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#650516 - 10/13/05 11:18 PM Re: Effect of ABS on Dry Pavement Stopping Distance
labman Offline


Registered: 03/14/03
Posts: 8711
Loc: Nothern USA
You can keep you Bosch systems requiring the expensive maintance. I will stick to my GM systems. Ran the ABS on my 92 Grand AM, early in the model year, first year as standard equipment, 10 years without a fluid change or any ABS problems. Have almost 4 years on my Cavalier now, same thing. When it comes to reliable quality at low cost, nobody matches GM's engineering.

Experince means nothing if you are still making the same mistakes the last 40 years. I will gladly give up a little dry road stopping distance for the control I gain in the wet and ice.

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#650517 - 10/14/05 12:45 AM Re: Effect of ABS on Dry Pavement Stopping Distance
Tosh Offline


Registered: 05/12/05
Posts: 2566
Loc: Silicon Valley
quote:
Originally posted by labman:
When it comes to reliable quality at low cost, nobody matches GM's engineering.

Why would you want to bait us like that?

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#650518 - 10/14/05 02:13 AM Re: Effect of ABS on Dry Pavement Stopping Distance
labman Offline


Registered: 03/14/03
Posts: 8711
Loc: Nothern USA
Was it BMW or Mercedes Benz that brought the masses the self starter, automatic transmission, floating caliper disk brakes, electronic ignition, EFI, computer control, ABS, and easy to service cartridge filters? My Cavalier has all of them except the automatic transmission. Instead it has a Getrag I have far more trouble sorting out 4'th and reverse than I did in my Grand Am with the made in Muncie 5 speed.

I don't think great engineering means expensive, complicated, maintenance intensive cars.

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#650519 - 10/14/05 03:08 AM Re: Effect of ABS on Dry Pavement Stopping Distance
XS650 Offline



Registered: 12/21/03
Posts: 12385
Loc: Northern CA
quote:
Originally posted by labman:

Experince means nothing if you are still making the same mistakes the last 40 years. I will gladly give up a little dry road stopping distance for the control I gain in the wet and ice.

That's called 1 years experiance 40 times, not 40 years experiance. [Big Grin]

I had some problems with ABS at first. After a fair amount of drivng on the edge of limits over the years I had developed an danm good braking ability. The feed back for the ABS working told my reptilian brain stem that I was losing traction so I would back off the brakes. That's bad when it's the rear ABS on a lightly loaded pickup that's sending the message. [Eek!]

It's also not particularly good to switch between vehicles with and without ABS. Now that I no longer have my non-ABS motorcysle, and all 3 four wheeled vehicle have ABS, I have no problem with it.

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#650520 - 10/14/05 07:28 AM Re: Effect of ABS on Dry Pavement Stopping Distance
White 03 Offline


Registered: 02/07/03
Posts: 339
Loc: Northern California
I think perception also plays a part in evaluating ABS performance. I know when I brake a normal or ABS system the more I push down the more I expect it to slow down. When the ABS activates the rate of slowing down doesn't keep getting more in spite of more pushing down so it feel like the vechicle is speeding up when it is not. Simularly when I brake on ice and the vechicle starts sliding it feels like it is accelerating; just because it is not slowing down any faster like I am expecting (or hopeing). I would tend to believe the objective measured tests and not my expectation ladened perceptions.

From what I have read except for soft dirt and snow which can be build up in front of the locked wheel, ABS systems stop fastest, eer slowest, oh whatever.

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#650521 - 10/19/05 09:36 AM Re: Effect of ABS on Dry Pavement Stopping Distance
1sttruck Offline


Registered: 03/20/04
Posts: 4378
Loc: Camas, WA
I had forgotten that potentially a big difference on ABS stopping distance is whether one has a stick or auto tranny. Our cars have autos, ABS, front disc and drum rear, and they accelerate going downhill which requires lots of braking, so there is no engine braking, in fact it's anti-engine braking. The truck has a stick, and being a 5.9 liter diesel it has very good engine brtaking, especially with 4wd engaged. I noticed today that when braking to stop while downshfting in the rain while turning that I could chirp the tires, so as expected ABS can't compensate for engine braking with a stick..

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#650522 - 10/19/05 12:04 AM Re: Effect of ABS on Dry Pavement Stopping Distance
Dark Jedi Offline


Registered: 09/20/05
Posts: 871
Loc: virginia
on my dodge dakota I only felt the ABS kick in one time when a truck stopped infront of me. it was scary feeling the peddle pulsating and thought I would never come to a stop. but without ABS I am quite sure I would of slid right in to the back of the truck. so a ABS system can be a blessing and a curse. guess its one of them nessicary evils we have to live with. while working on the B-52 Bombers got to see how a basic ABS system accually worked. its quite simple but I guess its more complicated on todays vehicles. after all those bombers was made in 1960 [Big Grin]

but in the ice and snow wouldnt you travel further with no abs compared to abs? your tires would turn into skis when they stop rotating?

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#650523 - 10/19/05 12:17 AM Re: Effect of ABS on Dry Pavement Stopping Distance
1sttruck Offline


Registered: 03/20/04
Posts: 4378
Loc: Camas, WA
"but in the ice and snow wouldnt you travel further with no abs compared to abs? your tires would turn into skis when they stop rotating? "

On packed snow and especially on ice I try to avoid 'heavy' downshifts, but in deeper snow the downshifting should help provided it's at a lower speed.

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#650524 - 10/19/05 01:11 AM Re: Effect of ABS on Dry Pavement Stopping Distance
Mitch Alsup Offline


Registered: 04/25/05
Posts: 640
Loc: Austin Texas
quote:
Originally posted by moribundman:
The ABS system will pulsate around that point. A experienced driver can "find" the close to skidding point and do a better job than the ABS system.

