# understeer vs. oversteer



## XKxRome0ox (Mar 3, 2003)

which is "better" or "worse" ... 
give me any and all reasons...

i began thinking about this because after switching from stock 16" style 45's to 17" style m68's with the staggered setup, i definitely notice the understeering

i was just trying to imagine scenarios in my head...
and my thought is that... understeer would be easier to deal with than oversteer... 
:dunno:


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## ·clyde· (Dec 26, 2001)

Understeer = going of the road while facing forward
Oversteer = going off the road backwards

Which is better and which is worse you have to decide for yourself.

:bigpimp:


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## OBS3SSION (Oct 1, 2002)

[email protected] said:


> *Understeer = going of the road while facing forward
> Oversteer = going off the road backwards*


:rofl: I guess that's the simplest way to describe it.

I guess BMW feels understeer is safer seeing as they equip cars with the staggered wheel setup, which I understand produces slight understeer. I think understeer is easier to correct from than oversteer. Once the ass end jumps on the merry-go-round, there's not much you can do besides enjoy the scenery.


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## Guest (Apr 30, 2003)

In a VERY oversimplified sense, "understeer would be easier to deal with than oversteer... " Yes. And that's why most cars have understeer designed into their suspension setups. The staggered tire setups on high performance BMWs and Porsches exist to add understeer. In the views of the manufacturers (and their lawyers) the mediocre driving public will be less alarmed by understeer as it is perceived as more "predictable". You just plow rather than spinning out (a common result of extreme oversteer). And the reaction to correct extreme understeer (braking until the car comes under control) is more intuitive to the masses than the reaction to correct extreme oversteer (stay on the gas and keep the front wheels pointed where you want to go - if you lift off the gas, you WILL spin).

With a driver that knows that they are doing, understeer sucks. Understeer generally numbs the front end response characteristics, dulling turn-in response, making one have to enter a turn much slower. Meanwhile, controlled extreme oversteer is what you've got when you're hanging the tail out. Still not always the fastest way around a track, but a lot of fun.

And I'm describing more extreme manifestations of both, so in daily street driving, the odds are you won't experience either in a pronounced fashion.

And, of course, all of this is WAY oversimplified as well as whole books have been written on the subject.


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## alee (Dec 19, 2001)

[email protected] said:


> *Understeer = going of the road while facing forward
> Oversteer = going off the road backwards
> *


LOL, my favorite is:
Understeer = driver is scared
Oversteer = passenger is scared


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## ·clyde· (Dec 26, 2001)

alee said:


> *LOL, my favorite is:
> Understeer = driver is scared
> Oversteer = passenger is scared
> 
> *


:thumbup:

Over the years I have been torn between the two descriptions. The one I used was the one that I woke up with today.


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## ·clyde· (Dec 26, 2001)

TD said:


> *The staggered tire setups on high performance BMWs and Porsches exist to add understeer. In the views of the manufacturers (and their lawyers) the mediocre driving public will be less alarmed by understeer as it is perceived as more "predictable". *


Don't forget cosmetics. Through time, the staggered setup has developed a connotation of performance. In most cases today, a staggered setup aids performance about as much as a screaming chicken decal on the hood.


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## Guest (Apr 30, 2003)

[email protected] said:


> *Don't forget cosmetics. Through time, the staggered setup has developed a connotation of performance. In most cases today, a staggered setup aids performance about as much as a screaming chicken decal on the hood. *


Yup. I didn't want to muddy the argument, but, of course, this is absolutely correct.

I love seeing posts where someone wants to bump their rears to 255s while leaving the fronts at 225 "for performance". Yeah, right. Can you say, "understeering pig"? I knew you could.


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## nate (Dec 24, 2001)

[email protected] said:


> *Don't forget cosmetics. Through time, the staggered setup has developed a connotation of performance. In most cases today, a staggered setup aids performance about as much as a screaming chicken decal on the hood. *


 Cars such as mid-engined Ferraris and rear-engined Porsches do need staggering to remain balanced.

I would also say that the M5 and M3 can use light staggering

But my car? No way, it understeers like a pig on equal sized tires


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## ·clyde· (Dec 26, 2001)

TD said:


> *Yup. I didn't want to muddy the argument, but, of course, this is absolutely correct.
> 
> I love seeing posts where someone wants to bump their rears to 255s while leaving the fronts at 225 "for performance". Yeah, right. Can you say, "understeering pig"? I knew you could. *


For the cars and types of driving we usually talk about here, yeah. If all you are interested in is the 1/4 mile, the needs change...skinny as possible out front and wide enough in back to control wheelspin. Drag racing is where the look part started being associated with performance.


