Understeer/oversteer?
11-25-01, 10:41 AM
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Understeer/oversteer?
I've read a number of auto magazine and newspaper reviews of the IS over the past few months, culminating in a purchase of a five speed '02 only about three weeks ago. What puzzled me the most, however, about the reviews I read was the debate that seemed to appear in every publication concerning the handling capabilities of the car. Several reviews said the IS has considerable oversteer (what you want... the back-end of the car sliding in concert with the front wheels in a hard corner... more difficult to control, but is designed for more experienced drivers), while some other reviews (the NYTimes, most notably) said the IS was designed with understeer (baaaadddd... made for out-of-control drivers... front end of the car digs into the road in a hard turn, slowing down the car). Soooo, what is YOUR experience with the steering of the IS300...
ALL I KNOW is that in the short time I've had my car, I've made one very hard 90-degree turn at, I'd say, 35-40mph-ish around a green light into a slight decline, and the a*s of my car went flying around the turn very wide... almost into the other lane of traffic (an oncoming car honked)... that, my friends, is oversteer. I also went for a day trip through the Blue Ridge Parkway (lots of winding roads), and at slower speeds, there might have been a slight hint of understeer, but it was tough to say, since I was generally at a considerable incline or decline at all times... very little flat road. Any thoughts?
ALL I KNOW is that in the short time I've had my car, I've made one very hard 90-degree turn at, I'd say, 35-40mph-ish around a green light into a slight decline, and the a*s of my car went flying around the turn very wide... almost into the other lane of traffic (an oncoming car honked)... that, my friends, is oversteer. I also went for a day trip through the Blue Ridge Parkway (lots of winding roads), and at slower speeds, there might have been a slight hint of understeer, but it was tough to say, since I was generally at a considerable incline or decline at all times... very little flat road. Any thoughts?
11-25-01, 11:19 AM
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Here's my take on the situation.
I drive a 5spd '02, and have had some oppurtunity to push mine a bit. My guess is that the people who indicate the IS300 exerts understeer are doing so with the traction control system enabled. Almost all the times ive tried to whip the back end around with TRAC enabled, it has competently regained control of the back end quite effeciently. Maybe not perfectly, as I've gotten it to slide very minorly, but I could see someone describing it as understeer.
On the other hand with TRAC off, I wouldnt be able to see how anyone could say this car doesnt oversteer. It recently rained here yesterday actually, and I had no trouble AT ALL getting the back end to lose its footing.
I'd also like to comment on the whole understeer vs oversteer topic. Traditionally understeer is actually a a lot more managable then oversteer. In otherwords, for the untrained driver it is easier to regain control of the vehicle. If understeer occurs, the front end of the car wants to maintain a straight line despite tires turned and trying to take it in another direction. The solution is simply to let off the gas and eventually the tires will regain their control and point the car where it needs to go. On the otherhand (to the untrained driver) oversteer is not as easily correctable. If the back end comes around simply laying off the gas will not correct the car's direction, and significant intervention is required to reqain control.
To a trained driver the story can be different. If a driver knows what hes doing an oversteer slide can actually be controlled to not only regain control of the vehicle, but potentially to put it in a situation where its like it virtually never lost control, and the turn can be taken with virtually no penalty for losing traction in the first place. In a professionally driven car that understeers, there is almost always a price to pay for the understeer, speed is lost and a diffferent (and less effecient) line needs to be taken to complete the turn.
So in the end I guess what im saying is it really depends on the driver, and possibly the traction control system. I know youve said that you managed to get back end around on a significant 90 degree turn, and that TRAC was probably enabled at that time (assumed), but I can see the car understeering on say a slalom course where the turns arent as sharp as 90 degrees (with TRAC on of course).. But like i said, with TRAC off, i fail to see how anyone could say this car understeers.
I drive a 5spd '02, and have had some oppurtunity to push mine a bit. My guess is that the people who indicate the IS300 exerts understeer are doing so with the traction control system enabled. Almost all the times ive tried to whip the back end around with TRAC enabled, it has competently regained control of the back end quite effeciently. Maybe not perfectly, as I've gotten it to slide very minorly, but I could see someone describing it as understeer.
On the other hand with TRAC off, I wouldnt be able to see how anyone could say this car doesnt oversteer. It recently rained here yesterday actually, and I had no trouble AT ALL getting the back end to lose its footing.
I'd also like to comment on the whole understeer vs oversteer topic. Traditionally understeer is actually a a lot more managable then oversteer. In otherwords, for the untrained driver it is easier to regain control of the vehicle. If understeer occurs, the front end of the car wants to maintain a straight line despite tires turned and trying to take it in another direction. The solution is simply to let off the gas and eventually the tires will regain their control and point the car where it needs to go. On the otherhand (to the untrained driver) oversteer is not as easily correctable. If the back end comes around simply laying off the gas will not correct the car's direction, and significant intervention is required to reqain control.
