I'm over my embarrassment

I went out in the snow before Christmas in Derbyshire in my X-reg TD5 manual Disco and slid on ice into a drystone wall very gently. I'm now over the embarrassment and feel I can tell you about it and having fixed the damage with about £60 worth of parts need to know something.

I was travelling down a steep road which was a thin layer of snow over sheet ice I later found out so I've come to think I didn't have a chance anyway. On the way down in low box with hill descent selected and the ABS hammering away all went quiet and we slid into the wall.

My question is if all the wheels stop moving at the same time how does the car know its moving at all. As far as i can tell the ABS stopped working as all four wheels stopped turning and so the slide was inevitable.

Its not a natural thing to release the brake on a steep hill when your sliding so I didn't do it. Then I realised that if I didn't hit the wall slowly then I would have to hit something further down the hill much faster.

A 90 came round the corner behind me a few minutes later saw me across the road and drove straight into the wall so I didn't feel that bad. Difference was there was nop damage at all to the 90, wish I still had mine.

Regards

borntobemild said:

I went out in the snow before Christmas in Derbyshire in my X-reg TD5 manual Disco and slid on ice into a drystone wall very gently. I'm now over the embarrassment and feel I can tell you about it and having fixed the damage with about £60 worth of parts need to know something.

I was travelling down a steep road which was a thin layer of snow over sheet ice I later found out so I've come to think I didn't have a chance anyway. On the way down in low box with hill descent selected and the ABS hammering away all went quiet and we slid into the wall.

My question is if all the wheels stop moving at the same time how does the car know its moving at all. As far as i can tell the ABS stopped working as all four wheels stopped turning and so the slide was inevitable.

Its not a natural thing to release the brake on a steep hill when your sliding so I didn't do it. Then I realised that if I didn't hit the wall slowly then I would have to hit something further down the hill much faster.

A 90 came round the corner behind me a few minutes later saw me across the road and drove straight into the wall so I didn't feel that bad. Difference was there was nop damage at all to the 90, wish I still had mine.

Regards

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ABS and the other related electronic aids will not work satisfactorily on ice as there is NO friction between any of the tyres and the road surface, so they'll all stop. ABS works by comparing wheel speeds - if they are all the same ie stopped, ABS won't help, as you found.

The best you can do is to feather-brake so you don't trip ABS.

As you said, the best thing to have done (once sliding) would have been to release the brake pedal - but it takes some stones to do that when you are already in a slide.

if you start sliding, get off the brakes, regain grip and direction (as much as you can) and feather break

I have had a few similar experiences this week (just without the wall) in the V8 Disco with ABS lucky for me each time I let the brakes off and regained it. I tend to take foot off naturally than hit the brake so not sure whats going on in my mind!

Glad to be back in mine without ABS!

Hi
On a manual car to make all 4 wheels lock up you must have had your foot on the clutch or out of gear. If not it would have stalled as the engine would still be trying to turn the wheels.
You must have lost traction on the ice and slid. As said before it is best to feather the brake and sometime you might also have to give the accelerator a little blip to get all the wheels moving again.
But in the conditions you describe it sounds like no matter what you did or what you drove you would have been in trouble.

thebiglad said:

ABS and the other related electronic aids will not work satisfactorily on ice as there is NO friction between any of the tyres and the road surface, so they'll all stop. ABS works by comparing wheel speeds - if they are all the same ie stopped, ABS won't help, as you found.

The best you can do is to feather-brake so you don't trip ABS.

As you said, the best thing to have done (once sliding) would have been to release the brake pedal - but it takes some stones to do that when you are already in a slide.

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HHHMMMMMMMMMMMMMMM interesting............ would ABS also fail going down a hill of slippy mud? I have no problem with my disco going anywhere, just a problem with it stopping!

Even if yer sideays on as long as the wheels are still rolling you have some kind of control of your vehicle. In some cases you actually have to gently increase the engine revs and accelerate to get your vehicle back in line. As soon as you lock the brakes up you will generally speed up instead of slowing down. Speeding up with rolling wheels is way better than speeding up with locked wheels.

The big problem is: how do you know that the adhesion limits are that low?

I had a very gentle slide at low speed last week. No damage and I stopped within the road limits (downhill to a very sharp right-hander, country lane)

I had slowed to a crawl to let a Defender coming the other way through the bend first, but as I turned into the bend it just gently slid away from me and I steered into the skid and stopped.

