Drive down a very icy hill in FWD - how ?
Discussion
Situation:
Damp during day, now 7pm clear sky,~ -4deg c, roads starting to really ice up, not gritted.
Come slowly ( 5mph ) around a corner to descend a reasonably steep hill.
Now i realise that this hill could now be a sheet of ice - i can see frost crystals all over it in the headlights. No cars have been down here recently.I am already on the hill and manage to stop, but now in an unsafe position.
Best thing to do now is to roll up onto the curb and walk somewhere, but i am in the middle of nowhere.
What is the best way to proceed down the icy hill?
Roll down in 1st without touching brakes?
Mount what looks to be a grippy pavement ( i am in the country and can see there are no peds )?
In 2nd with light foot braking?
Put handbrake on and release until wheels just start to move?
Well, i did make it down in 1st with steady pressure on footbrake, but what would an advanced driver do ?
( yes - but imagine you HAVE to get down the hill
)
Damp during day, now 7pm clear sky,~ -4deg c, roads starting to really ice up, not gritted.
Come slowly ( 5mph ) around a corner to descend a reasonably steep hill.
Now i realise that this hill could now be a sheet of ice - i can see frost crystals all over it in the headlights. No cars have been down here recently.I am already on the hill and manage to stop, but now in an unsafe position.
Best thing to do now is to roll up onto the curb and walk somewhere, but i am in the middle of nowhere.
What is the best way to proceed down the icy hill?
Roll down in 1st without touching brakes?
Mount what looks to be a grippy pavement ( i am in the country and can see there are no peds )?
In 2nd with light foot braking?
Put handbrake on and release until wheels just start to move?
Well, i did make it down in 1st with steady pressure on footbrake, but what would an advanced driver do ?
( yes - but imagine you HAVE to get down the hill
)The main thing is you want to keep the wheels rolling, that suggests in an FWD you want to use a lowish gear and footbrake as if the fronts lock up you can bring them back up to "speed" and start braking again.
At least that's how the 4WD boys get down steep and slippery slopes.
As to the actual gear I'd say it depends on the slope and conditions, you want the lowest gear that doesn't cause the front wheels to lock up or slide through engine braking. (Although unless you have a stupidly short first gear, you're probably in big uncontrollable trouble if that's going to happen.)
At least that's how the 4WD boys get down steep and slippery slopes.
As to the actual gear I'd say it depends on the slope and conditions, you want the lowest gear that doesn't cause the front wheels to lock up or slide through engine braking. (Although unless you have a stupidly short first gear, you're probably in big uncontrollable trouble if that's going to happen.)
1st gear. Feet off the pedals. Down you go slowly.
However. A mate of mine managed to do this in a rental car. Turned into a driveway to descend the hill to the lakeside house of a friend of ours. He'd forgetten that the roads were all heavily salted and gritted and that the driveway (steep) wasn't. We whooshed straight down the hill, over a wall and narrowly missed entering the friends house in the car via the kitchen window.
So try to avoid that situation if you can. Very bad.
However. A mate of mine managed to do this in a rental car. Turned into a driveway to descend the hill to the lakeside house of a friend of ours. He'd forgetten that the roads were all heavily salted and gritted and that the driveway (steep) wasn't. We whooshed straight down the hill, over a wall and narrowly missed entering the friends house in the car via the kitchen window.
So try to avoid that situation if you can. Very bad.
Chimune said:
( yes - but imagine you HAVE to get down the hill )
I think most sensible people would find out whether there was enough grip before starting the descent. If there isn't enough grip your choice boils down to walking down the hill leaving your car at the top, or walking down it leaving your car in the ditch half way down. )If you really don't care what happens to the car and decide to have a go regardless then I suspect the best approach would be the off-road technique of coasting down in gear, using the engine braking to produce a small amount of retardation but keep the wheels turning so that you still have some directional control. However, in icy weather you might find you don't have enough grip to stop the car drifting off the road.
Does the car have ABS? If so, you can retain control of the car (to some extent) by applying the brakes the whole way down.
If not, use cadence braking to simulate ABS.
Depending on the car, sometimes 1st gear is too low, and the wheels just lock. 2nd might be better, alternatively, a few revs will help.
If not, use cadence braking to simulate ABS.
