Safe Speed Forums

[ the following split from another topic... ]




I know quite a lot about wheel spin and understeer actually. I successfully campaigned a Gp N Nova Gte in the BTRDA national Rally series back in the 90's. Won my class quite a few times. beating Gp A Astra Gte's, Cosworths, etc on the way. Wheelspin carries you through understeer. No wheelspin and you slide straight on, unless you yank the h/b.

Seconded!

Ru88ell, I think you've completely misunderstood the original meaning of johnsher's post, as well as clutching at something which has nothing to do with anything. A page has been wasted on this non-issue!

Hes saying that when a car is understeering, on full lock full throttle can change the angle at which the car is pointing. If you don't give it full throttle, you yank the handbrake to bring the back end around.

A FWD car can understeer with and without wheelspinning/excess power (although it is easier with the former but that's not the point)

It's a low grip front wheel drive advanced technique. The spinning front wheels (probably on full lock) provide a 'thrust vector' that is a functional substitute for the ability to actually turn in. The Americans say pump the throttle in these circumstances, as a sort of 'cadence throttle' technique.

But if you want to drive properly you'll need RWD.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Thanks Paul. I guessed it was a bit advanced for some to comprehend. Not too full on the lock though - the d/s busts.



I haven't driven RWD for donkeys years. Mk 2 Escort probably the last. Did enjoy a Mazda 323 4x4 Turbo though. That was fun and quite similar in some respects, but with shit loads more grip!

interesting... I've heard that this works for 4wd but in my experience applying power to a fwd when it's already understeering just makes the problem worse. Is this really a technique that you'd want to try in the real world (as opposed to a rally course) if you're already heading for the trees or are you generally better off staying off the power?

I can't imagine a situation in the real world where a safe driver who posts to a road safety forum would need this technique. If you find yourself heading for the trees thinking about this I would suggest staying off the road altogether, rather than off the power.

There is absolutely no need to drive like this on the road. Feel free to try on track days, or off road on a piece of land with the owners permission.

You've posted that the way to counter understeer in a fwd is to power out of it and yet when I ask whether someone who's found themselves understeering into a corner should use this technique you say you'd be mad to try it... yup, I'm thoroughly confused now.

You seem to be missing the point again.
Ree.T was commenting on the traction available from raised junctions, not his tyres, not his driving style.
Of course it is debatable whether drivers should be feeling the need to resort to various techniques to overcome such problems, but I do believe the point was one of unexpected and needless danger from these junctions (wrapped in a little sarcasm).

I wouldn't claim to be a FWD expert, but I think mild understeer will get worse when wheelspin starts, but wild understeer may well benefit from the 'thrust vector' effect. The thrust vector effect works best with wild excesses of power. It's ugly and it's brutal.



You certainly don't want to be learning or experimenting with skid control technique while you're sliding into the scenery on a public road. I think I'm right in suggesting that most peoples' attempts at skid management make matters worse.

Learning under instruction on a skid pan and circuit is something that I'd like to see all genuinely responsible drivers doing. But if it's done without that genuine responsibility, that too can make matters considerably worse. I think the main problem is that such courses can deliver more confidence than ability and the resulting imbalance means more crashes.

[I'm going to split the skid management stuff to a new topic shortly]

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

I can't agree with you there. In extreme winter conditions, advanced skid control technique has proved to be extremely useful in my own experience. I've also had a couple of very nasty surprises with diesel spills on roundabouts, where such skills can literally save the day.

If we were talking about 'normal driving', I'd agree with you completely.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

This raises some very serious and interesting issues. What advice could we give to 'ordinary drivers' that might actually help them when skidding starts?

- If driving an abs equipped vehicle, plant the brake and try to steer where you want to go?

- If experiencing oversteer, drop everything. Hands off, feet off?

What can ordinary drivers REALLY manage when a skid starts?

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

A few years back I was lucky enough to have a go on the Police skid pan at Martlesham. At the time I was driving a RWD car with no ABS. The Police instructor suggested that the most consistent method to get out of an understeering skid was to turn the wheel in the direction you want to go while braking and then press the clutch and release the brake pedal. Most of the time the car will turn quite nicely even on ice. The only problem you then have is that you might now be heading towards another obstacle!

