check out the new roll cage

[Yukon Jack]

Originally Posted by Bishops Trucks

A rollbar that is not engineered properly can be more dangerous than a vehicle without one. There would be more tubing in the vehicle that could crush you. The rollbar looks good for something that stays on the main roads but for offroading you would need some bars added from oneside to the other and some verticle bars added to the sides. It would be a maze to get to the back seat.

I think a few properly placed bars could definitely make that rollbar safer. I think you want it to work properly whether or not the vehicle ever goes off road - you want it to work if needed and vehicles do roll occasionally on the street as we all know.

What worries me is the fact that in a roll over, the side bars at the rear point of the roll bar are probably going to bend towards the rear passengers. There is nothing to keep the bars in that area from collapsing inward.

I in no way have any experience with rollbar fabrication but it sounds like safety is a concern, as it should be, and it sounds like you are open for input so I would encourage those that do know what they are talking about to draw in recommended additions to the pictured bar that epsorenson could then show to his fabricator or some other fabricator for consideration.

Triangulation is key and I bet it could be done in a way that doesn't make a jungle gym out of the interior.

[vtblazer]

Originally Posted by epsorenson

yeah you've said that a few times now. i'm not sure what to make of it. i'm certainly not an engineer nor do i have an understanding of roll cages potential to withstand forces in roll over. the guy who built the cage and a few mechanic friends of mine whom i trust told me this thing is strong enough. your concerns obviously make me contemplate my kids safety. again, my main driving is surface streets at reasonable speeds just cruising around. i don't want to "over-engineer" something for the sake of doing so but you seem pretty convinced that this thing is not "functional" and it's not going to stay "intact" with a roll over...yikes

Yeah, I know I do.
The reason I keep bringing it up is that with each new person who reads this thread and includes "roll cage" with their response makes me nervous thinking that they might have the same design installed in their blazer all the while believing that their safe from a roll over, when it just isn't the case here.

Whoever is telling that it'll be "strong enough" needs to go back to physics class or cage building 101 or at least rethink the answer.
The cage has zero integrity to combat a sideways impact and during an actual roll and where will the highest forces being applied come from?
Think about it...

What could happen in anything more than a very light roll over is potentially:
1)The front hoop will push sideways, being there's nothing to prevent it from going sideways.
2)The rear legs will push inward and collapse, again because there is nothing structural to prevent them from doing so.

If nothing else a set of gussets would go a long way to building a better/safer cage.

[Chevyman63]

Originally Posted by vtblazer

Yeah, I know I do.
The reason I keep bringing it up is that with each new person who reads this thread and includes "roll cage" with their response makes me nervous thinking that they might have the same design installed in their blazer all the while believing that their safe from a roll over, when it just isn't the case here.

Whoever is telling that it'll be "strong enough" needs to go back to physics class or cage building 101 or at least rethink the answer.
The cage has zero integrity to combat a sideways impact and during an actual roll and where will the highest forces being applied come from?
Think about it...

What could happen in anything more than a very light roll over is potentially:
1)The front hoop will push sideways, being there's nothing to prevent it from going sideways.
2)The rear legs will push inward and collapse, again because there is nothing structural to prevent them from doing so.

If nothing else a set of gussets would go a long way to building a better/safer cage.

I don't believe anyone here is trying to trash your roll cage for the fun of it, we are all just thinking of you and your passenger's safety.

[AJs72K5]

I think we all agree that your roll bar looks nice. It compliments the lines of your rig well. I hate to put a post up from another board, but this is how you build a roll cage in a 1st gen K5: bigblock72's cage on CK5

[epsorenson]

oh yeah, i know there is no trashing intended. i'm just looking for honest opinions on this thing. i'm actually pretty darn discouraged now after paying good money to get this thing put in and am questioning why the heck they did it this way to begin with. this is a major reputable off road shop. i would think they would have done the right thing from the start. grrrrr...i'm a bit frustrated now. i need to take a step back from this and take a deep breath. i guess i should've just bought a stinkin kit that had more of a sturdy design and had it installed!! this is crazy...

so, can you guys help me with a diagram of how i can make this thing right and exactly where to add the tubes. just the bare minimum that will make this thing full fledged but not be too elaborate.

