Track forum general chit chat.

Chris_PDX · 06-26-2019, 04:56 PM

Quote:

Originally Posted by dogbone

I used Euro MDM on track for 4 years until the end of 2015. I drove every track in California with it. And I watched its behavior with an AIM Solo DL. I think it's fair to say I know it's characteristics.

When you push hard on track with the E9x M3's traction control system. The two main tools it uses are:

-dabbing a single front brake caliper to prevent oversteer in sweeper/rounder parts of the track.
-holding back power if you mash the gas too soon on corner exit. And then allowing the power to be applied by the engine smoothly and gradually when the car decides it's safe to do so after the corner. (This second tool is sneaky and it's harder to know when it's happening. You only really realize what it was doing when you turn off DSC and then experience the full rush of power when you press the gas and then finally understand that DSC was holding the power back. You just hope that you don't spin as you are realizing it......)

The yellow DSC logo on the dash doesn't always flash while DSC is doing it's thing.

While traction control usually works in the background and does small things to try to prevent crazy situations, we have seen videos of it pulling people out of tank-slapper situations that most people would not be able to overcome. (This can occur if you dropped two wheels off-track and then try to save it. The car hooks as it comes back on track and things get ugly really quick. We've seen DSC save that. Amazing.) Being able to grab individual brake calipers is a powerful tool. The system may have been developed over a decade ago, but that doesn't mean it's crap. I think it's main limitation is that you can't specifically program or tune it to act how you want it to act. (A Motec ECU has like 10 levels of traction control that can be fully tuned to do whatever the heck you want it to do.)

If a person wants to drive with DSC off, I highly recommend they spend time on a skid pad sliding a car around and learning how to effectively countersteer. Most of traction control's intrusions are done to keep the rear of the car in the rear. Traction control doesn't necessarily keep the car on track. It doesn't know where the track is. It's trying to stop you from spinning. So, learning the basics of countersteering-a-slide is the first step to driving without traction control. The second thing you can learn on the skid pad is how to apply the gas pedal. By purposefully applying too much gas, you can start to understand what the car feels like as the rear is breaking loose. Understanding that feeling is important. Different tires offer different traction. Different turns offer different amounts of grip. You need to learn what it feels like as the tires are losing grip so that you can adapt to the situation in each turn with whatever tire may be on the car. It is best to learn these lessons in a low risk environment like a skid pad where it's safe because experiencing them on a race track at full speed for the first time has way more risk. And a race track has so many other variables going on with other cars around and various track conditions, that you may not be able to concentrate on the nuts-and-bolts skill building while the car is sliding. You're too busy freaking out because there are other cars and walls around. Plus, most event organizers these days don't allow drifting. If they see a dude hanging the ass of his car out there repeatedly, he's getting called in.

An autocross course can also build good skill. But I would still HIGHLY recommend a skid pad where you can just go crazy hanging the ass of the car out there over and over and over. (Doing a wet skid pad is fine, but for learning purposes, I prefer dry pavement because that teaches you more what a regular dry track will feel like.) There is no substitute for understanding that feeling as the ass is about to start to step out, countersteering it, and then learning how to apply the gas pedal to keep the car going. As you do it more and more, you start to develop a Spider-Man sense for when it's about to happen. Porsche drivers who drive without traction control have an advanced Spidey-sense for when that tail is about to step out.

The other lesson you need to learn as time goes on is that countersteering has to be appropriate to each situation and to the speed you are going. Countersteering is not just a generic response. A skid pad countersteer at slow speed requires one amount of input. But a 90mph countersteer requires a different (less) amount of input. You have to feel your way through it. I bring this up because I watched a video recently of a driver who spun in a high speed left-hand turn and couldn't figure out why. My conclusion is that the rear stepped out just a little bit in the high speed turn (not even noticeable on the video). But he countered with a huge countersteer---like more than a full turn of the steering wheel. It was such a large countersteer, that the front tires grabbed and the nose of the car was moved noticeably to the right, and the car immediately came around to the left.......he spun instantly into the rocky dirt......In a high speed situation like that, you want smaller movements to keep the rear in the rear. At slower speeds, you may need to countersteer more. But again, you have to feel these things out. I think a racetrack is the last place you want to be feeling these things for the first time. It's the highest risk place to be experiencing it. What you want is a low risk place to do it for the first time.

I had an experience at Buttonwillow a few months ago that's related to this. I have a supercharged E90, so the car has a lot of power. Exiting the Esses at Buttonwillow at full throttle in a supercharged E90 is challenging, but it is possible. But you can't do it all the time. The condition of the tires affects whether you can stay full throttle. So you have to feel it out based on the condition of the tires. On this day, my Spidey sense was telling me that with the scrubs on the car, I could not stay full throttle on the exit of the Esses. But I wondered if I was really sensing the situation correctly. So, I pushed harder on a subsequent lap and the tail got a tad loose at 120+mph on the exit of the Esses. The tires weren't good for it. My Spidey senses were correctly interpreting the situation, but I was doubting them. From that experience, I am even more willing to listen to my Spidey senses now. At that speed, it was a small amount of inputs that brought the tail back. If I had gone wild with some freak out countersteer, the situation would have resulted in some kind of spin.

