How to stop things getting worse

How to stop things getting worse

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R_U_LOCAL

Original Poster:

2,690 posts

214 months

Thursday 15th March 2007
quotequote all
We all get things wrong sometimes. It's the nature of being a human being - no-one is perfect (except Mrs Local of course, but I wouldn't dare say otherwise, would I?), and we're all disposed to getting things wrong once in a while. I've mentioned before that a good driver learns from and remembers prior mistakes, without dwelling on them, and uses them in their future driving plans as what not to do in similar circumstances.

There are occasions, however, when you can get things wrong, and your actions in trying to correct that mistake can either save the situation, or bugger things up even more than you already have. I'm talking, of course, about skidding.

Now, there's some very good advice in Roadcraft, and I've taught and stood by it's principles for a long time now, but there's one area where I feel that Roadcraft is fundamentally lacking (apart from the overtaking position, and I think we've argued that one to death now), and that's the books teachings on certain aspects of skid control.

It's not that the book is wrong, exactly, it's just that it's teachings on skid correction are just too basic for what is supposedly an advanced drivers manual (bible, even). Of course, most people don't get the benefit of some skid training (although a damn site more, and - dare I say - all new drivers should), and so you could argue that any skid training is advanced, in that it's beyond what an ordinary driver would get, but for me, some of the techniques it recommends are clumsy, basic, and in one case actually dangerous if you're travelling at high speed.

*Reg looks up to a room of silence - you could hear a pin drop. A Police instructor who doesn't agree with Roadcraft? What the chuff is going on?*

Lets start with some stuff that I do agree with, just so you know I haven't gone completely hatstand.

Roadcraft's description of skids, how they occurr and it's advice that the best option with skidding is to avoid getting into skids in the first place is all spot on, and not worth repeating here.

Where it is lacking, however, is in it's description of how to control certain kinds of skids - specifically situations where a driver is experiencing oversteer and understeer.

Now, there are two main errors that a driver makes which induce oversteer and understeer. One is accelerating too harshly when cornering, with which Roadcraft deals, shall we say, adequately. The other one is by cornering at excessive speed, which is where I feel the book's advice is flawed.

Let's start with oversteer, and for my example, I want you to imagine that you're driving a rear-wheel drive car without traction control. *Reg sees the TVR drivers ears pricking up*

The advice in roadcraft if you've started to oversteer, is to first of all release the accelerator or declutch and release the accelerator. Now, if your oversteer is being caused by excessive bootage of the right pedal, then this advice is entirely correct - releasing the accelerator or pressing th clutch and lifting off will almost immediately stop the rear wheels from spinning, regain you some road grip, and providing you've counter-steered correctly, then you should have yourself back on the straight and narrow in next to no time.

But what if your oversteer is caused by travelling excessively fast for the corner? Let's start by having a look at what's happening to the car as it starts to break traction. As the car travels round the corner, it's weight is moving over the wheels which are on the outside of the corner. The more speed you carry into (or build up during) the corner, then the more weight is transferred onto the outer wheels. At the same time, the tyres on those outer wheels are trying to counter the cars natural tendency to travel straight on, by holding lateral (sideways) grip with the road surface. Now, as I've mentioned before, there's only a certain amount of grip available to the tyres, and by cornering harder, you're getting less grip from the inside wheels (because the weight transfer to the outside ones means there's far less weight pressing the inside wheels down), and you're demanding more grip from those outside tyres.

*And breathe*

The sum total of all that is that when the speed becomes too much for the corner, the car will start to slide. The natural tendency of the majority of rear-wheel drive cars is for the rear to start sliding first, so that the car starts to turn in towards the inside of the corner more than the driver wants it to, hence it's oversteering.

And what is Roadcraft's advice in this situation? The same as before - release the accelerator, or declutch and release the accelerator.

Let's think about that for a minute shall we? In a situation where the rear-end of a car is losing grip, Roadcraft is advising us to perform an action which will transfer weight towards the front of the car, and more importantly away from the rear of the car, thus removing grip from the rear at exactly the time when you want more grip, rather than less.

Not the best advice in my opinion.

So what should you do then Reg, you smartarse?

Don't lift off for starters - not completely anyway. The idea is for you to correct the skid using the steering and throttle by not adding any more speed, and by counter-steering.

When I say "by not adding any more speed", think about whet you do when you're in a 40MPH speed limit area - you accelerate up to your chosen speed, and when you've reached it, you relax the pressure on the accelerator slightly so that the car remains at that speed. Note the wording - you relax the pressure on the accelerator - you don't release it. If you released it, the car would start to slow down, whereas you just want it to stay at that speed, so you relax your pressure, but you definitely keep some pressure on the accelerator.

That's what you should do - relax the pressure on the accelerator just slightly, so that the car isn't gaining any more speed - it's what I'd describe as a slight feathering back on the throttle. Certainly not a release of the throttle.

