Porsche Stability Management

[funster]

I completely agree with everything that you are saying about a skilled driver being better able to better drive any car without the current technology that exists. And I also agree that I have the most fun when I turn as many of these off as I can. I have yet to notice the psm kick in when it's turned off. I also let a number of people drive my car because it is fun for them and introduces them to the experience of driving a Porsche. Someone gave me that opportunity and it led to me getting a Boxster S! When I let someone drive I do make sure that all of that technology is going. Even the most skilled of drivers take a bit to get used to a new car and it's nice to have these features for that. I really don't see the compromise (except for not being able to turn off the abs, but I'm sure there's a hack for that i just haven't found it yet!)

[Sammy]

I like ABS...

[Sammy]

Skilled driver with ABS = Faster than skilled driver alone

In my case...

Lousy driver with ABS = Closer to skilled driver alone than before

[MNBoxster]

Originally Posted by Sammy

Skilled driver with ABS = Faster than skilled driver alone

In my case...

Lousy driver with ABS = Closer to skilled driver alone than before

Hi,

Your 1st statement is untrue. ABS will not stop a car in as short a distance as without it. This is because the brakes are modulated, meaning very quick ON/OFF intervals. Whenever the Calipers are OFF, they're not bleeding energy (read speed) from the system. By modulating the way they do, ABS prevents wheel lock so the car remains steerable. No race car uses ABS Brakes and if they made the car quicker, by even 0.1 sec., they certainly would. The '89½ onward Esprit has ABS Brakes, and all their owners defeat them for Track Days in order to go faster.

Your 2nd statement is very true, and true of all the modern Driver Aids. The drawback to this though is that a Driver learns to rely on these systems to compensate for a lesser skill set. And, if this is the only type car you ever get to drive, your skill acquisition will be slower, if not totally impaired, especially if you ever have to drive without them.

But, since the majority of Sports Car (or high-powered Sports Coupe and Sedan) owners today never concentrate on improving their own driving skills, I think it's a good thing the majority of the cars on the road have these aids, especially if they're sharing the road with me....

Happy Motoring!... Jim'99

[funster]

A skilled driver with abs is not faster than a skilled driver alone. Here is a test that you can do which will illustrate my point. Get going along on a stretch of road with no one behind you and slam on the brakes hard to activate the abs and mark as far as it takes to stop. Then do the same test and apply the brakes as hard as you can without activating the abs and see how far it takes to stop. ( this may take a few tries if you are not familliar with where the car is about to lock up the wheels but eventually you will figure out where that is and you will have gained a new and valuable skill!) You will see that you can stop sooner if the abs does not activate. A skilled driver will stay on the verge of breaking loose and when some skid starts to occur pressure is released slightly to stop the skid then reapplied to the threshhold of skidding again for optimal braking. The same principles apply to psm If you can use as much power as you can put to the pavement by continuously being on that verge of breaking traction then you will go faster than if your car is not allowing you to do this.

[Sammy]

You guys must have had too many marsupial turds in your coffee... (I'm kidding, I just like using the phrase "marsupial turds"... kind of catchy)

In theory ABS is slower than non-ABS (I completely agree with this); however, a human being cannot break faster than ABS with any level of consistency regardless of skill. You can put Andretti, Montoya, Bondurant, etc, in the same car and let them stop in a straight line 100 times and if they are lucky they just might be able to outstop the ABS a few times. Put them in a turn and the liklihood decreases because the weight shift is much more complicated. As you have mentioned ABS pulses faster than any human being could consciously "lift" off the pedal due to the reaction time. There is no such thing as a zero second reaction time that when a driver recognizes the wheels locking up that he/she can instantaneous lift and reapply the brakes. On the other hand a skilled driver cannot consistently stay at the edge of locking the wheels... He/she can do it better than we can, but not faster than ABS.

I completely agree that it hinders the development of a driver because it acts as a crutch, but it also keeps people safe. We also aren't driving million dollar cars that if we wreck them a sponsor pays for a new one.

[funster]

Sammy, you are mistaken, the abs senses a skid and begins its pulsing and won't stop pulsing until it senses that all skidding has stopped. Once this happens your stopping power depends on when the wheel with the least traction stops sliding. Try this test if you ever have a car in the snow(and you are confident that you can do it safely). Drive with one side of the car on a plowed surface with good traction and the other side of the car on a slippery part and apply the brakes to activate the abs. You'll see it takes significantly longer to stop than if the wheels on dry pavement could utilize all their traction. (some abs systems are better at this test than others) The same principles are true on a race track when cornering. if you hit a small bump on a wheel on the inside of your turning circle and set off the abs you can decrease the ablity of your car to brake and fairly skilled drivers can do this better than the abs which is why they don't put abs on race cars.

