smart51
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| posted on 5/1/09 at 12:49 PM |
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quote:
Originally posted by britishtrident
A skilled driver using a conventional conventional braking system will stop in a shorter distance than ABS in all conditions --- in most conditions
the distance just a couple of feet or so.
A very bold statement if I might say so. Your expert driver will have to adjust the brake force to maintain all the wheels just on the edge of
locking without locking any of them. Perhaps on dry tarmac this could be possible.
quote:
Originally posted by britishtrident
The danger of running with the ABS fuse out is that most vehicles with ABS depend on the ABS to control the front/rear brake balance.
Not to mention the fact that many new cars use the ABS to measure the vehicle's speed. Unplug it and you lose the speedo.
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NS Dev
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| posted on 5/1/09 at 01:07 PM |
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quote:
Originally posted by carpmart
 Interesting replies to this thread!
RWD - So, my experience and the reason for posting in the first place is that with big fat tyres which are legal but well worn, in a RWD car trying to
hill start is pretty difficult! I live on the edge of the Chilterns, my route is back roads some of which are un treated. Its pretty slippy! This is
my experience! 
ABS - I find this pretty good in most situations except for snow with ice. My experience a couple of times with frozen road (snow on top) and with
ABS is that snow builds in front of the front tyres and causes a snow plow type effect. There is no traction underneath the snow and a wedge building
in front of the tyre. (this is exagerated further with fat tyres) If your going down hill at same time then its pretty lethal.
Finally, I have a little driving experience as I'm not the youngest forum member  Put it this way, I was clearing my daughters car of snow
this morning and she has been driving for a couple of years so at my age I have some practice in real weather! For my sins, I used to be a sales rep
and covered 60k miles per year in the 80's early 90's. I drove RWD Sierra's and got a new one every 12 -14 months, so I have some
practice in driving in all conditions. I also race a fireblade engined car with no differential so I'm pretty used to controlling RWD cars.
Anyway, as I said, there are some 'interesting' comments on the posts. All I will say is theory is one thing, how RWD and ABS works in
the real world can be quite different.
Must admit, I wouldn't want to have been driving my Locost this morning!!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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hellbent345
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| posted on 5/1/09 at 01:38 PM |
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quote:
Originally posted by smart51
quote:
Originally posted by britishtrident
A skilled driver using a conventional conventional braking system will stop in a shorter distance than ABS in all conditions --- in most conditions
the distance just a couple of feet or so.
A very bold statement if I might say so. Your expert driver will have to adjust the brake force to maintain all the wheels just on the edge of
locking without locking any of them. Perhaps on dry tarmac this could be possible.
i was under the impression that it just turned the braking force on and off to the wheel allowing it to unlock, rather than actually applying the
maximum possible braking force with the available traction, so a skilled driver could 'feel' the edge of traction, whereas the computer
would turn the brakes off and on at presumably maximum pressure (as we are told with abs to squeeze that brake pedal hard and not worry about trying
to feel grip etc) - quick cadence braking certainly but not as good as the feeling of the grip... certainly abs is of great use in all road conditions
with inexperienced drivers, whos first and only thought is to push the brake pedal hard to the floor and keep it there - they have been conditioned
with their normal driving that the harder you squeeze the pedal the more you brake, and its hard to get out of this subconscious thought pattern if
you havent had an amount of training. snow and abs is bad its basically just turns braking off altogether, whereas with normal systems there is a
limited snow wedge effect - this doesnt happen in icy conditions or anywhere else so anybody other than really expert drivers is probably going to be
better of in an abs car.
[Edited on 5/1/09 by hellbent345]
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Dingz
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| posted on 5/1/09 at 01:53 PM |
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Only drove across Bedford this morning in the robin Hood, worse bits were my road and the industrial estate was great fun!
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smart51
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| posted on 5/1/09 at 02:21 PM |
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quote:
Originally posted by hellbent345
i was under the impression that it just turned the braking force on and off to the wheel allowing it to unlock, rather than actually applying the
maximum possible braking force with the available traction
Perhaps a few decades ago. These days, ABS detects the rate of wheel deceleration and drops the pressure by enough to release the wheel. Once the
wheel speed has recovered, it then adds pressure in small pulses watching the wheel speed all the time. If the wheel starts to lock, it backs off the
pressure a little, waits for the speed to stabilise and adds more pressure little by little. It is always trying to keep the wheel turning, rather
than skidding, but trying to keep as much brake force on the wheel as possible for the given amount of grip.
Our ABS systems are for vehicles with air brakes. They estimate the grip on the road and the load on the vehicle to decide how big the pulses should
be when reapplying the brakes. Too big and the wheel just locks up again, too small and it takes too long to build the pressure back up. Its pretty
sophisticated stuff these days.
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carpmart
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| posted on 5/1/09 at 03:47 PM |
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Thanks all - Lots of 'interesting' comments and overall I thought it was an interesting topic of conversation!
You only live once - make the most of it!
Radical Clubsport, Kwaker motor
'94 MX5 MK1, 1.8
F10 M5 - 600bhp Daily Hack
Range Rover Sport - Wife's Car
Mercedes A class - Son's Car
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Liam
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| posted on 5/1/09 at 05:59 PM |
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quote:
Originally posted by carpmart
Thanks all - Lots of 'interesting' comments and overall I thought it was an interesting topic of conversation!
Well said! I'm just gutted that I'm currently using a FWD vectra instead of my usual 3 litre omega! Driving to work (in Bedfordshire,
too) would have been fun this morning in the meggy 
edit: Which reminds me - when I was drifting/sliding to work in last year's snow, I couldn't help but chuckle as I drove past a brand new
Audi A6 quattro in the ditch with Mr Rep standing along side in his suit with a puzzled look on his face. Almost stopped to explain to him 4WD
doesn't give you more grip, but i think it would have been lost on him
[Edited on 5/1/09 by Liam]
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Dingz
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| posted on 5/1/09 at 11:04 PM |
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quote:
Only drove across Bedford this morning in the robin Hood, worse bits were my road and the industrial estate was great fun!
More of a problem trying to get out of the car park this evening though as it is up a slight slope and it was very icy, just sat in second gear not
going anywhere! eventually made it.
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David Jenkins
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| posted on 6/1/09 at 09:10 AM |
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Liked a clip on the news last night, showing the chaos caused by 20mm of snow... a large 4x4 going slowly down a hill, clear road in front of
him/her, losing traction and going into the bank - at about 5 mph. Clearly has never been taught how to use all that wonderful technology to get down
a slippery slope without incident! (hint - engage low ratio gears, keep your foot off the brake).
[Edited on 6/1/09 by David Jenkins]
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