On 09 Dec 2003 08:42 PM, L.W.(?ill) ------ III posted the following:
> That test has a big time flaw, it uses the same vehicle and
> simply disconnects the ABS for the comparison tests, completely
> destroying the fine tuning engineering, about the same thing as
> disconnect the power brakes and saying that's the way regular brakes
> perform, if you think they do than turn off your engine and coat down
> a hill.

The ABS is designed to revert to a standard braking system when it is
disabled. It is nothing like disconnecting the power brakes. The
vacuum booster is unrelated to the ABS and what you have, in effect, is
a big expensive version of the proportioning valve in a non ABS rig. I
drove my former truck around for a couple weeks like this until the
dealer could replace an ABS wheel sensor and there was no adverse impact
on normal brake action except that there was no ABS.

----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

 

On 09 Dec 2003 08:42 PM, L.W.(?ill) ------ III posted the following:
> That test has a big time flaw, it uses the same vehicle and
> simply disconnects the ABS for the comparison tests, completely
> destroying the fine tuning engineering, about the same thing as
> disconnect the power brakes and saying that's the way regular brakes
> perform, if you think they do than turn off your engine and coat down
> a hill.

The ABS is designed to revert to a standard braking system when it is
disabled. It is nothing like disconnecting the power brakes. The
vacuum booster is unrelated to the ABS and what you have, in effect, is
a big expensive version of the proportioning valve in a non ABS rig. I
drove my former truck around for a couple weeks like this until the
dealer could replace an ABS wheel sensor and there was no adverse impact
on normal brake action except that there was no ABS.

----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

 

On 09 Dec 2003 08:17 PM, L.W.(?ill) ------ III posted the following:
> Del, I like to just check one thing for me. You said: "all 4 wheels at
> the point of maximum braking." I'd like you to crawl under your TJ and
> tell me how many brake lines are connected to your rear axle, then
> tell me how your ABS could release one locked wheel without releasing
> maybe the only other wheel with traction.

I never said my TJ had that exact system, but that doesn't mean that all
ABS equipped vehicles are that way. I have even driven a rig with ABS
only in the rear, now that was a messed up system to be sure. Point
being, that ABS can control the braking force applied to multiple wheels
simultaneously, something which you and I cannot do. Well, I do it in
airplanes, but that doesn't count. 8^)

If you want to pick nits, yes, the ABS in the TJ can only send one input
to the rear brakes, so the braking force is limited to the maximum that
the rear wheel with the least traction can take without locking. But
since the majority of the braking is done by the front wheels, which *
are* individually modulated, my point still stands.

The crucial thing that the rear ABS must do is keep the rears from
locking to maintain directional control. Getting the maximum braking
performance out of the rear wheels just isn't important since they
contribute so little to stopping the vehicle in a panic situation, when
most of the weight has transferred to the front axle. So there isn't
much benefit to separate brake lines and ABS inputs to the rear wheels,
as long as there is SOME means of keeping them rolling while the front
wheels do the work.

----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

 

On 09 Dec 2003 08:17 PM, L.W.(?ill) ------ III posted the following:
> Del, I like to just check one thing for me. You said: "all 4 wheels at
> the point of maximum braking." I'd like you to crawl under your TJ and
> tell me how many brake lines are connected to your rear axle, then
> tell me how your ABS could release one locked wheel without releasing
> maybe the only other wheel with traction.

I never said my TJ had that exact system, but that doesn't mean that all
ABS equipped vehicles are that way. I have even driven a rig with ABS
only in the rear, now that was a messed up system to be sure. Point
being, that ABS can control the braking force applied to multiple wheels
simultaneously, something which you and I cannot do. Well, I do it in
airplanes, but that doesn't count. 8^)

If you want to pick nits, yes, the ABS in the TJ can only send one input
to the rear brakes, so the braking force is limited to the maximum that
the rear wheel with the least traction can take without locking. But
since the majority of the braking is done by the front wheels, which *
are* individually modulated, my point still stands.

