crush cans, airbags, and other points of confusion

darw_n · Jan 4, 2005

OK, i was earlier asking about aftermarket bumpers, and I am getting confused, and I am having trouble searching out the answers...

I am replacing my front bumper, I cracked it, and have to replace it, so I am going for an aftermarket with good approach angle.

I am getting lost by the options and variables out there. I keep hearing people word answers in ways where it sounds like I don't need crush cans, or that I do need them, or that it is better to find a way to mount to the frame, etc etc.

can someone lay out the basics and the variables, including the airbag system, (is it important to keep, can you get rid of it? I hear airbags fetch a good dollar when sold ;-).

I just want a strong, good looking, and "effective on the trail" bumper. But like everything else I guess, I don't want to make a purchase, then find I could have done better, or I didn't notice a particular "problem" or variable before I made the expense.

Also, this is my first aftermarket purchase, and not to sound like an idiot, but who is "RTE"?

I appreciate an light shed on this subject!!

thanks

p m · Jan 4, 2005

Jesse,

here's my quick rendition of the old description made by J.Espelien on "Old DWeb" -
the airbag is triggered by the forward ac[de]celerometer;
the crush cans reduce the peak deceleration;
removal of the crush cans is likely to increase the sensitivity of the airbag deployment.

In short, with a stock bumper on crush cans, the airbag is likely to deploy at a frontal collision at ~40mph.
With a rigid steel bumper mounted without the crush cans, the airbag may deploy at the frontal collision at ~25-30mph.

mikem · Jan 4, 2005

RTE is Rovertym Engineering http://www.rovertym.com/

Crush cans are part of the bumper mounting system for airbag compatible bumpers and will be included when you purchase the bumper. Don't worry about them. Just decide whether you want an airbag compatible bumper or not.

If you are considering removing the airbags altogether, you probably don't need an airbag compatible bumper. Check out RTE, roversolutions (http://www.roversolutions.com) and safari gard (http://www.safarigard.com/) for bumpers.

Here is an explaintion of how airbags work http://auto.howstuffworks.com/airbag.htm

darw_n · Jan 4, 2005

has anyone removed airbags before? On a DII that is?

what are the benifits if any?

how do you remove them if there are benefits?

and **if** I do remove them, can you sell them, or how does that whole process work?

so to summarize : if I want to leave the airbags, then only get airbag compatable bumpers

if I find that removing the airbags has it's own benefits (I have never wrecked in 14 ears, knock on wood), then get an RTE bumper or similar, which do not have crush cans?

I am a beginner when it comes to wheeling, so I imagine that I will hit a few tree's and rocks down the road, I almost feel more "safe" with no airbags, am I wrong to think that?

Remeber, I am a N00b, so my ideas may very well be misguided from little experience...

Now what's up with some people saying it should be mounted directly to the frame, differently than a "normal" install? Apparently it has something to do with recovery links and winches, which is something I may explore in the future (recovery points probably immediatly)

p m · Jan 4, 2005

I think it may be illegal to remove them.

There are no significant benefits, except for selling one to some poor soul who's been in an accident and buying a used ARB bumper from the proceeds. Land Rover's airbags are not commonly known to deploy without a very good reason.

dmcfarlane · Jan 4, 2005

Couple of suggestions...

1. You do not want to remove the airbags. Only plausible reason to remove the airbags would be to remove the passenger side airbag if you are mounting a laptop (or other equipment) in front of it (or in place of it) which you don't want to turn into a projectile.

2. You can use any bumper you want to, irrespective of your having kept the airbags.

syoung · Jan 4, 2005

I've never heard of someone having an airbag deploy when offroad... usually when running trails, you aren't going fast enough even if you plant the bumper on a rock or stump you didn't see.

darw_n · Jan 4, 2005

thanks for the posts, I didn't know that it was illegal, I thought I read someone taking there's out, and thanks for pointing out that rover airbags are very stable...

and again, I hope I didn't come across as dumb or harsh/insensitive. It's my first purchase, and I want to make sure I go the correct path!

thanks again

1st Rover · Jan 5, 2005

I don't believe that removing an airbag on your own car is illegal. FMVSS requires them on the car from the manufacturer.

As O.J. Simpson found out, if criminal law doesn't get you then tort law will. Your personal liability from selling/operating a truck from which you have removed safety equipment, and having an accident, could be substantial.

If you don't want to use it offroad, you can probably just pull the fuse. Someone here can probably shed light on any proceedure necessary for pulling/re-installing the fuse.