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## in_d_haus (Jan 2, 2002)

The natural reaction to Understeer (car plowing) is to hit the brakes, while that makes the understeer worse it's still the best response for an untrained driver and why the auto makers build understeer into the cars


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## Jspeed (Dec 23, 2001)

understeer = front tire slip angle > rear tire slip angle
oversteer = front tire slip angle < rear tire slip angle

To over-simplify,
understeer is safer; oversteer is more fun

For road cars a bit of understeer is more desirable than neutral-steer b/c neutral-steer under steady-state cornering can quickly turn into oversteer with forward weight transfer (e.g. lifting off the throttle) or overloading the rear tires' traction (powering out of a corner).


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## Jetfire (Jun 20, 2002)

As someone who commutes with tens of thousands of drivers on a daily basis, many of them doing things like reading or applying makeup, I can tell you that I'm glad most cars tend to understeer at the limit. I'd rather have the typical driver slam on the brakes in an effort to regain control than try to figure out what to do when the rear swings around. That might make them lose their place on the sports page or drop their lipstick.


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## XKxRome0ox (Mar 3, 2003)

cool.
thanks for all the replies

now the best way to neutralize understeer would be .... ??
or is it better to leave it alone ?

my staggered m68's are inducing understeer PLUS the new michelin pilot sports are giving me such good traction that i can't drift as easily as before

i was thinking about taking my car to autocross this summer... 
and i am not knowledgeable enough to know if the understeering would necessarily be a good or bad thing
more input would be appreciated


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## Pinecone (Apr 3, 2002)

[email protected] said:


> *For the cars and types of driving we usually talk about here, yeah. If all you are interested in is the 1/4 mile, the needs change...skinny as possible out front and wide enough in back to control wheelspin. Drag racing is where the look part started being associated with performance. *


Actually Porsche and Corvette brought the look to the masses. To control massive oversteer. In a Porsche is is trailing throttle oversteer, in a Corvette power oversteer.


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## Pinecone (Apr 3, 2002)

XKxRome0ox said:


> *cool.
> thanks for all the replies
> 
> now the best way to neutralize understeer would be .... ??
> ...


To reduce understeer (or increase oversteer):

Wider tires in front or narrower in the the rear
Increase front tire pressure or decrease rear tire pressure
Less stiff front sway bar or stiffer rear bar
Increase front track (spacers) or decrease rear track (more offset wheels)

These are common things, but you have to test to see how your car reacts, and everything is interrelated.

To start with I would increase you front tire pressures by 2 - 4 psi and see if that helps.

Also excessive understeer can be the result of too much speed into the corner. What is an understeering pig to one driver, is fine for another. And the second driver will be faster.  Remember, Slow In, Fast Out.

Also too abrupt of steering input at the beginning of a turn will also increase understeer. See too much speed. Smooth is Fast, Fast is Smooth.

Trail braking (having some brake applied as you turn in) will reduce understeer. It shifts the weight forward givng more traction to the front tires. More load means more traction.


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## ·clyde· (Dec 26, 2001)

Pinecone said:


> *Actually Porsche and Corvette brought the look to the masses. To control massive oversteer. In a Porsche is is trailing throttle oversteer, in a Corvette power oversteer. *


Agree on "bringing to the masses"

There's still something cool about this:


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## F1Crazy (Dec 11, 2002)

I don't agree that staggered setup in high powered rwd cars is cosmetics, I think it actually helps not only to control oversteer but also aids accelerating but why is it on 330? :dunno: 

BTW do you know wheel sizes for Porsche Turbo and GT2, GT3? This may be interesting to compare awd and rwd setups.


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## TGray5 (Jan 22, 2002)

I just added some negative camber to the front of my M3 and it significantly reduced low speed understeer. You need to be careful with what you do though, because you might make a change that will make your car neutral on slow speed turns, but very loose (oversteering) on high speed turns. Probably best to limit your mods to tire pressure adjustments until you've had a chance to get some seat time with an instructor that can show you what understeer and oversteer feel like and how to handle them. The reason is...when you make piecemeal mods to your car, YOU are the test driver and therefore, you need to be able to feel what the mods are doing. I've seen too many people load their car up with mods to fix problems with handling that someone told them they had, but they had no clue and BAM, what happens, they spin and hit the wall at their first track event. Its very rare in my experience that a BMW with no mods gets into trouble at the track. Its not to mean, don't do them, rather, get some training first.


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## Jetfire (Jun 20, 2002)

F1Crazy said:


> *I don't agree that staggered setup in high powered rwd cars is cosmetics, I think it actually helps not only to control oversteer but also aids accelerating but why is it on 330? :dunno:
> *


For cosmetics. 

High-powered RWD cars do benefit somewhat from wide wheels in the back. But, as you pointed out, the 330 is not particularly high powered, and the staggered setup induces understeer. BMW probably did it for the understeer and for the looks.


