Hinting the steering
Discussion
Kawasicki said:
If the resonant frequency of roll and yaw are matched, it's not good.
Reminds me of shaft whirling speed.Kawasicki said:
When you steer the rear wheels opposite to the front, well the opposite happens. Now you have to wait not just for the normal body slip angle to develop, but also for the angle of the rear tyres. So the car really develops a big yaw rate overshoot, and the buildup of lateral acceleration is slow. At low speeds you have the advantage of small turning circle. At higher speeds tricky to control.
An extra third link which steers outwards under compression (eg outer wheel when cornering) is common to many modern cars. Will this not slow build-up of rear slip angle? 
Kawasicki said:
There is a whole pile of junk written about the way cars are set up for the average/crap driver. I can say, when it comes to the linear zone of vehicle dynamics, say 0-0.7g lateral in the dry, what is good for a bad driver is also good for an expert. Don't believe the oft repeated truisms.
MX5 Mk1 was criticised as being too sharp for many customers. With North America as its dominant but aggressively litigiously market, Mazda responded by "dulling" dynamic response. Isn't the extra third link part of this development?Kawasicki said:
Think for yourself.
I do thanks and I'm keen to expand my knowledge 
Edited by bigothunter on Thursday 18th February 09:52
My 5p worth... and that's 4.9p more than it's really worth.
The front tyres are trying to make the vehicle spin and the rear tyres are stopping them doing it. This is why injudicious use of the handbrake makes the car spin because you've removed the ability of the rear tyres to stop it from happening.
I won't bore anyone with slip angles, derivation and all that stuff. Suffice it to say that the driver can induce that 'starting to spin' using the steering wheel, but the car has to have started to turn before the rear tyres can do anything to stop it. So there's a finite window of time and distance where the attitude of the car is controlled by what the loose nut behind the wheel is doing with the wheel. How the driver shapes the steering controls a hell of a lot of things. What is generally accepted is that suddenly whanging a chunk of steering on is a bad thing, not least because you can get the fish-tailing that is remarkably easier to over control.
So hinting is how that first movement of the steering wheel is controlled. It can be smooth, almost sinusoidal or it could be a short sharp but small input followed by another sharp input once the rear tyres are doing something to stop the car from spinning. I've got a lot of in-car data from a whole range of drivers that show both techniques in action. Neither is the one true technique.
The front tyres are trying to make the vehicle spin and the rear tyres are stopping them doing it. This is why injudicious use of the handbrake makes the car spin because you've removed the ability of the rear tyres to stop it from happening.
I won't bore anyone with slip angles, derivation and all that stuff. Suffice it to say that the driver can induce that 'starting to spin' using the steering wheel, but the car has to have started to turn before the rear tyres can do anything to stop it. So there's a finite window of time and distance where the attitude of the car is controlled by what the loose nut behind the wheel is doing with the wheel. How the driver shapes the steering controls a hell of a lot of things. What is generally accepted is that suddenly whanging a chunk of steering on is a bad thing, not least because you can get the fish-tailing that is remarkably easier to over control.
So hinting is how that first movement of the steering wheel is controlled. It can be smooth, almost sinusoidal or it could be a short sharp but small input followed by another sharp input once the rear tyres are doing something to stop the car from spinning. I've got a lot of in-car data from a whole range of drivers that show both techniques in action. Neither is the one true technique.
bigothunter said:
Kawasicki said:
If the resonant frequency of roll and yaw are matched, it's not good.
Reminds me of shaft whirling speed.Kawasicki said:
When you steer the rear wheels opposite to the front, well the opposite happens. Now you have to wait not just for the normal body slip angle to develop, but also for the angle of the rear tyres. So the car really develops a big yaw rate overshoot, and the buildup of lateral acceleration is slow. At low speeds you have the advantage of small turning circle. At higher speeds tricky to control.
An extra third link which steers outwards under compression (eg outer wheel when cornering) is common to many modern cars. Will this not slow build-up of rear slip angle? Kawasicki said:
There is a whole pile of junk written about the way cars are set up for the average/crap driver. I can say, when it comes to the linear zone of vehicle dynamics, say 0-0.7g lateral in the dry, what is good for a bad driver is also good for an expert. Don't believe the oft repeated truisms.
MX5 Mk1 was criticised as being too sharp for many customers. With North America as its dominant but aggressively litigiously market, Mazda responded by "dulling" dynamic response. Isn't the extra third link part of this development?Kawasicki said:
Think for yourself.
I do thanks and I'm keen to expand my knowledge Edited by bigothunter on Thursday 18th February 09:52
I might have a look at american reviews of the first mx-5 over the weekend.
The thing with criticism of a cars handling is that you really need to be specific. “Too sharp“ just isn’t specific enough.
With cars (probably all vehicles really) you need to split the handling into at least two areas, the linear zone and the non-linear zone. Cars have to be tuned and developed to perform in both zones. Most effort goes into the linear zone, where most people spend most of their time driving.
