ABS in a spin?
Discussion
The theory goes that when you are spinning beyond recovery, you should apply the brakes hard enough to lock all four wheels. Since a locked wheel will not deploy any directional forces, you would keep traveling in the same general direction as before the spin, ideally staying on the track and not heading towards the tire wall, and will eventually smoke to a halt.
So what happens when your car has ABS? I've read that using the ABS early in a slide can stabilize the car, but that happens when you are already spinning? Won't the ABS release the brakes when the car is at a certain angle to the previous direction of travel, and it'll shoot off the road into the scenery?
Does anyone have experience or knowledge of this situation?
So what happens when your car has ABS? I've read that using the ABS early in a slide can stabilize the car, but that happens when you are already spinning? Won't the ABS release the brakes when the car is at a certain angle to the previous direction of travel, and it'll shoot off the road into the scenery?
Does anyone have experience or knowledge of this situation?
Cathar said:
The theory goes that when you are spinning beyond recovery, you should apply the brakes hard enough to lock all four wheels. Since a locked wheel will not deploy any directional forces, you would keep traveling in the same general direction as before the spin, ideally staying on the track and not heading towards the tire wall, and will eventually smoke to a halt.
That's a good theory, it's saved my bacon in the past.
Cathar said:
So what happens when your car has ABS? I've read that using the ABS early in a slide can stabilize the car, but that happens when you are already spinning? Won't the ABS release the brakes when the car is at a certain angle to the previous direction of travel, and it'll shoot off the road into the scenery?
Does anyone have experience or knowledge of this situation?
If you don't brake hard enough to lock the wheels then the car will accelerate sideways in the direction it is pointing i.e. towards the scenery. ABS prevents you from braking hard enough to lock the wheels. I haven't ever tried this technique in an ABS equipped car so I don't have first hand experience of it happening, but it's something I would be concerned about if I was taking an ABS equipped car on track.
Sticking your foot in and keeping it in does work in an ABS equiped car, it is less noisy that non ABS though! I've checked this myself a few times when practicing car control at Bedford in an ABS car. You don't slow quite as well as you do in a non-ABS car (IE: in those you can feel and hear the car screeching to a halt and you can feel the car leaning heavily over to the side in the direction you are sliding). Interestingly, if you start a spin and apply opposite lock and then stamp on the brakes whilst holding the lock ,the ABS car will recover and not turn around on you'd expect - although that is angle and speed dependent. Too much momentum and too much angle will still mean a spin. All a good laugh though.
Zod said:
It's something they teach on BMW Driver Training courses in M3s: if you can't catch it quickly with opposite lock, then stamp on the brake.. Despite the ABS, braking does arrest the spin.
Having stopped the spin, let's say the car is now at 45 degrees to the direction of travel. Does the ABS stop you lunging off the track sideways?
OK then I'm off down memory lane again (sorry 
) but here is a related consideration.
In the readers' letters section of a motoring magazine Autocar or Motor there was once a debate about the merits of deliberately spinning a car as an aid to shortening the stopping distance in an emergency stop situation. This, by the way, was in road driving, nothing to do with closed circuit stuff.
One chap reckoned that this was a technique he had used on several occasions from initial speeds of between 50 and 80 mph and he claimed he stopped more quickly by this method. It was something to do with absorbing some energy by making the car spin, thus leaving less energy to be dissipated in braking, hence a quicker stop.
I must say I have some reservations about a driving style that creates situations where this might be put to the test, but that's another matter!
The whole thing sounds highly dubious to me, but what do you think, apart from your probable feeling that the chap was a madman?
Best wishes all,
Dave.
) but here is a related consideration. In the readers' letters section of a motoring magazine Autocar or Motor there was once a debate about the merits of deliberately spinning a car as an aid to shortening the stopping distance in an emergency stop situation. This, by the way, was in road driving, nothing to do with closed circuit stuff.
One chap reckoned that this was a technique he had used on several occasions from initial speeds of between 50 and 80 mph and he claimed he stopped more quickly by this method. It was something to do with absorbing some energy by making the car spin, thus leaving less energy to be dissipated in braking, hence a quicker stop.
I must say I have some reservations about a driving style that creates situations where this might be put to the test, but that's another matter!
The whole thing sounds highly dubious to me, but what do you think, apart from your probable feeling that the chap was a madman?
Best wishes all,
Dave.
Doesn't wrk for me. The only way to induce rotation is to have an assymetric force applied to the car which implies that some tyres are producing less than the maximum possible grip. I don't see how spinning the car would produce more grip than simply stopping on four locked wheels, since the spinning car would result in the tyres producing some side force as well as braking force, which would reduce the total braking force. Simple school room physics, backed up by practical experience, tells you that in dry conditions a locked wheel produces less braking than one that is turning while at the limit of grip.
