Winter weather driving.

[pjs]

That no good at all on ice and snow as you are decreasing the kg/cm2 pressure ratio. The narrower the tyre the more pressure and therefore the more traction.

ah, ha - hmm. Well, I guess you see rally cars on ice on thin tyres, but did you ever see top gear do to the north pole dropping the tyre pressures on the hilux for a greater 'footprint'

hey, ho, cant beat a bit of sliding about for a cheap thrill...

 

[AANDYY]

Annoys me when people don't put there lights on for the conditions.
'I can see where I'm going' theory
What about us seeing you?
I also put mine on so the dorks that don't de-mist there windows properly can see me.

 

[jeremytaylor]

Many years ago I had a Ford Cortina... now that was very poor in icy conditions

But I bet it wasn't as bad as my old Moggy Minor. Virtually no weight over the driven wheels - a real challenge on ice!

 

[kjay]

Annoys me when people don't put there lights on for the conditions.
'I can see where I'm going' theory
What about us seeing you?
I also put mine on so the dorks that don't de-mist there windows properly can see me.

I'm amazed at the number of people who forget to put their lights when it's 'grey' let alone dark!!
I like the auto feature on the MB - It should be compulsory on all cars.

.Low pressure in the driving wheels may be good in snow, but in 'non' driving wheels - they're creating drag.
.

 

[Redline]

This tip is probably for those of us with older cars without all those fancy electronic TLA-thingys, but ballast is an absolute must! I've got two old washer fluid cans (5L) packed full of lead inside the spare wheel. Really helps with traction on slippery roads!

 

[fyonn]

When stopping an automatic RWD car knock it into neutral otherwise the front wheels will lock before it stops causing loss of steering control.

I'd be interested to know the reasoning behind this

 

[Chattonmill]

Have a good range of cars on the driveway for each season

 

[Chris Akabusi]

i would add (sorry if ive missed it already), if you can, for those who have rear wheel drive cars, add some extra weight in the boot to give some more traction.

I picked up my new CLC last night, but not brought it out today, just in case! My IS200 is also rear wheel drive and currently has 5 cases of lager in the boot to add some weight.

If i do get stuck, at least i can have a good time

 

[BTB 500]

When stopping an automatic RWD car knock it into neutral otherwise the front wheels will lock before it stops causing loss of steering control.

Surely ABS would stop the front wheels locking?

 

[grober]

I'd be interested to know the reasoning behind this

With an automatic gearbox drive is never really disconnected entirely from the rear wheels. Normally automatic cars are brought to a halt by using the front brakes overcoming any residual "drive" with the engine idling. In very slippery conditions this "residual drive" plus the impetus of car coming to a halt is enough to lock the front wheels reducing control. In the real world this doesn't amount to much but is enough to push your car a metre or so forward of where you intend to stop. This may mean the difference between stopping at a halt sign at a T junction and ending up in the middle of the road you are joining! You only have to experience this a couple of times to realise the "into neutral technique" is pretty good advice . All the while this is happening you will hear a jolly seasonal f**ting sound as the ABS [in hyperdrive!!] tries its best to brake the car [unsuccessfully] to a halt. There are times even the best ABS system struggles in conditions of almost zero grip.

 

[BTB 500]

In very slippery conditions this "residual drive" plus the impetus of car coming to a halt is enough to lock the front wheels reducing control.

...

There are times even the best ABS system struggles in conditions of almost zero grip.

Surely ABS simply detects that the front wheels are no longer turning, regardless of how much or how little grip there is? If ALL the wheels are locked I guess the system could assume the car is stationary and not modulate the braking input ... is that what you're talking about?

 

[chord]

I have to say I always anticipated that a rear wheel merc would be useless in the snow and ice but actually find its not that bad. I do take it extremely carefully in those conditions though. Many years ago I had a Ford Cortina... now that was very poor in icy conditions

A colleague mentioned that he has put the car into reverse and driven off in snow when stuck going the right way! Hence RWD becomes FWD! I guess it's for emergencies and short distances only!

 

[dougal74]

Great braking tip for RWD with auto there, but another is don't use the brakes at all (!), use the gear ratios to slow you down graually if things are really bad...

 

[grober]

Can't give you a definitive answer Bill to that one. The later multichannel ABS systems are a lot more sophisticated than the ones I am familiar with- early 90s. As far as I have experienced in 10 years of driving older Mercs in icy conditions what happens is if you brake on a very slippery surface (doesn't have to be hard braking) the ABS kicks in modulating the brake application to try to achieve maximum retardation without wheel lock. This is ineffective on a very slippery surface so the ABS unit increases modulation to the maximum its capable of hence the f**ting sound and pedal vibration in an endeavour to stop wheel lock. Because the friction is almost non existent its destined to fail. The system will continue to brake at maximum modulation even with all the wheels locked because the signal from the brake pedal will always be the "primary directive" for the system no matter what other sensors are doing to modify this. Well that's the way I rationalise it. The only time in normal driving conditions you get a taste of this is braking hard to a standstill in the wet at a halt sign and you hit either gravel or some of that slippery reflective paint they use for road markings. The instability angle Dieselman talks of comes from the fact that the lateral, or sideways, force coefficient of the tyre decreases to only about 10% of its full value when the wheel locks.
http://www.whnet.com/4x4/abs.html

 

[andy_k]

Had a thought tonight on my way home. Roads covered in ice and biting wind. Felt quite secure and safe in my car, BUT. Thing to remember, your car may be the safest on the road but others are not as fortunate, or have your driving skills. Be careful out there during this cold snap.

Any tips on winter driving would be welcome. No one knows it all.

My number one tip would be don't live in such a god forsaken place

secondly, if the conditions are that bad - leave the car at home if you haven't got winter tyres fitted

 

[s88]

When stopping an automatic RWD car knock it into neutral otherwise the front wheels will lock before it stops causing loss of steering control.

Any chance of more explanation onthis please, dont see the logic.

I thought it was bad to run autos in nuetral!

 

[renault12ts]

DM is no longer on here.

But knocking into neutral at the very low speeds he is advocating will be fine. Just don't do it to coast down a hill on a Motorway at 70!!

 

[trapperjohn]

For slow speed stops on ice or packed snow, I always put my auto into neutral. If I do not my 124 Eastate just become a very fast uncontrollable sledge.
In neutral you have so much more control for slow speed stops.
If you were in a manual car in the same conditions you would posssibly have dipped the clutch, been off the gas and just dabbing the breaks without even thinking about it. As renault12ts says dont try slipping your auto in "N" high speed

 

[andy_k]

Any chance of more explanation onthis please, dont see the logic.

I thought it was bad to run autos in nuetral!

if you leave the car in gear it will still be sending power to the rear wheels, gentle breaking (which is biased towards the front of the car) will mean the car carries on pushing forwards whilst you are trying to slow it down

 

[NormanB]

Apparently Mercedes has rushed out a new modification to help all Mercedes RWD cars - Link