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      05-01-2013, 07:15 PM   #1
M3Now!
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Understeer in the M - it achieves balance?

After successful negotiation on rates, the M is at the dealer getting new plugs, pads, filters etc., and I'm driving an F30 328

One interesting characteristic it has is being slightly tail happy in corners under trail braking, and (if you're really standing on it) under throttle. Which is pretty entertaining in a sort of micro-scale way.

But then I started wondering why the M is set up to understeer, and this occurred to me: Maybe it's because the understeer is so easy to defeat with the S65, that if the M was more balanced or had a rear bias we would be spinning off into the sunset a la old 911s? So it becomes balanced under aggressive driving, vs. more quickly moving to oversteer?

I dunno, not exactly a vehicle dynamics expert, was just curious what opinions others have.

Cheers
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      05-01-2013, 08:14 PM   #2
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Originally Posted by M3Now! View Post
I dunno, not exactly a vehicle dynamics expert, was just curious what opinions others have.
Neither am i, but i always thought most (if not all) street cars are purposefully set up for understeer as understeer is a lot easier to correct than oversteer.
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      05-01-2013, 08:47 PM   #3
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E9x does not understeer anything close to prior /M cars. Really annoying when people come here saying how much it "understeers" based solely on prior /M cars.
It was picked best drifting car; that isn't going to happen if it pushed all over the place. All the mags said its balance and may understeers at the limit, which no one should be close to on the street.

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      05-01-2013, 09:08 PM   #4
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Take it to the track in stock form. It understeers.
I'm sure it's set up this way because as mentioned, you won't get yourself into as much trouble in understeer as you can with oversteer. Also, from what most of us have found out, it takes a fair bit of negative front camber, square setup, and maybe some other suspension tuning to dial it out. That's not the type of car most buyers are looking for in stock form and really the understeer is only noticeable at the track (at least to me).
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      05-01-2013, 09:51 PM   #5
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I don't think I made my point clearly. It's true that cars are usually set up to understeer so they're easier to control in an emergency, for a driver with less skills. But if my understanding of this 328 is accurate, it's NOT set up to understeer, it's balanced and handily quick to oversteer.

In an M3, you'd expect (hope) that the typical driver has better-than-average skills, so it's odd that BMW would set up a 328 for balance, and an M3 for understeer.

So...maybe the M3 is set up for understeer simply because there will usually be enough throttle to balance it, and otherwise it would be rear-biased.

Cheers
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      05-01-2013, 10:37 PM   #6
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Quote:
Originally Posted by aus View Post
E9x does not understeer anything close to prior /M cars. Really annoying when people come here saying how much it "understeers" based solely on prior /M cars.
It was picked best drifting car; that isn't going to happen if it pushed all over the place. All the mags said its balance and may understeers at the limit, which no one should be close to on the street.

.
You're totally wrong. The M3 is an understeering pig. The front tires are too skinny for a 3700 lb car and the stock camber is too mild. It's set up to understeer from the factory so that the masses with more money than driving skill that buy this car don't end up wrapping it around a tree or lamp post.
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      05-01-2013, 10:42 PM   #7
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I don't think I made my point clearly. It's true that cars are usually set up to understeer so they're easier to control in an emergency, for a driver with less skills. But if my understanding of this 328 is accurate, it's NOT set up to understeer, it's balanced and handily quick to oversteer.

In an M3, you'd expect (hope) that the typical driver has better-than-average skills, so it's odd that BMW would set up a 328 for balance, and an M3 for understeer.

So...maybe the M3 is set up for understeer simply because there will usually be enough throttle to balance it, and otherwise it would be rear-biased.

Cheers
why would the "typical" driver of an M3 have better than average skill? Does bmw require an FIA superlicense before selling you an M3? As far as I know, the only requirement to buy an M3, or most other sports and supercars all the way up to a Veyron, is $$$. Just google all those rich doctors, lawyers, and hedge fund managers who buy those shiny brand new ferraris and lambos and fly upside down into a ditch just minutes after driving off the dealership lot.
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      05-01-2013, 10:45 PM   #8
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Originally Posted by M3Now! View Post
After successful negotiation on rates, the M is at the dealer getting new plugs, pads, filters etc., and I'm driving an F30 328

One interesting characteristic it has is being slightly tail happy in corners under trail braking, and (if you're really standing on it) under throttle. Which is pretty entertaining in a sort of micro-scale way.

But then I started wondering why the M is set up to understeer, and this occurred to me: Maybe it's because the understeer is so easy to defeat with the S65, that if the M was more balanced or had a rear bias we would be spinning off into the sunset a la old 911s? So it becomes balanced under aggressive driving, vs. more quickly moving to oversteer?

I dunno, not exactly a vehicle dynamics expert, was just curious what opinions others have.

