Taking a curve in neutral ?

[Dantilla]

The visitor's center at Paradise is the highest one can drive a car on Mt. Rainier.
Quite the curvy road snaking its way to the top.

Since a Porsche 921E has no power steering or brakes, I once shut the engine off when leaving the Paradise parking lot.

14 miles.

Coasting downhill, keeping as much momentum as possible around the dozens of curves allowed me to go 14 miles before needing help from the mighty sewing machine engine in the back for motivation.
For those familiar, I was able to get to the Kautz Creek mud flow area before cranking over those four tiny pistons.

At no time did I wish I was in gear.
Of course, this was for fun, and the experience I've had on the track no doubt helped.

[Tervuren]

Nothing different than floating the throttle to a neutral point.

My Jaguar has a shifter layout where it is very easy to go to neutral despite it being an automatic. There are situations where I go to neutral to conserve fuel where the level of engine breaking would be undesirable.

I do the same with a manual car.
If for a short time, I use the clutch and stay in gear.
If for a long time I want to unweight the clutch and go to neutral. (higher wear on thrust bearing to have clutch pedal in.)

Most cars have a front brake bias designed around dry weather driving.
This means the fronts are going to lose it under braking in the rain much sooner.
In a FWD car one could go to neutral in the rain under braking.
Or even stay in gear and go light throttle, but that is best not practiced in situ.

Originally Posted by Deschodt

I'm just asking from a physics standpoint, what difference does it make (if any?) to the car's handling if you are taking a curve in neutral vs with engine in gear, coasting (if you like assume it's a slight downhill curve to keep speed constant, also assume not at the limit but quick enough that you'd wanna be in gear, and finally let's say a cayman to avoid rear engine arguments) ..

There are situations in an auto where the it downshifting could upset the rear of the car in such a situation if on the limit.

I've had a heavy duty pickup with rock as the rear spring rate do that to me on a curly interstate ramp in the wet.
Que up eurobeat from Initial D.

I still wouldn't pick neutral for that, I'd pick to float the throttle.

[Deschodt]

Originally Posted by cockerpunk

why would you?

there are a half dozen, easy, small reasons to not, why would you?

I wouldn't, please re-read a tad slower ;-) I'm just questioning the "common wisdom" that it's a terrible thing when, after it happened to me by accident, it made *no difference at all* to the cornering. And I could not explain to myself why it would be so bad from a pure physics standpoint, based on what I know of tires/handling/circle of friction.. (aside of added controllability of the weight transfer you get from the gas pedal )

Just a simple physics question, looks like having the car on either side of coasting (slight power, slight decel) changes nothing in this case. In no way would I recommend driving like that, controlling the car on the gas is a great option to have.

Common wisdom is worth understanding sometimes... The first year I owned a 911, I was terrified of even getting off the gas (let alone brushing the brakes) in any turn situation, even at low speeds, because I'd read so much about them spinning backwards. Track days quickly disabused me of that notion and established the SC as an understeering pig, that would only spin if you completely screwed up or reacted by surprise at the limit. You actually drive these fast with the gas pedal/brakes more than with the steering wheel, so it's worth digging into common wisdom sometimes !

[masraum]

Originally Posted by Deschodt

I wouldn't, please re-read a tad slower ;-) I'm just questioning the "common wisdom" that it's a terrible thing when, after it happened to me by accident, it made *no difference at all* to the cornering. And I could not explain to myself why it would be so bad from a pure physics standpoint, based on what I know of tires/handling/circle of friction.. (aside of added controllability of the weight transfer you get from the gas pedal )

Just a simple physics question, looks like having the car on either side of coasting (slight power, slight decel) changes nothing in this case. In no way would I recommend driving like that, controlling the car on the gas is a great option to have.

Common wisdom is worth understanding sometimes... The first year I owned a 911, I was terrified of even getting off the gas (let alone brushing the brakes) in any turn situation, even at low speeds, because I'd read so much about them spinning backwards. Track days quickly disabused me of that notion and established the SC as an understeering pig, that would only spin if you completely screwed up or reacted by surprise at the limit. You actually drive these fast with the gas pedal/brakes more than with the steering wheel, so it's worth digging into common wisdom sometimes !

