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Fooling ABS?

Posted: Wed Dec 14, 2016 12:50 pm
by Horse
Posted on another forum: "you can lock all four wheels of an ABS-equipped car on sheet ice"

Really?

The suggestion was that the car will think it's parked, so switch of the ABS.

Re: Fooling ABS?

Posted: Wed Dec 14, 2016 1:01 pm
by jont-
I thought "Ice mode" was the other way around (ie won't let you brake as hard as you want). Although seems to be stability rather than ABS per-se.
Known "problem" on the VX220 and maybe early S2 111R Elise.
http://www.lotustalk.com/forums/f91/ver ... tim-70922/
http://sector111.blogspot.co.uk/2013/09 ... ation.html

Re: Fooling ABS?

Posted: Wed Dec 14, 2016 2:03 pm
by GTR1400MAN
Well both those pages linked too sound like EBA (Electronic Brake Assist) taking effect to me.

I braked firmly, but in control, for a running stray dog a few years ago in my Honda Civic. It thought it was an emergency and EBA kicked in, applied the brakes fully, and brought the car to a stop. Scared the hell out of me and the following car (which luckily was far enough away).

Re: Fooling ABS?

Posted: Wed Dec 14, 2016 3:19 pm
by angus
I would've thought they were both too old to have EBA? And the early Elises didn't have ABS (at least the ones at Hethel didn't, tho' it may have been turned off)

Re: Fooling ABS?

Posted: Wed Dec 14, 2016 3:26 pm
by jont-
angus wrote:I would've thought they were both too old to have EBA? And the early Elises didn't have ABS (at least the ones at Hethel didn't, tho' it may have been turned off)

The S1 and early S2 didn't even have a servo. IIRC the Toyota engined S2 was when ABS came in (along with a servo). And agreed, they won't have EBA. Not sure they even do now.

Re: Fooling ABS?

Posted: Wed Dec 14, 2016 7:26 pm
by GTR1400MAN
angus wrote:I would've thought they were both too old to have EBA?

Whoops, I didn't clock the date. :oops:

Re: Fooling ABS?

Posted: Wed Dec 14, 2016 8:22 pm
by crr003
GTR1400MAN wrote:
angus wrote:I would've thought they were both too old to have EBA?

Whoops, I didn't clock the date. :oops:

It was the golden age of motoring. None of the TLA "benefits" (ABS was some sort of legal thing due to production numbers?)

Re: Fooling ABS?

Posted: Thu Dec 15, 2016 9:34 am
by Astraist
Horse wrote:Posted on another forum: "you can lock all four wheels of an ABS-equipped car on sheet ice"

Really?

The suggestion was that the car will think it's parked, so switch of the ABS.


Doesn't sound likely.

What they could be getting at is that ABS can't actually work below a certain speed of a few miles per hour.

On ice, even that very slow speed can carry you for a long way so you are spending a substantial part of your braking distance with locked wheels.

Also, when you lift off of the pedal to allow for generation of lateral forces, there is appearantly a longer delay on ice before those forces actually start to take effect.

Anyhow, it's not a huge problem. People seem to forget that locked wheels still provide a hell of a lot of stopping force.

Re: Fooling ABS?

Posted: Thu Dec 15, 2016 9:52 am
by jont-
Astraist wrote:Anyhow, it's not a huge problem. People seem to forget that locked wheels still provide a hell of a lot of stopping force.

Only if there's some friction for them to work with. Quite a lot of people seem to think modern electronics exempts them from the laws of physics :lol:

Re: Fooling ABS?

Posted: Thu Dec 15, 2016 11:08 am
by Horse
jont- wrote:
Astraist wrote:Anyhow, it's not a huge problem. People seem to forget that locked wheels still provide a hell of a lot of stopping force.

Only if there's some friction for them to work with. Quite a lot of people seem to think modern electronics exempts them from the laws of physics :lol:


Not helped by items such as a [?]Vauxhall TV ad which claimed that the vehicle's systems allowed it to continue on in 'impossible' conditions . . .

Same as '4x4 = all terrain'. No, not if you don't have suitable tyres, limited slip/lockable diffs etc.