Re: The poop on ABS

[16v Jason <jason@scirocco.org>]

At 01:49 PM 8/24/99 , Ben Patterson wrote:
>	First off, I was the one driving the car you mentioned above, 
>not my wife (since I'm not married) and therefore can't blame the 
>accident on the Driving While Female syndrome (I apologize to the 
>women on the list before I get flamed, but I was almost killed by 
>another stupid woman in a Toyota last night, so bear with me). I also 
>didn't insinuate that ABS caused the brake dive - like I said, I 
>drove an 89' Accord without ABS for a few years before I got the 94' 
>Accord, and if anything the dive on the 89' was worse because the 
>suspension was shot.

Ben, forgive me for my argumentative tone... in advance. :)

In your original post, you said, and I quote: "I stomped the brakes and the
damn ABS wouldn't let me lock up- went right under his back bumper because
of the weight transfer forward.
If I had been driving the 89' I would have been fine.".  Okay, dunno where
I imagined the wife scenario, but that sentence, without reference to any
suspension, seemed to indict ABS as the cause of your brake dive.

And, I maintain, you're lucky the ABS _didn't_ let you lock up-- I didn't
make up those figures from Road & Track-- on a locked-wheel stop from
60mph, full lockup took 213ft vs 133ft with ABS.  Sure, it wasn't an
Accord, but I'd be willing to bet serious money that those results are
applicable to just about any car on the road.  I mean, it's a known fact
that the coefficient of friction is reduced with a sliding tire...
resulting in none other than longer braking distances.


>	Second, I do appreciate ABS for general braking applications. 
>It works great especially for wet pavement, snow, loose surfaces, 
>etc. I've pushed the 97' Accord as hard as it can go and the ABS has 
>been great, never failed and probably kept me on the road while doing 
>some pretty stupid stuff.

Hmmm.. strange; you're toting the benefits of ABS on the surfaces that it
actually _increases_ braking distances, while criticizing it's efficacy on
the surfaces where it actually works.  That's interesting... :)

>	When I purchased the 97', I drove the EX model with the ABS 
>and the LX model without it for almost 45 minutes each and spent a 
>lot of time checking the braking distances under the same driving 
>circumstances. (Before you flame me again, keep in mind this is only 
>personal experience and it's only with Honda Accords - haven't had 
>the chance to drive comparative models of other cars, at least as 
>half as hard as I drove these). The ABS helped keep the car under 
>better control in high performance situations (hard cornering and 
>speeds around 140mph), and it felt really good. I personally like it 
>more than non-ABS in terms of driving style, at least on the Hondas. 

Speeds around 140?  Strange, since the EX has a published top speed of 129mph.

>But what I did find was that the non-ABS car had shorter braking 
>distances at speeds less than 35 MPH on dry pavement with an educated 
>lock. My brother and 2 other Honda-owning friends also agree, even as 
>we swap each other's cars to check this out now. We all like ABS as a 
>general rule and paid the extra money to get it, but I will swear 
>till the day I die that if I had a car without ABS I wouldn't have 
>had that accident. If dropping ABS into a 'rocco wasn't a fortune I'd 


And mind you, I'm not saying ABS is the be-all and end-all of braking.
However, despite the fact that I think Honda has one of the least effective
ABS systems on the road (personal opinion, of course, based on lots of
driving in a Civic EX), I have a hard time swallowing many of your arguments.

#1: I find it hard to believe you're insane enough to be braking hard
enough on public roads at 140mph (an unattainable speed to begin with in an
Accord) to lock the wheels, much less to be able to comment on what ABS
does for stability at those speeds.

#2:  I do feel that at low speeds (20mph and below) stopping is probably
increased by ABS when compared to threshold-braking techniques... and
engineers obviously agree with me since ABS generally disengages at speeds
below 12mph... However, there are many other factors that determine the
braking distance in a panic stop.

  The one that comes to mind as the biggest factor is the time between
reaction and full braking.  If you mash the pedal as hard as you can,
you'll get to 100% braking immediately with ABS.  But if you're trying to
threshold brake, it's going to take you anywhere from a 1/2 second on up to
get that pedal to the sweet spot. It's this exact factor that explains
Mercedes et al's new "Brake Assist" system, which detects a panic stop,
even if full braking is not applied, and boosts brake pressure to full
braking.  My point is, that even though stopping from 20-12 mph (when the
ABS disengages) might take marginally longer, the benefits of achieving
full braking instantly while you're still at, say, 60mph, completely and
without question outweigh the longer braking.  Let's face it, 1/2 second at
60mph is 44 feet - a lot more distance travelled than an additional 2 feet
from 20-12 (A stop which probably only takes 15-20 feet anyways).  That is
the benefit of ABS in the real world.

>do it too, but hell, it's not worth the money. If you want ABS that 
>bad for the safety, why drive a Scirocco? Next thing ya know there 
>will be a thread on airbags... yeesh.

	Eeeh, don't even get me started on Airbags! :)
	I would love to add ABS to my Scirocco.  I won't, of course, because I
don't have the time...  But the ABS available in the A2 cars (which is what
I would use) was Bosch Generation I, which, in addition to its reputation
of not aging gracefully, wasn't a fast acting system to begin with.

>By the way..... switch to decaf dude, before you have an aneurism...heh
heh. =)

Fuck the coffee, I need a bowl. :)

Jason




----------
1987 Scirocco 16v
1989 Mercedes 190E Sport Euro


http://members.aol.com/rocco16v  

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