AEV & ARB front bumper Crush cans question

[rlynch356]

Another thread got me thinking...

Both the AEV and ARB use similar designs to extend the stock crush cans - which then trigger air bag deployment.
In my Defender (no Air bags) it is not totally unheard of to have a small impact with a dirt beam (as an example) or a smallish tree on a tight trail typically when its sloppy and you need momentum.
Both are low speed impacts but impacts the same.... Speed is Slow as possible / Fast as necessary...

Obviously i would like to avoid deployment of the airbags - but want to retain them for potential impacts on the street.

thoughts on not installing the crush can extenders?

 

[anviljk]

Are you talking about your 15' JK? I installed an Expo One DX bumper/skid on my 15' JK and there were no crash cans that I was aware of. Even if there were and I removed then without knowing, I took mine wheelin several times and hit tree's, rocks, sudden stops, etc all without an issue. There has to be several conditions met before the airbags will deploy such as speed and how fast you came to a stop. If an air bag goes off while wheelin theres probably a good reason other then you tapped a rock.

 

[Bennyhana]

The bumpers on JK's don't have sensors for the "crush cans" in the bumpers. You can cut the cans off on the stock bumper and the air bags will still go off in an accident.

 

[MTSN]

Typically vehicles use an inertia sensor more centrally located in the vehicle from what I understand that requires massive g forces and/or deceleration to set off airbags. It does not require crush cans to be in place for the airbags to deploy, but I personally wanted to keep them in tact for purposes of absorbing energy in a collision.

 

[crusaderJK]

You really should install the crush cans.
They prevent early airbag deployment, cause they reduce the energy of impact before it goes into the solid frame ends.

 

[onetraveller]

The crush cans have some relation to air-bag deployment, as noted above, but it's my understanding that a major part of their purpose is to comply with the feds 5mph bumper requirement. In essence, this requires that impacts under 5mph cause minimal damage to the vehicle. The crush cans are integrated into the front bumper and are easily replaceable.

Very few aftermarket bumpers include any sort of crush can, but I wouldn't be concerned about installing them with the ARB or AEV bumpers. They are two of the companies that have actually done the research necessary to include them.

Mike

 

[rlynch356]

Yes a 2015 Jeep JKU sport..
So is the Air bag triggered from an Inertia sensor?

I'm not opposed to putting them and have a take off bumper (the steel part which incorporates the crush cans) to use for the cut out (on an ARB install for instance), I just would like to understand the pro/cons of it. I have not been able to locate any sensors connected to the crush cans and they appear only to meet the 5mph requirement which for energy absorption purposes makes sense.
ARB for instance you cut out the stock crush cans and then bolt them to extensions on install..

I'm realistic i occasionally hit stuff on the trail either as the lesser of 2 evils or when your traction limited (sliding in mud, in other words) and cannot avoid it.

I am specifically not going with companies that do not test for frontal impacts - which limits me to ARB and AEV that i am aware of.

 

[Malarkey21]

Crush cans are used to help slow down energy transfer to the rest of the car. As they say, it's not the speed that kills, it's the sudden stop. They will "crush" and take energy from the impact instead of sending the shock into the frame of the car and causing more damage to you or your jeep. They are pretty common even in racing car because they work pretty well at taking away energy form the crash. That's why most racing crashes look bad because all the parts are flying off the cars are transferring energy into flying part instead of to the driver.

As said above new cars use accelerometers mounted as close to the center of the car as possible (normally can be found in the center console) at a programed rate of deceleration it will trigger the air bag. It also looks at other things like vehicle speed so the airbag won't go off if you tap a tree on the trail.

I think they stopped using impact sensors on bumpers once people found out you could set off the air bag by kicking the right spot on the front bumper. I think it was on mustangs? I could be wrong, but a good way to get back at that guy who took your parking spot lol

Hope I helped some! lol

 

[comptiger5000]

Jeep stopped using impact and frame twist sensors after the first 2 years of XJs having air bags. People were getting some chassis flex on the trails or tapping trees lightly, etc. and blowing the bags.

 

[rlynch356]

thanks for the confirmation ... last thing i worked on with air bags was a 92' 911 - which definitely used 2 sensors to trigger the air bags.

this confirms my thoughts and will install them when the time comes. I see no downsides