Crush cans / airbag operation?

[Oldbear]

Dumb question, but will the airbags on a JL operate properly if an aftermarket bumper, with no crush cans? If so, what purpose do the factory crush cans serve? Inquiring minds want to know! Thanks!!

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[WyoTex]

yes it should operate fine, the crush cans from my understanding help decrease the odds of airbag deployment with low impact collision

 

[entropy]

Dumb question, but will the airbags on a JL operate properly if an aftermarket bumper, with no crush cans? If so, what purpose do the factory crush cans serve? Inquiring minds want to know! Thanks!!

Crush cash are designed to absorb impact from really small collisions, think 10mph. Think about it, theyre just a thin piece of metal that crushes easily, therefore they absorb very little energy. They become negligible for collisions that would do more damage than to break a plastic bumper. Your steel bumper doesnt really need crush cans.

they are there to protect the rest of the vehicle from small non life threatening collisions and have nothing to do with airbags. For more dangerous collisions, right behind the bumper there are 2 beams that are removable and connected to the frame, theyre much sturdier than crush cans and designed to crumple to protect the frame. If those 2 crush and impact keeps traveling to the frame and bends it, then that force will probably be enough to set the airbags, in which case the crush cans would have had negligible to none effect in improving the collision results. Nothing to do with the little crush cans.

 

[Rubycon50]

Crush cash are designed to absorb impact from really small collisions, think 10mph. Think about it, theyre just a thin piece of metal that crushes easily, therefore they absorb very little energy. They become negligible for collisions that would do more damage than to break a plastic bumper. Your steel bumper doesnt really need crush cans.

they are there to protect the rest of the vehicle from small non life threatening collisions and have nothing to do with airbags. For more dangerous collisions, right behind the bumper there are 2 beams that are removable and connected to the frame, theyre much sturdier than crush cans and designed to crumple to protect the frame. If those 2 crush and impact keeps traveling to the frame and bends it, then that force will probably be enough to set the airbags, in which case the crush cans would have had negligible to none effect in improving the collision results. Nothing to do with the little crush cans.

What he said.
Your air bag system is not electrically connected to the the crush cans. They are an independent system and will deploy based on impact at predesignated forces with or without crushcans. The sensors for the air bags are in the front aprons and the base of the mid pillars for sideways impact. Installing an aftermarket bumper should not affect the air bag system at all but like always, call the bumper manufacturer to confirm for peace of mind.

 

[Oldbear]

Thanks Guys! That’s kind of what i thought but good to get confirmation!

 

[Shots]

Modern airbags don't work like the original ones did. The days of a contact sensors are long gone.

Airbag deployment is based on many factors that the vehicle is constantly monitoring. This includes seat belt usage, speed, yaw/pitch/roll, driver inputs, etc. This is all done through the Airbag Control Module (ACM) and to simplify the process it's main concern is change in velocity (or "delta V"). The purpose of crush cans, crumple zones, soft zones, and other type features is to extend the time it takes to slow down. We're talking milliseconds, but every little bit helps to reduce the deceleration* rate and minimize delta V.
As the others have said crush cans typically crush with very little force so you're not changing a lot. By removing them, you will slightly increase delta V but I doubt enough to affect airbag deployment. Actually they'll be more likely to deploy if anything.


*Note: Scientifically speaking "deceleration" isn't a thing. It's negative acceleration, but deceleration is a commonly used term so I used it for easier reading.

 

[WyoTex]

i had the same concerns until I took my bumper apart to install my ARB bumper, as stated above they are not connected in any manner to your airbags and in my honest opinion a joke. Dont let the decision of buying a new bumper be swayed by crush can compatible or not. Love my new ARB Bondi bumper by the way.

 

[leftystrat62]

Wow, I head the same misinformation about the crumple cans linked to the airbags. Thank you all for clearing that up. Looks like I can go ahead and save some weight on a aluminum front bumper.

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