The crucial thing that the rear ABS must do is keep the rears from
locking to maintain directional control. Getting the maximum braking
performance out of the rear wheels just isn't important since they
contribute so little to stopping the vehicle in a panic situation, when
most of the weight has transferred to the front axle. So there isn't
much benefit to separate brake lines and ABS inputs to the rear wheels,
as long as there is SOME means of keeping them rolling while the front
wheels do the work.

----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

 

On 09 Dec 2003 08:17 PM, L.W.(?ill) ------ III posted the following:
> Del, I like to just check one thing for me. You said: "all 4 wheels at
> the point of maximum braking." I'd like you to crawl under your TJ and
> tell me how many brake lines are connected to your rear axle, then
> tell me how your ABS could release one locked wheel without releasing
> maybe the only other wheel with traction.

I never said my TJ had that exact system, but that doesn't mean that all
ABS equipped vehicles are that way. I have even driven a rig with ABS
only in the rear, now that was a messed up system to be sure. Point
being, that ABS can control the braking force applied to multiple wheels
simultaneously, something which you and I cannot do. Well, I do it in
airplanes, but that doesn't count. 8^)

If you want to pick nits, yes, the ABS in the TJ can only send one input
to the rear brakes, so the braking force is limited to the maximum that
the rear wheel with the least traction can take without locking. But
since the majority of the braking is done by the front wheels, which *
are* individually modulated, my point still stands.

The crucial thing that the rear ABS must do is keep the rears from
locking to maintain directional control. Getting the maximum braking
performance out of the rear wheels just isn't important since they
contribute so little to stopping the vehicle in a panic situation, when
most of the weight has transferred to the front axle. So there isn't
much benefit to separate brake lines and ABS inputs to the rear wheels,
as long as there is SOME means of keeping them rolling while the front
wheels do the work.

----------------------------------------------------
Del Rawlins- del@_kills_spammers_rawlinsbrothers.org
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/

 

Lon, ABS (or anti-skid) was in use on A/C a long time before cars got
it, mainly because at high speeds a blown tire was the problem that
was gonna kill you fastest. The rule of thumb used when I was
instructing was that you wanted a 10% rolling skid. In other words,
the tire was not rotating at a speed to match the ground but a little
slower. The way you judged success was that if the marks you left
were the same color brown as your drawers, you did good, if they were
black you were in trouble.

With the extreme high pressure in those jet tires (180-200 PSI dry
nitrogen) the last place you wanted AS was on a rain soaked runway -
any hydroplaning with it on was akin to having no brakes at all.
That's from white knuckle observations on more ocassions than I like
to remember but I get the same feeling on wet roads with a car. Of
course, those of use who spent that many hours using differential
braking for steering tend to have a whole lot different outlook on the
matter - we learned to USE the brakes.

On Wed, 10 Dec 2003 04:02:35 UTC Lon Stowell
<LonDot.Stowell@ComcastPeriod.Net> wrote:

