Question about custom bumper fabrication

[jwkilgore]

My long-term goal is to get steel bumpers for my 2011 SR5. Right now SSS for the rear and Shrockworks for the front. I wanted a SSS front, but other factors have eliminated that one. Other things were coming first, specifically better undercarriage armor (skids and slides) and a upgraded springs/shocks to carry the weight.

But now things have changed. One, my wife rear-ended a boat and the prop trashed the grill and put a hole in the lower bumper cover. Second, I lightly side-swiped a tree during a reverse turnaround on the trail, which further scratched the lower cover (this is why the SSS bumper won't work). And finally, my dad (who retired about 2 years ago) may be finally running out of welding projects. He's fully capable of building a bumper if I leave the vehicle with him.

My concern is with safety, as this is a 95% daily driver for my wife. With the OEM bumper, a moderate impact (less than 20mph?) is mostly absorbed by the crush cans between the aluminum bumper support and the frame. But if the steel bumper is mounted directly to the frame, any impact will transmit the full force to the frame/occupants. This could cause a moderate impact to trigger the airbags when not needed, and/or bend the main frame instead of just the crush cans. This would factor both in a rear-end collision on the street and a hit on a tree or rock on the trail.

So...
1) Does the ARB bumper hang off the OEM crush cans, or do they incorporate new crush zones in their design?
2) I'm thinking it would be possible to have a 3-way system with a custom bumper:
- The winch would be on a separate beam hard-mounted to the frame, similar to a hidden-mount;
- The vertical weight of the bumper (and anyone standing on the bumper, and/or lifting the truck with a hi-lift under the bumper) would be supported by the primary frame and/or winch frame, but with slotted holes such that;
- The first few inches of longitudinal force on the bumper from external impact would go through either the OEM or hand-build crush cans.

I'd have to work out recovery points, because I don't think the crush cans would handle a hard snatch. Most likely I'd use access holes and the OEM points or else new points mounted to the frame. Or else locate the slotted longitudinal holes such that the bumper is free to move toward the vehicle but would be fixed if pulling away from the vehicle.

Any thoughts on this, [MENTION=66316]1engineer[/MENTION]?
[MENTION=104049]marshal[/MENTION], I saw that the frame horns were damaged in your wreck with the 4x4Labs bumper. Any thoughts from you?

Does this sound even remotely reasonable? Or am I overthinking this; just order the Shrockworks and be done with it?

 

[Hellamatic]

The ARB has crumple zones incorporated into the frame brackets. The factory recovery points are retained, so you can still use those for snatch recoveries. Personally, I'd just buy a bumper instead of fabricating and save the hassle, but if your pop has a plethora of time on his hands it couldn't hurt to try.

 

[1engineer]

My long-term goal is to get steel bumpers for my 2011 SR5. Right now SSS for the rear and Shrockworks for the front. I wanted a SSS front, but other factors have eliminated that one. Other things were coming first, specifically better undercarriage armor (skids and slides) and a upgraded springs/shocks to carry the weight.

But now things have changed. One, my wife rear-ended a boat and the prop trashed the grill and put a hole in the lower bumper cover. Second, I lightly side-swiped a tree during a reverse turnaround on the trail, which further scratched the lower cover (this is why the SSS bumper won't work). And finally, my dad (who retired about 2 years ago) may be finally running out of welding projects. He's fully capable of building a bumper if I leave the vehicle with him.

My concern is with safety, as this is a 95% daily driver for my wife. With the OEM bumper, a moderate impact (less than 20mph?) is mostly absorbed by the crush cans between the aluminum bumper support and the frame. But if the steel bumper is mounted directly to the frame, any impact will transmit the full force to the frame/occupants. This could cause a moderate impact to trigger the airbags when not needed, and/or bend the main frame instead of just the crush cans. This would factor both in a rear-end collision on the street and a hit on a tree or rock on the trail.

So...
1) Does the ARB bumper hang off the OEM crush cans, or do they incorporate new crush zones in their design?
2) I'm thinking it would be possible to have a 3-way system with a custom bumper:
- The winch would be on a separate beam hard-mounted to the frame, similar to a hidden-mount;
- The vertical weight of the bumper (and anyone standing on the bumper, and/or lifting the truck with a hi-lift under the bumper) would be supported by the primary frame and/or winch frame, but with slotted holes such that;
- The first few inches of longitudinal force on the bumper from external impact would go through either the OEM or hand-build crush cans.

I'd have to work out recovery points, because I don't think the crush cans would handle a hard snatch. Most likely I'd use access holes and the OEM points or else new points mounted to the frame. Or else locate the slotted longitudinal holes such that the bumper is free to move toward the vehicle but would be fixed if pulling away from the vehicle.

Any thoughts on this, [MENTION=66316]1engineer[/MENTION]?
[MENTION=104049]marshal[/MENTION], I saw that the frame horns were damaged in your wreck with the 4x4Labs bumper. Any thoughts from you?

Does this sound even remotely reasonable? Or am I overthinking this; just order the Shrockworks and be done with it?

I posted the physics of aftermarket bumpers and crashes somewhere.I will look for it.

 

[wfo9]

There is no easy answer to this one...

My opinion.... If your wife drives it most of the time, stick with OEM.

 

[jwkilgore]

There is no easy answer to this one...
My opinion.... If your wife drives it most of the time, stick with OEM.

Normally I'd agree with you. She likes it because it rides better than her older 2WD Pathfinder, and I let her drive it because my commute is about 36 miles round trip vs her 8 miles.

But this is my only off-road capable vehicle. I bought this specific vehicle before we got married because of its off-road capabilities, and I do use it off-road. Or more accurately, I use it on "roads" that aren't 2WD friendly, and some of them fully test the A-Trac system. :whip:

I'm not going to spend $$ on a new OEM plastic bumper when I can spend $$$ and get a significant upgrade to a steel bumper where I can eventually mount a winch. Worst case is we just swap keys and I drive the 4Runner, but I'd rather do everything I can to keep her both happy and safe while improving my off-roading capability.

Also, it's still speculation at this point. I'm still going to get skids and slides first (much more effective use of money), and I'll need a suspension upgrade at the same time as the bumper. I'm slowly getting back in control after all the financial issues over the past 9 months (starting with $5000 from a dog dying of stage 5 cancer after my wife pulled all the stops to save her, then going downhill from there), but I'm still working on it. :violin:

At the earliest this bumper wouldn't happen until late next spring, more likely next summer. It's just that all the recent damage to the OEM bumper got me thinking about it, and if I'm going to design one myself I need to get some information first. I'm going home for Thanksgiving and I'll yank off the bumper in my dad's shop so we can start scratching our heads.

 

[marshal]

Don't forget I broadsided a 7000lb truck at 40mph. I think trashed frame horns is a moot point.

The factory crush cans are in no way shape or form suited to be used as a recovery point. ARB uses their own integrated crumple zones.