To a trained driver the story can be different. If a driver knows what hes doing an oversteer slide can actually be controlled to not only regain control of the vehicle, but potentially to put it in a situation where its like it virtually never lost control, and the turn can be taken with virtually no penalty for losing traction in the first place. In a professionally driven car that understeers, there is almost always a price to pay for the understeer, speed is lost and a diffferent (and less effecient) line needs to be taken to complete the turn.
So in the end I guess what im saying is it really depends on the driver, and possibly the traction control system. I know youve said that you managed to get back end around on a significant 90 degree turn, and that TRAC was probably enabled at that time (assumed), but I can see the car understeering on say a slalom course where the turns arent as sharp as 90 degrees (with TRAC on of course).. But like i said, with TRAC off, i fail to see how anyone could say this car understeers.
11-25-01, 12:38 PM
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Great response, sphantom...
I'd have to say that with the tremendous attention to balance by the IS engineers, it's my opinion that the car is more incline to oversteer than under... the numerous reviewers that say otherwise I believe are misinformed.
There are many different issues here, however:
1) It's odd, but frankly, the '02, particularly the five-speed, is a different handling car than the '01. Comments welcome...
2) Certainly, understeer seems to be the safer, more-manageable design spec for everyday drivers. But, personally speaking, I'm not an everyday driver, and I wouldn't purchase a car that was designed to hide my control flaws... I want one that demands me to be a better driver.
3) You're right, there is a price to pay for oversteer (i.e. less efficient line, loss of speed)... but it is my understanding that one of the key advantages of oversteer is the fact that you generally must reapply the accelerator to regain control of the car if you want the car to keep moving (basically, counter-intuitive to someone who isn't used to driving that way)... otherwise, the car stalls in the turn. That is, you're re-accelerating more quickly after the turn, and at a generally higher gear than in a car than understeers.
Oversteer: foot on accelerator, tight turn, foot off accelerator, (back end slides, wide line, downshift one gear, reapply accelerator, upshift), reapply accelerator, haul a*s... everything in parentheses occurs during the turn, very rapidly... often, the gear changes aren't even necessary, particularly on wet or smooth roads (i.e. go ahead and keep the wheels spinning... they'll catch after the turn)... reacceleration can occur with very little hesitation, but you have a wide, white-knuckle of a turn (DON'T DO THIS if your Mom is a passenger, OR if you really DON'T KNOW what you're doing in general.)
Understeer: foot on accelerator, tight turn, front end plows in, car stays in control, but you lose lots of speed, downshift TWO gears, then reaccelerate... control and efficient line, but with loss of speed, and reacceleration takes longer.
3) Yes, the TRAC was activated during my L-turn, all the more reason why I was impressed that I got it to slide. This leads me to a separate question: someone please explain to me like I'm a child the difference between the limited slip and the traction control feature.
I'd have to say that with the tremendous attention to balance by the IS engineers, it's my opinion that the car is more incline to oversteer than under... the numerous reviewers that say otherwise I believe are misinformed.
There are many different issues here, however:
1) It's odd, but frankly, the '02, particularly the five-speed, is a different handling car than the '01. Comments welcome...
2) Certainly, understeer seems to be the safer, more-manageable design spec for everyday drivers. But, personally speaking, I'm not an everyday driver, and I wouldn't purchase a car that was designed to hide my control flaws... I want one that demands me to be a better driver.
3) You're right, there is a price to pay for oversteer (i.e. less efficient line, loss of speed)... but it is my understanding that one of the key advantages of oversteer is the fact that you generally must reapply the accelerator to regain control of the car if you want the car to keep moving (basically, counter-intuitive to someone who isn't used to driving that way)... otherwise, the car stalls in the turn. That is, you're re-accelerating more quickly after the turn, and at a generally higher gear than in a car than understeers.
Oversteer: foot on accelerator, tight turn, foot off accelerator, (back end slides, wide line, downshift one gear, reapply accelerator, upshift), reapply accelerator, haul a*s... everything in parentheses occurs during the turn, very rapidly... often, the gear changes aren't even necessary, particularly on wet or smooth roads (i.e. go ahead and keep the wheels spinning... they'll catch after the turn)... reacceleration can occur with very little hesitation, but you have a wide, white-knuckle of a turn (DON'T DO THIS if your Mom is a passenger, OR if you really DON'T KNOW what you're doing in general.)
Understeer: foot on accelerator, tight turn, front end plows in, car stays in control, but you lose lots of speed, downshift TWO gears, then reaccelerate... control and efficient line, but with loss of speed, and reacceleration takes longer.
3) Yes, the TRAC was activated during my L-turn, all the more reason why I was impressed that I got it to slide. This leads me to a separate question: someone please explain to me like I'm a child the difference between the limited slip and the traction control feature.
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