Yep. I was also a bit scared about lifting in corners. I started slowly probing, first at low speeds, by backing off the throttle and lightly hitting the brakes. But at low speeds it's not much of an issue because the grip from the rear is so high. Then I started at higher speeds, nearer the limits, by modulating the throttle. That's where I really noticed the ability to steer. I also tinkered with getting into the gas in corners to initiate more understeer. It was very cool. One one occasion, I was a bit crazy in a 270º on-ramp. I went in at ~60mph, right as I turned the wheel, I reverse-blipped the throttle, let completely off and then got right back into it. It was pretty cool, I drifted around about half of the on ramp. I had a few occasions over the years that I was driving where I went into a corner hot and had to reduce speed.

What really surprised me was that when I sold the 911 and bought a miata, the miata was about as easy to steer with the throttle as the 911. On at least one occasion, I had the miata catch me off guard and step way out because I'd let off in a corner. The main difference was that it caught itself since it didn't have the lump in the back like the 911.

[oldE]

The only time I recall cornering in neutral was with an automatic transmission, rwd vehicle, downhill on snowy streets. The small amount of drive on the rears would be enough to promote serious understeer, so I learned to pop them into neutral under those unique circumstances.

Best
Les

[ted]

It's a thing, racing/coasting Motorcycles down mountain curves with no engine assist.
Helps develop brake sensitivity and conserve momentum.

And my car trailer is always coasting and it does fine.

[svandamme]

Should never free wheel in a turn because it kills the balance.
getting through turns at speed is all about shifting weight

shouldn't brake in turns either same reason

you want weight off your non steering wheels and on your rear wheels.

Weight off fronts prevents your turned wheel on the outsidfe from being jammed under the weight while it's rotating in different direction then the car is moving, resulting in skid
Weight on the rear prevents rear from coming loose

Brake before entry : All weight transfers forward Good for braking, bad for steering
reapply minimal power in the turn . Car goes to more neutral balance
build up power as your grip allows to power out All weight transfers to the rear bad for steering great for grip on rear wheels and power delivery (and why FWD sucks balls)

[T77911S]

there is a track i go to that has a long sweeping curve out of a sharper one.
so i am excelling very hard but i also have to shift in the middle of the curve.
i was uneasy about it at first but all was fine,

i also have a circle track friend that is very good. i was telling him about getting sides in the 930 several times. he said, if you get into trouble just push the clutch in.

that takes all the weight distribution out caused by being on the gas or off the gas and the car goes "neutral"

[javadog]

It feels different because you’re used to having the car in gear and you can feel the difference in the forces that are operating on the vehicle and it feels unusual to you.

It really doesn’t matter because all cars understeer as designed by the factory and that tendency is not going to change. Removing longitudinal forces from the rear tires only gives them more capacity to grip in the lateral direction.

[ted]

Originally Posted by svandamme

Should never free wheel in a turn because it kills the balance.
getting through turns at speed is all about shifting weight

shouldn't brake in turns either same reason

you want weight off your non steering wheels and on your rear wheels.

Weight off fronts prevents your turned wheel on the outsidfe from being jammed under the weight while it's rotating in different direction then the car is moving, resulting in skid
Weight on the rear prevents rear from coming loose

Brake before entry : All weight transfers forward Good for braking, bad for steering
reapply minimal power in the turn . Car goes to more neutral balance
build up power as your grip allows to power out All weight transfers to the rear bad for steering great for grip on rear wheels and power delivery (and why FWD sucks balls)

Clearly you understand the principles.

Trail braking is a thing and can help during track in, but always to throttle before apex.
On the track we turn them with the pedals as much as the steering wheel.

[island911]

Turning a corner is an acceleration.

Braking is an acceleration. (negative acceleration)

doing the maths...

[GH85Carrera]

Originally Posted by ted

Clearly you understand the principles.

Trail braking is a thing and can help during track in, but always to throttle before apex.
On the track we turn them with the pedals as much as the steering wheel.

No doubt, no argument, on track trying to go fast, stay in gear. On the streets, with traffic of other idiots on the road, coming to a red light soon, in gear or not should make zero difference at 30 to 50% cornering ability.