> Roughly 12/9/03 18:39, Mike Romain's monkeys randomly typed:
>
> > Del, the makers even state ABS has a longer braking distance.
>
> Cite?
>
> >
> > There isn't any debate on that issue, do a google search.
>
> Well, I did. And up coughed a paper from the Society of
> Automotive Engineers, SAE 1999-01-1287.
>
> The purpose of the study was to determine if situations and
> or conditions occur where ABS equipped vehicles do not perform
> as well as vehicles without ABS.
>
> "For most maneuvers, on most surfaces, ABS-assisted stops
> yielded distances shorter than those made with the ABS
> disabled. The one exception was on loose gravel where
> stopping distances increased by an average of 27.2
> percent overall. [as you've noted many times, not a
> good idea offroad]. Additionally the vehicular stability
> observed during testing was almost always superior with
> ABS. For the cases in which instability was observed,
> ABS was not deemed responsible for its occurrence."
>
> All of the tests were conducted in the same vehicle with and
> without ABS, to avoid differences in basic vehicle stability.
>
> Without ABS, a professional driver was used to implement
> threshhold braking, with instrumentation to ensure that
> at no time was more than one wheel locked during this
> threshhold, aka, "best effort" braking. In every test
> on dry concrete, the ABS beat this driver in every vehicle
> tested. On wet Jennite with laden vehicles, the ABS beat
> the human every time. Only on wet Jennite with lightly
> loaded vehicles was the human able to beat ABS in one
> test out of 8. Same results on wet asphalt, an expert
> human beat the ABS only in 1 or 8 tests and only when
> the vehicle is lightly loaded. ABS and heavy load
> beat the human every time. And on wet grass. On
> gravel, the human beat the heck out of ABS, light or
> heavy load.
>
> Full wheel locked panic stops didn't do so good...although
> for most drivers they are still better than trying to use
> threshhold braking due to lack of experience.
>
> Same paper notes that crash databases clearly show that although
> 4 wheel ABS has produced some safety benefit, the net result
> from those crash statistics clearly indicates that these
> benefits in practice are far lower than predicted from
> engineering data and testing. e.g. single vehicle
> fatal crashes on wet roads were reduced 24% on ABS
> equipped vehicles, but the overall incidence of fatal
> single vehicle crashes increased 28% with ABS. And the
> safety ***** as well as the engineers that designed the
> systems wanted to know why. [Obviously none of them have
> ever driven in a Silicon Valley commute with a few soccer
> moms glued to their asses.]
>
> >
> > It is not operator error, it is a defective attempt to compensate for
> > drivers that were never trained how to drive.
>
> Nothing wrong with ABS. Problem is just the drivers don't
> engage it, end up sawing at the wheel, or think it is a
> magical get out of jail free card to allow excessive speed
> for conditions or following too closely.
>
> Well, almost nothing. Not entirely sure how the ABS would
> know the vehicle was on gravel all by its own inputs, but
> with input from the shock absorbers it easily should be
> able to figure out that it is best disabled.
> >
> > Same for air bags. Ever wonder why they are designed to stop an adult
> > with no seat belt on? To compensate for fools on the roads.
>
> To kill a few small women and kids to save those too stupid to
> buckle up.
>


--
Will Honea <whonea@codenet.net>

 

Lon, ABS (or anti-skid) was in use on A/C a long time before cars got
it, mainly because at high speeds a blown tire was the problem that
was gonna kill you fastest. The rule of thumb used when I was
instructing was that you wanted a 10% rolling skid. In other words,
the tire was not rotating at a speed to match the ground but a little
slower. The way you judged success was that if the marks you left
were the same color brown as your drawers, you did good, if they were
black you were in trouble.

With the extreme high pressure in those jet tires (180-200 PSI dry
nitrogen) the last place you wanted AS was on a rain soaked runway -
any hydroplaning with it on was akin to having no brakes at all.
That's from white knuckle observations on more ocassions than I like
to remember but I get the same feeling on wet roads with a car. Of
course, those of use who spent that many hours using differential
braking for steering tend to have a whole lot different outlook on the
matter - we learned to USE the brakes.

On Wed, 10 Dec 2003 04:02:35 UTC Lon Stowell
<LonDot.Stowell@ComcastPeriod.Net> wrote:

