Near miss

[fast1]

  Nortbound on Ospika this afternoon going to pick up our violinist's about quarter to four I encountered a southbound silver ?? who while changing lanes lost control and slid sieways through the meridians. Now on my side it did a 360 and stopped sideways across both lanes. A quick stab of the brakes told me immediately that any attempt to stop in time would be futile. Remembering Kaw-meisters adage "people die needlessly every year because they won't take the ditch", though in my case it was the sidewalk,which I ploughed free for the city. This of course required throttle on to gain the momentum required to stay in a straight line and not get stuck, proving the adage that when used responsibly horsepower will get you out of more trouble than it will get you in! No injuries or insurance claims. Thanks Paul! CHEERS.

[fast1]

  Soooo....just noticed 2 things. One: posting times are now accurate .Thanks Terry. Two: I posted this in the wrong section, can you fix this Terry? Thanks again. CHEERS.

[MaximX]

Good job on that one.....Previous to the icy streets we have now, (the last snow fall over a month ago) I was going slightly down hill to a stopsign.  Too late realized there was a lot of ice built up.  ABS kicked in immediately under low braking....and there was a Jeep coming down the street I was heading to.  So slide into him with the help of ABS or let off the brakes and turn the corner tight to the curb?  Did that and the other driver avoided me.  Soon after I pulled the fuse to the ABS.  On my car if one wheel stops turning it throws them all into the stupid ABS mode which makes for a much longer slide if some of the tires are not on as slippery a surface as the first wheel that set it in motion.  Even my car manual states that the abs system may make for a longer stop in some situations.  It's only use is to allow steering in a slide.

This got me curious.  I took my car out to an icy road and was able to stop in the same distance without abs as with it on.  I then took it to a road with packed snow.  From 50 km to a stop I was able to stop 9' sooner than the abs.  From 70km that went up to 18' sooner without abs.  That did it, the fuse stays out until the ice and snow are off the roads....I can put up with an amber abs light on my dash for a few more weeks.....

[Dennis]

A totally locked up set of tires will always stop in a shorter distance than anything else.  The problem is you have little control on where you eventually stop, and which direction you will be pointing when you do.

Peace & Grease, Dennis

[stevecrout]

I think I'd want to check and see if there would be any implications on my insurance if I had disconnected a factory installed safety feature of the car.

[MaximX]

I had thought of that Steve, weigh the options, have a car that can stop and keep me out of an accident or if I get in an accident pop that fuse back in right away.  I of course would never lie, if someone asked me if I had that fuse out I would say Yes I did.

[Rusty Bucket]

  My truck comes with an electronic differential lock, the activation of which disables the ABS.  Many owners take advantage of this by slightly modifying the wiring to allow the installation of a disable switch for the ABS.  I haven't yet looked into this myself - or ever done any empirical testing, which I think I find quite convincing - but the modification is particularly favoured, probably not coincidentally, by the hard-core off-roaders and those that live in the snowier parts of North America.
 
  Studded tires should give the wheels - and therefore the ABS sensors - the rotational rate input (and traction) to have the required data to manage effective decelleration, but apparently the system does not work as well as we might hope.  MaximX's tests, and the fairly wide use of a disable switch on my particular vehicle, suggest that there is - perhaps ample - room for improvement in braking safety, which is a surprise to me, and not something I have thought of previously.

  I haven't had any close calls yet this winter, but I will be thinking about this next time I feel the situation getting away from me..

[fast1]

    Things I had not thought of before either, thanks Mike. If that stupid little light is bothering you a small piece of black tape will make it go away. CHEERS.

[madmac74]

 Not Quite Dennis  .... actually, A tires Maximum amount of grip Comes JUST BEFORE it locks up.  Once it does lock, Its now just Newtons 3rd Law.
MAC

[Hans]

yup, instantaneous static friction > sliding friction.

[Kaw-meister]

as ABS is an 'option'. any vehicle does not require it to be installed. however, all braking systems must be maintained to fully function as the manufacture intended. I am not sure that ABS is considered a braking function, as it's whole purpose is to restrict the amount of braking to the wheels.

[Dennis]

Not Quite Dennis  .... actually, A tires Maximum amount of grip Comes JUST BEFORE it locks up.  Once it does lock, Its now just Newtons 3rd Law.
MAC

I'll gladly stand corrected.  I just remember somewhere reading back when ABS first came in, that an exhaustive study was done on this and fully locked up skidding tires consistently resulted in shorter (but uncontrolled) stopping distances.  I can't say I went back to the web for Newton's thoughts about it.

Peace & Grease, Dennis

[Hans]

actually Dennis, you're right to an extent.  A highly trained and sensitive person can outperform ABS via threshold braking, keeping the tire just on the verge of locking up.  That is where you get the best stopping power.  ABS may or may not be better than locking them up, I think it depends on the surface.  It's main purpose is to keep the tires turning so you have some amount of steering authority.  In a panic stop, most people just nail the brakes as hard as possible.  Also most people become target fixated, so they are just as likely to steer into something they are trying to avoid instead of looking for the escape route.

[MaximX]

Now I am wishing I'd done one stop without ABS and locking up the wheels to see how far that would go on that road....I prefer real world testing to speculation, haha.  What I did is by no means a real world standard, it was however what I could do on that day.  And yes it took more than one try to get my non ABS stop as short as it was.  I am no pro driver.  I am convinced that on a surface where one tire hits ice and the others have better traction you go a way lot further with ABS than without.  Did that several times before pulling that fuse, I had enough of that stupid system cutting in to send me sliding.  Often it was coming up to a stop sign, something I like stopping for if possible.  Yeah I know, if really smart you don't get caught off guard that way, but sometimes snow hides what you are on etc, etc.