger facing out than in. Triangles are the strongest shape, in many directions.
You can plan around the likely directions of crush. But it's doubtfull, a person can foresee all the stresses involved, without a lot of trial and error.
I'd plan for strength first, then directions of crush in a likely crash scenario, then for comfort.
I tend to think of the cage as an extension of the exisiting body, not as an independant structure. And try to make it strong, where the body is weak.
The last cage I built, actually folded the front tires under the drivers seat and spit the motor, tranny and transfer underneath and out the rear. Not good planing, more luck than anything else. You hit a five ton rock at 50+ MPH and something is gonna give.

 

[8Mud]

Sorry I don't know exactly how I double posted and I can't seem to make it go away.

 

[88XJScott]

Thanks for all the drawings, I think I will add those gussets. Definitely not hard to add them.

My A pillar is as close to the dash board as it can get. My light switch barely contacts it when I turn them on. Routing the cage through the dash would be the way to go, but it is not very easily to pull the dash out and it is hard to run the tube through the dash without interferring with the AC/defroster tubes. Thats why I didnt do it, I thought about, but decided not to.

 

[NXJ]

The fewer bends the better...

It's not a question about adding more bends, simply just pushing the A-pillar part of the cage forward, thus following the roof-line, resulting in greater support of the roof during a rollover.

 

[Fryphax]

approximetaly how much tubing did you use in the build of the cage?

 

[88XJScott]

I used 5 21' sticks, including my screw ups, so right around 100'.

I have some leftover to add to it once I roll it and have to cut the top off.

 

[8Mud]

I used 5 21' sticks, including my screw ups, so right around 100'.

I have some leftover to add to it once I roll it and have to cut the top off.

If your actually planning on rolling it, what about a diagonal from the rear view mirror area top windshield cross piece, to the middle of the cross piece inside the "B" pillar area you have running behind the seats. Won't mess with the back seating any, though it might bang your shoulders or elbow.
Maybe try a chunk of tubing in that space and see if your shoulders hit and/or it blocks your vision. Pad it if you decide it will work.
IMO that "A" piller is still the weak spot, though the "B" piller construction will likely prevent you from getting crushed.
A lot of vehicles have a weak "A" piller in a rollover, I think the XJ was strengthened some in that area in the mid 90's.