Builds 86 Xtra Cab Build (4Wheelunderground 3 link front, 4 link rear and 3.4 swap) (2 Viewers)

[aztoyman]

@Broski, I can't do that because I would be going through my rockers and the structure for the cab mounts. Not much room to shift the tubes away from important structure. I'll take another look and see if I can make it work though.

That's why I first tried the halo bar roof. I would have been able to tilt the main hoop forward and down and weld the tops before I put in the A-pillars. I think I can get to those.

 

[littlevulture]

Tube connectors are a no no but joining it back together with sleeves made of 1 1/2" x .120 wall DOM is a better option. If I can weld the tops , I won't cut it.

Why are those bolt together tubing connectors a no-go…I haven’t read any of the rulebooks but I assumed with how prolific they are online they were a legit solution.

 

[aztoyman]

@littlevulture Some of the rule books allow them for harness bars and less critical structure but even then discourage it. Sounds like it's a hinge point?? Maybe an engineer will chime in.

All the rollovers in my groups that I've witnessed were at slow speeds (except one) and the A-pillars caved. They were all Jeeps with whatever factory roll bars they came with. The hard tops got ripped off or really mangled.

I don't haul a$$ off road but I do drive it to the trails. I don't get on the interstate but I'll take the frontage or drive on two lanes at higher speeds so I don't want to chance it.

And then I watched the 4XInnovations videos where they push the Toyota over the bank numerous times and their roll cage holds up well. They use sleeved connections on the main hoop and larger sections for shipping reasons.

The rule books that allow a sleeve connection (usually a repair) specify how it should be done.

 

[aztoyman]

Just to add to the thought process, Marlin Crawler's interior roll cage kit has SIX of the tube couplers, no X-bracing, no back stays and is 1.5" HREW tubing. It does have gussets in the top corners.

Some of the factory tubes in my neighbor's Jeep remind me of the tubing used on my kids swing set.

I have no mechanical engineering education so I'm winging it and hoping I make the right choices.

 

[littlevulture]

I did a little research today…it’s been quite awhile since my statics/dynamics classes and those had a much different engineering focus, although the analysis is similar. I think with the correct hardware torqued properly connectors “could” be acceptable if you used them in the right spot. But I didn’t really see any options on the market that I’d trust.

Here’s some shear and tensile numbers for some standard fasteners, the Barnes 4WD connectors use 3/8 hardware (although they don’t mention thread pitch). McMaster sells similar fasteners with a 170k psi tensile strength. I think the trick to a safe connector design is positioning it in the cage somewhere the interlock takes most of the load instead of the bolts.

Worst case I can see with x2 3/8x16 grade 8 bolts (like the Barnes one) and the load applied in perfect shear on the threads you’d have failure at just under 14k pounds…I don’t think that’s enough to reasonably say the connection won’t fail if ya rolled even though a 100% shear load would be very unlikely. I think at a minimum I’d want larger hardware and a design that interlocks more to transfer more of the load away from the hardware.

Honestly I’m just speculating and not at all qualified but I think you’re probably on the right path avoiding them and using sleeved joins if it comes to it. One other thing I saw mentioned is a failed connector joint could impale you where a sleeved connection would likely just bend.

 

[aztoyman]

@littlevulture , The one set of rules that even mentioned the connectors specified 5/16 grade 8 bolts and locking nuts. No mention of thread pitch or positioning locations. Other than for non critical tubes. So for engine cage and such. Different organizations and race categories obviously have different safety criteria. I don't really fit any but I'm seeing what is "common" for most.

 

[aztoyman]

I haven't given up on this, just have a lot going on in my life. Plus our daily drivers both hit 200K so I've been spending time and money on a 2008 FJ Cruiser and a 2012 Ram 2500. They both were due for some attention.

I did get bits of time to pick away at my cage construction. More pics on the way.

 

[aztoyman]

Things are pretty tight. I can't get my roof diagonal bar in unless I lower the cage a bit. Separating one side would let me position it but doesn't do me any good because the joint under it needs to be welded first.

The diagonal bar is on the floor. Everything is just tacked at this point.

 

[aztoyman]

I fit up the single diagonal bar and the horizontal bar to the main hoop.

 

[aztoyman]

Since I can't cut holes in the floor to drop the cage for weld access, I looked for the best place to cut the cage. I first thought about above both door openings but there's not enough room to re-weld a sleeved joint. It looks like my best place is the two front legs. Marked with red.

I have room to re-weld and I shouldn't have to fight realigning it all. I hope. I should be able to slide it all rearward once cut from the rear base plates.