[-Greg72]

Take a deep breath....

It's nothing that can't be fixed. At this point you've lost very little....maybe the cost of the powdercoating that will need to be re-done, but that's a small price to pay. This is a safety item, and it's protecting you and your families' lives... that's worth a lot.

The simplest solution that I can see is to put a bar between the two bars that run front-to-back on that cage. Basically create a "square" when viewing it from above. That one bar will address the most glaring issue with the current design, which is that nothing will prevent those side bars from simply bending into the passenger compartment in a rollover.

From that one change, you can decide how much more to do....most people would tell you there's still quite a bit that needs improving.

Suggestions:

1. Put an X-brace across the top of the cage to triangulate that "square" shape that you created by adding the one extra tube that I suggested above.

2. Add an A-pillar structure to connect from the existing cage to the front windshield pillar areas. If you roll over, the existing hoop might protect your head, but there is nothing to prevent the windshield from collapsing down onto you. This basically converts your current 4-point cage to a 6-point cage.

3. Triangulate from the existing B-pillar from each upper corner down to the floor. This is a tougher one, because it WILL affect ingress/egress into the backseat area. Ideally, you'd run a bar across the floor directly behind the front seats and bring the two angled bars together in the center of the truck on top of that floor-bar. The intention is to prevent that main hoop from collapsing sideways in a rollover.....if you look at it now, it's basically a square shape (when viewed from the back of your truck) and a roll would probably just push it into a "parallelogram" shape...

4. Tie the cage to the frame underneath, or at least to plates underneath the truck. A cage that's only bolted to the sheetmetal of the truck isn't going to work very well.....more like an old-fashioned can opener. The forces will simply punch the cage right through the floor at the existing mounting points. Most of these early trucks have a lot of hidden rust in the floor areas (especially the front footwell areas) so it's even more important to KNOW that the cage is bolted to something equally strong.


You can get this corrected for a little extra money..... rarely does anyone get everything perfect on the first attempt, so don't beat yourself up over it. But the lesson is also to do your own research and don't necessarily trust a so-called "expert" unless they have relevant experience doing the type of fabrication you are asking for....

[epsorenson]

Originally Posted by -Greg72

The simplest solution that I can see is to put a bar between the two bars that run front-to-back on that cage. Basically create a "square" when viewing it from above. That one bar will address the most glaring issue with the current design, which is that nothing will prevent those side bars from simply bending into the passenger compartment in a rollover.

how about adding some tubes to make it similar to this?
this would add the support to address the lateral bending safety issue for rear passengers right?.

[-Greg72]

Sure, that's better.... the top bar in the rear is the important one. The photo you posted also has two triangulated tubes that appear to run from the b-pillar to the top of the rear wheelwells also. Again, it's better than nothing at all, but those bars aren't adding lateral strength to the cage. They are only helping to prevent the cage from collapsing backwards from the drivers area into the passenger area.

The triangulation that would be nice would happen from the upper corners of the b-pillar and travel diagonally down directly behind the two front seats and land in the center of the floor (just behind the center console) on a cage mounting plate.

Hope it's starting to make a bit more sense.....

[epsorenson]

Originally Posted by -Greg72

Hope it's starting to make a bit more sense.....

yep, it sure is...thank you for the help.

[DURRTY]

nice blazer ! the door gaps, cowl and fenders are lined up great.

[vtblazer]

Here's another cage that looks great in a K5.

I realize it's way more than you want in yours but it might inspire a couple ideas for ya.
It's had the same 'base' tube set as yours does.
Front hoop and rear legs are simalar, then they added on a bit from there.

[Yukon Jack]

Here is a link to a few articles I scanned in the past that might be good reading on this subject.

[gringoloco]

I think the cage is sufficient for your needs as long as it is tied into the frame. It looks decent and will likely be fine unless you go tumbling down a mountain. Jeeps to this day come from the factory with this exact setup...

[sandking]

Love the Blazer!!

Here is a better idea of triangulation. It is probably overbuilt for most people, but it is perfect for what I am using it for. It is obviously not done yet, but you get the idea.