Safe Speed Forums

I always thought that the reason people did skid pan training and the like was to improve their driving.

At a meet up today, we laid out a track in wet grass and had fun understeering around in it. My car likes to fishtail a lot despite being AWD and got a nice drift going on on the last corner.

Bear in mind that I've never driven in a situation like this before so you will probably to tell me what a terrible mess I made of the whole thing.

Anyway, on the way home, I found myself a lot more nervous on the road, especially on corners that I'd normally just blat through at the speed limit. Any idea why this may be. I thought wet grass mode would wear off fairly quickly but it doesn't seem to have.

Is this a good or a bad thing?

its probably a good thing.... with the wet grass you knew there wasn't much grip.. but i guess never really knew how much there actually was until you got there.

anything that makes us think harder about what we're doing is a good thing..... how do you know how much grip there's going to be when you're on the road? .. how confident are you in that guess?

i'm often uber cautious on wet tarmac after a dry spell.



my other thought is you've just experienced your car behaving outside the usual mostly linear handling region.... and realised actually your internal model of how driving your car works isn't that good!...takes a while to adjust the mental model....

hey i like the 2nd explaination better... in fact i vaguely recall seeing a few research projects & papers on the subject.

Likewise - I often find "lesser" cars catching up on me on twisty wet roads these days, yet I'm thinking to myself "I'm going as fast as I can".

Perhaps it's a case like Ed suggests - are you willing to bet your life on your assessment of available grip?

I certainly have very little confidence in the wet, and even less in the snow. Consequently I get middle-aged ladies following close behind in Fiat Stilos, Ford Ka's, Fiestas etc. I had a lift from my mother-in-law through welsh twisties a few times. She was merrily chattering away, turning the steering wheel one way and the other without a care in the world.

As we cornered I could feel/hear the vibrations/rumbling that inital understeer gives, and I even felt the back end slide into very subtle oversteer on one corner.

Now either my mother-in-law, and thousands like her is an awesome driver, or is blissfully ignorant to just how close she comes to sliding off the road.

Is that what you're finding Lum?

I think a sliding session wakes you up and makes you realise that bad things DO happen and it might be slower than you think. The worst part is that the road surface is beyond your control, so you start to drive assuming the worst possible scenario, rather than making a risk judgement.

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..similarly doing risk assesments for vehicle testing on closed circuits made me alot more cautious and aware of just how many things you dont have control over on the open road.

I think LUM has gone through Stage 1 of the process of learning to drive on low-grip surfaces.

Stage 2 is when you learn that the car isn't becoming wildly unpredictable, but is just as predictable as it is on dry tarmac, only (as someone said above) your mental model of what happens is wrong.

Stage 3 is that you correct this "mental model" and learn to recognise the signs that lead to each effect.

Once all this is in place you will discover that you actually have more confidence driving on the road, as you now know exactly what all the warning signs are that precede loss of grip. Thus you know when they are and aren't there and can drive faster or slower accordingly, choosing your own limit point based on how close to the limit of grip you wish to drive.

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Makes sense, but I'm not sure where I'd place myself in there

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I'm not sure that anyone can truthfully say they've completely mastered stage 3!

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There's nothing quite like circuit racing in the rain to bring it home to you just how little grip you have at very high speed on a wet road!

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"Politicians are the same the world over... We build bridges where there aren't any rivers." - Nikita Kruschev

Well, today I'm getting back up to speed, literally

Got my confidence back but my cornering technique has changed. I'm a little slower on the approach, apex it earlier then put the power down on the way out. I'm also finding I'm a bit more aware of what the back end of the car is doing.

I guess this is equivalent to dipping your toe in the water before jumping in.

I also did a bit of research and found that my car's AWD is 65/35 biassed to the rear wheels. Wonder why Subaru did that?

It gives you some ability to control the distribution of front / rear grip with the throttle.

A little later you may come to regard the throttle as a steering control and be grateful that you have some control of the rear of the car.

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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

It was certainly a steering control on the straight bit of the wet grass, just the direction wasn't always an option.

I thought it was weird because the manual gearbox version of the car has a 50/50 split on the diff.

I think I need to have a longer play on the grass some time, or perhaps a skid pan but I suspect that costs more than the fiver I paid for this event.