Within the linear zone different cars can have different levels of linear understeer. Linear understeer is a really interesting attribute. It is sort of equivalent to the yaw stability factor of a car. I'll write a bit more about it in the next day or so, or you can just google it yourself. A car with high linear understeer is probably foolproof in the linear zone, but it can be a death trap at the limit. A car with low linear understeer is a twitchy b
d at 0.3 g. The tyres aren’t even slightly close to losing grip, but the car needs a very steady hand to direct.Vehicle dynamics engineers think of understeer as something that happens not just at the limit.
BertBert said:
Scott Mansell is a big proponent of two phase steering for maximising grip on track. He calls it "introduce" and "load"
Scott is an excellent reference and I'm keen to secure training with him when Covid restrictions lift.Found this text on his website - it's the closest I can find to 'hinting the steering'
UNDERSTEER AT TURN-IN
To enter a corner as quickly as possible, it’s important to transition between braking and turning smoothly. As I spoke about in our grip article, there is only a certain amount of grip a tyre car give and taking it from using 100% of available traction for braking to 100% of available grip for turning is tricky. As I always say, being fast is about being smooth. If you try and turn the car in with a hard and fast movement, you’ll shock the tyres and cause them to break traction too early – reducing the speed you can take into the corner. You can also disrupt turn-in by trying to turn while braking heavily. If the tyre is beginning to under-rotate, even locking, then trying to turn at this point will just cause the tyre to slide. It’s better to reduce brake pressure slightly before you turn-in, allowing some grip to be available to turn the car. It’s also possible to brake too lightly going into a corner. Depending on your car’s setup you’ll likely want to turn in with a less brake pressure, leaving some weight and grip over the front tyres to aid turn-in..
ref: https://driver61.com/uni/understeer/
Can you point me to something specific about two-phase steering from Scott please?
Kawasicki said:
Within the linear zone different cars can have different levels of linear understeer. Linear understeer is a really interesting attribute. It is sort of equivalent to the yaw stability factor of a car. I'll write a bit more about it in the next day or so, or you can just google it yourself. A car with high linear understeer is probably foolproof in the linear zone, but it can be a death trap at the limit. A car with low linear understeer is a twitchy bd at 0.3 g. The tyres aren’t even slightly close to losing grip, but the car needs a very steady hand to direct.
Vehicle dynamics engineers think of understeer as something that happens not just at the limit.
Quick search via Google led to the classic Milliken dHW/dSISLIP v LATAC plot for steady state cornering (as below). Simple way of showing understeer progression as lateral acceleration (and corner speed) increase. I must investigate the broader topic further.d at 0.3 g. The tyres aren’t even slightly close to losing grip, but the car needs a very steady hand to direct.Vehicle dynamics engineers think of understeer as something that happens not just at the limit.
Your comments about linear understeer would be appreciated.
bigothunter said:
Can you point me to something specific about two-phase steering from Scott please?
Just had a quick squint through the "D61 uni" materials, but can't find it there, so that's not much help! He covers it in the Masterclass (which I did last year which was good but super expensive and didn't quite work for me) and also in the Sim driving courses he does (which I did before Christmas and was prenominal value for money). I'm wondering if he covers it in the sim driving seminar he did for MSUK at the bottom of the page here https://www.motorsportuk.org/competitors/competito...underwhelmist said:
I still don't know what technique "hinting" the steering is, could somebody explain? It sounds like it might be steering briefly in the opposite direction to the direction you want to turn, like a Scandi flick - is it?
Are you car drivers just jealous because on motorbikes we get to use countersteering?
The idea is to turn the wheel just a tad, a split second before really tuning it ... in the same direction you want to goAre you car drivers just jealous because on motorbikes we get to use countersteering?
I first heard the term hinting from Don Palmer, a respected limit handling coach. He spoke about taking up the slack in the tyres, pointing out that as the steering turns the front wheels first it needs to bend the front tyre before starting to turn the vehicle, and then as the car starts to rotate it has to take up the slack in the rear tyres before front and back tyres are providing cornering effort. I think he suggested that this would take about half a second.
He recommended starting to steer with a tiny movement before progressively increasing the steering in order to take up the slack in the tyres. The driving coach who used to post here as Stressed Dave used to say: "start to steer, and keep steering until the vehicle is on the path you want". Dave said you need less steering if you steer and use the throttle well.
I don't do any of this consciously, just try to operate all the controls smoothly and progressively including the steering. And Don said he liked my steering, whether or not he really did!
He recommended starting to steer with a tiny movement before progressively increasing the steering in order to take up the slack in the tyres. The driving coach who used to post here as Stressed Dave used to say: "start to steer, and keep steering until the vehicle is on the path you want". Dave said you need less steering if you steer and use the throttle well.
I don't do any of this consciously, just try to operate all the controls smoothly and progressively including the steering. And Don said he liked my steering, whether or not he really did!
waremark said:
I first heard the term hinting from Don Palmer, a respected limit handling coach. He spoke about taking up the slack in the tyres, pointing out that as the steering turns the front wheels first it needs to bend the front tyre before starting to turn the vehicle, and then as the car starts to rotate it has to take up the slack in the rear tyres before front and back tyres are providing cornering effort. I think he suggested that this would take about half a second.
