Why are cars more stable when in gear while cornering?

  • Thread starter oohhh yeah
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oohhh yeah

oohhh yeah

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oohhh8yeah
Hi guys,

It seems like whenever the car is in neutral, it seems very floaty and unstable. When the car is in gear, it seems a lot more stable. This is probably because of the effect of engine braking, giving the feeling of being more stable. But, it also feels that the car can corner faster when in gear, it somehow grips the road better. Is there an actual scientific explanation as to why this is? Why does the car seem to corner better when in gear? How does the engine braking accomplish this?

Thx
 
Are you talking about real cars or GT5? Because if you are cornering with the car in neutral, I'm concerned.

The reason it feels more stable is because you can shift the weight around with the throttle, which allows you to adjust slip angles, turn in, and planting the car via acceleration. Pretty basic physics and driving theory, really.
 
I'd say that it's Because even if you're not hitting the brakes you are Doing engine braking which slows you down thus making it more stable and of course you can accelerate to fix oversteer if need be
 
I think that the thrust of the engine makes the car more stable. Because there is a force pushing forward (rwd) or in the direction you want to go (fwd), then the force of friction from the tyre on the tarmac is diluted (addition of vectors). This way, the car doesn't feel quite as darty, so you can make corrections more subtly and with more confidence. Also, when in neutral, the car is slowing down due to friction. This slowing of the car shifts weight forward, a bit, and makes the car feel unstable, and it will be more prone to oversteer. Accelerating shifts weight rearward and makes the car more stable.

In fact, if engine braking were occurring during the corner, then the car would be only a bit more stable. The force of the engine 'braking' would stabilise the vehicle, but would also shift weight forward, so you have some of that stability negated. however, you should not, strictly speaking, be cornering without giving the car some throttle. As before, the forward acceleration does help to stabilise the car.
 
Beeblebrox237
I think that the thrust of the engine makes the car more stable. Because there is a force pushing forward (rwd) or in the direction you want to go (fwd), then the force of friction from the tyre on the tarmac is diluted (addition of vectors). This way, the car doesn't feel quite as darty, so you can make corrections more subtly and with more confidence. Also, when in neutral, the car is slowing down due to friction. This slowing of the car shifts weight forward, a bit, and makes the car feel unstable, and it will be more prone to oversteer. Accelerating shifts weight rearward and makes the car more stable.

In fact, if engine braking were occurring during the corner, then the car would be only a bit more stable. The force of the engine 'braking' would stabilise the vehicle, but would also shift weight forward, so you have some of that stability negated. however, you should not, strictly speaking, be cornering without giving the car some throttle. As before, the forward acceleration does help to stabilise the car.
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The car slows down in gear much faster than in neutral, I don't know what friction you are talking about but when the car is in gear there is much more friction involved
 
Maybe he means out of gear, like in a manual? I don't really feel that my car is more stable, but I have yet to drive it in anger.
 
What kind of car are you talking about anyway? What you describe can be very drivetrain dependent. FWD/RWD and open-diff/LSD will all do different things here. But I have to echo the rest, why are you taking turns in neutral?
 
The behaviour of tyres depends on the forces being shovelled through them - remember the grip circle.

A non-powered tyre will only have longitudinal forces from the road and lateral forces from the attempted motion of the car acting on it. A powered tyre will also have longitudinal forces from the engine. The combination of the forces generates the behaviour (oddly the tyre without engine loading may exceed the available grip where the tyre with it won't) and a car with no powered wheels will behave differently than a car with two or four powered wheels.
 
I'm talking about a real car in real life. Not GT5.

I'm not taking corners in neutral/with clutch pushed in, I am just wondering what is the scientific explanation for the increased feeling of stability.
Famine
The behaviour of tyres depends on the forces being shovelled through them - remember the grip circle.

A non-powered tyre will only have longitudinal forces from the road and lateral forces from the attempted motion of the car acting on it. A powered tyre will also have longitudinal forces from the engine. The combination of the forces generates the behaviour (oddly the tyre without engine loading may exceed the available grip where the tyre with it won't) and a car with no powered wheels will behave differently than a car with two or four powered wheels.
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Famine, great post. Yeah the car will behave differently depending on powered or unpowered. So, what's the reasoning for the increased stability? Regardless of drivetrain, all cars seem more stable.

Thanks
 
oohhh yeah
Famine, great post. Yeah the car will behave differently depending on powered or unpowered. So, what's the reasoning for the increased stability? Regardless of drivetrain, all cars seem more stable.

Thanks
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He answered that. It's the way the latitudinal and longitudinal forces work on the tyres.

"Regardless of drivertrain, all cars seem more stable"
How many cars have you driven to make you educated enough to make that statement?
 
hawkeye122
He answered that. It's the way the latitudinal and longitudinal forces work on the tyres.

"Regardless of drivertrain, all cars seem more stable"
How many cars have you driven to make you educated enough to make that statement?
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A couple, not too many, I'm no expert. It's my observation.
 
I think it's a weight transfer thing. Decelerating in gear, the weight is on the front tires, so you have a lot of turn-in grip, and then you get on the throttle and the weight shifts to the rear as the car comes out. The suspension is stressed at both points. In neutral you're wobbling around on springs and bushings that aren't compressed.
 
Not caring about anything else, I think a RWD car is going to be less stable in gear while decelerating. You're essentially using 100% rear biased brakes with a tiny amount of pressure applied (engine braking). A FWD will become more stable because the braking effect is applied at the front wheels, so it will be more understeer-prone than using a neutral amount of throttle to maintain the current speed.
 
It really depends on the suspensin setup and weight of the car. Reading that just made me think of the ITR which can be quite happy when you lift mid corner. As a general rule, I think you're right though.
 
When you are in neutral / have the clutch in, you have whatever momentum is in the car hurtling towards your current heading, lets call it 0°. When you turn, your momentum is still going towards 0° and the car leans in that direction, and because there are no other forces going through the wheels, it can feel quite floaty. If, however, you were to apply acceleration forces to the wheels whilst turning, then the momentum is somewhat nullified by the acceleration toward the new heading, the weight is transferred as well from being over on the side of the car where the momentum was taking it before to the rear, and the general weight of the car is changed.
 

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