M3 corner/high speed stability issues

[nike001]

Originally Posted by Ian1973

I haven't felt much understeer in this car, I can't think of a time at all honestly. I drive in the warm months without traction control. What I have noticed is the lack confidence in the rear of the car, you initiate turn in, get near the apex and add some throttle, the thing always has a transition point that feels like the rear is going to break free. I agree with CanAut, I think this is the solid mounted subframe.


The point of the story, I just got the car back yesterday and took it out for some spirited driving today and that feeling we all have felt is now scaring the crap out of me, that rear transition to throttle input mid corner. To the point I have it MDM for the first time in 2 years of ownership. It didn't feel very confidence inspiring today.

Yet I was following a new Camaro around a local lake(ie, some fun roads) on my sportbike and he was in it, driving pretty insanely for a Camaro. Granted he lived in the area I'm sure and knows the roads, where I didn't, but he was going pretty good and looked to be pretty dam planted.

Your explanation of the vehicle is exactly how the car was designed. a little understeer at the limits for the noobs, quickly able to be corrected for either a smooth transition through the corner, or oversteer. Take your pick. It's the best of 3 worlds for a RWD car. You want none of that? Get an AWD performance vehicle. This particular personality of the M's is exactly why they're RWD still.

Also, new Camaro's and Corvettes are DAMN fast and handle DAMN well. In the hands of a person with driver-mod, they're lethal track weapons. GM is currently making some of the best cars for the money.

Originally Posted by drkeng

just curious, in my 435 on the last stretch of highway (see map below) before my exit it is possible to hit triple digits (so I'm told) and on the offramp marked with the finger one can go about 40 tops without a lot of tire squealing, but the car feels stable. I think the "recommended" speed limit is 25, but those are yellow signs, highly conservative, geared to minivans and the like

I personally feel like this is an immature question to ask. Since my car doesn't seem to have this stability issue that this thread is based around, at least not that I can blame on the car, my thoughts on this thread is that everyone here is driving a car that has a higher performance threshold than the driver does. Most cars hide driver imperfections well; the F8x with the solid subframe doesn't do a particularly good job of it.. that's why people are noticing it. That's why people are saying turning DSC off helps, until they're in a ditch. These new-age cars are largely proactive instead of reactive in terms of DSC

Originally Posted by mm767cap

I think you might be on to something here. I entered a long corner last night, relaxed the throttle, got my understeer. Mid-corner turned off DSC and tried the same move. Understeer largely gone.

Will definitely report this to my SA. Thanks for the all the feedback here guys!

How is this an issue? Refer to my comment above

Originally Posted by CanAutM3

One thing I think could be causing this odd behaviour is the DSC applying the front outside brake in anticipation of a trailing throttle oversteer due to the sudden mid-corner lift-off. It is contrary to vehicle dynamics principles to have understeer increase with throttle lift-off. It could also explain why this behaviour is not present with DSC off and why it feels like the car is "rolling over" the front outside tire (it becomes very loaded in such a scenario).

That is a big reason I hate DSC (even Euro-MDM) at the track: because it prevents any type of throttle steer. When you do a quick lift to tuck the nose in, all you get is more push with the car going slower .

Again, how is this an issue? This is how the vehicle was tuned.

Of course the vehicle with stability control will brake the front outside brake because duh: understeer. Also, trail braking is a thing and the rear WILL come out with trail braking.

Everyone knows that the rear end of these cars are very stiff, and everyone here knows that with such a sharp front end and stiff rear end.. the rear WILL push the front so much that DSC potentially thinks there's less grip at the front than there actually is.

The entire basis of this thread is based around DSC helping the driver out because the driver isn't driving the car correctly. The car has a higher handling threshold than the driver, and DSC is smarter than the driver too. Turn DSC off and the car becomes very manageable in the hands of an experienced driver, and will quickly bite the next driver who thinks they're a better driver than they really are.

Either way, rock on guys. Drive the cars, and take it to the track to learn how the car reacts to your inputs. After learning the car, these "twitches" will go away.

[CanAutM3]

Originally Posted by nike001

Of course the vehicle with stability control will brake the front outside brake because duh: understeer.

Wrong!!

UNDERsteer would have DSC brake the INSIDE REAR wheel to get the car to pivot.

