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Old 09-23-2012, 02:59 PM   #21 (permalink)
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It is my understanding locking the brakes actual increase the stopping distance and that the only time locking the brakes is advantageous is on loose surface roads dirt or gravel where locking the brakes dig the vehicle in building up material in front of the tires.



The fastest methods of slowing down in high grip conditions

1. Threshold braking

2. ABS braking

3. Locked wheels

4. Cadence braking

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Old 09-23-2012, 08:41 PM   #22 (permalink)
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Quote:
Originally Posted by baldlobo View Post
you do know that proper braking technique can be learned for that; it's called threshold braking and steering...
I know about those, I've practiced them quite a lot. But you cannot brake hard and turn at the same time and stay in control. That's in part because when you hit the brakes, you are using the brakes on all four wheels at the same time. When you turn, the inside wheels are more lightly-loaded and will tend to lock up. Look at most race cars, especially those driven by less-experienced drivers, going into a corner. The inside-front wheel locks up.

Tires that slide on the pavement grip less than tires that are still rolling. Look up "static friction versus sliding friction". (Note those are incomplete models because tires do not use just friction to provide grip, but the models do partly apply.)

A modern ABS will monitor individual wheels and will back off the pressure on a wheel that starts to lock. So the inside wheel still slows you down because it is not sliding.

Threshold braking is the quickest way to bleed off speed in a straight line. ABS is the best if you are trying to slow down and turn the car at the same time. If you're trying for lap times, you are faster using threshold braking and then turning (using trail braking if your car really needs the help to turn in) and turning while not using the brakes at all. But if you're trying to avoid an obstacle, especially if you don't have a lot of training, "Stomp, Stay, and Steer" is the best way to go. You may not stop the car as early as you could in a straight line, but you slow it down and get around the obstacle.

Nemo has the facts in his post as well, but that does ignore turning.

-soD
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Old 09-24-2012, 04:53 PM   #23 (permalink)
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Quote:
Originally Posted by nemo View Post
It is my understanding locking the brakes actual increase the stopping distance and that the only time locking the brakes is advantageous is on loose surface roads dirt or gravel where locking the brakes dig the vehicle in building up material in front of the tires.



The fastest methods of slowing down in high grip conditions

1. Threshold braking

2. ABS braking

3. Locked wheels

4. Cadence braking
I have had an older car where 2 and 3 were swapped, maybe even worse than 4. My current cars with abs work pretty good, one of them might even compete with threshold braking, but I don't depend on them, and have practiced with the one I drive the most which has only rear wheel abs (to keep the back end from swinging arround).

My wifes car has all of the traction control/abs, in the snow and ice it was spinning and sliding everywhere, its traction control litteraly took its index finger put it between its lips wiggled it up and down while humming. My truck had some difficulty with the worst of the roads but the traction control consists of my left foot feathering the clutch and my butt giving me feedback as to what was happening. Its bad when the car with better tires, more traction and better stability sits on the sidelines to a lesser vehicle.

A co-worker was driving his mothers SUV (Blazer I think) and when he went to cross an intersection the tires spun a bit, then the engine shut down with the dash displaying a message "reduced traction-shutting down"
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Old 09-24-2012, 07:34 PM   #24 (permalink)
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Quote:
Originally Posted by Afrersize View Post
"ps. abs is dead weight brought to you by the nanny patrol(along with airbags)"
So your saying airbags should be removed?

threshold braking and good winter tires are reasonable
Only one of the vehicles I have has airbags, they are a mixed bag depending on what year you drive, also on the suburban the ABS system has caused us massive headaches since it basically disables the brakes, sliding would be better in all honesty. Result ABS delete.
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Old 09-24-2012, 09:55 PM   #25 (permalink)
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My first car with ABS was a 93 grand am, no memory, 2nd 94 explorer for 95% of drivers could maybe do better than the ABS does. 02 Mit Montero Sport only 2-3% could beat it. 02 suburban about the same, current wifes 2010 implala ABS & TC are almost perfect. Maybe 1/2 percent of driver can beat it in predictable(dry pavement) but doubt they'd be ready 100% of the time like the computer is, stomp on the pedal it does the thinking. It really needs the noise & feed back of the old explorer, impala is too smooth.

Rented at 2011 focus automated manual with ABS & TC, so seemless I pushed harder on the go pedal because TC was working(driving around Duluth MN last Feb.) it needs more feed back as well. Impala has a flashing light but noise would be a plus. Maybe 1% could beat them with pratice in the same exact situation that it's working without warning, but how often does that happen.

It's not a factor in buying a car for myself, but is for my wife and no way do I think I'm in the 1%. Then start factoring in when a car has 100,000 miles and the brakes aren't as balanced as they wear when new.

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