Depending on the car, sometimes 1st gear is too low, and the wheels just lock. 2nd might be better, alternatively, a few revs will help.
If you can see the ice crystals it probably isn't very slippery at all.
Assuming the surface is properly slick... the problem with going down in gear is that you're then restricted to the minimum speed the car wants to do in first gear, which could be 5 or 6mph. I really don't see the problem with descending using just the brakes; you can go slower. So what if a wheel locks - you're only doing 2mph and it's hardly rocket science to modulate the brakes at those speeds. Better to keep the speed right down than to risk going faster on the basis that remaining in gear *might* give you extra control.
Assuming the surface is properly slick... the problem with going down in gear is that you're then restricted to the minimum speed the car wants to do in first gear, which could be 5 or 6mph. I really don't see the problem with descending using just the brakes; you can go slower. So what if a wheel locks - you're only doing 2mph and it's hardly rocket science to modulate the brakes at those speeds. Better to keep the speed right down than to risk going faster on the basis that remaining in gear *might* give you extra control.
I've actually been in this situation in a Rover 420 where the conditions were so slippery that, while descending in 1st gear, foot off the brakes, the engine just died away to tickover because the front wheels had lost traction. All I could do was apply a bit of accelerator to match the road wheels to actual speed and try to steer for a gravelly bit at the edge of the road. My next plan was the hedge but fortunately we made it down OK.
Later that same night the traffic was queing down a steep village High St. (somewhere near Huddersfield). I was stationary and had been waiting for some minutes with the handbrake on for the traffic to move, when the car just started to slide downhill with the rear wheels locked. I had visions of me sliding into the car in front, which would slide into the next car, and so on. That really got my attention! Fortunately, releasing the handbrake and then gingerly using the foot brake stopped us again. I presume that the pressure of the car while stopped had been enough to melt the snow under the tyres. It did it again a couple of times but by then I was ready for it.
Incidentally, I'm not sure about ice but snow is the one condition in which ABS is useless. In fact, original Audi Quattros had a switch to turn it off when driving on snow.
Later that same night the traffic was queing down a steep village High St. (somewhere near Huddersfield). I was stationary and had been waiting for some minutes with the handbrake on for the traffic to move, when the car just started to slide downhill with the rear wheels locked. I had visions of me sliding into the car in front, which would slide into the next car, and so on. That really got my attention! Fortunately, releasing the handbrake and then gingerly using the foot brake stopped us again. I presume that the pressure of the car while stopped had been enough to melt the snow under the tyres. It did it again a couple of times but by then I was ready for it.
Incidentally, I'm not sure about ice but snow is the one condition in which ABS is useless. In fact, original Audi Quattros had a switch to turn it off when driving on snow.
gdaybruce said:
Incidentally, I'm not sure about ice but snow is the one condition in which ABS is useless. In fact, original Audi Quattros had a switch to turn it off when driving on snow.
I've always been fascinated by how this idea remains in the driver's psyche. Do you think the manufacturers don't do winter testing? Early ABS systems may have suffered problems but this was how long ago now? Twenty years or more?I have three cars: One fitted with *everything*, one fitted with ABS and one fitted with sweet FA. I have been on pretty much every driver training course you can reasonably go on: skid pans, road driving, track driving, off-road driving in old Defenders with nothing and top of the line Range Roveers will Hill Descent Control etc and whilst I'm no race driver I can handle a car well enough in most conditions.
I have *never* had ABS do anything other than be useful. And
that includes snow. Of the three cars the one that is *useless* in snow is the one fitted with nothing (a TVR).As has been said on this thread the single biggest factor in the car being able to handle snow and ice is the tyres. My bro lives in Sweden. For months each year they drive on hard-packed snow - i.e. they scrape off the fluffy stuff and simple crush the remainder flat. They use studded tyres that grip amazingly well. In less extreme conditions a winter compound may be sufficient - no studs necessary.
The problems we have is that since we only get lying snow, which never becomes hard-packed, for a couple of weeks a year studs are definitely not required - and a winter compound tyre is an extravagance for the period it is actually beneficial. So we soldier on with tyres that offer poor grip for the two/three weeks in January/February that matter and, well, no wonder there are crashes.
