Airbag deployment

pop058 · Post by **pop058** » Mon Jun 11, 2012 8:28 pm

Hi all.

Recently joined your forum and have a question (or 2) already. My daughter rearended a Tarago (am I allowed to say that here

) in her MY03 Liberty a little while ago. The crash did bend the front chassis rail, but did not set off the airbag.

I was looking on evilbay (amongst other places) for parts/wrecker to see if it was worth fixing. I found 2 others (Impreza and Outback) that had fairly substantial hits up the rear and in photos of the interior, no airbags were set off either. A 4th Liberty at the wreckers also had a big hit in the front and again, no airbag deployed.

My question(s) are, should the airbag/s have gone off and 2, if so has this happened to anyone else? and should I be asking "Subaru" itself some questions.

tks

Paul

Brumby Kid · Post by **Brumby Kid** » Mon Jun 11, 2012 8:56 pm

Hi welcome.
Ummmmmm. How hard was the crash? Dont car about speed, just was she hurt? Chassis Rails are ment to do that to absorb the shock.
Was she hurt? Any whiplash?
With a 5 star safety rating I really think that if it was hard enough they would have gone off.
If she was hard enough to hurt her ( and she doesn't bruise easily) and they didn't go off then I would be asking questions.

Cheers Cam

pop058 · Post by **pop058** » Mon Jun 11, 2012 9:21 pm

chest and rib bruising. (she is altitude challenged and sits fairly close to the wheel) and a sore neck (aggravated by previous accident)

Brumby Kid · Post by **Brumby Kid** » Mon Jun 11, 2012 9:32 pm

Yeah car should look like that. Should see my mates dad's vl wagon. Hit a tree real hard almost died. Car held up really well.
What did insurance say? You should have many more problems than just the front of the body. If the chassis is well, rather fu(ked. Then do not fix it yourself!!! Talk to insurance, talk to a suby repairer. What was the cause?
I would expect that if she was too close to the wheel then she should have that. And if airbags did deploy they may not have worked too well.

Cheers Cam

taza · Post by **taza** » Mon Jun 11, 2012 9:38 pm

Looks like a decent hit from the pics but no the airbags shouldn't of gone off. From where they are there isn't any damage.

There are only 2 airbag sensors on any Subie with front and passenger airbags (only 2). They are infront of oth front wheels in the fender guards attached to the chassis.
In the first pic I can just see one which is yellow where the bumper has been pushed forward.

If they haven't been damaged then they won't deploy. Luckily the car is wuite easily repairable.

d_generate · Post by **d_generate** » Mon Jun 11, 2012 10:59 pm

I've been buying and fixing Subi's for years, I look at the auctions most weeks and they do seem to take much more to get the bags to activate than most cars, good in most ways as the people wouldn't have been hurt badly if at all, I've seen Mercs and BMW's that look like they have just had a mild kick and all the bags have gone off making repairs much more than the initial little bump would have cost to repair or even made the car questionable to repair as the bags come to many many thousands to replace.

YouTube · Post by **El_Freddo** » Tue Jun 12, 2012 12:03 am

In a crash the ECU (or one of them as the case may be) will do a split second calculation to work out if the air bags will be a benefit rather than a health hazard to the occupants. They are meant to be a life saving device and not a life ending one. Set off in the wrong conditions and they can kill you!

So I'd say that while the car sustained this much damage, it wasn't severe enough to deploy the air bags.

Cheers

Bennie

Gannon · Post by **Gannon** » Tue Jun 12, 2012 6:12 am

If you read up in the SRS air bag part of the owners manual, it describes what is likely to set off the air bags.

As stated above, the damage does not look severe enough to have to have damaged the sensors. Im pretty sure they are located at the front of the chassis rails, where the chassis rail meets the radiator support panel.

littlewhiteute · Post by **littlewhiteute** » Tue Jun 12, 2012 7:34 pm

Not enough damage to deploy.

Airbags are deployed according to G-force above a certain minimum speed.

Some cars are G-force only, you could be stationary and have a car hit you at 100km/hr and YOUR airbag could deploy.

Crash sensors measure deceleration rate (Negative G force) and the module deploys the airbag accordingly. Damaging a crash sensor does not deploy the airbag.

Your car could also have a 2 stage airbag, and if your daughter sits close to the wheel this affects deployment strategy in the SRS module.

sven '2' · Post by **sven '2'** » Tue Jun 12, 2012 10:49 pm

I suggest that there are many other factors that the ECU considers before deployment. Is (near) impossible to suggest just looking at the end result to determine if the SRS AB should have deployed or not.

Vehicle postion, speed, decelerating or accelerating etc are just some of the inputs.

And as for sensors being disabled in a crash before deployment - a crash at high speed takes as little as 120ms compress the crumple zones - the trigger to deploy the airbags has already tripped in the first 90ms.

I would take my chances on a AB deploying over a steering wheel injury ANY day of the week.

Glad your daughter is ok.

woody.t · Post by **woody.t** » Tue Jun 12, 2012 10:51 pm

we touch on it once during a physics lectuer at uni... an extremely simplistic way at looking at, (number of other parameters taking into account in reality) it takes about 20Gs for them to be deployed that is 20 times the acceleration of gravity around about 190 ms^2 of deceleration which is equivalent to breaking from 100 in well under half a second.. crumple zones in the front of cars are designed to collapse in stages under accelerations and forces far less then the airbag is needed for, airbags are pretty much your last hope.. so to answer your question, i'm not surprised it didn't go of and not surprised alot of cars with what have had some what serious weren't violent enough to trigger an airbag deployment...

Subyroo · Post by **Subyroo** » Wed Jun 13, 2012 1:59 pm

pop058 wrote:chest and rib bruising. (she is altitude challenged and sits fairly close to the wheel) and a sore neck (aggravated by previous accident)

If your daughter is altitude challenged and sits fairly close to the wheel be she should be thankful in one way that the airbag didn't go off.

A female friend of mine in Townsville is also altitude challenged and sits close to the wheel, she slid off a roundabout in wet weather doing 40 km/h and hit a lamp post smack amidships, she ended up with facial bruising and a broken sternum thanks to the airbag.

I have seen a Rent-A-Car Falcon where both airbags went off and both the driver and the passenger still left their head imprint in the windscreen, yes they died.

pop058 · Post by **pop058** » Thu Jun 14, 2012 7:56 pm

Thanks for the replies people.

Paul

Tweety · Post by **Tweety** » Thu Jun 14, 2012 9:08 pm

Well airbags were a worry for me riding tweety.

If someone rear ended me.

But then I realised my misses being seated so close behind and a bit above me...I have the best airbags I've ever felt....

You go to Target and ask for size xxxxxxxx

Gannon · Post by **Gannon** » Thu Jun 14, 2012 10:11 pm

Tweety wrote:I have the best airbags I've ever felt....

You go to Target and ask for size xxxxxxxx

Photos or we dont believe you!

YouTube · Post by **El_Freddo** » Thu Jun 14, 2012 10:30 pm

Gannon wrote:Photos or we dont believe you!

Without being dirty, he's on the money...

Cheers

Bennie

Tweety · Post by **Tweety** » Fri Jun 15, 2012 8:53 am

oh if I have to!!!

and I have that heater in front of my thighs to keep my greatest assets warm....

guyph_01 · Post by **guyph_01** » Fri Jun 15, 2012 10:57 am