Plan is to shift it all back and let the front drop down so I can weld the tops.

I still have taco gussets to fab up and cut short tubes for gussets where needed.

 

[Broski]

Great looking work!

It’s hard to tell in the pictures, from what I can see the fits look to perfect for good penetration of the welds
There’s no back bevels.

 

[aztoyman]

You are right @Broski. It's just tacked up for fit. I left them a little long at first and had to fine tune the length so I didn't end up short and waste tube. I still have to grind some bevels and fine tune a couple joints yet. Good eye!

I even dialed in my welder settings on scrap tube joints. Trying to get this right. THANKS for checking my work! Feel free to point out anything or question why I did what I did.

I have to drill two more holes in the rear floor plates and paint the bottoms. The front ones were showing rust so they are already done.

The tubing is 24 footers and don't fit in my garage so I made sure to clean surface rust with phosphoric acid which also gets any mill scale off. And I hit the tubes with a DA sander after I bent them because it sucks to try to sand an installed cage.

Parts came in for my Ram so I'll be on that tomorrow.

 

[Lucille]

After just putting a cage in my first gen i feel your pain with getting it to fit high and tight. Why cant you cut holes in the floor to lower it down? Are you going to run a dash bar behind or in front of the dash?

 

[aztoyman]

@Lucille , I put my base plates right above the cab mount structure. The floor is 3 layers of sheet metal thick there and has gussets that I'd be hole sawing through.

I have to see what I have to work with on the dash bar. I am going to try to put the dash pad back if I can. Cut as needed and relocate the two outer A/C vents. I have to be mindful of keeping access for removal of my heater and A/C or any other under dash components. Don't want to weld myself into a corner.

I've seen the clamp on dash bars but they don't look to be a structurally sound solution. The bolted on factory bar goes across right where my A-pillar bars bend. I thought about tying it in to my A-pillars.

Suggestions are welcome.

 

[littlevulture]

What about removing the factory dash bar and moving the mounts for the dash and related components to a new structural bar for the cage that goes in the same spot? I didn't pay super close attention last time I pulled a dash but I seem to remember that crossmember being more or less a tube.

 

[aztoyman]

I'm considering that, but it's not as simple as it seems. It's kind of a triangle shaped sheet metal tube on driver side that turns into a tube to the passenger side. It's doable though.

 

[littlevulture]

Just looked that part up and I'd agree that it doesn't look trivial...unfortunate cause that'd be a super clean way to do that. I found this guy on YotaTech that sunk his A pillar bars into the factory dash cross bar...maybe that's an option with appropriate reinforcement of the dash bar.

 

[aztoyman]

@littlevulture , yep, that's kind of what I was thinking but mine is a bit different than his and it's maybe about 1 1/4" diameter tube on the passenger side so I didn't think it was going to be strong enough. It's pretty thin. Plus my A-pillar is not as far forward as that guys.

I thought about just having a bracket on my A-pillar post to bolt it to since it's right next to where it bolts to the body on each side. Thinking it might add a little more support. Like the sheet metal gussets that you often see between the A-pillar and windshield frame.

I'm going to see if I can just weld a 1 3/4 tube across somewhere it will fit. Most of the cage construction specs say to put the dash bar as high as possible WITHOUT going above the top surface of the dash.

I really want to keep my HVAC working and accessible for service. Trying to keep a glove box for my wife. Not planning on a sound system and it won't bother me if I have to fab a gauge panel.

I appreciate your input. Thanks for the link. When I get my Ram and the Wife's FJC up to snuff I hope to get on it again. I've also had a lot of medical testing going on and more scheduled. I don't want any of you guys to think I'm losing interest in this build. The last couple weeks all I could do was get a few minutes here and there to stare at it and think about how to make this come together.

I just went out and took some pics. I might be able to squeeze a tube right where it needs to be. Across and just to the rear of the factory brace. Right where each A-pillar bends. I definitely have to make some major dash mods. I don't really want to pull the factory brace but I will if it comes down to it.

 

[aztoyman]

Looking at these pics make me think my best option is to eliminate the factory brace and tie everything attached to it to the dash bar I weld in. Even tie the end to the body like the factory did. Any opinions or other ideas?

 

[littlevulture]

Another idea from looking at your pictures...can you ditch the stamped part of the OEM bar on the drivers side and run the cage inside the remaining tubular part of the crossbar as an internal sleeve then tie it into the A pillars with gussets? That'd keep keep you from having to remake all the mounts on for the stuff on the passenger side and keep it in the space that was already allocated for the cross brace.