The only case I can see where putting the car sideways is worthwhile, is if the brake balance is significantly wrong. For example in an extreme case of a kart with no front brakes it will stop quicker if you put it sideways. If this ever applies to a road car I want it taken off the road immediately!
The only case I can see where putting the car sideways is worthwhile, is if the brake balance is significantly wrong. For example in an extreme case of a kart with no front brakes it will stop quicker if you put it sideways. If this ever applies to a road car I want it taken off the road immediately!
GreenV8S said:
The only case I can see where putting the car sideways is worthwhile, is if the brake balance is significantly wrong. For example in an extreme case of a kart with no front brakes it will stop quicker if you put it sideways. If this ever applies to a road car I want it taken off the road immediately!
Putting the car sideways can also help stopping on loose surfaces, as it means all 4 wheels are pushing a wedge of gravel with the side of the tyre, as opposed to a smaller wedge building up in front of the treads of front tyres and the back wheels following in their path.
you can scrub off a surprising amount of speed by hanging the car out one way or the other on gravel - thats part of why the entry speed for a scandinavian flick has to be quite high, if its not you'll lose to much speed as you try and unbalance the car.
I can't see a situation where putting it sideways would help braking on tarmac though, the only situation i can see it helping would be getting the car pointed the way you want it to be going when you come off the brakes. which is something that probably shouldn't be used on the road unless you really have to.
GravelBen said:
Putting the car sideways can also help stopping on loose surfaces, as it means all 4 wheels are pushing a wedge of gravel with the side of the tyre, as opposed to a smaller wedge building up in front of the treads of front tyres and the back wheels following in their path.
I see, yes that makes sense. I don't "do" gravel - not deliberately, anyway!
GreenV8S said:
GravelBen said:
Putting the car sideways can also help stopping on loose surfaces, as it means all 4 wheels are pushing a wedge of gravel with the side of the tyre, as opposed to a smaller wedge building up in front of the treads of front tyres and the back wheels following in their path.
I see, yes that makes sense. I don't "do" gravel - not deliberately, anyway!
fair enough - I find gravel good for having more fun with an underpowered 4wd car than you would otherwise 
Will have to buy a 'proper' car at some stage though.
the abs does not work well unless the angle is small if the car is sideways then the car tries to regain its grip
but as the need for locking the brakes and spinning in a straight line is usually need when not on the black stuff
in my case anyway
abs dosn't work on loose stuff properly with normal bog standard family hatch ABS
and if you are still on the black stuff you have time to place the car and enough grip to help things out
once the car has passed the point of no return the abs is lost as to what is happening
the other option is to use if in doubt power out with no ABS
i use this to keep the rears spinning and allows the front to be used to increase or decrease spina and slight variations in directions
may i point out i do this on a track
but as the need for locking the brakes and spinning in a straight line is usually need when not on the black stuff
in my case anyway
abs dosn't work on loose stuff properly with normal bog standard family hatch ABS
and if you are still on the black stuff you have time to place the car and enough grip to help things out
once the car has passed the point of no return the abs is lost as to what is happening
the other option is to use if in doubt power out with no ABS
i use this to keep the rears spinning and allows the front to be used to increase or decrease spina and slight variations in directions
may i point out i do this on a track
TripleS said:
OK then I'm off down memory lane again (sorry ) but here is a related consideration.
In the readers' letters section of a motoring magazine Autocar or Motor there was once a debate about the merits of deliberately spinning a car as an aid to shortening the stopping distance in an emergency stop situation. This, by the way, was in road driving, nothing to do with closed circuit stuff.
One chap reckoned that this was a technique he had used on several occasions from initial speeds of between 50 and 80 mph and he claimed he stopped more quickly by this method. It was something to do with absorbing some energy by making the car spin, thus leaving less energy to be dissipated in braking, hence a quicker stop.
) but here is a related consideration. In the readers' letters section of a motoring magazine Autocar or Motor there was once a debate about the merits of deliberately spinning a car as an aid to shortening the stopping distance in an emergency stop situation. This, by the way, was in road driving, nothing to do with closed circuit stuff.
One chap reckoned that this was a technique he had used on several occasions from initial speeds of between 50 and 80 mph and he claimed he stopped more quickly by this method. It was something to do with absorbing some energy by making the car spin, thus leaving less energy to be dissipated in braking, hence a quicker stop.
Just had a thought about this...does anyone remember the works C6 GT1 car at, I think, Sebring 12/24hr this year (you can see my memory for detail is crap!)? He was going along the main straight, hit braking zone (at major velocity!), on TV you saw a puff from the left-front wheel as the brake disk disintegrated. Car twitched, then straightened. THEN he put it deliberately into a spin as he headed straight into the tyre wall before the concrete.
havoc said:
TripleS said:
OK then I'm off down memory lane again (sorry ) but here is a related consideration.