The last thing I will recommend is that, if you have been driving with MDM on track for awhile and you want to drive DSC-off, back the speed off a bit, and then slowly work back to your full pace. There will be some "ah ha" moments where you feel the throttle come on immediately that will surprise you. At a slower pace, you can deal with that.

For most of us, motorsport is about having fun and learning. Unfortunately, big egos get in the way. Or public shaming causes someone to turn it off and then that person gets in over their head. I was ridiculed endlessly for using traction control. I didn't care. No one else was gonna pay for my car if I messed it up. I turned DSC off when it felt right to me. How did I turn off traction control after 4 years with it on?----I had been on the skid pad several times. I had been practicing on track with DSC-off about 25% of my track time at lower speeds for almost a year. (When I was in traffic on track, I would turn MDM back on.) The first day I really drove at full pace with DSC off, I was on a semi-exclusive day at Buttonwillow, and there was no one else on the track. I was literally the only one there. I spent a whole day getting comfortable with it at full pace with no one else around.

Agree with this 9000%. Clearly those of us on this forum are hardcore track rats and have no issues driving with DSC completely off. My E46 M3's DSC module is totally fucking-fucked with my suspension setup so I have to have it off, rain or shine, or it cuts power and applies the brakes with any turn of the steering wheel.

As an instructor, I always ask M3 drivers what they normally drive with. Most of them say MDM on, and a few say DSC off. Don't even get me started on driving with DSC off on the street (why tho). I usually use the first session to see how they drive. Nine times out of ten, I tell the MDM crowd to leave DSC on for the next session because we're tank slapping all over the place.

I have never been in the right seat with someone in the Novice or Intermediate groups that has successfully proven they are faster with it off. They may feel it's faster, but seat of the pants and right seat stopwatch says differently. Advanced drivers are a different story.

MaX PL · 06-26-2019, 06:42 PM

Quote:

Originally Posted by Datka

Talking to me? If you read my post carefully my message was directed towards novace, inexperienced track drivers.
As far as my own driving, I do drive with euro MDM sometimes and I don't find it very intrusive. And that's what I would recommend to novace/intermediate drivers.
How does 1:59 lap time sound in a street legal e92m3 at WGI? That time was done with TC off.
Does it sound like I am putting around the track and not pushing hard

you have video of this lap?

kyippee · 06-26-2019, 10:18 PM

This MDM discussion is good. I'll admit I've been driving with euro MDM on, winning some HPDE trophies (really low-level TT stuff) and running in advance groups keeping my shit together.

I've had friends ride along and get the "why don't you turn it fully off? you're reacting correctly when things go sideways and it's slowing you down" and may make the leap soon. Will step down run groups to something like a high-intermediate (fast advance > slow advance > high int > low int > novice) so I can dial things down to a few notches in pace and get comfortable. I think I've hit a wall in driver development with euro MDM.

dogbone · 06-26-2019, 10:25 PM

Quote:

Originally Posted by Chris_PDX

My E46 M3's DSC module is totally fucking-fucked with my suspension setup so I have to have it off, rain or shine, or it cuts power and applies the brakes with any turn of the steering wheel..

hehe with full aero, slicks, BBK, race pads, suspension, weight reduction and supercharger in my car, the poor DSC system just doesn’t know what the heck is going on....haha!

PrimeBMW · 06-26-2019, 11:22 PM

Quote:

Originally Posted by Chris_PDX

Quote:

Originally Posted by dogbone

I used Euro MDM on track for 4 years until the end of 2015. I drove every track in California with it. And I watched its behavior with an AIM Solo DL. I think it's fair to say I know it's characteristics.

When you push hard on track with the E9x M3's traction control system. The two main tools it uses are:

-dabbing a single front brake caliper to prevent oversteer in sweeper/rounder parts of the track.
-holding back power if you mash the gas too soon on corner exit. And then allowing the power to be applied by the engine smoothly and gradually when the car decides it's safe to do so after the corner. (This second tool is sneaky and it's harder to know when it's happening. You only really realize what it was doing when you turn off DSC and then experience the full rush of power when you press the gas and then finally understand that DSC was holding the power back. You just hope that you don't spin as you are realizing it......)

The yellow DSC logo on the dash doesn't always flash while DSC is doing it's thing.

While traction control usually works in the background and does small things to try to prevent crazy situations, we have seen videos of it pulling people out of tank-slapper situations that most people would not be able to overcome. (This can occur if you dropped two wheels off-track and then try to save it. The car hooks as it comes back on track and things get ugly really quick. We've seen DSC save that. Amazing.) Being able to grab individual brake calipers is a powerful tool. The system may have been developed over a decade ago, but that doesn't mean it's crap. I think it's main limitation is that you can't specifically program or tune it to act how you want it to act. (A Motec ECU has like 10 levels of traction control that can be fully tuned to do whatever the heck you want it to do.)