At the same time, you should steer in the direction you want to go.

The steering part isn't any more complicated than that. I could harp on for ages about steering in the direction of the skid, counter-steering and opposite lock, but all you need to know is that you should steer in the direction you want to go.

You should, of course, be careful not to steer too far in the direction you want to go, as this could induce a secondary skid, and these are, on the whole, much worse than the primary skid, and your trousers probably couldn't cope with the additional stress.

So steer just enough in the direction you want to go, and no less.

What about understeer then Reg? Some of us drive Astra VXRs and Golf GTIs - what about us.

Patience my children.

If you're understeering due to excessive acceleration, then, again, Roadcraft's advice is sound. Release the accelerator, or declutch and release the accelerator, take a little steering off, and you should be all smiles again almost instantly.

But again, Roadcraft is lacking somewhat when it comes to understeer due to excessive speed. Many front-wheel drive cars will react to a lift on the throttle in a similar (although not identical) way to a rear-wheel drive car. They will pitch into oversteer as a reaction to the transfer forward of the cars weight which is associated with a lift on the throttle. This FWD oversteer can be even more difficult to catch than in a RWD car, and so, unless you're playing on a circuit or skidpan, should be avoided at all costs.

So, you've carried too much speed into a corner, the car is running wide and not responding to extra lock, and you're suddenly becoming very concerned about an imminent expensive alloy wheel / kerbstone interface - what do you do?

As explained earlier, don't lift off the throttle completely, but feather back on it slightly. In this case you do want to lose a little speed, so that feathering back should be a little more than you would in the oversteering TVR. The reason you want to lose speed is because this will transfer some weight back onto the front wheels, regain you some front-end grip, and, together with steering towards where you want to go, will have you pointing back in the right direction presently.

I'd better just add that practising this stuff on the road isn't to be advised. You could find a quiet roundabout somewhere and have a go, but there's always the possibility that something could go badly wrong and you may well end up with a dented car, a dented ego, a dented driving licence, a dented wallet and.... I'm sure you get the picture.

My advice if you want to have a go at this stuff is this - pay out a few quid and have a half-day at a skid school. It'll be in someone else's car, so you're car won't get dented, you'll have someone who really knows what they're doing sat next to you, so your ego will remain intact, it'll be off-road, so your licence is safe and although the cost might dent your wallet a bit, the pay-off may well come back and save you a fortune at some time in the future.

Go on - you know it makes sense.


Edited by R_U_LOCAL on Thursday 15th March 22:44

R_U_LOCAL

Original Poster:

2,690 posts

214 months

Thursday 15th March 2007
quotequote all
Major Bloodnok said:
Excellent post, as ever, Reg. Couple of points to introduce into the discussion:

Surely there's a significant difference between just coming off the throttle, and dipping the clutch. Dipping the clutch will remove all drive from the wheels, so I would have thought the tendency would be for the car to centralise its weight front/back (not side to side, of course), whereas leaving the clutch engaged while coming off the throttle would cause a noticeable braking effect at the driven wheels, causing a greater weight shift to the front.


The difference isn't as significant as you might think, and dipping the clutch immediately removes a control that's vital to good skid control - the throttle. Any slight advantage in weight transfer caused by dipping the clutch is easily outweighed by still having the option of maintaining some throttle control. Don't forget the main thrust of my point - Roadcraft's advice of releasing the throttle / declutching is fine if the oversteer has been induced by excessive wheelspin. I just think that my way is better for oversteer which has been induced by excessive cornering speed.

Major Bloodnok said:
I've been on a skid pan course (Police pan somewhere in Shropshire...) and they had us dip the clutch in every case (rear wheel, front wheel and all wheel). It seemed to work. One technique we were shown, that you haven't mentioned, is for an all-wheel skid, where you apply firm brakes and turn the wheel. At some point (where it's safe!), you come off the brakes, the wheels dig in and the car steers in the chosen direction (e.g. into a side road). Comments?


I imagine that the skids you were correcting on your course weren't at very high speeds. I'm not knocking your training at all - you'll be a much better drive for it, but skid pans by their very nature are designed to allow you to experience skids at fairly safe speeds. At those speeds, the weight transfer isn't as much of an issue, and the clutch in/throttle lift would normally work fine. At higher speeds, however, the weight transfer is more of an issue, and some cars can be very sensitive to even very small throttle inputs at the limit - ask any Peugeot 205 GTI or older Porsche 911 drivers - they'll be nodding their heads reading this.

One other issue with de-clutching. Don't do it if your car is fitted with traction control, as it completely takes away any effect that the TC would have. Traction control systems are becoming more and more sophisticated - some of them, such as the BMW system, will actually brake individual wheels to help you keep control. However, if you dip the clutch, the systems won't kick in, so you're best leaving that clutch pedal well alone.