In the readers' letters section of a motoring magazine Autocar or Motor there was once a debate about the merits of deliberately spinning a car as an aid to shortening the stopping distance in an emergency stop situation. This, by the way, was in road driving, nothing to do with closed circuit stuff.
One chap reckoned that this was a technique he had used on several occasions from initial speeds of between 50 and 80 mph and he claimed he stopped more quickly by this method. It was something to do with absorbing some energy by making the car spin, thus leaving less energy to be dissipated in braking, hence a quicker stop.
) but here is a related consideration. In the readers' letters section of a motoring magazine Autocar or Motor there was once a debate about the merits of deliberately spinning a car as an aid to shortening the stopping distance in an emergency stop situation. This, by the way, was in road driving, nothing to do with closed circuit stuff.
One chap reckoned that this was a technique he had used on several occasions from initial speeds of between 50 and 80 mph and he claimed he stopped more quickly by this method. It was something to do with absorbing some energy by making the car spin, thus leaving less energy to be dissipated in braking, hence a quicker stop.
Just had a thought about this...does anyone remember the works C6 GT1 car at, I think, Sebring 12/24hr this year (you can see my memory for detail is crap!)? He was going along the main straight, hit braking zone (at major velocity!), on TV you saw a puff from the left-front wheel as the brake disk disintegrated. Car twitched, then straightened. THEN he put it deliberately into a spin as he headed straight into the tyre wall before the concrete.
Spinning a vehicle won't improve the stopping distance - you can't change the laws of physics. However the creation of angular momentum means that provided you don't hit the wall at the moment you are running straight, you'll suffer less speed loss in subsequent collisions. In other words you take longer to stop but the risk of injury falls.
Not that I'd necessarily recommend this as an appropriate procedure for injury avoidance
havoc said:
Just had a thought about this...does anyone remember the works C6 GT1 car at, I think, Sebring 12/24hr this year (you can see my memory for detail is crap!)? He was going along the main straight, hit braking zone (at major velocity!), on TV you saw a puff from the left-front wheel as the brake disk disintegrated. Car twitched, then straightened. THEN he put it deliberately into a spin as he headed straight into the tyre wall before the concrete.
Haven't seen that. I guess that with one brake disc missing there's be no braking at that wheel so the ABS took the braking away? Chucking the car sideways sounds like a smart move, but a desperate one. Do you reckon the driver might have been into karts in an earlier life?
GreenV8S said:
Chucking the car sideways sounds like a smart move, but a desperate one.
This chap was travelling well into 3 figures when he started braking...I'd have been desparate too!!!
Was watching it on Motors TV a few months back, remember seeing it twitch, pause, then spin and thought it looked odd (only later saw puff from front-left). Impact surprisingly good on the car - no shell intrusion at all...did hit pretty much squarely side-on though.
havoc said:
Just had a thought about this...does anyone remember the works C6 GT1 car at, I think, Sebring 12/24hr this year (you can see my memory for detail is crap!)? He was going along the main straight, hit braking zone (at major velocity!), on TV you saw a puff from the left-front wheel as the brake disk disintegrated. Car twitched, then straightened. THEN he put it deliberately into a spin as he headed straight into the tyre wall before the concrete.
Sounds like he was doing what all good racing drivers do: aiming to hit an empty space. You can't hit an empty space when faced with a tyre wall, but you can try to increase the distance travelled before it is hit (therefore hitting as much empty air as you can before hitting something solid). This would obviously mean trying to hit the wall at an angle less than perpendicular.
With one brake disc gone and a desperate situation, it is no wonder he spun.
Ok, I did some research:
I went on track with the 928 yesterday, on a drift day - the track was watered and kept wet for the whole session. I spun several times (at relatively low speeds however), and had no problems predicting where I was going to end up. I never had ABS kicking in when was braking going sideways.
I still don't know what would really happen if I lost the rear end it at high speeds (50+ mph) - there wasn't enough space on the track to try that. I did several 3rd gear drifts in the longer turns, but only rather cautiously.
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I went on track with the 928 yesterday, on a drift day - the track was watered and kept wet for the whole session. I spun several times (at relatively low speeds however), and had no problems predicting where I was going to end up. I never had ABS kicking in when was braking going sideways.
I still don't know what would really happen if I lost the rear end it at high speeds (50+ mph) - there wasn't enough space on the track to try that. I did several 3rd gear drifts in the longer turns, but only rather cautiously.
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Edited by Cathar on Saturday 1st July 12:11
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