The Chevy Cobalt ignition is one of those included in the recent GM recall of 1.6 million vehicles. Machine Design editors Lee Teschler and Ken Korane took apart an ignition assembly from a 2007 Chevy Cobalt, and give viewers an up-close and personal view of the part causing all the controversy.
Hosted by: Lee Teschler and Ken Korane Edited by: Curtis Ellzey
datsallfolks commented on April 03, 2014
My understanding is that somehow, the air bag sometimes wouldn't go off in an accident after the switch had worn down. You can find a bit more about it here: http://www.nbcnews.com/storyline/gm-recall/gms-silence-over-13-names-denies-hundreds-closure-n69981
hugin8 commented on April 02, 2014
It's great to see the part up close, thanks for the great video!
I haven't been following this recall and I'm not a car guy, so I had to do a little reading for context. In case anyone else has the same questions...
What exactly is the controversy?
Car's with this ignition switch could be turned OFF very easily WHILE DRIVING. A slight tug on the key, perhaps even with just your knee, could turn the key and shut off the car's engine.
So, as mentioned in the video, a stiffer spring will increase the force needed to turn the key. At 1:22-1:25, the pencil points right at the ridges on the cam surface that the ball moves over when the key is turned.
But, Why exactly is the car being turned off a problem?
Turn off your car and you basically lose the brakes and steering.
Why do you lose the brakes?
When you press on the brake pedal, your car's modern 'power brakes' use a 'vacuum booster' to boost the force that gets applied to the brake pads. This vacuum booster needs a pump to work. In diesel engines, it's a standalone pump, but in regular cars the vacuum is applied by the engine. The vacuum booster is designed with a check-valve to, "provide enough boost for a driver to make several stops in the event that the engine stops running" and not much more...
And the steering?
Similarly, modern cars are also equipped with 'power steering'. That typically means that a pump maintains a reservoir of steering fluid at high pressure. When you turn the wheel, a valve mechanism (depends on the specific setup, either 'rack-and-pinion', or 'recirculating-ball') amplifies the force that gets applied to the wheels.
Also, there's anti-theft device which will cause the wheel to lock when the key is not in correct position.
Corsair commented on April 02, 2014
It would have been nice to see the wear on the plastic detents. Would not a stronger spring on the steel plunger cause more wear on these detents reducing the MTBF?