I wouldn't remove an airbag from my truck as long as I'm using it on-road. My (formerly) accident-free brother just ran into a piece of construction equipment in his LC at ~60, his biggest injury was a compound-fractured leg. The truck was destroyed. There is no question in my mind that the airbag contributed to protecting him from more serious injuries to the brain or spine.

craig · Jan 5, 2005

I think the term "airbag compatible" is misleading. All of the bumpers will work with the airbags. The bumpers that are tagged as being airbag compatible will just do so in the same manner as the factory bumper. The ones that aren't certified will (as posted earlier) just deploy with a less substantial impact. The important thing here is that the airbag becomes more sensitive to crashes rather than less sensitive. The airbag works with all of them though.

p m · Jan 5, 2005

Jeff - it may be illegal, if you get an SRS discount in your auto insurance. I am not sure that disabling the ABS is legal, either - for sure you could be sued if you rear-ended someone and disabled ABS was deemed to cause it.

Just came across this -

from NY Times, today: (West Coast Customs has recently been fined by federal regulators for removing front air bags to make room for extra video screens.)

1st Rover · Jan 5, 2005

FMVSS does require airbags as a passive restraint, from the manufacturer.

ABS on the other hand is not required by any law in the U.S., only braking performance is regulated. In the case of the brake performance regulations, the braking system must also perform satisfactorily with the ABS system inoperable.

But as we both mentioned, tort law could bite you as it could be claimed that an accident would have been either avoidable or injuries less severe would the ABS had been funcional or if air bags would have been functional.

I have been called to testify in court and severity of injuries vs any variables is a main-line arguement by attorneys.

I would prefer to disable ABS and air bags when off-road, and re-enable when re-entering the roadway.

I do agree that early deployment is the problem with "non-air bag certified" bumpers / bull-bars. Although this might not sound like a big deal, having a "fender-bender" and having a couple thousand dollars worth of airbags deploy wouldn't make my day, I'd spring for the extra $$ for the certified bumpers. Having the punch to the face is also not pleasant, especially if you wear glasses, are drinking from a coffee mug, etc.

turbojedi · Jan 5, 2005

A common misconception is that airbags are triggered when crashing at a certain speed This is incorrect. Most modern SRS systems are triggered by rate of deceleration in an accident. For instance, if you hit an elk at 75 miles an hour your abags may not deploy. The animal moves so that your car does not come to a stop fast enough. On the flipside, you may hit a wall at 25 or 30 and your bags may deploy. Crush zones are very important in that they determine airbag timing. If the crushzones are too stiff, the bag deploys too early, deflates and your face hits the wheel. If the zones crush too fast, the sensor causes the bag to go late or not at all. (face still hitting wheel) Something to keep in mind is that if you disable the SRS system your seat belt tensioners may not work either. These are often linked with the bags. I manage a collision shop and when we see a car w/bags gone or SRS system disabled we will not even work on the car for liability reasons.

The long and the short is, a non airbag compatable bumper may affect air bag timing. This would also depend on the type of accident. Hope this helps

nosivad_bor · Jan 5, 2005

http://www.expeditionexchange.com/ics2/indexmain9.shtml

ARB Bumper (non airbag meaning no crushcans)

Bags did not go off.

rd

darw_n · Jan 5, 2005

so...

that guy *had* to know that he was going to get in that situation...

right?

turbojedi · Jan 5, 2005

my guess is he wasn't going 40

p m · Jan 5, 2005

turbojedi said:
A common misconception is that airbags are triggered when crashing at a certain speed This is incorrect. Most modern SRS systems are triggered by rate of deceleration in an accident.

of course. Isn't that what's been said already?

p m said:
the airbag is triggered by the forward ac[de]celerometer;
the crush cans reduce the peak deceleration;
removal of the crush cans is likely to increase the sensitivity of the airbag deployment

But, the deceleration is not what one's instrument panel shows. So, the comparison of speeds of full frontal impact at which the airbag is likely to deploy is easier to grasp.

Jeff - that's what I wanted to say.

lacrits68 · Jan 5, 2005

airbags and after market bumpers

Hi!

i wake's a qustion, when you say that its illegal to disable airbags....

how gan you mount an aftermarket bumper (non-airbag compatible kind) without doing something illegal?

if bumper is not airbag compatibel you have to remove crush cans and that means no airbag, that means you are doing something thats not leagal?

or do i missundestan the whole situation?
(sorry my bad english...)

--J--

p m · Jan 5, 2005

that may not be illegal, but -
if you put a non-airbag-compatible bumper on your truck, get into a frontal collision, the airbag deploys when it shouldn't have, and leave you blind or with broken wrists, you can't sue Land Rover for damages.

this is different from disabling the airbags altogether - then they won't deploy no matter what.

lacrits68 · Jan 5, 2005

Ok...

next question is is there any aftermarket bumper that are air bag compatible AND give you an good approach angel...(as goos as rovertym forexample)?

"They" (who know) say that ARB is poor as original one what comes to approach angels....!

--J--

crush cans, airbags, and other points of confusion

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