Cheers
being tail happy may not be intentional in the 328. It is possible the softer suspension allows too much brake dive, leading to less traction at the rear and easier spin outs. Also under acceleration the skinny tires may not be up to par in putting power to the road. None of these design traits are there to make the car fun to drive. They are there to cut costs and make the ride more comfortable and soft. Ultimate driving machine my ass.
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      05-01-2013, 11:25 PM   #9
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Quote:
Originally Posted by M3Now! View Post
I don't think I made my point clearly. It's true that cars are usually set up to understeer so they're easier to control in an emergency, for a driver with less skills. But if my understanding of this 328 is accurate, it's NOT set up to understeer, it's balanced and handily quick to oversteer.

In an M3, you'd expect (hope) that the typical driver has better-than-average skills, so it's odd that BMW would set up a 328 for balance, and an M3 for understeer.

So...maybe the M3 is set up for understeer simply because there will usually be enough throttle to balance it, and otherwise it would be rear-biased.

Cheers
I agree and it makes sense. A rear drive car with more power and under steer would balance out and a car with less power and neutral steer would be more prone to balance.
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      05-02-2013, 02:39 AM   #10
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Does everyone find the E92 M3 has too much understeer?
While my E46 M3s had too much understeer, my E92 M3 seems really quite well balanced.
I do have a few extra psis in the front tyres which improves the turn in but I doubt it makes that much difference. Sure I can make it understeer, try to carry too much speed and throttle into the corner and it will push across the road but thats not a sensible way to corner.
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      05-02-2013, 07:22 AM   #11
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IMO, the M3 does understeer quite a lot when pushed closer to the limit. Not something one would notice driving at 8/10th though.

When discussing the "balance" of a car, it is steady state (constant speed) balance that is implied. Therefore, I think it is important to define what steady state understeer and oversteer are. Tires, while generating lateral grip, have an inherent amount of slip. When the front tires slip more than the rears, it is understeer. When the rears slip more, it is oversteer. So yes, the M3 understeers in stock form. With a neutral car cornering at constant speed, all four tires slip equally. When slightly more throttle is applied, the weight transfers to the rear and the car understeers. If slightly less throttle is applied, weight is transferred to the front and the car oversteers. A neutral car is much easier to steer with the throttle, however it can be done to some extent with ant type of car.

Power on oversteer is something not realy related to the steady state balance of the car. When way too much throttle is applied, the grip of the tire is overcome and the rear end steps out. However, when a car is more neutrally balanced (less dialed-in understeer), its takes less throttle input to overcome the rear grip.

Last edited by CanAutM3; 05-03-2013 at 06:23 AM.
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      05-02-2013, 09:00 AM   #12
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Quote:
Originally Posted by Majin Buu
why would the "typical" driver of an M3 have better than average skill? Does bmw require an FIA superlicense before selling you an M3? As far as I know, the only requirement to buy an M3, or most other sports and supercars all the way up to a Veyron, is $$$. Just google all those rich doctors, lawyers, and hedge fund managers who buy those shiny brand new ferraris and lambos and fly upside down into a ditch just minutes after driving off the dealership lot.
Simple logic.

1. The driver who spends the extra coin for an M3 is either a serious poser, or is a driving enthusiast. By definition, an enthusiast is someone who's more interested in the subject than average, and thus should know more about how to drive well.

2. The percentage of people who track their M3 is conservatively 5-10%. That's 5-10% more than drivers of passats, or optimal, or avalons, etc, and someone who's been even reasonably successful on the track should understand more about driving dynamics.

And finally, remember that an average is just that. I didn't say there wouldn't be M3 drivers who suck, or drivers that are way beyond merely good.

Cheers
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      05-02-2013, 09:18 AM   #13
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Simple logic.

1. The driver who spends the extra coin for an M3 is either a serious poser, or is a driving enthusiast. By definition, an enthusiast is someone who's more interested in the subject than average, and thus should know more about how to drive well.

2. The percentage of people who track their M3 is conservatively 5-10%. That's 5-10% more than drivers of passats, or optimal, or avalons, etc, and someone who's been even reasonably successful on the track should understand more about driving dynamics.

And finally, remember that an average is just that. I didn't say there wouldn't be M3 drivers who suck, or drivers that are way beyond merely good.

Cheers
True. That is correct for all performance cars. But I think you underestimate the number of non-driving enthusiasts who buy performance cars in general, including the M3. Performance cars are bought for many reasons, like looks and styling, power and acceleration, posing, bragging rights, or just a desire to own something nice. Your own numbers prove it. You claim that the "typical" M3 owner would have good driving skills yet you state that only 5-10% of M3 owners go to the track. If only 10% at most of performance car buyers, like M3 owners for example, push it to the limits on a track, then that means there is a 90% chance the guy driving the M3 is no better than his next door neighbor in a camry or prius. Just browse this forum for all the owners asking how to operate a manual gearbox, how to start the engine, how to open the window, how to turn the steering wheel. Or my personal favourite, that giant thread about how turning off DSC on the road = immediate death in a flaming inferno of an M3

That's why car companies like BMW never offer aggressive suspension and tail happy handling on a road car. They may appease the 5-10% of talented drivers among their customers, but when the other 90-95% fly off the road straight onto the nearest tree trunk, the lawsuits will pile up, sales will plummet, and the company will go bankrupt.