As for the all-wheel skid, I'll be honest and say that I've never tried that method, so it's not really fair that I comment at the moment. I'm sure someone else will, and rest assured, as soon as I get an opportunity, I'll give it a go and then give you my opinion.

Edit to say that I've just read your last line again, and I lied. I'd mis-read it the first time, and that method of skid control does work, providing you haven't got ABS fitted. Contrary to what I first wrote, I have tried it as a method of controlling understeer and four-wheel skids, and found it a little, how can I put this? Agricultural. It does work, if you'r of a mind to hit the brakes hard enough, but you should be very sure of what your cars reaction will be, as that kind of braking mid-bend can introduce a whole new meaning to "snap oversteer".



Edited by R_U_LOCAL on Thursday 15th March 23:31

R_U_LOCAL

Original Poster:

2,690 posts

214 months

Friday 16th March 2007
quotequote all
GreenV8S said:
Some pretty poor advice.


I can't believe you've read through my post and decided to write that the advisable course of action is to slam on the brakes. At a time when the balance of a car is crucial, and any small action that a driver makes can literally make or break them, you're recommending that they perform an action which throws most of the cars weight forward, away from wheels which may well be starting to lose grip anyway, and then basically pray for a safe ending.

This is an advanced driving forum, and you're advocating the basic reaction of someone whose driver training ended with their DSA test.

The title of my thread gives a clue here - how to stop things getting worse. This suggests that things have already gone wrong, and you're trying to limit the damage. Trust me - in the situations I've described, more often than not, hitting the anchors with all your might will make things far worse.

R_U_LOCAL

Original Poster:

2,690 posts

214 months

Saturday 17th March 2007
quotequote all
GreenV8S said:
Some more stuff


Oh, I see - I think you may have posted in the wrong thread. This is the "how to stop things getting worse" thread. I think you wanted the "how to stop things getting even worse when things have already gone wrong, you've tried everything you possibly can, and it's still going wrong" thread.

You're right of course - if you've tried everything else, and you're still heading for the scenery at a strange angle, your last chance to save everything (or to minimise the damage to you and your car) is to press the brakes - hard.

It is the last option though, and your original post made me think that you were recommending it as a first option, which it clearly isn't.

vonhosen said:
Some other stuff about modern electronic driver aids


I've been lucky enough to experience some of these driver aids first hand in a safe environment, and they're very good. I'll not go into all the different acronyms on here, as each manufacturer seems to come up with a new one, and I don't want to start getting my ESPs mixed up with my DSCs.

Needless to say, these systems work in similar ways, with a combination of wheel sensors, pitch sensors, yaw sensors, roll sensors, and other such electric trickery which all link into a central unit which constantly monitors what you're doing with the car. If things start to go wrong, this unit can take control of various aspects of the cars controls, such as throttling back and even applying individual brakes, in order to bring the car back under control.

As an example, if a car starts to oversteer in a right-hand bend, the unit can apply the rear offside brake individually, which helps the driver to regain control of the car.

It's all very clever stuff, and having tried it in the same car, switched off and then on, I can say it works brilliantly. Well, as good as a very good driver anyway.

Just remember though, if you take the option of pressing the clutch, the majority of these driver aids won't work properly, as you'll take away the drive from the wheels. So if your car has these aids, bear that in mind.

A little story for you (completely true, as I dealt with the accident, so I promise you it's not one of those Policeman's urban legends).

I went to deal with an accident once, I think it will have been in about 1997 or 1998. The driver of a 2.5 litre Vauxhall Omega had lost control on a right-hand bend, done a 180 degree rotation, and then left the road on the offside, landing in a ditch. The car was written off, but the driver, although shaken up, was uninjured.

I spoke to him about what had happened, and I expressed some surprise, as I knew that Omegas were fitted with traction control.

He agreed with me, especially as he said "I know - and I religiously turn it on every time I get into it".

I asked him if he had read his owners manual, and if he knew that the switch which turned the traction control light on on his dashboard actually turned the system off.

I've never seen anyone do a better Homer Simpson "D'OH" in all my life.

Quick lesson there for everyone - RTFM - Read The Flippin' Manual.


Edited by R_U_LOCAL on Saturday 17th March 12:39

R_U_LOCAL

Original Poster:

2,690 posts

214 months

Thursday 24th May 2007
quotequote all
Blue160 said:
I'm afraid I have no idea what limit point analysis is confused

Would be great if you could explain
I've written some stuff on cornering. The first one, with some stuff about limit point use is here...

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Some advice on bend assessment without the limit point is here...

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

And one about linking corners...

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

I will be posting more on the subject, including some videos, but I'm getting married next week, so I haven't had much time to write recently.

Keep an eye on this forum for more soon.