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Airbag equipped vehicles and homemade bullbars
Posted: Sun Jul 23, 2006 4:05 pm
by mtb4x4mad
Does anybody know the exact regulations in NSW for airbag equipped vehicles and bullbars?
There must be a huge number of competition cars (GU's etc.) out there today which have airbags and yet still have some sort of tube bar that doesn't appear to cater for the airbag sensors.
My guess is that you can't put a homemade bullbar on an airbag equipped vehicle, but how do so many of the newer vehicles have tube bars and the like?
Posted: Sun Jul 23, 2006 4:37 pm
by Roctoy
i personally wouldn't put a home made bar on an airbag equiped vehicle.
I just think there must be a very good reason why the big companies put so much r & d into their airbag compiant bullbars.
I wouldn't want one going off in my face unless i really needed it to.
Chris
Posted: Sun Jul 23, 2006 4:56 pm
by -Scott-
I was in a store recently which had bullbars on display. It looked like the "airbag compatible" bars used detachable "crush boxes" in the mounting system.
Perhaps the crush boxes are commercially available items?
Scott
Posted: Sun Jul 23, 2006 8:07 pm
by Harrow
100 series dont use the crush zone box the bull bar just bolts straight on. so i guess it depends how your cars air bars are set off. cause i would put a home made bar on my 100 series.
Posted: Sun Jul 23, 2006 9:03 pm
by Thor
as above.. maybe worth checking the system of recording a crash that allows the airbag to deploy.
jeeps for eg. have a deceleration sensor and not an actual crush box
Posted: Sun Jul 23, 2006 9:14 pm
by Steve F
Yep, my homemade bar bolts on the same as a stock bar does but also uses the optional reinforcement holes that the factory tow hook package uses. The jeep uses a decelerometer so in theory it doesn't matter what the front bar is like or how it attached the airbags still go off.
Cheers
Steve
Posted: Sun Jul 23, 2006 9:18 pm
by Gribble
There was a thing going around about SRS not being an ADR requirement so techincally if you render the system inoperative then you dont need a bullbar that is manufactured to suit SRS.
Best to check with RTA or an engineering signatory on that one.
Posted: Mon Jul 24, 2006 10:08 am
by turbo gu
Gribble wrote:There was a thing going around about SRS not being an ADR requirement so techincally if you render the system inoperative then you dont need a bullbar that is manufactured to suit SRS.
Best to check with RTA or an engineering signatory on that one.
from what l have been told is that if a car comes fitted with airbags they must work and are not allowed to be disabled even if you fit all the parts from a non airbagged model eg column steering wheel. i would say if a car is fitted with airbag there would be a ADR relevant to it on that car.
As for bull bars i reckon the reason that airbag ones are different would be they would have move give/crush than non airbag bars so the bar would give/crush in a accident thus giving a similar decel rate to a bumper bar equiped model so not to give a false rate of decel causing the air bag to go off when not actually required
Posted: Mon Jul 24, 2006 10:36 am
by Steve F
turbo gu wrote:
As for bull bars i reckon the reason that airbag ones are different would be they would have move give/crush than non airbag bars so the bar would give/crush in a accident thus giving a similar decel rate to a bumper bar equiped model so not to give a false rate of decel causing the air bag to go off when not actually required
On my Jeep when they went from non airbag to airbag nothing changed, the bumper mounted the same etc etc. If a decellerometer is used then it doesn't matter what you have strapped to the front of a 4WD, if it stops quickly enough to set off the airbag then you need it, if it doesn't stop quickly enough to set of the airbag then you dont need it. Simple
More than likely the airbag will go off a little sooner with a bullbar and decellerometer than without as there will be less crush and a more sudden stop.
Cheers
Steve
Posted: Mon Jul 24, 2006 1:23 pm
by mtb4x4mad
Steve F wrote:turbo gu wrote:
As for bull bars i reckon the reason that airbag ones are different would be they would have move give/crush than non airbag bars so the bar would give/crush in a accident thus giving a similar decel rate to a bumper bar equiped model so not to give a false rate of decel causing the air bag to go off when not actually required
On my Jeep when they went from non airbag to airbag nothing changed, the bumper mounted the same etc etc. If a decellerometer is used then it doesn't matter what you have strapped to the front of a 4WD, if it stops quickly enough to set off the airbag then you need it, if it doesn't stop quickly enough to set of the airbag then you dont need it. Simple
More than likely the airbag will go off a little sooner with a bullbar and decellerometer than without as there will be less crush and a more sudden stop.