My previous Mondeo - a 2000 ST24 - had truly awful ABS. It would kick in if a tyre came into contact with a damp leaf, and would seriously affect the rate of decelleration to the point of being scary. On snow or ice, I would so much rather have full (manual) control of the brakes. My current 2006 Mondeo has much, much better ABS but I'm still unconvinced of its worth.
I've never been involved in an incident in which I felt ABS would have made a worthwhile contribution, though I do a bit of rallying so my right foot might be better trained than most. In my younger days - i.e. when I used to drive like an idiot - I had a couple of near-misses during which being able to lock the brakes saved the day. I can't be bothered to go into the details, but I'm not convinced I'd have been able to get away with those moments if the car had been fitted with ABS.
I've never been involved in an incident in which I felt ABS would have made a worthwhile contribution, though I do a bit of rallying so my right foot might be better trained than most. In my younger days - i.e. when I used to drive like an idiot - I had a couple of near-misses during which being able to lock the brakes saved the day. I can't be bothered to go into the details, but I'm not convinced I'd have been able to get away with those moments if the car had been fitted with ABS.
Don said:
gdaybruce said:
Incidentally, I'm not sure about ice but snow is the one condition in which ABS is useless. In fact, original Audi Quattros had a switch to turn it off when driving on snow.
I've always been fascinated by how this idea remains in the driver's psyche. Do you think the manufacturers don't do winter testing? Early ABS systems may have suffered problems but this was how long ago now? Twenty years or more?i seem to remember reading somewhere that the quickest way to stop in soft snow is to lock the wheels. they then sink in & build a ridge of snow in front of them that slows them more than normal braking could.
basic ABS is a good thing in most situations IMHO, however stability control & all that crap is bloody dangerous. the amount of times when i used to drive new volvos that id brake in a corner as i was being silly & needed to tighten the line to find the DSA (dynamic stabilty assist?) only allowed the outer wheels to brake was scary. i used to turn it off everytime along with the traction control that didnt let you use the power to pull the front around a corner.
basic ABS is a good thing in most situations IMHO, however stability control & all that crap is bloody dangerous. the amount of times when i used to drive new volvos that id brake in a corner as i was being silly & needed to tighten the line to find the DSA (dynamic stabilty assist?) only allowed the outer wheels to brake was scary. i used to turn it off everytime along with the traction control that didnt let you use the power to pull the front around a corner.
Hooli said:
i seem to remember reading somewhere that the quickest way to stop in soft snow is to lock the wheels. they then sink in & build a ridge of snow in front of them that slows them more than normal braking could.
basic ABS is a good thing in most situations IMHO, however stability control & all that crap is bloody dangerous. the amount of times when i used to drive new volvos that id brake in a corner as i was being silly & needed to tighten the line to find the DSA (dynamic stabilty assist?) only allowed the outer wheels to brake was scary. i used to turn it off everytime along with the traction control that didnt let you use the power to pull the front around a corner.
Well you may think stability control systems are crap - but this is not what I have found personally (mine's a Porsche and PSM is MAGNIFICENT). I can also add that the Swedish road safety mob (according to my bro) reckon that stability control has had an excellent result on road safety.basic ABS is a good thing in most situations IMHO, however stability control & all that crap is bloody dangerous. the amount of times when i used to drive new volvos that id brake in a corner as i was being silly & needed to tighten the line to find the DSA (dynamic stabilty assist?) only allowed the outer wheels to brake was scary. i used to turn it off everytime along with the traction control that didnt let you use the power to pull the front around a corner.
I reckon for 99% of drivers 99% of the time they're better off with the toys. Sure - you can come up with the cases where a skilled driver can do better...but that's not what the systems are for.
I conducted a little test in the snow with my Audi Quattro where upon I tried to bring myself to a halt from 10/15mph in snow with the ABS and without the ABS. I didn't notice any difference between the two, the only time there was any difference was when I had the ABS off and turned the steering wheel whilst having my foot hard on the brake pedal to aviod the wheels unlocking. It appeared that I had a huge snow build up infront of the tyres that brought me to a stop abit quicker.
As for going downhill in the snow/ice, its like having a car on rollerskates if you have wide tyres. I did struggle on the odd occasion to bring it to a halt but there are no big hills near me and I made sure that I would keep plenty of room between me and the car infront. I did however see so many cars resting against kerbs/walls/cars/houses after the last lot of snow we had...
