Airbag Deployment with an Aftermarket Bumper (1 Viewer)

[Appolyon]

How does the airbag deployment work with the aftermarket bumpers.(specifically ARB) I understand that some of them are airbag compatible, but some are not. What does that mean for airbag deployment in the case of a headon collision? I have read scottm's accident info, and I know that the airbags do deploy in an accident.

I really would like to know what is required (how much force) to trigger the airbag in the FJ80 when there's an ARB on it. What does a winch add to that kind of impact? (more weight I'd assume, but anything else)

Also with that, would putting crash harnesses into a LC be a good idea? How would that factor into airbag deployment? (I'm thinking along the lines of 5 point restraints....) Is this a reasonable concept, or am I going overboard like always? In the event that i'm not crazy for thinking about putting 5point seats and harnesses into my LC, then has anyone done it? What about a harness bar? I know that I can't be the first person to think of this, so what has your decision been?

I'm trying to find do my research before I present this to the 'rents. (yes, this means that a number of you are old enough to be my parents ). I know my parents will find the ARB page that says that the bar isn't airbag compatible, and they're going to want to know what that means, as well as what i'm doing for safety. (They're all for vehicle armor, but not at the cost of occupant safety)

I'm putting this in the 80's section because according to ARB's compatibility charts, they aren't airbag compatible.(Everything under 100 isn't....) The 80 series is definitely very resilient, and safe inside the passenger compartment as shown by this thread and J-Bo's accident, where the airbags did deploy, even though his seatbelt stopped him from reaching them.

Clearly the airbags do deploy when necessary, but what is "necessary"? It seems like I'm going to have to find a Toyota guy (cruiserdan Maybe?) who can explain it...

Finally, now that't you've reached the end of my horribly long, and probably very annoying thread , I have a question.

Romer: Can we get this put into the FAQ so that it's easy to find for newbie's like me. Please feel free to connect all the airbag discussions to this, because it'd be very nice to add this to the FAQ section.

 

[d0ubledown]

airbag deployment has nothing to do with the bumpers design. its all about the abrupt change in (forward?) momentum and there are sensors (not in the bumpers) that detect this. at least thats how i understood it...

 

[firetruck41]

I have a previous post from a long time ago about this, I think it even had the documents relating to the activation. Basically, there is a deceleration sensor near the center console , if conditions are right, and the system is armed, then a accelerometer will trip the airbags if the sensor detects a specific deceleration. Basically, the sensor is in the cabin next to you, so whenever the appropriate deceleration reaches it, it will trip the airbags, regardless of what is on the front of the vehicle.

EDIT: here are some excerpts from the FSM

 

[IdahoDoug]

Airbags (SRS, actually) are designed to work with your restraint system so never drive in an SRS equipped vehicle without seatbelts expecting them to protect you.

SRS systems use a sensor or sensors to detect deceleration of the vehicle. Some systems have one or more in the area behind the bumper to detect the impact slightly earlier than sensors placed in the center console area, which nearly all have. They compare notes in milliseconds and if 2 or more don't agree a collision is happening the system won't deploy the airbags. Some newer systems use a single sensor in the console area as experience and reliability were proven for sensors over the years, allowing this strategy.

Roughly speaking, the threshold speed is about 15mph into a solid object such as a wall, tree or bridge. Also roughly speaking, the impact must come from the front within 15 degrees to each side of dead center for a swath of about 30 degrees.

The ARB bars for the 80 were not put through the expensive testing procedure to certify them as this was a time when SRS was just appearing on the scene. Later 100 models and beyond may have been. Adding the bumper adds structure to the front end that is extremely helpful in minor collisions to prevent a disabled vehicle and stranded occupants such as a deer strike or fender bender. In severe collisions it would most likely offer even more help by tying the front frame tips together securely and helping ensure the tough frame continues to be involved in resisting crush as the front end collapses. Without it, the factory bumper basically gives up early in the crushing. This is all theoretical and the wide variety of crash factors make the extent of help impossible to estimate.

I have a background in vehicle design and personally feel they're so effective that I put one on both our 80s specifically for increased crash protection - not for offroading. If my wife is out with the kids on a lonely dark road and wacks a deer on the way home, I want her to remain mobile with headlights and radiator intact despite severe damage. Ditto a minor fender bender in a bad part of some town. I don't want her sitting immobile under any circumstances - rural or urban. Those safety issues are even more likely to benefit us from having an ARB than the severe crash scenario, and they all contribute to total vehicle and occupant safety.

How would an ARB affect SRS deployment? Hard to say as there are situations I feel it may deploy them faster or earlier and other situations it may slightly delay SRS deployment. Overall, I think the total safety is improved with having an ARB.

EDIT: Nice post Ben - appeared while I was typing.

DougM

 

[Appolyon]

Perfect Explanation Thanks

What does "incompatible" mean then if the airbags do go off anyway in the event of an accident?

I posted this question in response to firetruck 41, but IdahoDoug beat me there... and answerd my question perfectly.