[ted]

I never use neutral on a straight or a corner.

[masraum]

Originally Posted by svandamme

Should never free wheel in a turn because it kills the balance.
getting through turns at speed is all about shifting weight

shouldn't brake in turns either same reason

you want weight off your non steering wheels and on your rear wheels.

Really? Reduced weight on the steering wheels means reduced traction and understeer. It's the same reason why accelerating out of a corner results in understeer. So accelerating out of the corner removes weight from the front wheels and makes them not steer as well. Braking and putting weight on the front wheels makes them turn better because they have more traction (It also increases the size of the circle of friction, but reduces rear traction because that weight had to come from somewhere, which could result in a spin). So if you could balance the front/rear weight, you should have more balanced f/r traction and have reasonable turn in with less risk of a rear slide.

Weight off fronts prevents your turned wheel on the outsidfe from being jammed under the weight while it's rotating in different direction then the car is moving, resulting in skid
Weight on the rear prevents rear from coming loose

Yes, weight on the rear increases traction which reduces the possibility oversteer, but increases understeer.

Brake before entry : All weight transfers forward Good for braking, bad for steering

It's good for steering, actually, great for steering because it increases the size of the circle of friction and allows for better turn in as long as you don't over power the fronts.

reapply minimal power in the turn . Car goes to more neutral balance

which would be the most similar balance to coasting in neutral

build up power as your grip allows to power out All weight transfers to the rear bad for steering great for grip on rear wheels and power delivery (and why FWD sucks balls)

You contradict yourself a couple of times in your post.

[javadog]

I was going to point out that half of what he said made no sense but I don’t have time to get into that discussion. Thanks for doing the rest of us a favor.

[T77911S]

Originally Posted by javadog

I was going to point out that half of what he said made no sense but I don’t have time to get into that discussion. Thanks for doing the rest of us a favor.

me too

mine.
stock cars are great track cars.
cheap, full roll cages, cheap motors.
mine has a quick change rear end so i can gear it for the track i am at.


couldnt upload it

[vash]

in my youth I did something dumb. well, one of my dumb things.

I was going down a twisty road.
In my moment of brillance I decided to coast down. I pushed in the clutch, and put the car in neutral. WEEEEEEEEEEE!! FUUUUUUNNNNNN! it took very little time to build up some speed. I almost lost it going around a corner immediately. okay, let's stop this stupidity. I put it back into the appropriate gear and motored down the road. Glistening from a fresh sheen of sweat.

I would never corner in neutral ever again. in a 911SC that would have been potentially catastrophic. no bueno. maybe a slow-ass corner, like into a parking space.

[cockerpunk]

Originally Posted by svandamme

Should never free wheel in a turn because it kills the balance.
getting through turns at speed is all about shifting weight

shouldn't brake in turns either same reason

you want weight off your non steering wheels and on your rear wheels.

Weight off fronts prevents your turned wheel on the outsidfe from being jammed under the weight while it's rotating in different direction then the car is moving, resulting in skid
Weight on the rear prevents rear from coming loose

Brake before entry : All weight transfers forward Good for braking, bad for steering
reapply minimal power in the turn . Car goes to more neutral balance
build up power as your grip allows to power out All weight transfers to the rear bad for steering great for grip on rear wheels and power delivery (and why FWD sucks balls)

this is incorrect.

proper, fast, braking will including braking while entering the corner.

[cockerpunk]

Originally Posted by ted

Clearly you understand the principles.

Trail braking is a thing and can help during track in, but always to throttle before apex.
On the track we turn them with the pedals as much as the steering wheel.

this is also incorrect.

if you are on the power before the apex, you've run too late of an apex line, and over slowed.

proper throttle application is at the apex. this will also help you learn how much of a late apex you should be taking. on the power before the apex = too late. on the power after the apex = too early.

[flipper35]

Originally Posted by CurtEgerer

It's trick we occasionally used on snow/ice in a front-wheel-drive car to momentarily interrupt the understeer. But only as a last ditch effort to keep from going off road/track.

I always used both the gas and brake to get the back end to swing out to rotate the car. Gas keeps the front wheels turning some so the brake balance is shifted rear wards.