Roll cage design recommendations with pictures

[Greg72]

Brian,

I think as this idea matures, you are going to have to give up on the "removeable cage" idea....

You won't be able to do a 3-point seatbelt if you remove the cage that holds the upper belt mount. (I don't think you are supposed to use 3-point seatbelts with lowback seats anyway, or any sort of non-headrest seat)

The amount of work to remove the cage when you want it off will be significant...and if you don't build it right, it will never lift straight out of the truck anyway. Odds are that some of the tubes will become wedged somewhere as you try to lift it out. The chances of you scratching your paint or denting panels as you wrestle with a 300 or 400Lb cage are pretty high also.

On a 1st Gen, it's more important than usual to get the torsional stiffness of the cage working to your advantage. Without a top, the body wants to twist badly (even with good rocker boxes, and they seldom are). By the time you tie the cage to itself (with triangluation) and to the frame (if desired) to create a truly safe and rigid structure, it's not likely to be a shape that you can remove or deal with comfortably. Look at 70jimmy's cage photos again....it's strong and well-built, (and removeable) but I certainly wouldn't want to be pulling that sucker out of the truck more than once.

How married are you to the hardtop? I live in the snowy Northeast now and I'm seriously considering giving up on it completely. They are heavy, leaky and expensive to restore. I think I could build a snug-fitting custom softtop that would use the rollcage as it's framework to provide shape and tension. I hate the feeling of the hardtop when it's on anyway....I'm a fresh-air 1st Gen kid!

Ultimately, I think you can come up with a permanently mounted cage design that will be very serviceable for those Home Depot or dump runs and will provide adequate ingress/egress for all the passengers. I've got a turkey to cook right now, but I'll grab a copy of that simple Solidworks (?) image and draw you an MS Paint rollcage later on with some of my ideas....

 

[rdn2blazer]

If you look at my cage design the bed area is still completely open. I will have my rear bench mounted to the cage but it will be removable ofcourse and the truck will have a flat floor when the seat is out. I'm working on this now. I will a have rear seat belt tube behind the rear seat but it will be removable by using 6 bolt style tube clamps. I will have some "X" bracing that will be bolted in with tube clamps too to the seatbelt tube. That will give plenty of lateral bracing that can unbolt and be removed if necessary too. With the seat and X bracing out I will be able to lay down/sleep straight in the back of my K5 no problem.

 

[bp71k5]

Well, it does appear that I may have to rethink the removable part of the idea. The more I think about it and the more ideas from you guys has pushed me that way.

I suppose I could have a more simple "permanent" cage for the home depot runs, and then bolt in strategic sections or pieces for times when the likelyhood of damage goes up (like driving to blazerbash)?

It might even be a neat idea to build the cage in a way that allows me to attach removable "hard" sections of a top to seal out the rain and snow. Maybe I can cut up my top instead of rebuilding it for that purpose. I plan to use the k5 to go snowboarding with the family or friends and the softtop doesn't cut it for that.

Thanks for the feedback everyone! I'll rethink this and post up some ideas after turkey.

 

[bp71k5]

(I don't think you are supposed to use 3-point seatbelts with lowback seats anyway, or any sort of non-headrest seat)

Adding headrests to the requirement list... this could get complicated.

 

[jms]

No turkey to do here, so a few comments...

I would nix the removeability. You seem to imply that driving around town without a top would be safer that running a trail in Moab. I'd seriously question that. In Moab, it's you and the trail. On the street, it's you and a gazillion nitwits, many of which are on the phone, texting, or under the influence.

Forget the jungle gym and 5 miles of triangulation - a lot of that you see on Pirate may look really cool, may also be functional, but is typically not engineered based on numbers, just built. A solid 6- or 8-point cage with triangulation as Chris indicated would serve you well. Maybe a bar across to tie the bottom of the B-pillars together, maybe a bar to tie bottom of A and B-pillars together for rigidity.

Did you want a one-time-use cage - as in protect occupants in a single accident, or a multiple use cage - as in rock buggy where you can roll this multiple times with being no worse for wear?

Seats and belts should be mounted to the same structure - either both to the body, or both to the cage.

Next, a cage presents a hazard for head injuries, particularly in an accident on the street where speeds are (typically) higher than on a trail, resulting in higher forces on occupants, seats, and belts. Padding only goes so far. I'd make the young-ins wear helmets from the start.

 

[bp71k5]

You seem to imply that driving around town without a top would be safer that running a trail in Moab.

I can see how that came across. If I leave it the way things are now, I have low back bucket seats bolted to 1 layer of sheetmetal floor, and two point seat belts. Even with a roll bar, any kind of accident would not be pretty. I already know the lack of safety in its current condition is really unacceptable even for going to home depot. After all, I wouldn't hesitate to add seat belts to any car I drove no matter how "classic" it was.

So I can either do nothing and leave it stock as a garage queen or I can add SOME kind of extra protection. After all this discussion, I think I need to re-evalutate what kind of extra protection I want and how it fits in with my use of the truck. I've just been very hesitant to over-molest a classic truck.

Forget the jungle gym and 5 miles of triangulation - a lot of that you see on Pirate may look really cool, may also be functional, but is typically not engineered based on numbers, just built.

