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Discussion Starter #1
I've been reading a few threads, and it seems as though BMW's are notorious for understeer. However, isn't RWD=Oversteer???
I mean when i'm taking a corner i can definitely feel the oversteer, so wheres all this understeer i've been hearing about?
 

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NEWBIEFANATIC said:
I've been reading a few threads, and it seems as though BMW's are notorious for understeer. However, isn't RWD=Oversteer???
I mean when i'm taking a corner i can definitely feel the oversteer, so wheres all this understeer i've been hearing about?
Most cars made today (including BMWs) have understeer built into them. This is intentional, as it makes the masses feel a little safer if they take a hard corner. If your car is stock, then you can't possibly be feeling oversteer.

(the only mass-production car I know of that was renouned for oversteer was the previous generation 911 - doesn't mean there aren't others, but there aren't many)
 

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Discussion Starter #4
ok, FWD has understeer and RWD has oversteer, this is just physics. Now 50/50 weight distribution and BMW designing their cars to limit oversteer is not disputed, and mechanisms like DSC help to alleviate oversteer in dangerous situations. I do have stock and i'm sure anyone who's taken a corner hard can attest to the fact that their tails will slide past their front end and of course DSC is there to save the day, unless of course you turn it off and can get into a controlled slide. so my question remains.
 

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Oversteer or understeer isn't necessarily a function of being a front or rear wheel drive vehicle. Engineers, or anyone with an adjustable suspension for that matter, can dial in either characteristic regardless.

Understeer or push is seen to be the safer choice for the general public. Not only does it keep the car going in a more controlled direction if the driver enters a corner to hot, but it also scrubs off speed quite effectively which can aid a driver in regaining control.

Controlling oversteer or being loose requires a bit more skill from the driver.
 

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You can have oversteer or understeer with either FWD or RWD. It all depends on which tires lose traction.

If you jerk the wheel hard (with a car with non-proportional steering) left or right while going 70mph the car doesn't immediately turn; the front tires loose traction for a bit, then bite. This is understeer; it can happen with either FWD or RWD.

I am willing to bet that you are forcing the oversteer by giving too much gas through a sharp turn. Most people encounter understeer (which is the safety measure) while putting the brakes on while turning.
 

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First off, understeer/oversteer doesn't really matter where the drive wheels are. A FWD car can oversteer, and RWD can understeer, it has no bearing on where the drive wheels are.

Second, i can tell you all new bmws understeer. Look at the new M3, with staggard wheels and stock suspension settings has natural understeer with power-on oversteer. If you are getting oversteer in your e46 then you are driving beyond its limits. You should be feeling understeer all the way through the corner. And with a e46 non m3, I doubt you are having a problem with power on oversteer.
 

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You can make the car oversteer, but you have to really push the car to get it to happen and go into a corner pretty hot, I'd imagine. At that point, you have gone beyond the realm of normal driving, and shouldn't be on the street.

Anyway, my original point was that BMWs are designed to understeer in most cornering applications, so in general you would never feel oversteer unless you really really pushed it. Heck, all cars will oversteer (particularly RWD) if you push it around a corner. But the car's natural inclination will be to understeer.

Of course, it's a bit easier to do in an M3. If it didn't have those big tires on the back (well, and DSC), it'd spin out like a mofo.
 

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Discussion Starter #10
DRIVE WHEELS DO MATTER!!! The best racers, ie F1, drive RWD, y? Controlled steering and quickness off a turn, not to mention aspects of power. I do not believe i drive past the limits of my car, i know it. Does anyone feel me on this being physics? I had an integra before, and i would take a corner waaaaay too fast but still not be worried about spinning out, cuz you just can't under normal conditions. I'm new to RWD and so i'm totally respecting that when i enter a turn. However, it is a WIP.
 

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nate328Ci said:


He is right though
Not necessarily. There are other very important variables other than hp. Driving style, suspension setup, weight distrobution and tire pressures all play a very big role.

Lifting the throttle abruptly on a front wheel drive car at near maximum grip levels while cornering will cause the car to snap into an oversteer condition.
 

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From http://www.dur.ac.uk/r.g.bower/PoM/pom/node32.html

Causes of Oversteer and Understeer

If we start with a neutral steering car --- one with the front and rear traction limits equal --- we can create a table of the effects of accelerating and braking. For acceleration, the effect depends on whether the front or rear wheels are driven. Most modern road cars driven through the front wheels. The results also depend on whether or not the weight transfer compensates for the additional traction required for braking/accelerating.

The likely effects of acceleration and braking are summarised in the following table.



To understand the entries in this table, draw the traction circles for the balanced car, and add the cornering forces. Now redraw the traction circle allowing for the weight transfer, add the vectors showing the driving/braking forces, and determine whether the vector sum of the forces is closer to the traction limit at the front or rear of the car (closer at front leads to understeer, at rear leads to oversteer). The entry marked assumes that most of the braking force is applied at the front wheels.

--------------------------------------------------------------------------------

Richard Bower
Thursday October 8 16:09:30 BST 1998
 

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And with a e46 non m3, I doubt you are having a problem with power on oversteer.
Yes, that is a bold statement. Granted it is much easier with the M under the bonnet, but still. Oversteer can occur on an M52TU E46, especially if modded.

I don't know if this statement was made in arrogance, but I'm a bit discouraged by portion of M owners on here, and that I've met in person.

They think the E46 M3 is the greatest thing on 4 wheels. I love the M3 and I would kill to have one, but honestly, if I have $50k to blow, I'm looking for a used Porsche. Not to mention for that kind of money you can have an S4 that is on par with an M3 if not faster.

I didn't even mention what $50k and a 2JZ will do.

I love the M3, I don't love the engine failures, and I'm beginning to dislike some of the arrogance.

Personally I would rather have an E30 M3 (prefererred) or E36 M3 (best handling) and cash to play with.

The E46 is sweet, but it's too bloated compared to previous 3ers.
 

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Discussion Starter #19
You can have wat i have, a m3, porsche turbo, so on and so on, but RWD has a natural tendency to oversteer. Now everyone can quip and say that this car or that is extra special and it's engineers are the best in the world. As far as i know, i think its true that designers will try and "beat" this natural effect, but its not possible. Some RWD cars will oversteer less than others due to this, but the fact remains that forces will pull a car in its natural direction (in a turn). It lies in the skill of the driver to match actions against reactions and so forth. And for those of you who think otherwise, that may be a serious mistake in the future cuz the car will do only so much for you. And a non m3 e46 could definitely oversteer
 
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