Airbags & winch bumpers

[BBQ BOY]

Let's start a topic here where everyone can come and give their educated "guess" on how adding a rigid winch bumper effects airbag deployment.
I for one get very diverse opinions on the issue. For example on Toyota mechanic who is a Mud member told me that adding any sort of rigid bumper can cause premature or early deployment. That includes bumping a cement post in a parking lot while parking your car. That is a $2,000 boo boo.
For me I'd hate to buyba bumper that isn't airbag compliant and bump anything that could cause a $2000 mistake or even cause early deployment in a real accident. If that were to happen the chances of the airbags deflating after impact when you need them the most is a high probability since there are large exhaust holes in the back of the airbags.
I am surprised companies are not forced to meet a standard of compliances within this realm.
I for one love certain bumpers that are not airbag compliant such as the BlueBerry and even Slee tells you up front that if airbags are important to you then go with ARB.

 

[1loudLX]

Know a way to not make your airbags go off? Dont hit things.

 

[dclee]

But sometimes things hit you. Lot of dumb/bad drivers out there...

 

[BBQ BOY]

Theoretically they could deploy on the trail if come in contact with a tree, mound or rock. I have seen 100's/LX's hit objects fairly hard and never seen any airbag deployments nor have I heard of it happening.

 

[rking]

Well if you haven't seen or heard of it happening then there might be your answer. Also if you want you can mount the sensors on your grill, that way if your steel bumper is flexing enough that you'd need airbags more than just what your seatbelt can do then they would deploy? Maybe... I just don't see the vibration of tapping a concrete wall generating the amount of force needed to deploy airbags, I've been in 2 accidents that I was very surprised the airbags didn't go off and one where they did and caused more harm than protection, if you have your seat belt on then that should protect you just as much. I know when a seat belt locks, due to force on it I can't even reach the steering wheel with my head, and my arm would probably hit me in the face anyways with the way I drive... In a more serious accident at say 75 mph if your sensors are placed in the grill they will still go off based of the forces acting on the vehicle. Just my .03 cents and a little food for thought.

 

[TheFuzz]

As mentioned in another recent thread, don't LC's (at least 100s) use an internal airbag sensor located somewhere in the dash that senses overall deceleration of the vehicle? If that's the case, I have a hard time seeing how a different bumper on the front of the truck would change the dynamics enough to cause a deployment from striking a concrete post. I wonder, is there a difference between something being "certified" as airbag compliant (such as a large company like ARB paying for the official certification testing, which I would imagine costs a ton), versus a bumper actually affecting how the airbags deploy? What I mean is, just because a company hasn't paid for the certification, does it mean that bumper will actually affect how the airbags perform in a crash or are they just missing a piece of paper from NHTSA or whoever does the certifying?

I'm no expert...which is why I went with ARB. Wife and kiddo's safety is important to me. But I saw NO sensor(s) up front when installing my ARB earlier this week, and I would imagine something would have to be mounted up front or at least be visible if they are actual "impact" sensors, and are supposed to go off around 5-10mph. You wouldn't get that much intrusion into the bumper at that speed, depending on what you hit...so if they aren't visible, I'm thinking that they aren't there, which means that the sensors probably detect deceleration rather than the actual impact, so the bumper would theoretically have very little to do with airbag deployment.

My brain hurts.

 

[BBQ BOY]

Hey Robert. Sorry I missed you today but I hoped you liked it. I decided to take the day off.

Back on topic. The oem bumper is designed to absorb most of the energy upon impact. Correct? With that being said, if you add a winch bumper the energy is passed through the entire car causing premature deployment. Correct?

 

[DWNUNDR]

Makes sense in practicality. What sort of offroad truck would it be if airbogs went off with a 5-10mph bump on the trails...

As mentioned in another recent thread, don't LC's (at least 100s) use an internal airbag sensor located somewhere in the dash that senses overall deceleration of the vehicle? If that's the case, I have a hard time seeing how a different bumper on the front of the truck would change the dynamics enough to cause a deployment from striking a concrete post. I wonder, is there a difference between something being "certified" as airbag compliant (such as a large company like ARB paying for the official certification testing, which I would imagine costs a ton), versus a bumper actually affecting how the airbags deploy? What I mean is, just because a company hasn't paid for the certification, does it mean that bumper will actually affect how the airbags perform in a crash or are they just missing a piece of paper from NHTSA or whoever does the certifying?

I'm no expert...which is why I went with ARB. Wife and kiddo's safety is important to me. But I saw NO sensor(s) up front when installing my ARB earlier this week, and I would imagine something would have to be mounted up front or at least be visible if they are actual "impact" sensors, and are supposed to go off around 5-10mph. You wouldn't get that much intrusion into the bumper at that speed, depending on what you hit...so if they aren't visible, I'm thinking that they aren't there, which means that the sensors probably detect deceleration rather than the actual impact, so the bumper would theoretically have very little to do with airbag deployment.