A TNT truck behind me wasn't quite as lucky, although he saw me slide, but he was already too fast down the hill and he got into a bit of bother.

If you don't know it's that bad, then all the electrickery in the world won't help.

Peter

mrnice said:

HHHMMMMMMMMMMMMMMM interesting............ would ABS also fail going down a hill of slippy mud? I have no problem with my disco going anywhere, just a problem with it stopping!

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So, going downhill off-road, you would be in low ratio so you would be using "Hill Descent" control. This would analyse each individual wheel speed and apply abs braking, if one wheel is slower than the others, that wheel gets no braking.

Ultimately all these systems rely on friction between tyre and ground. If there is no grip, you're bûggered.

The real issue here is to grasp that ABS works in a particular way and is an amazing safety device in most normal road conditions. Sheet ice means no grip so don't use brakes of any kind.

Unfortunately I think a number of people have been caught out by their ABS brakes thinking that they will save them, no matter how little common sense is applied by the driver.

listerdiesel said:

The big problem is: how do you know that the adhesion limits are that low?

I had a very gentle slide at low speed last week. No damage and I stopped within the road limits (downhill to a very sharp right-hander, country lane)

I had slowed to a crawl to let a Defender coming the other way through the bend first, but as I turned into the bend it just gently slid away from me and I steered into the skid and stopped.

A TNT truck behind me wasn't quite as lucky, although he saw me slide, but he was already too fast down the hill and he got into a bit of bother.

If you don't know it's that bad, then all the electrickery in the world won't help.

Peter

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So you need to continually be checking the amount of grip you have, a quick dab of the brakes will tell you - and go slow

Downhill on an icy bend is a bad situation, but there's a couple of techniques that can help.

Obvious one first, be in a highish gear, at least the next gear up to what you'd normally be in, at much lower revs. Easy to do ..

If you need to brake, don't back off the throttle fully, try to keep keep the wheels turning whilst slowing them down, feathering the brake/throttle and balancing them. Left foot braking is also good so you can do the whole thing smoothly. Quite hard to do ..

When it does start to slow down, keep it in as high a gear as possible, don't clutch/change gear until it's getting close to stall point and do it as smoothly as you can. Fairly easy to do ..

During all this you can also, whilst braking, try blipping the throttle very slightly .. spins wheels a bit faster, hopefully keeping them rotating enough to find grip. Quite hard to do whilst still slowing down ..

The left foot braking thing is a great technique to learn for of-roading anyway .. works a bit like Traction Control .. when a wheel's spinning, a dab or three, not heavy, with the left foot brakes the spinning wheel, slows it down and sends a bit more power through the diff to the other wheel on the same axle, hopefully getting it rotating and out of the gloop ..

borntobemild said:

I was travelling down a steep road which was a thin layer of snow over sheet ice I later found out so I've come to think I didn't have a chance anyway. On the way down in low box with hill descent selected and the ABS hammering away all went quiet and we slid into the wall.

My question is if all the wheels stop moving at the same time how does the car know its moving at all. As far as i can tell the ABS stopped working as all four wheels stopped turning and so the slide was inevitable.

Its not a natural thing to release the brake on a steep hill when your sliding so I didn't do it. Then I realised that if I didn't hit the wall slowly then I would have to hit something further down the hill much faster.


Regards

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I'm slightly confused by this - if you had HDC on then you shouldn't be touching the brakes, and as said above you can't normally lock all four wheels unless you hit the clutch.
A problem I have had with HDC is as follows: it's possible for the transfer box to jump into neutral if low is not fully selected. Has happened sooner or later on all my landies, Series III onwards. If this happened, your HDC would stop working, althoughyou ought to hear a chime. Your natural reaction would be to hit the brakes, and with ABS this should be OK. However if you also hit the clutch, OR if your transfer box is in neutral you could possibly lock the wheels and turn into a big sledge.
Most likely cause therefore is your transfer box jumping into neutral.
As a rule of thumb, never touch the clutch when in danger of slipping. It's far better to stall the engine. And always double check that the transfer lever is fully home.

Yep I think you're right Pastmaster. I think I probably hit the brake and then the clutch before contact with the wall. The thing is I was already 45 degrees to the slope and half a car length from contact before I did that but up to that point thought I was doing OK.

It took me about 10 minutes of moving back and forward about a foot at a a time before I could persuade the front end to go down the hill before the back end and I could use the couple of foot of frozen grass up to the wall to get some grip where I parked the car as close to the wall as possible and left it for the night. The couple of miles walk back into Hathersage was magical in the snow as was the train ride to back to Sheffield.