I am going to have to disagree here. There are ABS systems that can simply stop the car faster than even the most experienced driver can (by modulating the brakes). And, then again, there are cars with ABS systems where this is not true.

ABS systems that cycle by decreasing brake pressure slowly until traction is found and then increasing pressure slowly until traction is lost, can operate the tire much closer to the edge of traction than any driver can reaslistically hope to achieve, even under ideal circumstances. There may be 25 drivers in the whole world that can achieve better stopping distances than these systems in ideal test setups. Throw in debris on the road, water, leaves, children in the back seet and there is no hope for a driver to achieve as good a stopping distance as these cars. Ferraris, Porsches, some Mercedes, and some BMWs get these systems. Other higher end cars may also get these systems.

Unfortuantely most ABS systems decrease the braking pressure too fast and then increase the braking pressure too fast. Operating like dozens of tiny skids per second rather than cycling around the point of best traction. Even here, though, ABS will beat 95% of all drivers 95% of the time. Many suspensions are not sufficiently stiff (and damped) to enable ABS systems to find the point of best traction.

And then there is the problem of upgrades to the suspension, brakes, tires and wheels. An ABS system has its time constants and valving sized for the tractio of the default tire combination and the rotational inertia of the original tire/wheel/brake rotor combinationi. Changing any of these variables can move the ABS system far away from its optimal performance. No manufacture, that I know of, will give the average back yard mechanic the information required to move the ABS system back towards optimal. (Think Lawyers)

Finally, as tires age they loose traction. You may feel that getting 80,000 miles from a set of tires is saving you money. You might be surprised to find that best case braking performance at 79,000 miles is 30 or more feet longer than identical tires when new.

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#650525 - 10/19/05 01:19 AM Re: Effect of ABS on Dry Pavement Stopping Distance
XS650 Offline



Registered: 12/21/03
Posts: 12385
Loc: Northern CA
quote:
Originally posted by 1sttruck:
I had forgotten that potentially a big difference on ABS stopping distance is whether one has a stick or auto tranny. Our cars have autos, ABS, front disc and drum rear, and they accelerate going downhill which requires lots of braking, so there is no engine braking, in fact it's anti-engine braking. The truck has a stick, and being a 5.9 liter diesel it has very good engine brtaking, especially with 4wd engaged. I noticed today that when braking to stop while downshfting in the rain while turning that I could chirp the tires, so as expected ABS can't compensate for engine braking with a stick..

ABS still helps, even though it doesn't control engine braking. It will let you use a lot of braking while geared down because you can mash down on the brakes to get full front wheel braking while not locking the rears up any more than the engine braking alone is doing.

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#650526 - 10/20/05 10:20 PM Re: Effect of ABS on Dry Pavement Stopping Distance
Fatboymoe Offline


Registered: 04/30/04
Posts: 468
Loc: Stockton, Ca.
My BMW motorcycle has anti-lock,intergrated brakes and I just recently received a warning from BMW Motorad about the ABS system. According to BMW, the anti-lock system on the bikes have a real problem when the road is dry and bumpy. As the wheels oscilate over the bumps, the brake system oscilates the brake pressure, which in turn makes the stopping length more. I, personally have not encountered this, but I could see how this could happen on a washboard type surface. I know this is about auto and light truck ABS systems, but I think the principle is the same.

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#650527 - 10/20/05 10:48 PM Re: Effect of ABS on Dry Pavement Stopping Distance
moribundman Offline


Registered: 06/02/03
Posts: 23591
quote:
Originally posted by moribundman:
The ABS system will pulsate around that point. A experienced driver can "find" the close to skidding point and do a better job than the ABS system.
----------------------------------------------------
I am going to have to disagree here. There are ABS systems that can simply stop the car faster than even the most experienced driver can (by modulating the brakes). And, then again, there are cars with ABS systems where this is not true.

So you disagree while agreeing? [Razz]

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#650528 - 10/21/05 02:51 AM Re: Effect of ABS on Dry Pavement Stopping Distance
Mitch Alsup Offline


Registered: 04/25/05
Posts: 640
Loc: Austin Texas
My point was that there are ABS systems that no driver can outbrake.

While your point was that some drivers can.

I disagree that some drivers can the best ABS systems*.

[*]Excluding the 25 drivers in the whold who have the tallent, reflexes, attention, and car in perfect operating order. And, no, none of the magazine drivers qualify in this top 25, and less than 1/2 of the active F1 drivers even qualify!

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#650529 - 10/21/05 06:33 AM Re: Effect of ABS on Dry Pavement Stopping Distance
oily boyd Offline


Registered: 05/23/05
Posts: 506
Loc: WI
Dark Jedi,

White 03 has it correct.

Snow and gravel will build a wedge in front of the locked tires (think of a doorstop). This will slow a car faster than relying on ABS.

Audi's used to have an ABS off switch for such occasions (maybe still do?)

[Cheers!]

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#650530 - 10/21/05 11:41 PM Re: Effect of ABS on Dry Pavement Stopping Distance
JohnBrowning Offline


Registered: 05/01/03
Posts: 9448
Loc: USA
Anyone that has trained himself well can use thresh-hold breaking and out break ABS especialy on dry pavement. I used to bet people money on this very topic and won the bet everytime!!! Few people though keep themselfs in a well trained state. I used to practice various emergency,offensive,deffensive driveing tech. weekly for a long time.


I am out of practice now but am sure I could still do it.

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