> Roughly 12/9/03 18:39, Mike Romain's monkeys randomly typed:
>
> > Del, the makers even state ABS has a longer braking distance.
>
> Cite?
>
> >
> > There isn't any debate on that issue, do a google search.
>
> Well, I did. And up coughed a paper from the Society of
> Automotive Engineers, SAE 1999-01-1287.
>
> The purpose of the study was to determine if situations and
> or conditions occur where ABS equipped vehicles do not perform
> as well as vehicles without ABS.
>
> "For most maneuvers, on most surfaces, ABS-assisted stops
> yielded distances shorter than those made with the ABS
> disabled. The one exception was on loose gravel where
> stopping distances increased by an average of 27.2
> percent overall. [as you've noted many times, not a
> good idea offroad]. Additionally the vehicular stability
> observed during testing was almost always superior with
> ABS. For the cases in which instability was observed,
> ABS was not deemed responsible for its occurrence."
>
> All of the tests were conducted in the same vehicle with and
> without ABS, to avoid differences in basic vehicle stability.
>
> Without ABS, a professional driver was used to implement
> threshhold braking, with instrumentation to ensure that
> at no time was more than one wheel locked during this
> threshhold, aka, "best effort" braking. In every test
> on dry concrete, the ABS beat this driver in every vehicle
> tested. On wet Jennite with laden vehicles, the ABS beat
> the human every time. Only on wet Jennite with lightly
> loaded vehicles was the human able to beat ABS in one
> test out of 8. Same results on wet asphalt, an expert
> human beat the ABS only in 1 or 8 tests and only when
> the vehicle is lightly loaded. ABS and heavy load
> beat the human every time. And on wet grass. On
> gravel, the human beat the heck out of ABS, light or
> heavy load.
>
> Full wheel locked panic stops didn't do so good...although
> for most drivers they are still better than trying to use
> threshhold braking due to lack of experience.
>
> Same paper notes that crash databases clearly show that although
> 4 wheel ABS has produced some safety benefit, the net result
> from those crash statistics clearly indicates that these
> benefits in practice are far lower than predicted from
> engineering data and testing. e.g. single vehicle
> fatal crashes on wet roads were reduced 24% on ABS
> equipped vehicles, but the overall incidence of fatal
> single vehicle crashes increased 28% with ABS. And the
> safety ***** as well as the engineers that designed the
> systems wanted to know why. [Obviously none of them have
> ever driven in a Silicon Valley commute with a few soccer
> moms glued to their asses.]
>
> >
> > It is not operator error, it is a defective attempt to compensate for
> > drivers that were never trained how to drive.
>
> Nothing wrong with ABS. Problem is just the drivers don't
> engage it, end up sawing at the wheel, or think it is a
> magical get out of jail free card to allow excessive speed
> for conditions or following too closely.
>
> Well, almost nothing. Not entirely sure how the ABS would
> know the vehicle was on gravel all by its own inputs, but
> with input from the shock absorbers it easily should be
> able to figure out that it is best disabled.
> >
> > Same for air bags. Ever wonder why they are designed to stop an adult
> > with no seat belt on? To compensate for fools on the roads.
>
> To kill a few small women and kids to save those too stupid to
> buckle up.
>


--
Will Honea <whonea@codenet.net>

 

Lon, ABS (or anti-skid) was in use on A/C a long time before cars got
it, mainly because at high speeds a blown tire was the problem that
was gonna kill you fastest. The rule of thumb used when I was
instructing was that you wanted a 10% rolling skid. In other words,
the tire was not rotating at a speed to match the ground but a little
slower. The way you judged success was that if the marks you left
were the same color brown as your drawers, you did good, if they were
black you were in trouble.

With the extreme high pressure in those jet tires (180-200 PSI dry
nitrogen) the last place you wanted AS was on a rain soaked runway -
any hydroplaning with it on was akin to having no brakes at all.
That's from white knuckle observations on more ocassions than I like
to remember but I get the same feeling on wet roads with a car. Of
course, those of use who spent that many hours using differential
braking for steering tend to have a whole lot different outlook on the
matter - we learned to USE the brakes.