The FRONT OUTSIDE brake is applied to correct OVERsteer.

Originally Posted by nike001

Again, how is this an issue? This is how the vehicle was tuned.

Also, trail braking is a thing and the rear WILL come out with trail braking.

Everyone knows that the rear end of these cars are very stiff, and everyone here knows that with such a sharp front end and stiff rear end.. the rear WILL push the front so much that DSC potentially thinks there's less grip at the front than there actually is.

The entire basis of this thread is based around DSC helping the driver out because the driver isn't driving the car correctly. The car has a higher handling threshold than the driver, and DSC is smarter than the driver too. Turn DSC off and the car becomes very manageable in the hands of an experienced driver, and will quickly bite the next driver who thinks they're a better driver than they really are.

Either way, rock on guys. Drive the cars, and take it to the track to learn how the car reacts to your inputs. After learning the car, these "twitches" will go away.

Perhaps you should re-read my post and try to comprehend what I wrote...

IMO, contrary to what you are saying, the DSC is simply very conservatively tuned to be SAFE for the average driver. It does however prevent the experienced driver to fully exploit the chassis and natural handling dynamics of the car.

[mm767cap]

Originally Posted by nike001

Your explanation of the vehicle is exactly how the car was designed. a little understeer at the limits for the noobs, quickly able to be corrected for either a smooth transition through the corner, or oversteer. Take your pick. It's the best of 3 worlds for a RWD car. You want none of that? Get an AWD performance vehicle. This particular personality of the M's is exactly why they're RWD still.

Also, new Camaro's and Corvettes are DAMN fast and handle DAMN well. In the hands of a person with driver-mod, they're lethal track weapons. GM is currently making some of the best cars for the money.



I personally feel like this is an immature question to ask. Since my car doesn't seem to have this stability issue that this thread is based around, at least not that I can blame on the car, my thoughts on this thread is that everyone here is driving a car that has a higher performance threshold than the driver does. Most cars hide driver imperfections well; the F8x with the solid subframe doesn't do a particularly good job of it.. that's why people are noticing it. That's why people are saying turning DSC off helps, until they're in a ditch. These new-age cars are largely proactive instead of reactive in terms of DSC



How is this an issue? Refer to my comment above



Again, how is this an issue? This is how the vehicle was tuned.

Of course the vehicle with stability control will brake the front outside brake because duh: understeer. Also, trail braking is a thing and the rear WILL come out with trail braking.

Everyone knows that the rear end of these cars are very stiff, and everyone here knows that with such a sharp front end and stiff rear end.. the rear WILL push the front so much that DSC potentially thinks there's less grip at the front than there actually is.

The entire basis of this thread is based around DSC helping the driver out because the driver isn't driving the car correctly. The car has a higher handling threshold than the driver, and DSC is smarter than the driver too. Turn DSC off and the car becomes very manageable in the hands of an experienced driver, and will quickly bite the next driver who thinks they're a better driver than they really are.

Either way, rock on guys. Drive the cars, and take it to the track to learn how the car reacts to your inputs. After learning the car, these "twitches" will go away.

If you read back, you will see that I've owned and driven a wide variety of high performance cars. I've done racing in a variety of classes and many driving schools. Your assertion that the initial question is "immature" is ridiculous. Just because YOUR car doesn't display this behavior doesn't mean some don't. If you haven't experienced the issue, you aren't in a position to comment on whether it's "the way the car was designed". The car I'm coming from is a 550bhp RWD Jaguar F-Tyoe R Coupe. That car is WAYYYYY more tail happy than the M3. And I could enter the same corner at 50mph, modulate the throttle, and have zero adverse effects. The car felt planted throughout. In my M3, at 30mph, same corner, same throttle modulation, the front end feels like the tires rolled off the wheels. In MDM or TC off, the problem goes away. In other words, if (as you say) the design of the TC system is such that it causes this behavior SO FAR from the limit of grip, then the system sucks. The fact that most owners don't seem to have this specific issue makes me think it might not be an issue for all cars, because TRUST ME, it's alarming when it happens to you.

[Pic18]

Originally Posted by nike001

...my thoughts on this thread is that everyone here is driving a car that has a higher performance threshold than the driver does. Most cars hide driver imperfections well; the F8x with the solid subframe doesn't do a particularly good job of it.. that's why people are noticing it. That's why people are saying turning DSC off helps, until they're in a ditch. These new-age cars are largely proactive instead of reactive in terms of DSC

......

