Side Air Bags Deploy In Autocross

[X25]

Originally Posted by fielderLS3

This happened to a 2011 Camaro at an autocross I was at two weekends ago. I was in grid, so I didn't see it, but I heard it go off. The driver said he was going through the Chicago box. The car never hit anything, but the event was on an oval race track, so perhaps the small amount of banking was a contributing factor.

Well the banking should not impact max lateral g since it helps by changing the direction of centerpetal force (so it starts pushing you down rather than sideways).

I've also heard of a 2011 model having this issue. Someone was suggesting that the sensors were recalibrated for 2012 MY when ZL1 was released.

[Norm Peterson]

Originally Posted by X25

Well the banking should not impact max lateral g since it helps by changing the direction of centerpetal force (so it starts pushing you down rather than sideways).

Which then gives you more sideways grip to work with, and higher lateral g's are the result when you use it all . . . the only difference being that "lateral" isn't horizontal any more and neither is what the sensors "see" their lateral direction as being.


Norm

[X25]

Originally Posted by Norm Peterson

Which then gives you more sideways grip to work with, and higher lateral g's are the result when you use it all . . . the only difference being that "lateral" isn't horizontal any more and neither is what the sensors "see" their lateral direction as being.


Norm

It would depend on the design of the sensor. At least not the ones on other cars that I've experimented with. I don't think the kind of sensors they use on the cars for lateral G compensates for car's own axis (baking), so it will only measure the component of the G force perpendicular to the car, which will be limited by the tire that still has the same traction limits.

[Norm Peterson]

All true, and I am thinking in the car's co-ordinate system where its "vertical" and "lateral" directions are with respect to the banked pavement.

In a banked turn, the normal force that the lateral force is developed from will then be greater than the static weight of the car. Basically, your tires will think that your 4000 lb car weighs maybe 4500 lbs, and develop 1.whatever lateral g's worth of cornering force based on that. But since it will still turn like it only weighs 4000 (the centripetal force does not add any mass even though it is adding grip) you'll have a greater amount of lateral g available.

Picky, but of course we're assuming banking to be "on-camber". That off-camber corners cost you lateral g's is simply the flip side to this.


Norm

[BMR Sales]

Originally Posted by SPCBA

Please don't pull the fuse on your car made to crumple around you.

I understand your point, but I don't agree with the broadness of it.

If I had an '11 and I was A/Xing it, I would pull the Fuse. The chances of hitting anything are very low.

The financial side of your AirBags going off could total your car.

On a Road Course, I would have other safety features, so in most cases, I would still pull the Fuse. An AirBag going off at Speed for no real reason, could obscure your vision and cause a Crash.

Remember, AirBags are deployed by an explosive charge which can break bones. If you Steering Bag goes off and your Arms are crossed up, you can lose control. If that same Bag goes off & knocks you out or breaks you nose, you're going to crash.

So I guess, it's which basket you want to put your eggs into

[bannonm]

Originally Posted by JusticePete

Bannon got his from the black box. The G load it showed was, imo, impossible to generate under the conditions in which he was running and operating, but they did. From the information I have gathered the side curtain bags deploy during a motorsport event when the computer calculates a potential rollover.

Steve_RS_Camaro was on a rumble strip with the associated vibration. In my personal experience since 2009 in Camaros of all years that I have been at the track with I have seen only one air bag deployment. It was the Lingenfelter L/28 when the drive shaft coupling failled during an AC run. The violence of the banging haft tripped all the bags.

In general, it is not a concern. In terms of safety, if things go really wrong, you want your air bags to deploy. If you have a cage, racing seats, helmets, HANs and harnesses get rid of the bags. If not, leave them in and leave them on.

I contacted Pete about my incident after it happened asking if he heard of this being a problem. Two weeks later his Camaro blew the bags, though for different reasons. I believe my issue was similar to Steve_RS_Camaro's in that coming out of a right hand turn, I probably caught the rumble strip and a dip in the course with the right rear wheel. My instructor at the time had just said to "hug" this turn and you can fly through it. He was right the first 10 times I did it. A combination of speed, rough road, and hard turning is what set mine off. Probably similar to what Pete's car did in that the violent force of hitting the rumble strips shocked the sensors to think I was rolling over. At the time I was running 10 inch wheels all around with coilovers, solid rear bushings, sways, and Pfadt control arms. I'm sure my setup being like a go-cart was more than the SIR system was configured to operate in when pushing the car. So if my car was stock and I did the same thing, the air bags probably would have never gone off.

Word of advice, if you track your car and this happens to you don't bother going to GM to fix it. You'll get a warranty lock on the car if there's any modifications that they can find, and trust me they will find them. In my case they sent out a Raytheon engineer who pulled the ECM data which showed I was tuned, took a butt load of pictures of my suspension mods and wheels. I essentially had a 1LE setup before the 1LE was announced. Final verdict was you modded the car, too bad for you.

[bannonm]

Originally Posted by BMR Sales

I understand your point, but I don't agree with the broadness of it.

If I had an '11 and I was A/Xing it, I would pull the Fuse. The chances of hitting anything are very low.

The financial side of your AirBags going off could total your car.

On a Road Course, I would have other safety features, so in most cases, I would still pull the Fuse. An AirBag going off at Speed for no real reason, could obscure your vision and cause a Crash.

Remember, AirBags are deployed by an explosive charge which can break bones. If you Steering Bag goes off and your Arms are crossed up, you can lose control. If that same Bag goes off & knocks you out or breaks you nose, you're going to crash.

So I guess, it's which basket you want to put your eggs into

Having experienced side curtains going off, yeah it was a little scary not being able to see on either side of me. Fortunately I was leading the pack by a pretty good distance and was able to slow down and pull off.

Having the steering bag breaking your nose or knocking you out?? I always wore a full face helmet so not an issue, anything less is not as safe.

If I were doing just auto-X I would probably disable the SIR system if I knew the course wasn't going to jeopardize anyone else or me if I lost control. For an HPDE or racing, not sure I agree with removing that safety feature unless I had the proper safety equipment like a roll cage, etc. Pete's is the only car I am aware of that deployed all the air bags, the others have all been side curtains. If you hit a wall, guard rail, or another car head on at high speed, those frontal air bags may save your ass. Your car not so much. I personally think the side curtains are a waste, especially on the track since you have to drive with your windows open. Mine just pushed out when they went off. You have to be prepared to pay if you want to play in this sport.

[E. Bryant]

Originally Posted by X25

It would depend on the design of the sensor. At least not the ones on other cars that I've experimented with. I don't think the kind of sensors they use on the cars for lateral G compensates for car's own axis (baking), so it will only measure the component of the G force perpendicular to the car, which will be limited by the tire that still has the same traction limits.

Keep in mind that the car doesn't just have a 3-axis accelerometer (which can indeed figure out where the car is relative to a reference frame), but also a two- or three-axis angular rate sensor. This provides the ability to calculate yaw and roll, both of which can be interpreted by the passive-restraint system as inputs to the bag-deployment logic.

I can't speak to the exact logic used by the Camaro SRS, but large roll-angle changes are often used as indications of an impeding roll-over. Dropping a wheel off the pavement or hitting some banking could certainly cause something that "looks" like a potential upset event.

[Stock Boy]

I have a quick question, when I track my car I'm replacing the seats with Sparco fixed seats. Naturally, the air bag light on the dash goes on because the seats aren't connected. When the airbag light is on because of the seats, is the whole system disabled?

[JusticePete]

That is what I have been told by some GM techs.

[Stock Boy]

Thanks for the quick response JP

[White_SS/RS]

I kind of suspected it to be an all or nothing system.