winch bumpers - airbag - mot

[roy]

looking at some of the winch bumpers available there are some for cars with airbags and some for those without.
my question is does it matter which you fit ?
i am not really bothered if i have an airbag or not.
surely if you are going to use your car offroad it will not take long to accidentally set of the airbag.
so is it best to disconect the sensors for the airbag ?
and does this affect your M.O.T. as the airbag is a factory fitted saftey device ?


cheers roy

 

[Chris]

Air bag doesn't deploy quite like that. These are built as off roaders and hitting a tree at off road speed won't set it off.. The bag only goes off if you have a major off road moment where you NEED and airbag. Don't go disconnecting things would be my advice.
I think it unlikely that anyone will condone doing that either Roy. Not on here. MOT or not.


Chris

 

[roy]

thanks for the advice, leave alone and get the bumper for cars with an airbag

i was not sure as this is the first car/4x4 i have owned with an airbag

cheers roy

 

[Chris]

What I am not sure of Roy is what the air bag bumper does. Is there a place to mount a sensor - sort of thing. Having had a 90 and having removed the bumper I didn't see anything connected directly to it.

Worth a bit of digging perhaps.

Chris

 

[Jon Wildsmith]

AFAIK the main thing with air bag compatible bumpers is they have been tested to make sure they don't affect air bag deployment. Also AFAIK, the sensors that provide the primary inputs are deceleration / g sensors mounted inside the truck.

 

[KZJ90]

What I am not sure of Roy is what the air bag bumper does. Is there a place to mount a sensor - sort of thing. Having had a 90 and having removed the bumper I didn't see anything connected directly to it.

Worth a bit of digging perhaps.

Chris

The sensor is bolted to the chassis, it´s under the center console.

 

[Scott]

I'm not sure about the 90 series but on another 4x4 that I own, the airbag is trigger by atleast two sensors agreeing that there has been an impact.

As Jon has mentioned, one of those is the 'deceleration' sensor, another is usually called a 'crush can' which are often mounted on each of the front chassis rails. During a large impact the deceleration sensor would see the rapid slowing of the car, and if a crush can also registers deformation of the chassis rail then the airbag(s) would usually be deployed.

If you bolt a winch bumper in place of the original bumper, then you've changed the way the front of the car is constructed. Effectively you've joined the front chassis rails together with a large piece of steel. So now the car won't behave, as it was designed to, during an impact.

Don't quote me 100% percent on this, but from the airbag compatable winch bumpers that I have seen, it looks like the bumpers mounts are only designed to withstand a certain amount of impact force, before they will deform and pass the force onto the chassis. This will then allow the chassis to take the impact force, and if the force is great enough, the chassis will deform and the crush cans would be triggered, as per the manufacturers original design.

I personally have managed to trigger a 'deceleration' sensor seven times in one morning whilst driving baddly corrugated desert tracks at speed, and as per the manufactures design the airbag was never set off, because the 'crush cans' never saw any chassis deformation.

Hope that all makes sense.

Cheers.

 

[Chris]

It does to me Scott.

The crush cans on the 120 were very clearly visible.

Chris