I had the same thought. I want a decent cage that protects the occupant in a single rollover accident. The truck itself does not need to survive a serious roll down a cliff as long as I DO. I will just part-out the truck wherever it lands and take the bus home in that case. I would however like it to still be drivable after simple flops to one side of the other.

 

[bp71k5]

How married are you to the hardtop? I live in the snowy Northeast now and I'm seriously considering giving up on it completely. They are heavy, leaky and expensive to restore. I think I could build a snug-fitting custom softtop

I'm not married to the stock hardtop itself, but I keep thinking having something that looks similar to a stock hardtop would be nice. I've been driving around with the soft top, and it leaks water. I'm not sure there's a good way to completely seal a softtop (around the windows especially). It's also pretty loud at speed on the freeway so long trips are rough in that way. Maybe I'm getting old.

 

[2.5chevy]

im new on here so my opinion is only worth what it is.

i agree with the guys who said that removability has to be forfeited. and i also second that alot of the fancy tubework you see is just that, fancy tube work and is not entirely necessary for an idividual just wanting protection for a daily driver/grocery getter that isnt a hardcore trail buggy that expects to flip multiple times per trip.

i recently went through the same thing with my truggy, i couldnt decide on internal or exo. then my bud and his wife got in a fender bender in their blazer and both of them smacked their melons on the crossbar on his internal cage(ouch). exo was just more desirable for me cus although i drive my truck on the street, i dnt wanna hafta worry about if im gonna roll or not.

i decided to go exo cus it kept my body in perfect condition post install and protects all body panels from most standard trail rash. double b pillar and 16 points of frame contact made from 1.75 dom. i plan on rolling mine quite often so i went as heavy duty as i could view as reasonable. still have my doors, windows, ac, heat, bench seat etc.

you cant have one cage that will yield the benefits of all others. its a sacrifice as always but dont forget the main purpose of a cage in the first place: passenger survivability. sounds to me like a standard 6 or 8 point internal cage is in order, nothing fancy but just as strong as it needs to be in order to save your skin in the event of a roll. gussets and triangulation where needed. dom all the way. just my take on the situation.

 

[colbystephens]

lots of good information here - but i'll admit i didn't read all of it, so i hope the bit i'm going to add isn't too much of a repeat. i get the impression that your wheeling style is not super hardcore - so a jungle gym isn't necessary for you. here's a thought on the removable cage idea...

what about building a hoop that is permanently mounted to the floor at the A pillar that goes up and over the dash - closely following the contours of the dash. Then, get some stacked cage flanges and mount these to the hoop that goes over the dash:

these are great for portions of cage that you want to be removable because that center pin prevents any shear and the bolts you get simply have to have enough tensile strength to keep these two flanges together - which wouldn't be too much for a grade 8 bolt.

this would allow you to build something permenent for the A pillar that would be very structurally sound, but the visible part of the cage from the exterior of the vehicle when the cage is removed would be very minimal. then you could have a 6 point cage - a hoop behind the driver's seat and a hoop at the back of the rig. the mounting points for these are obviously easy to access and the cage could be lifted straight up to remove.

if you had the A pillar permanently fixed to teh rest of the cage, it would be difficult to remove because you'd have to work around the front seats - thus, the flange might just be the solution for you.

a note - since you want the cage to be removable, you'd likely not mount the seats to it. thus, you wouldn't want to mount your seat belts to the cage - imagine the cage pulling away in a hard roll - trying to take to the seat belts with it, while you remain stuck to the seat that goes with the truck...

 

[Greg72]

Brian,

Here's a simple rendering with a few ideas and comments:

This is nothing more than a traditional 6-point "family style" cage with a couple of extra braces from the main hoop (b-pillar) to the floor. This is about the least intrusive way to add protection for four occupants while trying to minimize the inconvenient aspects of a rollcage.

A-pillars could be run down tightly with the windshield frame and through the dash to minimize interference with the door opening, so that getting in and out isn't any tougher.

The braces at the B-pillar are not ideal, but are better than nothing and will help fight against the "parallelogramming" effect of the main hoop in a side rollover. Ideally, you'd do an x-brace but then access to the back seat becomes almost impossible when the soft top/hard top is on.

Rear C-Pillars are kept tight to the bedsides to maximize the utility of the rear bed area for HD and dump runs. With the rear seat removed, you'd still got plenty of utility with this setup.

The overall shape is such that you could use it as a basis for a custom softtop frame. With a little creativity around the front windows (for weatherproofing) it just might be good enough to say goodbye to the hardtop forever.


UPGRADES:

Depending on your own needs and wants, there are some "weak" areas in this simple illustration. It's really just a matter of how far down the "jungle gym continuum" you want to travel.

- More diagonal bracing across the top hoops (improves strength, but starts to close-off the "fresh-air kid" feeling.

- Dash bar across the a-pillars, either above or below the dash to add more rigidity (aesthetically undesireable and a potential knee-banger)

- Diagonal tubes from the upper C-pillar area corners toward the wheelwell area (adds strength, but begins to look like a spiderweb)

- Spreader bar across the tailgate area (would add strength at the expense of utility. This would be a good candidate for a removeable bar, maybe with those door bar release pins like drag cars use?)

