mike gray wrote:

> Matt Whiting wrote:
>
>> mike gray wrote:
>>
>>> Matt Whiting wrote:
>>>
>>>> Except that only the best of professional race drivers can modulate
>>>> their brakes with sufficient competence to beat ABS. And then only
>>>> on a perfect surface. Put one side of the car on pavement and the
>>>> other on wet pavement, snow, ice, etc. and ABS will win every time.
>>>
>>>
>>>
>>> Hardly. I'll train you to beat yer ABS in 15 minutes. And with
>>> practice, you'll never get into yer ABS again, even in a panic stop.
>>>
>>> Go to an SCCA drivers school and watch the novices in street car
>>> classes where disabling the ABS is against the rules. The ones going
>>> deepest into the corners never activate the ABS.
>>>
>>> ABS is like synchros, nice for the soccer moms but a waste for the
>>> drivers.
>>
>>
>> Yes, and I suppose you could also adjust your spark advance faster
>> than the computer controlled system, and you'd like to return to
>> manual mixture controls and chokes...
>
>
> Manual advance was replaced by mechanical (centrifugal) advance, which
> was simple, cheap, and reliable if you knew how to set yer timing and
> gap. Then came crank fire with simple, reliable electronics (the racers'
> choice was the Chrysler unit, btw). I'm not convinced that the ECU is
> any great leap forward, unless you are able to program it yerself.

Trouble is the optimum timing depends on more than just RPM. Yes, I
know that there were also vacuum driven distributors to allow factoring
in MP, but optimum timing depends on more than just RPM and MP. My
point is that automatic controls, well designed, will beat a human every
time. I don't if the automation is mechanical or electrical/electronic.

In the case of spark timing, since it depends on several factors, only
two of which I mentioned above, electronic control is the way to go.



>>
>> I don't know if I can find it now, but I saw a test several years ago
>> where lots of people said they could stop a motorcycle without ABS
>> faster than one with ABS. They ran a test with several magazine
>> editors who are all fairly proficient riders and a couple were regular
>> racers. I believe that only one of the racers beat the ABS equipped
>> bike and that was on dry pavement. Add in some water, sand, etc., and
>> the ABS bike won EVERY time. And it won almost all of the time even
>> on dry pavement.
>
>
> I don't know anything about bikes, except that they stop on one wheel.
> Pass.
>
>> I don't know if a similar test has been done with cars, but I'll bet
>> the result would be the same.
>
>
> It's been done many times on cars, and ABS loses every time.

Do you have a reference? Under what conditions were the tests done?
What was the skill level of the drivers?


>> And driving on a fairly smooth, dry, paved race track is nothing like
>> driving in the real world with wet and oil roads, cases where one lane
>> is dry and the other is black ice, etc. No human can beat ABS in
>> these real conditions as you can't modulate each wheel separately as
>> can the ABS system. So it matters not how much braking skill you have.
>
>
> You haven't done much racing. We race in the wet. Oil (and coolant) and
> dirt/gravel is a constant hazard, and if you have both wheels on the
> pavement, yer not taking the corner right. Race cars (other than
> showroom stock, IT, and similar "street legal" classes) do not use ABS.
> Not in pro racing, not in Sunday afternoon amateur racing.

Probably because the rules don't allow them. They've been introduced
and subsequently banned in manner classes of racing, Formula One being
an example. They gave too much of an advantage to the teams using them
and the driver's machismo got in the way as well.

This is one of the best discussions I've seen on ABS systems.
http://www.geocities.com/nosro/abs_faq/

I personally am not a big fan of them, but only because I live in a
climate that has snow on the roads for 5 or so months each year. ABS is
almost hazardous on snow, at least until you get used to it. The
stopping distances of my minivans with ABS are much longer than my truck
which has conventional brakes. On hard surfaces though, I've rarely
noticed ABS being a handicap. And if you are really good at threshold
braking, the ABS won't engage anyway so a really sharp driver won't even
know it is there. And if they do feel it kick in, then they aren't as
good at braking as they thought.


>> The only place I've seen, both from reading and from personal
>> experience, where ABS falls short is in conditions of deep snow or
>> very loose material like deep sand. In these situations, the locked
>> tire is worse than "almost" locked tire, falls apart. If the tire is
>> able to push up a mound of snow or sand by being locked, then the car
>> will actually stop shorter. However, on most other surfaces a wheel
>> that locks will lose traction compared to one at incipient lock-up.
>
>
> The justification for ABS is that it does work in an understeering car
> while cornering. On yer next trip to the grocery, watch the brake lights
> in front of you and you will see that most drivers turn in and apex far
> too early and continue to brake way beyond the apex, usually all the way
> to the exit of the turn. ABS works very very well under that condition.
> But ya don't have to be Sebastien Loeb to know that that's not how to go
> around corners. ABS is just a poor substitute for minimal driving skill.

I'm not saying ABS is a substitute for better driving skills. I'm
saying that ABS can do things that a human simply can't do, such as
modulate the braking at each wheel independently to cover situations
where each wheel is seeing a different mu. No way you can do that with
one brake pedal. And if I gave you four brake pedals, you couldn't do
it fast enough to be effective.

Matt