He recommended starting to steer with a tiny movement before progressively increasing the steering in order to take up the slack in the tyres. The driving coach who used to post here as Stressed Dave used to say: "start to steer, and keep steering until the vehicle is on the path you want". Dave said you need less steering if you steer and use the throttle well.
I don't do any of this consciously, just try to operate all the controls smoothly and progressively including the steering. And Don said he liked my steering, whether or not he really did!
"Slack in the tyres" is an interesting concept He recommended starting to steer with a tiny movement before progressively increasing the steering in order to take up the slack in the tyres. The driving coach who used to post here as Stressed Dave used to say: "start to steer, and keep steering until the vehicle is on the path you want". Dave said you need less steering if you steer and use the throttle well.
I don't do any of this consciously, just try to operate all the controls smoothly and progressively including the steering. And Don said he liked my steering, whether or not he really did!
bigothunter said:
"Slack in the tyres" is an interesting concept
Think more of pre-loading the whole steering system from the fingerpads, steering wheel and column, rack, tie rods/joints, hub, wheel and (relatively sloppy cos they're rubber..) tyres. Once all that slack is gone, any input at the wheel is much more quickly and accuratelt transmitted to where it matters.dvenman said:
bigothunter said:
"Slack in the tyres" is an interesting concept
Think more of pre-loading the whole steering system from the fingerpads, steering wheel and column, rack, tie rods/joints, hub, wheel and (relatively sloppy cos they're rubber..) tyres. Once all that slack is gone, any input at the wheel is much more quickly and accuratelt transmitted to where it matters.dvenman said:
Think more of pre-loading the whole steering system from the fingerpads, steering wheel and column, rack, tie rods/joints, hub, wheel and (relatively sloppy cos they're rubber..) tyres. Once all that slack is gone, any input at the wheel is much more quickly and accuratelt transmitted to where it matters.
It's loading up the whole suspension - the bits that are meant to move more than just taking up the slack as it were - the springs!BertBert said:
dvenman said:
Think more of pre-loading the whole steering system from the fingerpads, steering wheel and column, rack, tie rods/joints, hub, wheel and (relatively sloppy cos they're rubber..) tyres. Once all that slack is gone, any input at the wheel is much more quickly and accuratelt transmitted to where it matters.
It's loading up the whole suspension - the bits that are meant to move more than just taking up the slack as it were - the springs!BertBert said:
It's loading up the whole suspension - the bits that are meant to move more than just taking up the slack as it were - the springs!
I'm only talking about any slack in any part of the system which affects the direct transmissibility of the driver's input to the contact patch on the road. It may be the springs and mounts et al have a little slack in them but actually compressing the springs by any non-negligible amount, nah.I like to use circuit driving as an extreme condition which is useful to illustrate the point.
A very common driving error is clipping the apex of a bend too early, which slows exit speed and can mean you run off the tarmac on the bend exit. Almost all drivers learning on circuit exhibit this early apex error and it creeps in even when experienced.
I combat this temptation by intentionally driving straight ahead holding the wheel firmly whilst braking heavily, and then turn precisely but smoothly to align with the late apex. Rate of steering input is fairly fast. Trail braking can be adopted during this turn-in phase.
On certain lower speed bends such as Lodge at Oulton, intuitively I 'counter-steer' on entry: small left steer input before turning right into the bend. This excites the car in yaw which reduces understeer and improves turn-in.
Both of these techniques apparently conflict with 'steering hinting'. Also if 'steering hinting' results in actual steering deflection, the car will move towards centre of track spoiling a decent corner entry line.
This whole subject of 'steering hinting' remains a mystery to me, unless it's simply to alleviate nasty on-centre steering friction?
A very common driving error is clipping the apex of a bend too early, which slows exit speed and can mean you run off the tarmac on the bend exit. Almost all drivers learning on circuit exhibit this early apex error and it creeps in even when experienced.
I combat this temptation by intentionally driving straight ahead holding the wheel firmly whilst braking heavily, and then turn precisely but smoothly to align with the late apex. Rate of steering input is fairly fast. Trail braking can be adopted during this turn-in phase.
On certain lower speed bends such as Lodge at Oulton, intuitively I 'counter-steer' on entry: small left steer input before turning right into the bend. This excites the car in yaw which reduces understeer and improves turn-in.
Both of these techniques apparently conflict with 'steering hinting'. Also if 'steering hinting' results in actual steering deflection, the car will move towards centre of track spoiling a decent corner entry line.
This whole subject of 'steering hinting' remains a mystery to me, unless it's simply to alleviate nasty on-centre steering friction?
Think about it as slowly building the initial slip angle of the tyre.
https://suspensionsecrets.co.uk/tyre-slip-angle/
https://suspensionsecrets.co.uk/tyre-slip-angle/
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