Body mounted roll cage (2 Viewers)

[nukegoat]

So I'm of the mind that a frame mounted cage is preferable for strength, but I think it comes with some compromises when you have a compliant-mounted body on the vehicle. I'm not quite ready to have some broletariet truggy so I decided to stick with a cage that's mounted to the body. Arguably since the seats are mounted to the body, even if the frame detached from the body, you'd at least stay in the little body capsule should worse come to worse.

People have lots of opinions on that, but they also have opinions on exo vs interior cage. I wanted this thing to protect the lives of the occupants, not necessarily protect the vehicle body. I think most exo cages look like hell too. At the same time, I couldn't figure out how to get a cage in the driver's area that wasn't in the way of my head. So, after seeing enough destroyed rolled 80s and seeing @joez hybrid cage, I decided to adopt and adapt.

Inevitable controversy. Or maybe not, whatever.

To start with, I needed a place to mount the A pillar. The front door mounts are quite stout, and when built as a system (read: a large monolithic structure connected to all 8 mounting locations), the shear strength is really high. Even with 2" .120 wall tube, I'm convinced that a REALLY bad roll would still crush the A pillar first.

So I bent up a tube.

Then removed my interior and made it look like I had been in an accident:

Started experimenting with plates that could be rosetted to the floor for sheer strength, but across a very large span to distribute the load. Additionally I bent minor profiles into a lot of them to add I-value.

Started jabbing tubes through the roof and down into sandwich plates that capture parts of the body with multiple bolts near large seamed areas:

 

[nukegoat]

Made a large truss behind the driver seat

Woe to any full sized rear passengers who like to spread their legs whilst sitting:

Sorry about the paint. Spatter rubs right off. But look at that weld

Made a D-to-C pillar triangulation. That jute burns really easy. Pro tip.

And then I made Simon Cowl:

UH, that's where we're at right now. Roof shot (taken earlier, but illustrative)

 

[Malleus]

Love it. Agree 100%. Are you planning to support the rear, or just leave it cantilevered?

@roadstr6 can post a shot of a bent A pillar to prove your assumption.

EDIT:
Since you're never going to use that sunroof again, can I get your rear drain tubes?

 

[nukegoat]

Love it. Agree 100%. Are you planning to support the rear, or just leave it cantilevered?

@roadstr6 can post a shot of a bent A pillar to prove your assumption.

EDIT:
Since you're never going to use that sunroof again, can I get your rear drain tubes?

Thanks. My sunroof still slides! Just doesn't tilt.

I have mixed feelings on the rear. It's hard to penetrate through the D pillar down to the floor. I would if it were obvious how to do so, but my thought is that it's fairly stout under typical rollover scenarios already and having a hoop over it will distribute any rollover loads across the entire surface of the roof as well. Like a rock slider for my roof. I never have passengers back there. But part of me wishes I had added vertical D pillars just for completeness. A small part of me. Edit: After seeing @roadstr6's thread, I now have less confidence in the D pillar to 'hold its own' in a rollover. But I think I'll be ok.

 

[nukegoat]

I should mention that I don't think the amount of triangulation on the roof is really necessary but I couldnt' figure out a more straightforward way to keep everything triangulated. But given my use of 2" .120 wall DOM, it's probably 100 lbs of steel up there now. And about an additional 250 lbs altogether - I used over 100 ft of tube. So it's probably more likely to rollover now. But at least I have a cage for that.

 

[junior80]

you know those front guards are bolted on right? ie can be removed without cutting them lol. cage looks great btw

 

[nukegoat]

you know those front guards are bolted on right? ie can be removed without cutting them lol. cage looks great btw

They're known as fenders in Freedomland, but mine are not removable any more without the help of lil mr. angle grinder. Anyone borrowing any cues from my design should definitely REMOVE their fenders, and not cut them. When I trimmed my fenders originally, I didn't create bolt-on pieces to reconnect the interior fender to the exterior but rather welded sheet metal on. I regret that choice in hindsight, but they're all smashed up anyway so I don't care about cutting them off and welding them back on. A lot of people who trim fenders just leave open stabby pie-cut pieces (You guys know who you are) that make the outer fender super weak and flimsy.