The entire basis of this thread is based around DSC helping the driver out because the driver isn't driving the car correctly. The car has a higher handling threshold than the driver, and DSC is smarter than the driver too. Turn DSC off and the car becomes very manageable in the hands of an experienced driver, and will quickly bite the next driver who thinks they're a better driver than they really are.

Although I agree with some of the intent of your post (or at least how I read it) I disagree that this issue is solely a "driver mod" problem. Looking through the posts I notice that many are reporting this happening on on-ramps or similar turns at fairly moderate speeds. When they take the same turn with DSC off, the problem goes away (and they didn't fly off the road!). What I surmise from that is that the DSC is being "proactive" as you mention and intervening before an excess amount of slip has occurred, not because the driver is driving "incorrectly", but rather the car is being overly cautious.

I do not know any of these drivers, so it is possible that some may be exceeding their own driving limits (or that of the vehicle), but as mentioned above it does not seem that way. Although I have never personally felt the "rolling over" sensation mentioned by OP, I will say I have experienced numerous occasions in many different BMWs where DSC was a bit aggressive. I am not a professional or licensed race driver, but am confident enough in my own ability (to include on the track) to know when I have pushed the car beyond its limit. In my experience DSC is not only over aggressive but can make the car behave in a manner you do not expect and hence feel "twitchy".

Long story short I agree that this is an inherent feature of the vehicle/DSC system, but I do not believe that if you are driving and your inputs cause DSC intervention that you are necessarily driving the car incorrectly. I love BMWs and my F80, but my biggest (and only) complaint is the programming of the DSC system. I believe GM has figured this out so not sure why BMW cannot.

P.S. I personally think drivers should leave some level of DSC on while on the street as a) you are probably not as attentive as you may be on the track, and b) to many variables and not much safe run off on the road.

[gatorfast]

Originally Posted by Pic18

P.S. I personally think drivers should leave some level of DSC on while on the street as a) you are probably not as attentive as you may be on the track, and b) to many variables and not much safe run off on the road.

Agree with that. If you are driving so hard on the street that DSC intervention is a constant issue then maybe you should re-evaluate your driving style for your own and other's safety.

[bmrwrld]

Just start drifting. That take care of your cornering issue.

[mechanic75]

What part of 30mph corner do you guys not understand? So that's on the limit now is it? I get this issue in certain scenarios and it is nothing to do with on limit behaviour. Imagine hitting a patch of black ice or as one poster says it feels like the tyre has rolled off the rim momentarily.

I personally think it is a tight diff issue as the car is driving you forward when it shouldn't. It was much more prevalent early on. I can't remember the last time it has happened as I am on 12k miles and drive in mdm (shock horror) all the time now.

[Colinv6]

I've been playing about in MDM mode lately in the dry, on many of the roads I had this problem previously, it's significantly reduced...

My non competition M3 was always rock solid so I wonder if there is a software tweak that BMW can do to alleviate this, as I don't fancy using MDM in the wet, and as said above this can happen at low speeds.

[mm767cap]

Originally Posted by mechanic75

What part of 30mph corner do you guys not understand? So that's on the limit now is it? I get this issue in certain scenarios and it is nothing to do with on limit behaviour. Imagine hitting a patch of black ice or as one poster says it feels like the tyre has rolled off the rim momentarily.

I personally think it is a tight diff issue as the car is driving you forward when it shouldn't. It was much more prevalent early on. I can't remember the last time it has happened as I am on 12k miles and drive in mdm (shock horror) all the time now.

I can confirm exactly what you are saying after playing with this for 1000 miles or so. It's a DSC thing with my car. With DSC on, I get the weird understeer easily at almost any speed WAY far away from the limit with any lifting mid-corner. Select MDM and the car handles beautifully. Very predictable and maybe the slightest hint of trailing throttle oversteer. The "nanny state" of my DSC is truly shocking.... and quite alarming actually. Don't know if mine is acting differently than most, but it's now a full-time MDM car for me.

[Colinv6]

Anyone had any updates or been to the dealers for any tweaks to the DSC software of an alignment?

Mine is still doing it, less so in MDM, but I'm currently less happy with this car than I was with my previous non ZCP car.

