Span 180 degrees today

Discussion on Advanced and Defensive Driving.

Postby James » Sun Dec 14, 2008 6:14 pm


ESP was off but then I usually have it off, otherwise all I get is a flashing light whenever I try and put power down. However it is over sensitive and reacts too soon... for example in the dry:

ESP ON: Pulling away hard in 1st two gears = Almost instant power cut in first, and in second whenthe boost comes in at around 3 / 3.5k full power cut, which gets returned on half to 3/4 boost at around 5k.... useless. Sometimes you get the d-d-d-d-d-d-d with the wheels as the power comes back in and suddenly turns them, causing slip and a then you get a cut again (its really quite comical).

ESP OFF: Pulling away hard in 1st two gears = The driver has full control, and steady application of the throttle allows no slipping but a clean pull away even though the ESP if on would have thought it was too much. Burying the throttle to the floor would usually also produce no slip, but can sometimes cause ever so slight wheel spin in 1st. Not enough to warrant any sort of ESP activiation though.

I wonder whether the ESP would have saved me then. What would it to when the back started to turn - would it cadence brake on different wheels to stabilise it? I had ESP cut in on me in Spring when I was going round a very wet very adverse cambered RAB. This was me testing out th limits of the car mind you, and seeing how the ESP responded. I remember it activiating at a fairly sensible speed mid RAB andit felt/sounded very violent, like a stomping of ABS.
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Postby waremark » Sun Dec 14, 2008 7:21 pm


James, I quite understand why you would turn ESP off in the VXR - the system is obviously not designed to cope with the extra power of your car, and I have to say it sounds like rather a crude system. With ESP on in an oversteer skid, you should apply opposite lock as normal, and the ESP system would pulse the brakes on (in your case) the left side of the car to stop the oversteer continuing. I expect it would have got you back under control pretty much as soon as the back end started to step out.

As I mentioned before, it is a salutary lesson for all of us that a highly trained driver has this experience when driving normally and as he perceives it comfortably within limits. It is also a powerful argument for those of us with satisfactory ESP systems to leave them switched on!!
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Postby James » Sun Dec 14, 2008 7:43 pm


What are your thoughts? Someone else said:

Someone wrote:
FWD cars can pull themselves out of slides if you keep your foot in. Keeping the throttle shut with the clutch out in a FWD car that's oversteering is actually the worst thing to do, as the front wheels are breaking which gives the rear something to pivot around. The idea of turning into a slide is so that the car follows the direction of the slide, at the same speed as the slide which keeps the car pointing in the right direction. If you keep the throttle shut in this situation then the front and back ends of the car will be doing different speeds, causing the angle of the slide to change.

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Postby SeanP » Mon Dec 15, 2008 12:59 am


Diesel is usually my conclusion with these sorts of incidents.

I've been caught out two-or-three times with what I have always assumed to be diesel spills, on the small R/Bs in Chesham (but not to the extent of a 180, usually a bit of 'ohh, sideways' ;-) ). DSC on, which always does a superb job of 'saving the day' in these instances -- unlike your vehicle, the DSC is unobtrusive, and even allows a bit of controlled rear-end fun (on track of course :twisted: ), before intervening.

One usually can see the 'rainbow' on the tarmac after a re-visit, thereafter wonders why it wasn't observed during the r/b approach :oops: :roll:
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Postby TripleS » Mon Dec 15, 2008 10:21 am


waremark wrote:James, I quite understand why you would turn ESP off in the VXR - the system is obviously not designed to cope with the extra power of your car, and I have to say it sounds like rather a crude system. With ESP on in an oversteer skid, you should apply opposite lock as normal, and the ESP system would pulse the brakes on (in your case) the left side of the car to stop the oversteer continuing. I expect it would have got you back under control pretty much as soon as the back end started to step out.

As I mentioned before, it is a salutary lesson for all of us that a highly trained driver has this experience when driving normally and as he perceives it comfortably within limits. It is also a powerful argument for those of us with satisfactory ESP systems to leave them switched on!!


Yes, I guess that's right.

....and then how much more difficult is it for those who have had no special training....and have no ESP?

In that case I suppose we just have to go very slowly and warily all the time....and hope for the best. :(

It makes one wonder how the great mass of drivers - with no particularly high level skills, and little interest in the subject - cope at all; but IMHO they do pretty well, on the whole. I would suggest they deserve more credit than they usually get.

Best wishes all,
Dave.
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Postby waremark » Mon Dec 15, 2008 6:07 pm


TripleS wrote:....and then how much more difficult is it for those who have had no special training....and have no ESP?

In that case I suppose we just have to go very slowly and warily all the time....and hope for the best. :(

It makes one wonder how the great mass of drivers - with no particularly high level skills, and little interest in the subject - cope at all; but IMHO they do pretty well, on the whole. I would suggest they deserve more credit than they usually get.

Incidents like James's are incredibly rare. I cannot remember an unpredictable skid in my 35 years of driving on the road (There were a couple of skids in my early driving days which I did not predict, but I now know I should have predicted them!). For most of the 35 years obviously I had no ESP.

Now with ESP, we no longer know whether we might have lost control without it.

How often have others been taken by surprise by skids?
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Postby Renny » Mon Dec 15, 2008 6:10 pm


Apart from the low grip surface, have you checked your tyre pressures James?