So back to the other part. What would be the advantage of harness restraints instead of the standard seatbelts? Disadvantages?

Thanks Doug and Ben for both of you... (When I turn 21)
EDIT: Ben Posted the second time while I was writing
EDITX2: Ben Answered the Question I changed, so now i have a shortened question, and my next question.

 

[firetruck41]

As far as I have been able to tell, it means they have not been tested with airbags, and they do not "accept" liability, if you are using the bumper on an airbag equipped vehicle. It doesn't mean it will/won't work, it's just legal stuff to protect them from a lawsuit.

 

[CycloSteve]

x2^^ to IdahoDoug's comments...I feel much safer with my Slee Shortbus bumper, as compared to the tin-can-thin OEM one (which was bent by the PO in a parking lot). I too live in the country, and my wife has hit a deer before with our previous 4x4, and likely that will happen again. Better to be able to drive-away, then have to call a tow-truck.

Back to the original question...since the system is triggered by the accelerometer in Post #3 (which I have had to replace), I am confident that the SRS system will work no different from the factory setup.



Steve

 

[sandcruiser]

has anyone ever retrofitted SRS into an earlier 80 series?

I seriously doubt I will actually do it, but curious to know how difficult it would be to do.

 

[firetruck41]

has anyone ever retrofitted SRS into an earlier 80 series?

I seriously doubt I will actually do it, but curious to know how difficult it would be to do.

Never heard of it. Would never consider it.

You would have to change the dash and steering wheel out, and get the entire SRS system. Also, you would have to see if the pre-OBDII ECU would even communicate the needed info to the SRS system, then I would still never be confident that the system would work as designed. I would be hoping it would not go off when not needed, and hoping it would go off when needed. But, anything is possible with enough time/money.

 

[80t0ylc]

Back in 2001 when I purchased and installed my ARB, I thought I recalled seeing a SRS warning affixed to the bumper. After seeing this thread I was curious to see if it was still there and amazed to see it firmly intact. That was 8 years ago, mine is a '94 with out SRS, and a lot more is known about bumper performance, now. I don't know if ARBs for 80s that are sold new today still have this warning, but here is what the warning looked like that was put on non - SRS ARBs back then:

 

[Devil's Slide Doug]

Can I be the one to point out that (according to your sig line you have a 91) if your 91 fj80 has no airbags then it simply is not a concern. As far as the five point harness goes, I have no doubt it would restrain you better better but would be unwilling to install one in my daily driver/road trip vehicle where I prefer the convenience and comfort of a traditional lap/shoulder belt.

 

[Appolyon]

Okay

Can I be the one to point out that (according to your sig line you have a 91) if your 91 fj80 has no airbags then it simply is not a concern. As far as the five point harness goes, I have no doubt it would restrain you better better but would be unwilling to install one in my daily driver/road trip vehicle where I prefer the convenience and comfort of a traditional lap/shoulder belt.

Ya... I was wondering about that... Does the '91 not have any airbags? I thought it had a drivers side bag...

I don't mind the harnesses... My friend has one in his mustang, and i actually like it better than the lap belt. Feels much more secure. (and definitely is...)

Any ideas of how to put in a 5 point? I'm looking Sparco Seats and Toyota Supra harness bar. How wide across inside is the FJ80 from the inside of the B pillar to the opposite pillar? (Thanks Ben for the Correction: the pillar right behind the drivers seats, where the passenger doors are bolted.)
I would check, but I don't have access to my 80 right now... Can someone run out to your rig with a tape measure for me?

Edit: I'm considering either the Supra bar and the Sparco seats, or Yota Gods Forbid, a set of Jeep seats and harness bar...

 

[-Spike-]

No bags before '95.

 

[firetruck41]

How wide across inside is the FJ80 from the inside of the C pillar to the opposite pillar? (i'm guessing that's which one it is... I'm talking about the pillar right behind the drivers seats, where the passenger doors are bolted.)

That would be the "B-pillar". The windshield pillar is "A", the one behind the driver door is "B", the one behind the passenger door is "C" and the one at the back of the cargo area would be "D". Sorry, no measurements.

 

[Ebag333]

In severe collisions it would most likely offer even more help by tying the front frame tips together securely and helping ensure the tough frame continues to be involved in resisting crush as the front end collapses. Without it, the factory bumper basically gives up early in the crushing. This is all theoretical and the wide variety of crash factors make the extent of help impossible to estimate.

One concern I have heard is that if the vehicle is too stiff, the impact transfers to the occupants. Hence the design of crumple zones.

 

[firetruck41]

One concern I have heard is that if the vehicle is too stiff, the impact transfers to the occupants. Hence the design of crumple zones.

Some truth to that, but the other vehicle will become a crumple zone. Also, there is a lower end threshold where you would rather have some energy transferred to the occupant rather than sacrifice your OEM front bumper/grille/radiator/hood/lights/quarterpanel, and there is a higher end threshold beyond which, you would rather have the energy transferred to the occupants rather than have the cabin deformed and trapping/injuring/killing the occupants. There is a limited middle ground where I would rather have a crumple zone, but the low end and high end benefits of something like an ARB bumper, far outweigh that limited middle ground.