[momo3605]

Originally Posted by Colinv6

Anyone had any updates or been to the dealers for any tweaks to the DSC software of an alignment?

Mine is still doing it, less so in MDM, but I'm currently less happy with this car than I was with my previous non ZCP car.

I also tried the same corners in MDM and the feeling of the rear wheels sliding off is almost entirely gone! You could try Euro MDM if you don’t have it already

[Colinv6]

Originally Posted by momo3605

I also tried the same corners in MDM and the feeling of the rear wheels sliding off is almost entirely gone! You could try Euro MDM if you don’t have it already

I'm from the UK so I already have that, it's a huge improvement but driving in MDM in the pouring rain with my 16 month old daughter isn't always something I want to do.

Booked in Tuesday the 5th to see if they can find anything wrong. Let's hope they don't blame my ACS springs,

[mose121]

I'm still trying to figure out why people are suddenly lifting mid corner.

[Colinv6]

Originally Posted by mose121

I'm still trying to figure out why people are suddenly lifting mid corner.

Your not understanding, we aren't lifting mid corner, you can be following traffic at 30/40mph round a corner or a roundabout and ease off due to the traffic flow speed, and you still get this washout understeer feeling.

We're not steaming into bends and 80mph and suddenly lifting right off.

[Thescout13]

Originally Posted by Colinv6

Your not understanding, we aren't lifting mid corner, you can be following traffic at 30/40mph round a corner or a roundabout and ease off due to the traffic flow speed, and you still get this washout understeer feeling.

We're not steaming into bends and 80mph and suddenly lifting right off.

Maybe this has been mentioned previously but I wonder if it is a combination of the weight shifting forward when easing off mixed with the electronic steering that is causing the understeer feeling. I generally feel like torque happy cars have a really shitty weight shifting issue when going around a bend in traffic.

[OF Hero]

As a soon-to-be new owner...is this a widespread issue to be aware of??

[mm767cap]

Originally Posted by Thescout13

Maybe this has been mentioned previously but I wonder if it is a combination of the weight shifting forward when easing off mixed with the electronic steering that is causing the understeer feeling. I generally feel like torque happy cars have a really shitty weight shifting issue when going around a bend in traffic.

I'm thinking it should be the opposite. With the weight shifting forward, the front should bite and the back should get light and potentially get loose (i.e. Trailing throttle oversteer).

But what I have discovered is that MDM mode or TC off completely solves the problem, so it's not the electronic steering. It's the way the TC system is programmed.

[mm767cap]

Originally Posted by OF Hero

As a soon-to-be new owner...is this a widespread issue to be aware of??

It doesn't appear to be in every car, or if it is, folks haven't run into it yet or didn't notice. But honestly, now that I know what the cause is, it's not a big deal. If I'm gentleman driving and want to keep full TC on, I'm not going fast enough around bends to make it a major issue. When I want to be more spirited in the corners, I just plop it into MDM and problem is completely gone

[Thescout13]

Originally Posted by mm767cap

I'm thinking it should be the opposite. With the weight shifting forward, the front should bite and the back should get light and potentially get loose (i.e. Trailing throttle oversteer).

But what I have discovered is that MDM mode or TC off completely solves the problem, so it's not the electronic steering. It's the way the TC system is programmed.

Interesting, thanks!

[Colinv6]

Just to update. I've been at my dealers a few times now to remedy this issue...

So far I've tried...

666M with spacers - had issue
666M without spacers - had issue
Aftermarket wheels - same issue
Tyre pressures bang on
Alignment is perfect - still have issue

Just yesterday I had the latest software update on the car to see if this cures it, roads were very cold and wet on the way home so couldn't get a chance to really demonstrate it but I did go round a roundabout twice while easing off the pedal and it stayed straight and true...

[Wills2]

The latest software has transformed mine as well in combination with the MP HAS and a KDS alignment.

[maniz]

Originally Posted by Strongbad

My car also came from the dealer with the front splitters/lip installed but does not have the M performance spoiler installed so I am wondering if that is messing with the stability of the car at higher speeds because I have read that BMW recommends installing both the splitters and spoiler together.

Yes, they specifically mention this in the MP aero kit installation guide, but I don't see how it would cause an issue like this at the low speeds you're describing.