A sudden breakaway at the rear can be caused by low/punctured rear tyre pressures, often unnoticed with todays low-profiles and stiff sidewalls.
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Postby TripleS » Mon Dec 15, 2008 8:08 pm


waremark wrote:
TripleS wrote:....and then how much more difficult is it for those who have had no special training....and have no ESP?

In that case I suppose we just have to go very slowly and warily all the time....and hope for the best. :(

It makes one wonder how the great mass of drivers - with no particularly high level skills, and little interest in the subject - cope at all; but IMHO they do pretty well, on the whole. I would suggest they deserve more credit than they usually get.

Incidents like James's are incredibly rare. I cannot remember an unpredictable skid in my 35 years of driving on the road (There were a couple of skids in my early driving days which I did not predict, but I now know I should have predicted them!). For most of the 35 years obviously I had no ESP.

Now with ESP, we no longer know whether we might have lost control without it.

How often have others been taken by surprise by skids?


I can remember three significant ones in 51 years:

1. Approx. 1961 in the Sprite, 40 (ish) mph on a snowy road, RH bend, did a 270 deg. spin and went off backwards (but harmlessly) onto a grass verge.

2. Approx. 1961 again in the Sprite, (slow learner!) 55 mph through a snowy S bend, tail came unstuck on 2nd half of bend, did a tank slapper for about 200 yards, and then went off and had minor contact with drystone wall.

3. September 1969 in the 3.8 Jaguar, 75 mph through the same S bend but in the opposite direction, and this time on a very wet road, tail came unstuck on the first half of the bend (the RH bit) but fortunately my correction technique proved adequate and we continued, though a bit more soberly.

Since then I've devoted much more careful attention to reading and evaluating road surfaces.

Best wishes all,
Dave.
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Postby TripleS » Mon Dec 15, 2008 8:20 pm


Renny wrote:Apart from the low grip surface, have you checked your tyre pressures James?

A sudden breakaway at the rear can be caused by low/punctured rear tyre pressures, often unnoticed with todays low-profiles and stiff sidewalls.


Pardon ?

I thought it was the old cross ply tyres that had stiff sidewalls, and when radial ply tyres arrived they were then said to have much more flexible sidewalls.

Am I wrong about this ? I can appreciate that a low profile tyre will feel stiffer than a tyre with a taller sidewall, other things being equal, but I thought radials ply tyres are not generally of stiff construction - apart from the braced tread that used to be talked about in the old Michelin X days. That braced tread was said to be the reason for the much longer life obtained from the Michelin X - less squirming and tread block shuffling on the road surface etc. I know I once got 86,000 miles out of a pair on the back of the Sprite - which was about three times as much as I got from the Dunlop 'Gold Seal' tyres of that era.. :P

Best wishes all,
Dave.
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Postby James » Mon Dec 15, 2008 9:55 pm


My tyres could prob do with a check so will do that tmrw.

FWIW its the first time I have ever lost control and ended up at a standstill on the road since I started driving, so I guess that ties in with the rare bit.

Goes to show it can and will happen though.
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Postby Renny » Tue Dec 16, 2008 2:11 pm


TripleS wrote:Pardon ?

I thought it was the old cross ply tyres that had stiff sidewalls, and when radial ply tyres arrived they were then said to have much more flexible sidewalls.

Am I wrong about this ? I can appreciate that a low profile tyre will feel stiffer than a tyre with a taller sidewall, other things being equal, but I thought radials ply tyres are not generally of stiff construction - apart from the braced tread that used to be talked about in the old Michelin X days. That braced tread was said to be the reason for the much longer life obtained from the Michelin X - less squirming and tread block shuffling on the road surface etc. I know I once got 86,000 miles out of a pair on the back of the Sprite - which was about three times as much as I got from the Dunlop 'Gold Seal' tyres of that era.. :P

Best wishes all,
Dave.


The ultra-low profile tyres that are fashionable nowadays (sounding almost as old as you Dave :lol: ) do not visibly deflect as noticably when underinflated compared to the 60-70% profile tyres that used to be common. I recall finding myself pointing the wrong way on a roundabout when my mini had a rear puncture.
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Postby jbsportstech » Tue Dec 16, 2008 4:42 pm


Was this in an astra ?? vxr by any chance.
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Postby James » Wed Dec 17, 2008 1:00 am


Yes :oops:
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Postby James » Wed Dec 17, 2008 7:12 am


Someone else on another forum wrote:
rear wheel drive if you slide and you lift off it will correct it but front wheel drive is the oposite, lift of on a fwd car in a slide and its going to go full circle on you.

Advance driving instructors drive BMW's most of them and there rear wheel drive and if this is the info they have given you then its false and when (touch wood you dont) lose control and you lift of and it all goes wrong you can thank your advisors for there misleading advice.



The majority of people I am chatting to on another site (no, its not PH) are all saying you need to power out of an oversteer motion on a FWD. If this is the case that is certainly something I have never been told.. not sure whether to be surprised or not to be honest.
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Postby Renny » Wed Dec 17, 2008 10:22 am


I think rather than "Power out", which might imply adding a lot of power, which could destabilise the front grip, keep some power to the front wheels effectively dragging the car in the desired direction (controlled by steering).

Natural instinct is to lift off power which will transfer weight from the rear, making the slide worse. This may be one reason that most FWD cars are set up with inherent understeer as for most drivers it is simpler to cope with. The FWD cars with a tendancy to oversteer, may be more responsive to steering inputs (less understeer), but if the limit is reached and the rear breaks away, it is more likely to end up in a spin or a backwards visit to the scenery, e.g Peugeot 205
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