An example of the low end threshold would be a 15mph accident where you rear end someone, with a stocker, you might not have a sore neck, but you destroyed the hood/radiator/bumper/lights/quarter panels. If you had an ARB, you might have a stiff neck for a few days, and need to spray bomb the ARB.

An example of the high end would be ScottM's accident, running into an excavator parked on the side of the freeway at 55mph (brakes never applied), the ARB he had probably transferred more energy through the frame, causing slightly quicker deceleration, but the cabin did not collapse enough to kill him, though he was severely injured. Chances are, if he didn't have that ARB, there would have been further structural collapse of the cabin, which would have very likely killed him. I know he credits the ARB with saving his life, after he went back and viewed the wreckage.


In conclusion, I really wish I had a stout aftermarket bumper, instead of my dinged up stocker.

 

[greentruck]

No doubt that some of the issue in modifying the bumper is concern in changing the engineering parameters that govern the operation of the SRS system. It's designed to work within a specific set of parameters. But quite honestly, much of it is CYA that is driven by the need to avoid legal liability.

But let's return to engineering parameters. My mom had an accident just this week. No not in an 80. It was in a 4-door Lincoln. She had a spell where she passed out, which they still aren't sure the cause of. She's pushing 80 - the age, not the vehicle!

Anyway, the car drifts off the road, heads across the field, takes out a couple of trees about 6" in diameter, before coming to rest. The passenger side air bag deployed, but not on her side (she was alone in the car.) The seat belt wacked her good and she seems to have wacked her head some on the steering wheel a little, too.

So, the impact of the trees was at an angle that caused the PS to deploy, as seen in the FSM illustrated above, but didn't work on the DS. The SRS is not a be-all, end-all. It must be used with seat belts and then the accident has to occur in such a direction and with such a force to cause the air bags to deploy.

Fortunately, my mom will be OK and didn't cause anyone else to be hurt. Her driving days are likely over if they don't figure out the cause, as no one wants to take a bet on that happening again.

Add the ARB bumper, wear those seat belts and get a '95 or newer 80 with the airbags and this should be a good and safe solution to meet your parents concerns.

There is no perfect solution to safety. The best solution to safety is defensive driving, i.e. YOU as the driver have as much to do with it as the vehicle does. In all my years of driving, my paying attention to those around me has kept me out of multiple accidents. Bad luck still got me a couple of times, but that's life. Good luck to you.

 

[Appolyon]

That would be the "B-pillar". The windshield pillar is "A", the one behind the driver door is "B", the one behind the passenger door is "C" and the one at the back of the cargo area would be "D". Sorry, no measurements.

Thanks Ben- Darn- Anyone? please? I need the interrior measurements between the B pillars-

No doubt that some of the issue in modifying the bumper is concern in changing the engineering parameters that govern the operation of the SRS system. It's designed to work within a specific set of parameters. But quite honestly, much of it is CYA that is driven by the need to avoid legal liability.

Add the ARB bumper, wear those seat belts and get a '95 or newer 80 with the airbags and this should be a good and safe solution to meet your parents concerns.

There is no perfect solution to safety. The best solution to safety is defensive driving, i.e. YOU as the driver have as much to do with it as the vehicle does. In all my years of driving, my paying attention to those around me has kept me out of multiple accidents. Bad luck still got me a couple of times, but that's life. Good luck to you.

Glad to hear your mom's okay-

I totally agree with you on the subject of defensive driving... and I drive very calmly for a teenager- due to being the victim in a bicycle versus Porche accident... I am still very careful, but I've nearly been hit or hit other people, all of whom ran reds (where I live has a high number of elderly people, and they sometimes don't notice the light change...) So far being careful has paid off, and I haven't had any accidents. (minus a very very minor rear fender bender with a stupid person parking their Mazda... but that was fixed with a c-clamp and some bodyweight...)

I wish that my parents had purchased the '95+ but i've got the '91 and for the forseeable future that won't be changing... so since i don't have airbags, would the 5 point harnesses be a good idea for my truck? see post #13 for what i'm looking at...

 

[IdahoDoug]

I don't think anyone would argue against a 5 point harness' superior restraint ability and better load dispersion in a serious impact. However, having this improperly done (unprofessionally done anchors, bolting it instead of welding, a pipe near the back of your head to administer severe head injuries, etc) would be worse than using the carefully researched and installed factory seatbelts in a crash. So, yes that a 5 point harness would help, lots of doubt on my part it would/could be done correctly outside of a race shop and $2000.

Best strategy for me would be drive slowly and defensively, be sure the vehicle's tires/brakes/suspension are well maintained, and get in the habit of having the seat far back from the steering wheel as your new driving position. I'd rather see the $$$ spent on having the vehicle able to avoid accidents. I avoid a minor accident per year and a major one every few years that takes pretty extreme vehicle handling of the 80.

DougM

 

[firetruck41]

I agree with Doug. Find something else to spend your money on.