Another one of my weird ideas. Any engineers reading this?

I know the topic of whether or not an aftermarket bumper changes the front impact profile of our trucks has been discussed before. I’m convinced that it absolutely does, and significantly so.

What I’m wondering is how much the impact profile might be preserved in a front collision in a Tacoma that has a plate bumper installed, with the stock crash bar mounted on the front of it (removed when off-road).

Yes it would definitely look dumb as all hell, but I’m just wondering at this point, because I want a new bumper but the thought of risking my family’s safety won’t allow me to do it. I’d happily try to figure out a way to mount the crash bar to the front of the bumper if this would significantly preserve the collision safety features of my truck.

 

I'm an engineer. I can say with 100% certainity a plate bumper is going to change the energy absorption rate of the vehicle. Basically this means more force will get transmitted to passengers and less will be absorbed by the vehicle. How much? Who knows. There is a reason that the vehicles are crash tested, a very expensive test. Only aftermarket bumper that is tested is ARB.

 

Any thoughts about mounting the stock aluminum crash bar to the front of a plate bumper might preserve that absorption rate? I realize the only way to know is to test it. Short of that, perhaps math will give some clues. I don’t know how to do that math however!

The ARB bumper is tested but I’ve never seen the results. Have you?

 

And I am not an engineer... but I've responded to more MVA's than I can remember...

I can say that, front bumper or no, the seatbelt is your BEST line of defense in a crash. Stock trucks, modified trucks, doesn't matter... sometimes the airbags blow when you didn'tthink they would, sometimes they don't when you think they should.

I know you didn't specifically ask about airbags but I'm just saying... as long as you are wearing your seatbelts, you stand the best chance of surviving a crash, regardless of how your front bumper looks.

 

MVA = motor vehicle accident?

I am thinking of airbag deployment actually. I definitely don’t want to rely on the airbags, but it is a safety feature I prefer to have functional.

 

Yes and felt them.

 

Seatbelts + crumple zones ftw. If you have a rigid vehicle that transmits full energy to a belted in passenger, then the passenger will still be in the seat, just in pieces.

 

The frame of your truck has crumple zones that are designed to collapse and absorb impacts. The crash bar is mainly for light impacts, so after a collision you can replace the bumper face, crash bar and other cosmetic parts.

 

Yes, MVA. Or MVC.

I'm telling you, my friend, lots of times the things simply don't activate when you'd expect them to. I have no statistical data to support this at all, just anecdotal.

This is simply my opinion but there's no need to worry about them not firing because of bumper modifications when lots of times they don't fire when the vehicle is totally stock.

 

Right. That’s what I was thinking.

 

The addition of that plate changes the dynamics completely. The calculations are not complicated but the simulations need computer power I do not have, nor do I have the software.

What kills me is the cab mount chop for fitting large tires. You know why the cab mount is designed the way it is? To keep the tire and wheel from entering the cabin on offset crashes, yet people actually cut away that safetu feature.

 

My concern is more that they’ll fire prematurely on a light impact due to the decrease in energy absorption.

 

Aerospace stress analyst (certification test specialty) here. Done plenty of testing, but mainly static testing and not much dynamic testing except some fuel tanks.

I definitely think the plate bumper will have less effect than generally expected, assuming it still mounts similarly to the frame and doesnt prevent the frame from crushing like an accordion. Just watching the test crash films and looking at post crash photos, it doesnt look like much percent energy is absorbed by that bar (at high speed crashes). Mounting that original crash bar on the front of a plate bumper will have negligible additional effect on crashes at high speeds. (Note, not discussing energy absorption at lower speeds, like less than 20 mph).

As Masterofnone states, I think the biggest safety effects are just the physical crushing distance between bumper and cab, stiff cab, and numerous very effective airbags, at knees and chest.

 

I did not know that! No cmc here, which is why I decided to keep my stock wheels and go with skinny tires.

 

This.

I believe from my experience with the ARB bumper to walk away with no injury.

If I was just stock, probably would’ve been a little bit more damaged.

Without a crumble zone bumper at all, man... I don’t even want to think about it.

 

Agreed on that, and that intrusion destroys legs and traps the occupant...

 

Never seen or heard that happen but the physics definitely supports that. Ouch.

 

ARB also specifically advertises that it’s a protection from animal strikes so that when you’re out in the “wild” it won’t leave you stranded because of a busted radiator... I run an ARB deluxe bull bar and I love it, but I haven’t had to “use it” and hope that I never do.

That being said, every crash is different and in some circumstances a steel plate bumper will absolutely help... in other cases, yeah I think it could hurt - you never know. But one thing is for sure, as @Masterofnone said you’re best line of defense is the seat belt. Period.

Edit: I am not an engineer. Just a dude with a bumper who hopes never to crash...

 

keyboard engineer here so completely unqualified. but my two cents.

Pretty much comes down to energy absorbed and what would that energy do other wise. a crash going 60 has 16 times more energy than a crash at 15 and a crash bar only absorbs so much.
the crash bar is pretty much for low speed impacts in that 15mph range. The frame takes the bulk of the energy on moderate to highspeed impacts. That is why we so many tweaked frames on here from a "small" collision in the 25-45 mph zone. plate bumper would transfer more energy to the frame though and smaller impacts ones that would just crush the crashbar would maybe dent the bumper, tweak where its mounted to and give you a good ringer, not to say you wont get a little shaken in a hit with the crashbar still on.

 

Ok. Well I’m not sure where to go with this. Maybe it’ll have to be the ARB, but I’m not a fan of how big it is...