ABS range? [Archive] - GrandAmGT.com Forum

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cwcole
02-18-2004, 09:27 AM
Does ABS have a speed range that it only works in?

Say if the range is 0-60mph and you are going 70mph and slam on the brakes then the ABS will not be active and the wheels will lock.

Another questions
Is there any reason for ABS not to work?

Blackrider
02-18-2004, 09:53 AM
Anything below 5KPH and it wont Engage, it will engage at any other speed IIR

cwcole
02-18-2004, 10:02 AM
Next question
If my ABS did not work at 65-70mph and I was expecting it to (would have been able to avoid collision) is there anyone I should talk to at GM?

Blackrider
02-18-2004, 10:06 AM
Originally posted by cwcole
Next question
If my ABS did not work at 65-70mph and I was expecting it to (would have been able to avoid collision) is there anyone I should talk to at GM?

If you have warrenty left yes, if not dont bother.

preed4962
02-18-2004, 10:47 AM
NHTSA would probably be very interested in what you have to say. But it would be difficult to prove whether or not the ABS worked, unless your car has the little black box, and its data is still readable...

2002AmSE
02-18-2004, 02:18 PM
Do our GA's have blackbox recording things? I heard that newer cars are getting them... Does ours have one?

tenspeed
02-18-2004, 02:55 PM
Originally posted by cwcole
Next question
If my ABS did not work at 65-70mph and I was expecting it to (would have been able to avoid collision) is there anyone I should talk to at GM?

Maybe it would help if you explained what happened or what you expected the ABS system to do.

Did your brakes lock up and you thought they wouldn't? Or did they not lock up and you expected a full lock up under emergency braking.

cwcole
02-18-2004, 03:01 PM
look here (http://www.grandamgt.com/forum/showthread.php?s=&postid=354317)

They completely locked in an emergency where I needed to manuver.

From the pictures, I was able to make my initial direction change, brake hard, but not regain control cause the wheels where locked.

Other than having no control after braking very very hard, and the serious amount of rubber on the ground I do not know if ABS worked. I assume that it didn't though.

Blackrider
02-18-2004, 03:16 PM
Originally posted by cwcole
look here (http://www.grandamgt.com/forum/showthread.php?s=&postid=354317)

They completely locked in an emergency where I needed to manuver.

From the pictures, I was able to make my initial direction change, brake hard, but not regain control cause the wheels where locked.

Other than having no control after braking very very hard, and the serious amount of rubber on the ground I do not know if ABS worked. I assume that it didn't though.

Damn that sucks! Did you take pics of your skid marks?

cwcole
02-18-2004, 03:17 PM
unfortunetly no.

Blackrider
02-18-2004, 03:59 PM
damn, Have you been back? they might still be there.

tenspeed
02-18-2004, 04:12 PM
I believe that they worked as designed.

ABS (anti-lock brake system) is designed to release a locked up wheel or two when braking. It senses the lock up by comparing the inputs from the other wheels. If all inputs are the same as when all wheels are locked and skidding, ABS will will do nothing. Actually, locking the brakes may have given you the shortest stopping distance. Not much comfort when you wanted to steer away from danger.

There are many times in the winter that I would like to disable the ABS like I am able to disable the traction control.

cwcole
02-18-2004, 04:36 PM
Are you saying that if all wheels are locked (all same, not moving) then ABS is working properly.

If I would have known that I would have let off the pedal at the last minute.

tenspeed
02-18-2004, 05:08 PM
I'm saying that if all four wheels are locked, the ABS does not know that the car is in motion. If that's the way the ABS is designed, then it is working properly.

Easing up on the pedal and the last moment would have given you some steering. It's hard to judge just when that last moment occurs. With the ABS on, the car will still plow forward some, you may have to allow more room than you would think. I hope you never get another on road chance to try out the theory. Personally, I'm planning on trying out a few things in a snow covered parking area to see what happens.

Stomping on the brakes is a natural reaction, there's nothing you can change about your experience. Maximum braking and getting to the slowest speed possible is the best thing to do before hitting someone or something that can not be avoided. You did the right thing and you walked away. The car can be replaced, it's expendable.

preed4962
02-18-2004, 05:37 PM
Whether or not the wheels are locked is irrelevant. The ABS computer is smart enough to know that its impossible for the car to be moving 65 mph one second and 0 mph the next. The abs should activate whether or not one or all wheels stopped moving.

Mike_99GAGT
02-18-2004, 06:24 PM
Preed is correct.......each wheel has a speed sensor, and the computer does know the approximate weight of the car, and approximate stopping distance with 100% traction, its not actually sensing that the wheel is "locked" is limiting the speed at which the wheel stops spinng....if the computer feels that the wheel is slowing to fast (attemping to lock) than it should, ABS is engaged

Gimli
02-19-2004, 06:02 AM
I think what might've happened in your case is that if you over-corrected when you turned your front wheels might've been at an angle too high with the direction of the car and in a case like this, ABS or not, the wheels will lock. The damage to your tire seems to indicate that too.