ABS in Snow & Ice ?

Author
Discussion

Rich 36

Original Poster:

13,739 posts

200 months

Friday 25th January 2008
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So would time spent somewhere big & open on snow or ice, be time well spent.

Sounds like fun, I'll try the local snowdome overnight!

RacingTeatray

2,430 posts

150 months

Friday 25th January 2008
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Morningside said:
I found a bigger pain was Traction Control combined with ABS.
Last year I was trying to exit the local supermarket in the snow and the exit has a very slight slope with a small and gentle bump.
The BMW just would NOT climb it, powered up, moved slightly then powered down again. I could understand what it was trying to do (ie crawl) but it just did not work as it just slid down again.
In the end I just turned it off.

I also got stuck in a muddy field as well, with exactly the same problems. I honestly thing IF the Traction Control was turned off I would have made it out of the rut BUT it just 'lost' power leaving me stuck frown
Can you not turn it off? I used to be able to switch off the traction control in my old S3 and my 156 GTA also has this feature - it's absolutely necessary in the types of scenarios you describe. I'd never have got out of the steep mudbath masquerading as a carpark at Goodwood FoS last year otherwise!

cptsideways

12,789 posts

186 months

Friday 25th January 2008
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doc3 said:
cptsideways said:
People seem to forget that driving in snow on summer tyres can increase stopping distances by X 10!!!!!! sheet ice can be even more!. For some reason people assume there car should stop quicker than this ABS or NOT. I guarantee any modern ABS equipped car will outbrake 99% of non ABS'd drivers every time & in a straighter line. I'll even put money on it.

Its the lack of coefficient your missing & no-one seems to realise!!! they justy blame the ABS rolleyes

Edited by cptsideways on Friday 25th January 00:07
Who, on this thread, has forgotten that? I see no comments that suggest people expect ABS to make stopping distances constant whatever the weather.
I did'nt say constant, I've defined it well above, what I'm saying many are "expecting" to stop with a normal'ish amount of braking. When in fact you may have less than 10% available ABS or not.

Modern ABS is 4 channel, fast cycling systems with G-force sensing, not stuff from the 80's (though some Nippon made 80's systems some were quite good)

51mes

1,094 posts

134 months

Friday 25th January 2008
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RacingTeatray said:
Morningside said:
I found a bigger pain was Traction Control combined with ABS.
Last year I was trying to exit the local supermarket in the snow and the exit has a very slight slope with a small and gentle bump.
The BMW just would NOT climb it, powered up, moved slightly then powered down again. I could understand what it was trying to do (ie crawl) but it just did not work as it just slid down again.
In the end I just turned it off.

I also got stuck in a muddy field as well, with exactly the same problems. I honestly thing IF the Traction Control was turned off I would have made it out of the rut BUT it just 'lost' power leaving me stuck frown
Can you not turn it off? I used to be able to switch off the traction control in my old S3 and my 156 GTA also has this feature - it's absolutely necessary in the types of scenarios you describe. I'd never have got out of the steep mudbath masquerading as a carpark at Goodwood FoS last year otherwise!
Had a 530d Auto and yes you could turn the traction off - the problem with the 5 in my experience was however a complete lack of weight over the driven wheels especially with the nice low profile 265 tyres - they just sat on mud/snow whatever and didn't grip. We had a light flurry - less than a centimetre and I will say it was one of the more "interesting" driving experiences I've had - grip at the front none at the back...

My 156GTa was much better although the big V6 at the front caused problems on at least one occasion in a coupleof inches of snow at the top of a steep hill... wink

Simes.

kambites

55,102 posts

155 months

Friday 25th January 2008
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I drove a brand new American thing (bugger knows what) in Canada a couple of years ago and tried an experiment in an empty car park. Sped up to about 25 mph and floored the break pedal, then went back and looked at the tyre tracks in the snow. The brakes we on less than 10% of the time. eek

Tried it again with the ABS disabled and the car stopped in less than 1/4 the distance (but, as has been said, with no control).

Tried cadence braking and the car stopped a tiny bit slower than just flooring the pedal (still under 1/3 of the distance that it took with ABS on) and completely controllably.

If you know how to brake, ABS is a menace on ice.

Edited by kambites on Friday 25th January 09:15

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tigger1

8,224 posts

155 months

Friday 25th January 2008
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ELAN+2 said:
i learned cadence braking before taking my teast, on a skid pan, and have had several training sessions on skid pans since. this can be a pain when the abs gets thoroughly confused when i try to Cadence brake though!.
As useful as Cadence braking is in a non-ABS car, I'm pretty sure (99.9%) that all the advice with ABS is that in an emergency stop situation, press brake - keep foot in carpet until stopped. If you didn't bend the pedal you didn't brake hard enough. You should not be cadence braking with ABS IMHO.

RacingTeatray

2,430 posts

150 months

Friday 25th January 2008
quotequote all
51mes said:
My 156GTa was much better although the big V6 at the front caused problems on at least one occasion in a coupleof inches of snow at the top of a steep hill... wink

Simes.
The GTA's main issue is ground clearance! The front spoiler acts like a shovel in anything over about 3-4 inches of snow.

shoestring7

5,698 posts

180 months

Friday 25th January 2008
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Good Lord there are Luddites on this forum.Do you really think a bunch of very very smart Bosche engineers working in the alps have not considered this?

Current ABS sytems (not some cheap US system) stops working below a low speed threshold so avoid the not-stopping thing, and if you nail the pedal ing hard , you can override ABS anyway.

And frankly the main danger in snow is the 'average' driver running into you - I'd rather he/she had some way of braking and steering to increase my chances of excaping unscathed.

SS7

cptsideways

12,789 posts

186 months

Friday 25th January 2008
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Watch this 5th gear special, need I say more

http://www.youtube.com/watch?v=JcQaHhSMGKM

otolith

35,834 posts

138 months

Friday 25th January 2008
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There was an experiment done in Sweden in 1995, measuring stopping distances on snow and ice with and without ABS. They used 66 ordinary drivers in Volvo 850 on snow and ice, polished ice and roughened ice. They found that under all conditions the average stopping distance was shorter with ABS, but that the best stopping distances on snow came from locking the wheels. They also found that the car went off the track in 94 of 706 tests without ABS and 1 test out of 707 with it.

http://www.veta.se/abs66ice.htm

Conclusion seemed to be that the average driver will stop quicker on ice with ABS than without, that he might stop quicker on snow without ABS, but he probably won't. Agrees with the simple advice that ABS can be counter-productive on loose surfaces. Also, he is much less likely to lose control. That was with a mid 90's ABS system. The difficulty in beating a modern system is that you only have one brake pedal and the ABS system has four.

ELAN+2

2,232 posts

166 months

Friday 25th January 2008
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tigger1 said:
ELAN+2 said:
i learned cadence braking before taking my teast, on a skid pan, and have had several training sessions on skid pans since. this can be a pain when the abs gets thoroughly confused when i try to Cadence brake though!.
As useful as Cadence braking is in a non-ABS car, I'm pretty sure (99.9%) that all the advice with ABS is that in an emergency stop situation, press brake - keep foot in carpet until stopped. If you didn't bend the pedal you didn't brake hard enough. You should not be cadence braking with ABS IMHO.
Absolutely, however if you hit the pedal hard enough the wheels will lock momentarily before the abs releases them.On early systems, its possible to 'beat the system' albeit briefly. I had to try it to see what would happen. In most conditions and circumstances ABS will out perform a human, hence its a sensible feature to have.