Anyway... that's a few ideas while I sip my coffee and promise myself that after yesterday I'm never going to eat again!

 

[bp71k5]

a note - since you want the cage to be removable, you'd likely not mount the seats to it.

Yes, this is an aspect I need to be aware of and can probably work around. I'm fairly married to the stock seat appearance, but not necessarily the stock seat brackets or even small modifications to the seats themselves. I'd even be open to fabricating some kind of headrest mount onto the seats and having a custom headrest made with the same walrus grain vinyl pattern.

I wonder if I can build seat mounts into the cage and then attach separate headrests to the cage instead of the seats themselves? A potential problem with that is the seats and headrests would have to be made to ensure they don't separate in a crash. That problem alone might make the idea unfeasible.

This is nothing more than a traditional 6-point "family style" cage with a couple of extra braces from the main hoop (b-pillar) to the floor.

That's feels like the right amount of jungle-gym vs. safety that can work for me even if the cage is permanent. I could probably even add some additional bracing with removable sections.

I think my original idea of removing the entire cage came from seeing images of super-elaborate cages that would make getting into and out of the truck challenging and changed the appearance of the truck too dramatically. I guess it's somewhat silly to be concerned with the appearance when talking safety, but it is one of many important factors to me.

After all, if safety was the only important factor in my vehicle selection, I'd have to get a volvo and not a 40 year old k5.

 

[TDAWG1]

bRIAN did you get that software we were looking for. That looks cool. Definantly make that sucker right if you are going to do it at all. It should definantly tie in to the frame and support or be supported

Here's a picture with no bars on it.

I actually have seen all of those cages and like them a lot. The problem I have with those cages is that it would diminish the non rock-crawling usefullness of my truck with all that tube. I convinced my wife to let me buy it so we'd have something to haul junk to the dump with.

Maybe I'm going about this the wrong way. If I throw out the requirement about easy removal, my even more basic question is what are the basic requirements for any cage?

Another way to ask might be...how many parts from each of those cage examples could be removed before the cage became useless? After asking that, I'm thinking that there may not be an easy answer since the protection that a cage provides can vary a lot with what happens to it in a crash. It also may be that every piece adds some structure so removing any of it might make it less "protective".

I've got a stock roll bar right now so at a minimum I want some protection for the rear seat passengers. Make sense?

 

[bp71k5]

did you get that software we were looking for.

No, I put it together using some brochures and pictures. The model is not 100% accurate, but I will adjust it as I learn more about which dimensions are critical to the cage. I suspect even if I got it to match the factory drawings, my blazer might not even adhere to those numbers anymore after rusty body panels and other stuff may have allowed things to shift around.

 

[bp71k5]

update on cage planning

So I took the advice of pretty much everyone here and canceled the idea to make the cage removable. It will still "bolt" in to make it easier to weld up and install, but it won't need to come out after that.

Here's what the basic cage looks like now in the "Home Depot Mode" with no back seat. I can still fit sheets of plywood in there and the two front seats still have basic protection.

I think Chris mentioned not to try and tie the windshield frame into the cage. What are the issues in doing that? My hardtop ties into the same spot so it "seems" like it would be ok. I don't mind being wrong though.

 

[bp71k5]

And for "Moab Mode", here's the rear seat back in with some additional bracing (green bars) to reinforce that upper rear corner bend. I'll have to find a way to tie those in properly to make sure they don't come loose in a roll over.

Is this additional bracing worthwhile or would putting it somewhere else make more sense?

 

[Hogback Fabrication]

Just toss some gussets on this design and it will be fine. No need to add anything else IMO.

 

[bp71k5]

Just toss some gussets on this design

Are tube gussets like you added any better than using triangular plate?

 

[Hogback Fabrication]

Are tube gussets like you added any better than using triangular plate?

Tube gussets are better for sure.

I've heard that the plate gussets will cut/fold the tube (kinda like a can opener) though I don't know how much truth there is in that.

 

[bp71k5]

What about the question abou tieing the windshield frame to the cage in the same way the hard top does? I don't want to damage anything by doing that, but it would help hold the door gaps without a top.

 

[Big Blzn]

So I took the advice of pretty much everyone here and canceled the idea to make the cage removable. It will still "bolt" in to make it easier to weld up and install, but it won't need to come out after that.

Here's what the basic cage looks like now in the "Home Depot Mode" with no back seat. I can still fit sheets of plywood in there and the two front seats still have basic protection.

I think Chris mentioned not to try and tie the windshield frame into the cage. What are the issues in doing that? My hardtop ties into the same spot so it "seems" like it would be ok. I don't mind being wrong though.

Brian, your pic in post #34 is exactly what I have currently in my rig. If I didn't know better I would have thought you copied it to a tee. Mine looks really good and goes well with the body lines of the first gens. I'll see if I can dig up some pics. Mine also uses the tube gussets. My cage is 2" and I think the gussets are about 1 1/4" or so. I am going to beef mine up a bit down the line and tie the seats into the cage too.