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## EdCT (Mar 14, 2002)

*Understeer is GOOD*



TD said:


> *
> 
> With a driver that knows that they are doing, understeer sucks. *


Every road circuit prepared race car has understeer built in. In fact, next time you watch an F1 race; watch the in car shots of the front suspension; you'll see quite a lot of understeer.

This subject is generally quite misunderstood; understeer is a GOOD thing (too much, though, isn't).

Ed


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## Andre Yew (Jan 3, 2002)

Personally, I've found understeer to be less intuitive to deal with than oversteer. My instinct is to steer more when your car understeers when you should probably be unwinding the wheel. Steering traction also comes back very suddenly, so you have to be ready to deal with it.

And more often than not, I've found understeer to be driver-induced rather than car-induced.

--Andre


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## F1Crazy (Dec 11, 2002)

*Re: Understeer is GOOD*



EdCT said:


> *Every road circuit prepared race car has understeer built in. In fact, next time you watch an F1 race; watch the in car shots of the front suspension; you'll see quite a lot of understeer.
> 
> This subject is generally quite misunderstood; understeer is a GOOD thing (too much, though, isn't).
> 
> Ed *


The way the car is setup depends a lot on the driver, we see people like Montoya, Raikkonen or Hakkinen that just hate understeer because it makes them back off the throttle and others like Ralf that prefer understeering car. Tires also play a huge role in what we see race car do and they may chnage it from oversteering into understeering car over the race distance.
Also I don't think I'll buy that the race car has understeer built in, at least it's not the case in F1. Many times teams struggle a lot because of the way the car comes out and they have to fight either oversteer or understeer. Honestly I don't know, maybe you're right and engineers try to built understeer in because it's easier to cure than oversteer but I still doubt they do it because it's a good thing.


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## 330iGT (Feb 1, 2003)

F1Crazy said:


> *BTW do you know wheel sizes for Porsche Turbo and GT2, GT3? This may be interesting to compare awd and rwd setups. *


235f/315r. It was on the "sticker" of a gt2, posted on fanatics.

P.S. I have quite a bit of oversteer with my sways set at stiff all around, and having the same sized tires all around as well. I'm going to set the front to medium, Fun none-the-less.


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## Pinecone (Apr 3, 2002)

StahlGrauM3 said:


> *I just added some negative camber to the front of my M3 and it significantly reduced low speed understeer. You need to be careful with what you do though, because you might make a change that will make your car neutral on slow speed turns, but very loose (oversteering) on high speed turns. Probably best to limit your mods to tire pressure adjustments until you've had a chance to get some seat time with an instructor that can show you what understeer and oversteer feel like and how to handle them. The reason is...when you make piecemeal mods to your car, YOU are the test driver and therefore, you need to be able to feel what the mods are doing. I've seen too many people load their car up with mods to fix problems with handling that someone told them they had, but they had no clue and BAM, what happens, they spin and hit the wall at their first track event. Its very rare in my experience that a BMW with no mods gets into trouble at the track. Its not to mean, don't do them, rather, get some training first. *


THAT'S the one I forgot. 

To reduce understeer:

Add more negative camber to the front, or more positive camber to the rear.


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## Pinecone (Apr 3, 2002)

*Re: Understeer is GOOD*



EdCT said:


> *Every road circuit prepared race car has understeer built in. In fact, next time you watch an F1 race; watch the in car shots of the front suspension; you'll see quite a lot of understeer.
> 
> This subject is generally quite misunderstood; understeer is a GOOD thing (too much, though, isn't).
> 
> Ed *


Not true. Road course cars are set up to match the driver's style and the driver's preferenace for how the car handles.

And the set up is for as close to neutral as possible, as this is the fastest.

And even with a given setup that is close to neutral the caar will understeer in some corners, and oversteer in others. In fact in some corners, it will understeer through parts of the corner and understeer through other parts. All based on the technique and what part of the corner. This comes down to wieght transfer

For a well setup car, without massive amounts of power, a car oversteers inthe first part of the turn, is neutral through the middle part of the turn, and understeers on the exit. All because of weight transfer.


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## FSelekler (Jan 15, 2002)

330iGT said:


> *235f/315r. It was on the "sticker" of a gt2, posted on fanatics.
> 
> P.S. I have quite a bit of oversteer with my sways set at stiff all around, and having the same sized tires all around as well. I'm going to set the front to medium, Fun none-the-less. *


Porsche TT: Front: 8"x18 225/40, Rear: 11"x18, 295/30 (same on C4S)
Porsche C2: Front: 8"x18, 225/40, Rear: 10"x18, 285/35
Porsche GT3: Front 8.5"x18, 235/30, Rear: 11"x18, 295/30 (not 100% sure of rear tire size however)

GT2: Front 8.5"x18, Rear: 12"x18 with tire sizes provided by 330iGT


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