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      05-02-2013, 09:47 AM   #14
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Quote:
Originally Posted by Majin Buu View Post
Your own numbers prove it. You claim that the "typical" M3 owner would have good driving skills yet you state that only 5-10% of M3 owners go to the track. If only 10% at most of performance car buyers, like M3 owners for example, push it to the limits on a track, then that means there is a 90% chance the guy driving the M3 is no better than his next door neighbor in a camry or prius.
The number of people who track their M3 should not be used as a proxy for "serious driving enthusiast". There are likely quite a few track enthusiasts, like me, that see the need for a dedicated track car, and wouldn't think of regularly putting an fairly new daily driver on the track. That said, I suspect 5-10% is probably too high as a percent of people who track their M3, but may not be too far off from the percent of people who track in general, so that still leaves a fair amount of people driving the M3 without skills acquired from track driving.
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      05-02-2013, 09:58 AM   #15
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Maybe Im weird? To me oversteer is easier to control then understeer
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      05-02-2013, 10:08 AM   #16
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Quote:
Originally Posted by CanAutM3 View Post
When discussing the "balance" of a car, it is steady state (constant speed) balance that is implied.
When I talk about balance I see it (maybe mistakenly) as a combination of things...such as how the car turns in, how it adjusts to throttle inputs, how it gets out of the corner etc.
I can see that steady state cornering at the limit will expose the cars ultimate tendency to under or over steer but who takes a corner like that IRL?
I certainly don't find the car to understeer "quite a lot"...it doesn't take much of a tyre grip differential front to rear to make the car tend to oversteer rather than understeer.
I wonder how much the DSC tries to balance the car in a turn near/at the limit by inducing understeer?
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      05-02-2013, 10:13 AM   #17
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That said, I suspect 5-10% is probably too high as a percent of people who track their M3, but may not be too far off from the percent of people who track in general, so that still leaves a fair amount of people driving the M3 without skills acquired from track driving.
I would say less than 1% of M3 owners track their car.
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      05-02-2013, 10:18 AM   #18
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Quote:
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I would say less than 1% of M3 owners track their car.
thats a low estimate.
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      05-02-2013, 10:23 AM   #19
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I'm by no means an expert but currently run with 'intermediate' groups on track days. I'd like a little more oversteer on the M3 but IMO feel like it's more balanced driving it hard on the track. So I'm not really complaining or planning to make adjustments, though I'm coming from Audi's so I probably suffer from traumatic understeer stress disorder...
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      05-02-2013, 10:47 AM   #20
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The number of people who track their M3 should not be used as a proxy for "serious driving enthusiast". There are likely quite a few track enthusiasts, like me, that see the need for a dedicated track car, and wouldn't think of regularly putting an fairly new daily driver on the track. That said, I suspect 5-10% is probably too high as a percent of people who track their M3, but may not be too far off from the percent of people who track in general, so that still leaves a fair amount of people driving the M3 without skills acquired from track driving.
5-10% is way, way, way, to high of a percentage of people who track their cars. It's probably less than 1% of this country as an average.
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      05-02-2013, 10:53 AM   #21
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Originally Posted by Majin Buu View Post
True. That is correct for all performance cars. But I think you underestimate the number of non-driving enthusiasts who buy performance cars in general, including the M3. Performance cars are bought for many reasons, like looks and styling, power and acceleration, posing, bragging rights, or just a desire to own something nice. Your own numbers prove it. You claim that the "typical" M3 owner would have good driving skills yet you state that only 5-10% of M3 owners go to the track. If only 10% at most of performance car buyers, like M3 owners for example, push it to the limits on a track, then that means there is a 90% chance the guy driving the M3 is no better than his next door neighbor in a camry or prius. Just browse this forum for all the owners asking how to operate a manual gearbox, how to start the engine, how to open the window, how to turn the steering wheel. Or my personal favourite, that giant thread about how turning off DSC on the road = immediate death in a flaming inferno of an M3

That's why car companies like BMW never offer aggressive suspension and tail happy handling on a road car. They may appease the 5-10% of talented drivers among their customers, but when the other 90-95% fly off the road straight onto the nearest tree trunk, the lawsuits will pile up, sales will plummet, and the company will go bankrupt.
You don't have to take your car to the track to be a better than average drive. To be an excellent driver yes, but not better than average. I have never taken my car to the track, but I'm sure I'm a better than average driver. I'm sure that for most people that own M3s that don't go to the track, they are better drivers than average.
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      05-02-2013, 11:02 AM   #22
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Maybe Im weird? To me oversteer is easier to control then understeer
Famous quote:

"Oversteer scares the passengers. Understeer scares the driver"

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