 

[nukegoat]

Also, after some deep consideration about how the 80 body is assembled, I would not recommend anyone just cut their rocker panel off. There's a lot of structure built into that, and a lot of structure that connects the body mounts to the rest of the body. IMO, anyway.

 

[roadstr6]

I like where this is going. Here's a pic of an 80 that flopped on its roof. Not much protection IMO.

 

[mudgudgeon]

Looks good. Love seeing someone not afraid to take a saw, grinder etc to Mr T's sacred sheet metal!

Before you weld your Freedom fenders back on, can you connect your A pillar down tube into the body's A pillar. Maybe above the top door hinge?
Looks like the weak point will be lack of triangulation on the A pillar down tube, or lack of horizontal connection between left and right A pillar. If these tubes can bow outward in a roll over, your roof cage can still crush downward at the top of the windscreen. Your triangulation in the roof will stop it pushing sideways, but maybe not down.
Lots of exo cages have a tube between A pillars at the bottom of the windscreen. If you can get a good tie into the body near the top of your fender, I think you'd achieve a lot more stability.

It's a shame to see a joint in the A pillar tube. A lot of racing regulations call for the A pillar tube to be a single piece from floor, to B pillar joint. But hey, I guess your not taking it ultra 4 racing? And it's multitudes stronger than no cage.

Also, after some deep consideration about how the 80 body is assembled, I would not recommend anyone just cut their rocker panel off. There's a lot of structure built into that, and a lot of structure that connects the body mounts to the rest of the body. IMO, anyway.

There's actually not a lot in the rocker. An inner skin, and outer skin (2 layers) is about it with some gussetting at pillar intersections. Toyota beefed up the structure of rockers on the 100 series with multiple layers inside the rocker.

I contemplated cutting rockers out of my 80 for weld in RHS sliders, pulled out as many bungs etc as I could to suss it out, but never got as far as cutting it, but i did go all out on hacking rockers out of my HZJ105

 

[mudgudgeon]

I like where this is going. Here's a pic of an 80 that flopped on its roof. Not much protection IMO.
View attachment 1632814 View attachment 1632815

Pooch looks proud of what you guys done to the 80!

 

[bajaphile]

Looks great!

Just curious, what do you use for notching your tube?

 

[White Stripe]

Looks good. I like all the triangulation. I agree that the big floor plates will make it pretty strong. How long has it taken you so far to do This?

 

[inkpot]

Your last pic makes it look like your rig is now too tall to get out of the garage door?

 

[nukegoat]

Looks good. Love seeing someone not afraid to take a saw, grinder etc to Mr T's sacred sheet metal!

Before you weld your Freedom fenders back on, can you connect your A pillar down tube into the body's A pillar. Maybe above the top door hinge?
Looks like the weak point will be lack of triangulation on the A pillar down tube, or lack of horizontal connection between left and right A pillar. If these tubes can bow outward in a roll over, your roof cage can still crush downward at the top of the windscreen. Your triangulation in the roof will stop it pushing sideways, but maybe not down.
Lots of exo cages have a tube between A pillars at the bottom of the windscreen. If you can get a good tie into the body near the top of your fender, I think you'd achieve a lot more stability.

Look at the 2nd to last pic. Theres a connector across the cowl... but yep.

It's a shame to see a joint in the A pillar tube. A lot of racing regulations call for the A pillar tube to be a single piece from floor, to B pillar joint. But hey, I guess your not taking it ultra 4 racing? And it's multitudes stronger than no cage.

Yep. Agreed. My first cage... and bending and notching and assembly logistics are a nightmare with a hybrid cage! Order of operations is crazy.

 

[nukegoat]

Your last pic makes it look like your rig is now too tall to get out of the garage door?

See build thread. I have a suckdown winch for that

 

[nukegoat]

Looks good. I like all the triangulation. I agree that the big floor plates will make it pretty strong. How long has it taken you so far to do This?

Hard to say... probably 80 to 100 man hours

 

[nukegoat]

Looks great!

Just curious, what do you use for notching your tube?

Jd2 notchmaster. Roll cages require way more notches than bends... so buy a good notcher!

 

[ChaseTruck]

...

Best low-profile roof rack on this board, hands down. You should sell these

 

[baldilocks]

"broletariet" Nice work! Big balls! Who did the welds?