My brain hurts.

 

[TheFuzz]

The oem bumper is designed to absorb most of the energy upon impact. Correct? With that being said, if you add a winch bumper the energy is passed through the entire car causing premature deployment. Correct?

I wouldn't say it absorbs "most" of the energy, but probably some...hence the accordian mounts on the newer ARBs. Have you seen what's behind the front fascia on a 100 though? A steel crossmember going from frame horn to frame horn. While I'm sure that it would give more than an ARB does, the 98-02 ARB bumpers don't use accordian mounts do they? But are still airbag rated?

Or do I have that wrong? Either way, deceleration is deceleration...whether or not the truck stops moving after 6" of crumple or two feet of crumple, it's still stopping. Maybe a little more violently with an aftermarket bumper because it gives less/slows down more quickly, but I still don't see it setting off the airbags "earlier" per se...once the sensors reach their threshold they will detonate the bags...even if they are detonated earlier due to a more violent impact, your body will be moving forward more violently as well so in theory everything should be where it's supposed to be lol. I could be looking at this from the completely incorrect perspective, but I'm sure that someone will enlighten me.

 

[TheFuzz]

Makes sense in practicality. What sort of offroad truck would it be if airbogs went off with a 5-10mph bump on the trails...

I'm probably off on the 5-10mph thing, that was just a generalization/guess.

 

[bamabrock]

Makes sense in practicality. What sort of offroad truck would it be if airbogs went off with a 5-10mph bump on the trails...

all airdbags are designed to only go off after a certain speed is reached.

 

[rking]

Crumple zones, were designed to help absorb some of the energy when you have a car crash. Most of those are designed when it is a single vehicle accident into a rigid surface (hitting a pole, concrete wall or building) Now, when you hit another vehicle, this should cause less damage to your truck and more to their rear end. Meaning that your rigid surface will transfer more energy from our large heavy truck into their soft mushy bumper....

https://forum.ih8mud.com/100-series-cruisers/375658-damage-arb-what-do-now.html

Just an example. And I may be wrong and proven wrong by others but thinking about 2 objects hitting, one being rigid and one being semi solid most of the energy would be transferred into them.

and lunch was amazing

 

[bamabrock]

I worry about rigid mounting a metal bumper to a vehicle because I would rather the bumper and accordian mounts take the brunt of a mild collision (like say with a whitetail deer that are all over the place) than have that energy transmitted directly to the frame.

I guess it depends on what you will use the truck for. For crawling, a rigid mounted thick steel bumper is better, but IMO an accordian setup might be better for a DD/weekend warrior.

 

[Trunk Monkey]

I hit my 80 series ARB on a rock HARD. No airbags popped. Friends wife hit a parked city bus with their ARB bar'd 80 at 20mph and both popped. Again, from the other thread, if you're in a situation where they need to work, they will.

Someone should start a thread about tires sizes or shocks.

 

[dclee]

I wouldn't say it absorbs "most" of the energy, but probably some...hence the accordian mounts on the newer ARBs. Have you seen what's behind the front fascia on a 100 though? A steel crossmember going from frame horn to frame horn. While I'm sure that it would give more than an ARB does, the 98-02 ARB bumpers don't use accordian mounts do they? But are still airbag rated?

Or do I have that wrong? Either way, deceleration is deceleration...whether or not the truck stops moving after 6" of crumple or two feet of crumple, it's still stopping. Maybe a little more violently with an aftermarket bumper because it gives less/slows down more quickly, but I still don't see it setting off the airbags "earlier" per se...once the sensors reach their threshold they will detonate the bags...even if they are detonated earlier due to a more violent impact, your body will be moving forward more violently as well so in theory everything should be where it's supposed to be lol. I could be looking at this from the completely incorrect perspective, but I'm sure that someone will enlighten me.

Actually, I believe the crush zones do have an impact on deceleration of the vehicle (though probably imperceptible to us). So if you change the crush zone (or eliminate it), you effectively change the deceleration rate of the vehicle. It should now decelerate faster, given a constant amount of crash energy to be dissipated. Thus, possible premature airbag deployment. But no, bumping a rock on the trail is not what we're talking about. We're talking about high speed impacts where a lot of energy is dissipated. As someone else mentioned, I'm not sure if the airbags (especially the newer multi-stage bags) will even deploy under a specified mph threshold. But I could be wrong about that.

And the older bumpers do have accordion mounts. The difference is that the winch is mounted on a separate cradle directly to the frame horns. So all of the weight of the winch, cradle, and strength reinforcements is not being carried by those accordion mounts. Again, IMHO, a better design from an engineering standpoint. But maybe more costly to manufacture, or install? I don't know. I'm still not sure why they moved away from that design.

 

[TheFuzz]

Someone should start a thread about tires sizes or shocks.

Be careful what you wish for....

*Queue the bi-weekly "what shocks should I get?" thread*

Where is John when you need him?