The next day my son and I went back out to try and recover it. Just before we got to the car a tractor went up the hill as if it were there was no snow or ice on the road. The back wheels had dug right down through the ice to the tarmac. Once we managed to get the car out of the grassy slope at the edge of the road we slowly went down the ridges left by the tractor. What does a tractor weigh?

Next question for you all is snow chains? Have any of you any experience with using them. One set for the front wheels or two sets for all wheels? And how do you know when is the time to put them on?

Thanks for being kind to me I expected a harsher response for sliding one of Solihull's best.

Regards to all 'and remember, take care out there'.

borntobemild said:

Next question for you all is snow chains? Have any of you any experience with using them. One set for the front wheels or two sets for all wheels? And how do you know when is the time to put them on?

Thanks for being kind to me I expected a harsher response for sliding one of Solihull's best.

Regards to all 'and remember, take care out there'.

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Re snow chains, my mate used them recently on his Defender and found them brilliant for giving grip to stop, steer and go and bad for vibrations and you have to drive REALLY SLOWLY. He put them on his front wheels only.

Incidently, a lot of the local delivery drivers round here fit studded tyres on their front wheels. Takes 5mins to swap over (if you're well organised) and gives all the grip you'll need.

Interesting thread, this. I had a very minor slide similar to Peter, no drama, no damage. But... On the way down in low box with hill descent selected and the ABS hammering away all went quiet and we slid into the wall.
Doesn't the Td5 have potentiometers and accelerometers as part of the ABS & HDC system? Or does it not matter what is reading what if there's a complete loss of traction / adhesion?
Or am I talking out of my chuff?

Part of the reason I've raised this is because my Disco has done me proud over the past few weeks, to the (slightly smug) extent of pulling neighbours, a Parcelforce van and a 7.5 tonner that have been stuck in our road.

So when I had my brown trouser moment it wiped the smug grin off my face! I'm wondering why it decided to go a little bit sideways even though I was being careful...

Answering various bits of these posts -

going uphill is easier than going down. I'm not sure of the physics but uphill a TD5 with TC is virtually unstoppable. Going downhill though, it can be virtually unstoppable...

I think studded tyres are illegal in UK Biglad. They really rip up the tarmac once the snow has gone. They were made legal once while I lived in Germany (that wd be about 1970) and the damage was so bad they banned them the following year.

I used snow chains and a few bags of sand over the rear axle in my Sherpa van. They are great in snow but awkward to fit and not much use in most of UK because they have to come off once you get on a hard surface. Milkmen use them a lot (or used to), as milkfloats tend to have big traction problems in snow. So they would be good in the country. No good here in C London.

I may be speaking out me arse here but you must have been going too fast, in condidtions like we've just had treat evey road as if your driving on Ice..go as slow as possible and keep away from the brakes... if some t*sser behind thinks you're going too slow let'em overtake.... any ways least no one was hurt

PASTMASTER said:

Answering various bits of these posts -

I think studded tyres are illegal in UK Biglad. They really rip up the tarmac once the snow has gone. They were made legal once while I lived in Germany (that wd be about 1970) and the damage was so bad they banned them the following year.

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I don't know about the legal aspects of using them in the UK, you may be right. But your next comment shows how little you understood what I said.

The baker who delivers round here looked at the weather in the morning and when it turned really bad he invested less than 10 mins to put 2 studded tyres on the front on his fwd truck. As soon as the roads are clearer he whips them off again. There is no question of running with them on tarmac as you would have very little grip (by comparison to an ordinary road tyre) Horses for courses.

thebiglad said:

So, going downhill off-road, you would be in low ratio so you would be using "Hill Descent" control. This would analyse each individual wheel speed and apply abs braking, if one wheel is slower than the others, that wheel gets no braking.

Ultimately all these systems rely on friction between tyre and ground. If there is no grip, you're bûggered.

The real issue here is to grasp that ABS works in a particular way and is an amazing safety device in most normal road conditions. Sheet ice means no grip so don't use brakes of any kind.

Unfortunately I think a number of people have been caught out by their ABS brakes thinking that they will save them, no matter how little common sense is applied by the driver.

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i F(&&in hate HDC, if its that bad you should only ever need low box 1st gear & engine braking-SLOW DOWN!

ere foss shouldn't you be at work??