[Sammy]

Originally Posted by funster

Sammy, you are mistaken, the abs senses a skid and begins its pulsing and won't stop pulsing until it senses that all skidding has stopped. Once this happens your stopping power depends on when the wheel with the least traction stops sliding. Try this test if you ever have a car in the snow(and you are confident that you can do it safely). Drive with one side of the car on a plowed surface with good traction and the other side of the car on a slippery part and apply the brakes to activate the abs. You'll see it takes significantly longer to stop than if the wheels on dry pavement could utilize all their traction. (some abs systems are better at this test than others) The same principles are true on a race track when cornering. if you hit a small bump on a wheel on the inside of your turning circle and set off the abs you can decrease the ablity of your car to brake and fairly skilled drivers can do this better than the abs which is why they don't put abs on race cars.

I vaguely remember that Formula 1 use to allow ABS and banned it...

I agree that ABS is not faster in all situations.

[racer_d]

Originally Posted by funster

... which is why they don't put abs on race cars.

Yes and no. The use of ABS on a race car is dictated by the sanctioning body, not the race car maker. Many series don't allow it for 1) "man vs machine" arguments as to who is doing the actual driving - driver or car; 2) Cost ; 3) Potential for using the ABS to do other things (like a traction control or Stability management program which would give the car an unfair advantage)

Porsche (with the help of Bosh) has developed some very advanced and capable ABS brake systems. Their systems actually allow a certian percentage of "lock" that is dialed out of a street cars ABS system.

ABS doesn't always improve or hurt a cars stopping distance (there are way to many variables to discuss here, like the one above about driving on snow and clear pavement at the same time) but it DOES make a car safer, since it allows one to maintain STEERING capabilities to aviod accidents.

Originally Posted by funster

Sammy, you are mistaken, the abs senses a skid and begins its pulsing and won't stop pulsing until it senses that all skidding has stopped. Once this happens your stopping power depends on when the wheel with the least traction stops sliding. Try this test if you ever have a car in the snow(and you are confident that you can do it safely). Drive with one side of the car on a plowed surface with good traction and the other side of the car on a slippery part and apply the brakes to activate the abs. You'll see it takes significantly longer to stop than if the wheels on dry pavement could utilize all their traction. (some abs systems are better at this test than others) The same principles are true on a race track when cornering. if you hit a small bump on a wheel on the inside of your turning circle and set off the abs you can decrease the ablity of your car to brake and fairly skilled drivers can do this better than the abs which is why they don't put abs on race cars.

Hey Funster, in your example (one side on snow one side on pavement) at least the car will track reasonably straight...right? At least this has been my experience. And an advantage of a car with ABS.

[MNBoxster]

Originally Posted by Sammy

...In theory ABS is slower than non-ABS (I completely agree with this); however, a human being cannot break faster than ABS with any level of consistency regardless of skill. You can put Andretti, Montoya, Bondurant, etc, in the same car and let them stop in a straight line 100 times and if they are lucky they just might be able to outstop the ABS a few times. Put them in a turn and the liklihood decreases because the weight shift is much more complicated. As you have mentioned ABS pulses faster than any human being could consciously "lift" off the pedal due to the reaction time. There is no such thing as a zero second reaction time that when a driver recognizes the wheels locking up that he/she can instantaneous lift and reapply the brakes. On the other hand a skilled driver cannot consistently stay at the edge of locking the wheels... He/she can do it better than we can, but not faster than ABS...

Hi,

Sorry, not buying it. I have demonstarted this and seen it done by professionals. ABS is not even designed to decrease the stopping distance, it's sole purpose is to prevent wheel lock, it does not increase the brakes efficiency. In fact, because the calipers are not clamped continuously (where mechanical energy is transferred to heat energy and expelled from the system), it reduces the brakes efficiency and results in longer stopping distances. And this says nothing of where the threshold is set by the control unit. It can be argued that if you activate the ABS at all, you're already doing it wrong. It is possible to understand and feel when the car will lockup and thereby avoid it...

Happy Motoring!... Jim'99