On Wed, 10 Dec 2003 04:02:35 UTC Lon Stowell
<LonDot.Stowell@ComcastPeriod.Net> wrote:

> Roughly 12/9/03 18:39, Mike Romain's monkeys randomly typed:
>
> > Del, the makers even state ABS has a longer braking distance.
>
> Cite?
>
> >
> > There isn't any debate on that issue, do a google search.
>
> Well, I did. And up coughed a paper from the Society of
> Automotive Engineers, SAE 1999-01-1287.
>
> The purpose of the study was to determine if situations and
> or conditions occur where ABS equipped vehicles do not perform
> as well as vehicles without ABS.
>
> "For most maneuvers, on most surfaces, ABS-assisted stops
> yielded distances shorter than those made with the ABS
> disabled. The one exception was on loose gravel where
> stopping distances increased by an average of 27.2
> percent overall. [as you've noted many times, not a
> good idea offroad]. Additionally the vehicular stability
> observed during testing was almost always superior with
> ABS. For the cases in which instability was observed,
> ABS was not deemed responsible for its occurrence."
>
> All of the tests were conducted in the same vehicle with and
> without ABS, to avoid differences in basic vehicle stability.
>
> Without ABS, a professional driver was used to implement
> threshhold braking, with instrumentation to ensure that
> at no time was more than one wheel locked during this
> threshhold, aka, "best effort" braking. In every test
> on dry concrete, the ABS beat this driver in every vehicle
> tested. On wet Jennite with laden vehicles, the ABS beat
> the human every time. Only on wet Jennite with lightly
> loaded vehicles was the human able to beat ABS in one
> test out of 8. Same results on wet asphalt, an expert
> human beat the ABS only in 1 or 8 tests and only when
> the vehicle is lightly loaded. ABS and heavy load
> beat the human every time. And on wet grass. On
> gravel, the human beat the heck out of ABS, light or
> heavy load.
>
> Full wheel locked panic stops didn't do so good...although
> for most drivers they are still better than trying to use
> threshhold braking due to lack of experience.
>
> Same paper notes that crash databases clearly show that although
> 4 wheel ABS has produced some safety benefit, the net result
> from those crash statistics clearly indicates that these
> benefits in practice are far lower than predicted from
> engineering data and testing. e.g. single vehicle
> fatal crashes on wet roads were reduced 24% on ABS
> equipped vehicles, but the overall incidence of fatal
> single vehicle crashes increased 28% with ABS. And the
> safety ***** as well as the engineers that designed the
> systems wanted to know why. [Obviously none of them have
> ever driven in a Silicon Valley commute with a few soccer
> moms glued to their asses.]
>
> >
> > It is not operator error, it is a defective attempt to compensate for
> > drivers that were never trained how to drive.
>
> Nothing wrong with ABS. Problem is just the drivers don't
> engage it, end up sawing at the wheel, or think it is a
> magical get out of jail free card to allow excessive speed
> for conditions or following too closely.
>
> Well, almost nothing. Not entirely sure how the ABS would
> know the vehicle was on gravel all by its own inputs, but
> with input from the shock absorbers it easily should be
> able to figure out that it is best disabled.
> >
> > Same for air bags. Ever wonder why they are designed to stop an adult
> > with no seat belt on? To compensate for fools on the roads.
>
> To kill a few small women and kids to save those too stupid to
> buckle up.
>


--
Will Honea <whonea@codenet.net>

 

In article <3FD682CC.90815E85@***.net>, L.W.(=?iso-8859-1?Q?=DFill?=) ------
III <----------@***.net> writes:

> I suggest you were not going fast enough to worry about not having
>brakes as the thirty percent more fatal off road crashes found out when
>inertial threw them from the road when the ABS released.

when their foot released the pedal when the ABS kicked in and startled them.
* * *
Matt Macchiarolo
www.townpeddler.com
www.wolverine4wd.org
http://wolverine4wd.org/rigs/macchiarolo_ml.html

 

In article <3FD682CC.90815E85@***.net>, L.W.(=?iso-8859-1?Q?=DFill?=) ------
III <----------@***.net> writes:

> I suggest you were not going fast enough to worry about not having
>brakes as the thirty percent more fatal off road crashes found out when
>inertial threw them from the road when the ABS released.

when their foot released the pedal when the ABS kicked in and startled them.
* * *
Matt Macchiarolo
www.townpeddler.com
www.wolverine4wd.org
http://wolverine4wd.org/rigs/macchiarolo_ml.html