Cheers
Steve
If this is the case then does anybody know what sort of system a 2001 GU Patrol uses?
Posted: Mon Jul 24, 2006 1:38 pm
by muppet_man67
Steve F wrote:turbo gu wrote:
As for bull bars i reckon the reason that airbag ones are different would be they would have move give/crush than non airbag bars so the bar would give/crush in a accident thus giving a similar decel rate to a bumper bar equiped model so not to give a false rate of decel causing the air bag to go off when not actually required
On my Jeep when they went from non airbag to airbag nothing changed, the bumper mounted the same etc etc. If a decellerometer is used then it doesn't matter what you have strapped to the front of a 4WD, if it stops quickly enough to set off the airbag then you need it, if it doesn't stop quickly enough to set of the airbag then you dont need it. Simple
More than likely the airbag will go off a little sooner with a bullbar and decellerometer than without as there will be less crush and a more sudden stop.
which could be a problem. If the airbag deploys to soon then it wont protect you as effectivly in an accident. (in theory)
Cheers
Steve
Posted: Mon Jul 24, 2006 3:38 pm
by Steve F
muppet_man67 wrote:Steve F wrote:More than likely the airbag will go off a little sooner with a bullbar and decellerometer than without as there will be less crush and a more sudden stop.
which could be a problem. If the airbag deploys to soon then it wont protect you as effectivly in an accident. (in theory)
When I say sooner I mean because the vehicle may have a more sudden stop due to a more ridged front end. Not sooner as in before you need it. The forces that trigger the airbag sensor are the same forces acting on your body regardless of what you hit etc etc. When the threshold is reached the airbag goes off, simple as that, it doesn't care if you have a sleeper strapped to the front of the car, if you stop quickly enough to damage YOU then it will be enough to trigger the airbag. Just because you have a bullbar does not mean the forces acting on your body will be any different at the point they are high enough to trigger the airbag than without a bar. The forces will just come in to play at a different point in the accident, possibly higher forces earlier.
Hope that makes sense.
Cheers
Steve
Posted: Mon Jul 24, 2006 4:27 pm
by Gribble
turbo gu wrote:Gribble wrote:There was a thing going around about SRS not being an ADR requirement so techincally if you render the system inoperative then you dont need a bullbar that is manufactured to suit SRS.
Best to check with RTA or an engineering signatory on that one.
from what l have been told is that if a car comes fitted with airbags they must work and are not allowed to be disabled even if you fit all the parts from a non airbagged model eg column steering wheel. i would say if a car is fitted with airbag there would be a
ADR relevant to it on that car.
As for bull bars i reckon the reason that airbag ones are different would be they would have move give/crush than non airbag bars so the bar would give/crush in a accident thus giving a similar decel rate to a bumper bar equiped model so not to give a false rate of decel causing the air bag to go off when not actually required
There is an australian standard relavent to SRS systems I know that for a fact, ill have a look through my paperwork to see if there is a relavant ADR for SRS systems.
Posted: Mon Jul 24, 2006 8:12 pm
by ats4x4dotcom
Generally, airbags need 3 things to deploy, one is a speed sensor, so doing more than 29\8kph.
2 is a weighted switch [coil spring with a weight, which throws out when de acelerating, making contact]
3, chassis rail sensors which pick up a specific shock wave in the crushing chassis, which the crush cans let off when crushed, which srs compliant bull bar mounts are designed to do also.
if you made a custom bar which used compliant mounts, and the bar was aprox as ridgid as the bar the mounts were designed to go onto, you could make your own bar, with compliant mounts.
Posted: Tue Aug 01, 2006 1:24 pm
by millers1
I'd be checking with your insurance as well, cause as far as I've been informed it's ilegal to fit a non approved bullbar to a vehicle equiped with air bag, could be wrong only what I was told !!. Regards Steve M
Posted: Tue Aug 01, 2006 9:56 pm
by andrew e
we have rebuilt a landrover disco 11 from the ground up and the airbag sensor is under the center console. The bullbar has the crush section to stop the shock of hitting somthing small and triggering the sensor. I have heard the GU is in the same spot. Ive never heard of chassis rail sensors.
Andy