 

[TheFuzz]

Actually, I believe the crush zones do have an impact on deceleration of the vehicle (though probably imperceptible to us). So if you change the crush zone (or eliminate it), you effectively change the deceleration rate of the vehicle. It should now decelerate faster, given a constant amount of crash energy to be dissipated. Thus, possible premature airbag deployment. But no, bumping a rock on the trail is not what we're talking about. We're talking about high speed impacts where a lot of energy is dissipated. As someone else mentioned, I'm not sure if the airbags (especially the newer multi-stage bags) will even deploy under a specified mph threshold. But I could be wrong about that.

I agree with this...and looking at the details I guess we can somewhat assume that the reduction/elimination of the front crumple zone will cause the deployment speed to be affected. My mind has pretty much been changed on that one. But to what degree?

I see the concern here - airbags inflate almost instantaneously (they are essentially inflated by explosives), and then deflate nearly as quickly so your head meets a nice "soft" cushion as opposed to a rigid, completely filled bag (that would probably do more harm than good).

Like I mentioned above, I guess my question is this:

How is the rest of the vehicle and the occupants affected by the faster deceleration? The vehicle is stopping faster, but so is everything else, including the people. So, thanks to Newton's law, we can expect a more violent impact, that's a given. Seatbelt injuries are more likely because of this. As far as the airbags go, they are detonating faster just as the occupants of the vehicle are going forward in the cabin at a faster rate (or I guess a more approriate way of looking at it is that they are maintaining more of their initial velocity for a split second since they aren't "attached" to the vehicle, if that makes sense). So, in theory, wouldn't the occupants meet the airbag at roughly the same time either way?

 

[dclee]

I worry about rigid mounting a metal bumper to a vehicle because I would rather the bumper and accordian mounts take the brunt of a mild collision (like say with a whitetail deer that are all over the place) than have that energy transmitted directly to the frame.

I guess it depends on what you will use the truck for. For crawling, a rigid mounted thick steel bumper is better, but IMO an accordian setup might be better for a DD/weekend warrior.

^^^ Yes ^^^

Remember Physics 101 and the Law of Conservation of Energy. That crash energy cannot be destroyed. It has to go somewhere. That is the whole purpose of crush zones (and the accordion mounts are intended to retain the front crush zone). Dissipate some of that energy before it goes into the rest of the chassis and passenger cabin. That is one reason why unibody vehicles are inherently safer than body-on-frame. Now, the body-on-frame vehicle will be in better shape after the crash because it has transferred a lot of that energy to the "softer" areas of the vehicle, like the interior, thus the exterior/frame will not deform or "crumple" as much. This leads to the misconception that the vehicle has faired better in an accident, thus the human cargo has also faired better. That is untrue. It just means that more crash energy has been passed into the cabin. Sure, the humans might still be OK, but that is a relative thing. They would have been even better in a unibody.

In the same case, the unibody has totally crumpled, but therefore has transferred less energy to the interior, instead dissipating more of the crash energy as heat and sound because more metal and other materials have crumpled. Also, most unibodies are designed with "paths" or "channels" of compression, allowing engineers to flow that crash energy around the cabin. So for example, in a head-on collision, you might destroy not only the front end, but the sides of the vehicle as well, since some of that energy has been channeled around the cabin and toward the rear. But if safety is paramount (as it is for those of us with kids), then that should not be a concern. So the unibody has basically sacrificed itself for the benefit of its human passengers.

 

[rking]

Dclee: wouldn't the energy be transferred into the frame since it is a direct connection into the frame? Now if the accident is severe enough the body would still crumble because the bumper would still fail..... In a car on car accident I'd assume the energy would transfer into the other vehicle, which would be impaction from a solid object to a semi solid

 

[dclee]

Dclee: wouldn't the energy be transferred into the frame since it is a direct connection into the frame? Now if the accident is severe enough the body would still crumble because the bumper would still fail..... In a car on car accident I'd assume the energy would transfer into the other vehicle, which would be impaction from a solid object to a semi solid

Say the total energy released in the accident equals 100% (of course). 50% of that goes into your Cruiser. So that is the only portion we're talking about, the energy going into the other car has already gone there. But that 50% is enough to squash a human to a pulp if not otherwise absorbed by the vehicle (actually, "absorb" is probably the wrong word, but suffices for the sake of this discussion). You are right, in a body-on-frame vehicle, most of that energy probably would go into the frame. And that is the problem. The frame is incredibly rigid. It won't easily fold up and "absorb" the energy. Since conservation of energy states that energy cannot be created or destroyed, it has to go somewhere. Where is the path of least resistance? Right into the cabin. Not good for the humans...

Of course, all that said, I bought a Cruiser rather than a unibody Jeep or something, because there were other features that were very important to me as well (build quality, reliability, etc.). Plus, it's a Cruiser, and that's almost reason enough! So, I'll take every safety advantage I can, understanding the limitations of body-on-frame.