Here's a nice demonstration of "limit" handling - this is Cooperman escorting me around one of the driving tests on the East Anglian Classic Rally the day before yesterday...

clickie here

For an explanation of why the car is already 30 degrees sideways with half a turn of opposite lock applied before we've actually arrived at the corner you'd better ask the man who was twiddling the steering wheel - I'd say that probably qualifies as "Stage 3 stuff" per my earlier definition...

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CSCP Latin for beginners...
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Correct..

The original Audi "Quattro" had 50/50 split which made it very difficult to drive in competition - it understeered like a pig... Hannu Mikkola was the first person to come to terms with the beast - and he found that the only way to drive it quickly, especially on loose surfaces, was to left-foot-brake as if it was a powerful front-wheel-drive car. Problem was, with a big turbo and lots of horses (for the day) it beat the crap out of the brakes. The later cars had the split adjusted to 65r/35f - 70r/30f, which made them a lot more driveable as they could be driven "on the throttle" like a rear-wheel-drive car (just with a lot more traction!).

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"Politicians are the same the world over... We build bridges where there aren't any rivers." - Nikita Kruschev

Welcome to proper driving of a Subaru Lum.

The technique is to scrub off the speed so that you lift off the brake as you turn in, and then to power through and out. Its all about balancing the car and as said earlier the rearward power bias makes this easy - the worst that you will get is a very slight drift of the rear under acceleration, be prepared to correct the steering to allow for this. Because you loose most speed before the turn it is easy to correct for less grip being available by using less throttle. The common mistake is to aim to be still slowing up to the apex, if you do this then you can get under-steer (or more correctly a skid) as the overloaded front tyres loose grip, or you can just slide off totally if somebody has spilled diesel on the road.

The more aggressive drivers will use heel and toe or left foot braking to keep the turbo on boost and can take corners at speeds that would scare the pants off unprepared passengers, but would not be anywhere near the limits of the car.

Note that this is for AWD cars - if you haven't looked already, I would recommend a browse through the Driving Techniques section of Scoobynet which includes a lot of input from rally drivers, hill climbers and other racing drivers. Just remember to practice them on your grass track or safe roads first, many described techniques are not really for use on public roads

http://bbs.scoobynet.co.uk/forumdisplay.php?f=354

...i thought this was pretty standard advanced method, choose your speed & gear before turning in.

(not sure about heavily loaded tyres having less grip than lightly loaded tyres either tbh but thats a digression)

Not load in terms of weight, but load in terms of the turning force that you are trying to get out of them at the same time as reducing the downwards force by lifting off the brakes.

Yes you are right it is the standard advanced method, but unless you have a very enthusiastic driving instructor it is unlikely that it would have been covered while learning. There is a common misconception (I certainly had it until I investigated more) that to take corners fast you go slowest at the tightest point (the apex), so you brake up to the apex, and then power out. This off course gives very little in terms of margin, and is very bad when trying to push a car on a public road. It is so much safer to have complete braking as you turn in, especially when there are 3 or 4 horses in the middle of the road around that blind corner.

Actually I don't agree with this. I think braking into the bend leaves you much better set up to deal with an obstruction. For a start, having your foot on the brake gives an immediate 0.2 second advantage (i.e time to move foot and bring the brakes to biting point). And if you do have to do disaster recovery then at least you already have the suspension balanced towards braking forces. I very much like using the brake to give a bit more turn in sharpness (forwards weight transfer, more front tyre grip), but as the chassis sets, I blend out the brake and I'm just using it for 'attitude control' by the time I'm (what?) 20% into the bend. When the vision starts to open up, THAT'S the time to squeeze the power.

So I've gone from

17 to 27 years old - braking into bends
27 to 34 (?) Full brake-gear / brake-steer separation
34 to now A blended system with brake gear and brake steer overlap in a balanced - and balancing - way.

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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

doesn't most of this assume you are cornering close enough to the limit to observe and use these (subtle) effects..... which on the roads 90% of the time we shouldn't be doing anyway.

That's an interesting and important point.

I see it this way. It is my duty to maintain the maximum margin at all times. Subtle effect or not, I'll take every percent I can find, not to increase my speed but to increase my margin.

It seems to me that optimum technique is optimum technique whether you are driving at 10 tenths or 2 tenths.

On the other hand, of course, if you're nowhere near needing to brake for a bend it would be rather silly to brake...

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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

Think Lum already has done!

http://bbs.scoobynet.co.uk/showthread.php?t=509932

Looked fun!

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