Most of us just don't get the chance to practise skids like this and a controlled slide on a skid pan is very different to trying to recover from a mistake made on the road.

Absolutely.

The theory that I'm working on is that skid control on the road isn't working. People don't remember inough in the split second and often make matters worse. So many people wind ON the opposite lock, FAIL to wind it OFF and experience a vicious 'secondary' skid.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Ooooo interesting!

It seems completely logical that winding on a load of lock and stomping on the throttle can "drag" the car round in theory but in practice, I've tried it a few times and never managed to make it work! Now part of that is probably because I can't try it much on a public road but I was lucky enough to have a couple of long goes on a skidpan in Blackburn and it didn't work in the slightest there! The only thing was, the cars were a bit unlike anything "real". They were ordinary front wheel drive (1600-ish) cars but with bald back tyres that had 80psi in them. The result was that they generally oversteered - but, of course, never on the throttle - when they understeered. The transition between the two was somewhat vicious too!

Anyway, the conclusion we came to was that if the car is understeering significantly, its because there has been a loss of grip at the front tyre contact patches. Spinning the wheels faster doesn't really make any difference to this because they've already lost traction anyway! Although the "vector" pulling you in the right direction exists, it is orders of magnitude smaller than the force trying to keep the car going in a straight line.

I'm not doubting that there might be circumstances on loose surfaces where the technique could work but I think this is via a different mechanism. I think that the loose dirt thrown sideways by the tyres spinning provides and equal and opposite thrust to the direction in which it is moving. That might make the difference.

As far as "Joe Public" and what he can do, I think that even "Joe Bloody good driver" is very limited in a real-life panic situation. Unlike the race track or rally stage, real life public road driving can throw several different factors together in a fraction of a second that nobody could really be expected to cope with. We'd all like to "think" we'd know how to get out of it but, most of the time, I think, if we're brutally honest with ourselves, our options are very limited. This has given rise to the general agreement that the "smart" driver is the one who doesn't get into the situation in the first place!

Increasingly, modern cars are set up to try and save your life for you anyway. My 807 is a case in point. It has ABS, traction control, Electronic Stability Control, Brake Assist and so on. If I "horse" it into a wet bend and it starts understeering too much, the first thing it does is lift off the (electronic) throttle for me (whether I like it or not). If that doesn't tighten the line enough, it starts braking the rear wheel on the outside of the bend to see if that helps. Beyond that, I'm not sure what it will try! In a panic (straight line) braking situation, it controls all the wheels and the thorttle independently to bring it to a halt in the shortest possible distance. I've no idea what yanking the handbrake on to try and decrease understeer would do but it's really a bit to heavy (and tall!) for me to want to try and find out!

I am constantly reminded of (more than one) racing driver that has told me:

"It's all bu11sh1t really, when you've properly lost it, the best thing you can to is stand on the brakes, take your hands offthe wheel and wait for the world to stop moving"!

That's the best general advice I can think of. In some situations there are better options, but if you are smart enough to decide that, you probably wouldn't have got yourself into trouble in the first place and certainly wouldn't be asking advice from strangers on an internet forum. Standing on the brakes doesn't require any great skill of presence of mind, and it should be the thing you do by default if things start getting away from you.

I'd add that if you're heading for a gap you must look at the gap and not the obstacles. Even if you think you're out of control, you have a tendancy to go where you're looking.

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Peter Humphries (and a green V8S)

in my experience .. inexperienced drivers make the right kind of corrections in oversteer... but they're not tuned in to respond to the right thing so often just make things worse!

the problem with hands off, feet off in oversteer is that whenever the tyres regain grip you'll head off in whatever direction you happen to be pointing.... and on the road that might be into oncoming traffic.

my training (for test tracks so plenty of run off area) taught me to plant your foot on the brake & lock the wheels when you lose it.... this way you spin in the direction you were travelling until you stop... on the road if you're lucky this means down the road, else into the hedge.

Has anyone here had skidpan training, and was it money well spent?

I keep toying with the idea