As for going downhill in the snow/ice, its like having a car on rollerskates if you have wide tyres. I did struggle on the odd occasion to bring it to a halt but there are no big hills near me and I made sure that I would keep plenty of room between me and the car infront. I did however see so many cars resting against kerbs/walls/cars/houses after the last lot of snow we had...
Don said:
Hooli said:
i seem to remember reading somewhere that the quickest way to stop in soft snow is to lock the wheels. they then sink in & build a ridge of snow in front of them that slows them more than normal braking could.
basic ABS is a good thing in most situations IMHO, however stability control & all that crap is bloody dangerous. the amount of times when i used to drive new volvos that id brake in a corner as i was being silly & needed to tighten the line to find the DSA (dynamic stabilty assist?) only allowed the outer wheels to brake was scary. i used to turn it off everytime along with the traction control that didnt let you use the power to pull the front around a corner.
Well you may think stability control systems are crap - but this is not what I have found personally (mine's a Porsche and PSM is MAGNIFICENT). I can also add that the Swedish road safety mob (according to my bro) reckon that stability control has had an excellent result on road safety.basic ABS is a good thing in most situations IMHO, however stability control & all that crap is bloody dangerous. the amount of times when i used to drive new volvos that id brake in a corner as i was being silly & needed to tighten the line to find the DSA (dynamic stabilty assist?) only allowed the outer wheels to brake was scary. i used to turn it off everytime along with the traction control that didnt let you use the power to pull the front around a corner.
I reckon for 99% of drivers 99% of the time they're better off with the toys. Sure - you can come up with the cases where a skilled driver can do better...but that's not what the systems are for.
i guess someone must make a good one if only due to the balance of probability.
Hooli said:
i seem to remember reading somewhere that the quickest way to stop in soft snow is to lock the wheels. they then sink in & build a ridge of snow in front of them that slows them more than normal braking could.
The downside being you then can't 'climb' over the ridge to get moving again.BTW, surely this is even more of a problem (downhill on very slippery surface) in RWD cars.
Don said:
gdaybruce said:
Incidentally, I'm not sure about ice but snow is the one condition in which ABS is useless. In fact, original Audi Quattros had a switch to turn it off when driving on snow.
I've always been fascinated by how this idea remains in the driver's psyche. Do you think the manufacturers don't do winter testing? Early ABS systems may have suffered problems but this was how long ago now? Twenty years or more?I have three cars: One fitted with *everything*, one fitted with ABS and one fitted with sweet FA. I have been on pretty much every driver training course you can reasonably go on: skid pans, road driving, track driving, off-road driving in old Defenders with nothing and top of the line Range Roveers will Hill Descent Control etc and whilst I'm no race driver I can handle a car well enough in most conditions.
I have *never* had ABS do anything other than be useful. And
that includes snow. Of the three cars the one that is *useless* in snow is the one fitted with nothing (a TVR).As has been said on this thread the single biggest factor in the car being able to handle snow and ice is the tyres. My bro lives in Sweden. For months each year they drive on hard-packed snow - i.e. they scrape off the fluffy stuff and simple crush the remainder flat. They use studded tyres that grip amazingly well. In less extreme conditions a winter compound may be sufficient - no studs necessary.
The problems we have is that since we only get lying snow, which never becomes hard-packed, for a couple of weeks a year studs are definitely not required - and a winter compound tyre is an extravagance for the period it is actually beneficial. So we soldier on with tyres that offer poor grip for the two/three weeks in January/February that matter and, well, no wonder there are crashes.
So would be hugely beneficial for the whole winter period. Not just for the odd snowfall. But are not a legal requirement in the UK!
Hooli said:
maybe they progam theirs to work with you not against you? i wouldnt know the volvo one was the only one ive tried & i hated it.
i guess someone must make a good one if only due to the balance of probability.
I have been to play with Volvos on frozen lakes in Sweden many times. Even the best drivers cannot beat their newer 'DSTC' systems - though you may have more fun with them off. If you are understeering and need to tighten the line, you turn the steering wheel more (opposite of what you might do without a stability programme) and the system pulses the brakes on the inside wheel to bring the car round. It works amazingly, and the newer systems do it much more smoothly and with less retardation than the older ones. Incidentally, newer Volvo's do not allow you to turn the system off.i guess someone must make a good one if only due to the balance of probability.
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