If a person wants to drive with DSC off, I highly recommend they spend time on a skid pad sliding a car around and learning how to effectively countersteer. Most of traction control's intrusions are done to keep the rear of the car in the rear. Traction control doesn't necessarily keep the car on track. It doesn't know where the track is. It's trying to stop you from spinning. So, learning the basics of countersteering-a-slide is the first step to driving without traction control. The second thing you can learn on the skid pad is how to apply the gas pedal. By purposefully applying too much gas, you can start to understand what the car feels like as the rear is breaking loose. Understanding that feeling is important. Different tires offer different traction. Different turns offer different amounts of grip. You need to learn what it feels like as the tires are losing grip so that you can adapt to the situation in each turn with whatever tire may be on the car. It is best to learn these lessons in a low risk environment like a skid pad where it's safe because experiencing them on a race track at full speed for the first time has way more risk. And a race track has so many other variables going on with other cars around and various track conditions, that you may not be able to concentrate on the nuts-and-bolts skill building while the car is sliding. You're too busy freaking out because there are other cars and walls around. Plus, most event organizers these days don't allow drifting. If they see a dude hanging the ass of his car out there repeatedly, he's getting called in.

An autocross course can also build good skill. But I would still HIGHLY recommend a skid pad where you can just go crazy hanging the ass of the car out there over and over and over. (Doing a wet skid pad is fine, but for learning purposes, I prefer dry pavement because that teaches you more what a regular dry track will feel like.) There is no substitute for understanding that feeling as the ass is about to start to step out, countersteering it, and then learning how to apply the gas pedal to keep the car going. As you do it more and more, you start to develop a Spider-Man sense for when it's about to happen. Porsche drivers who drive without traction control have an advanced Spidey-sense for when that tail is about to step out.

The other lesson you need to learn as time goes on is that countersteering has to be appropriate to each situation and to the speed you are going. Countersteering is not just a generic response. A skid pad countersteer at slow speed requires one amount of input. But a 90mph countersteer requires a different (less) amount of input. You have to feel your way through it. I bring this up because I watched a video recently of a driver who spun in a high speed left-hand turn and couldn't figure out why. My conclusion is that the rear stepped out just a little bit in the high speed turn (not even noticeable on the video). But he countered with a huge countersteer---like more than a full turn of the steering wheel. It was such a large countersteer, that the front tires grabbed and the nose of the car was moved noticeably to the right, and the car immediately came around to the left.......he spun instantly into the rocky dirt......In a high speed situation like that, you want smaller movements to keep the rear in the rear. At slower speeds, you may need to countersteer more. But again, you have to feel these things out. I think a racetrack is the last place you want to be feeling these things for the first time. It's the highest risk place to be experiencing it. What you want is a low risk place to do it for the first time.

I had an experience at Buttonwillow a few months ago that's related to this. I have a supercharged E90, so the car has a lot of power. Exiting the Esses at Buttonwillow at full throttle in a supercharged E90 is challenging, but it is possible. But you can't do it all the time. The condition of the tires affects whether you can stay full throttle. So you have to feel it out based on the condition of the tires. On this day, my Spidey sense was telling me that with the scrubs on the car, I could not stay full throttle on the exit of the Esses. But I wondered if I was really sensing the situation correctly. So, I pushed harder on a subsequent lap and the tail got a tad loose at 120+mph on the exit of the Esses. The tires weren't good for it. My Spidey senses were correctly interpreting the situation, but I was doubting them. From that experience, I am even more willing to listen to my Spidey senses now. At that speed, it was a small amount of inputs that brought the tail back. If I had gone wild with some freak out countersteer, the situation would have resulted in some kind of spin.

The last thing I will recommend is that, if you have been driving with MDM on track for awhile and you want to drive DSC-off, back the speed off a bit, and then slowly work back to your full pace. There will be some "ah ha" moments where you feel the throttle come on immediately that will surprise you. At a slower pace, you can deal with that.

For most of us, motorsport is about having fun and learning. Unfortunately, big egos get in the way. Or public shaming causes someone to turn it off and then that person gets in over their head. I was ridiculed endlessly for using traction control. I didn't care. No one else was gonna pay for my car if I messed it up. I turned DSC off when it felt right to me. How did I turn off traction control after 4 years with it on?----I had been on the skid pad several times. I had been practicing on track with DSC-off about 25% of my track time at lower speeds for almost a year. (When I was in traffic on track, I would turn MDM back on.) The first day I really drove at full pace with DSC off, I was on a semi-exclusive day at Buttonwillow, and there was no one else on the track. I was literally the only one there. I spent a whole day getting comfortable with it at full pace with no one else around.

Agree with this 9000%. Clearly those of us on this forum are hardcore track rats and have no issues driving with DSC completely off. My E46 M3's DSC module is totally fucking-fucked with my suspension setup so I have to have it off, rain or shine, or it cuts power and applies the brakes with any turn of the steering wheel.

As an instructor, I always ask M3 drivers what they normally drive with. Most of them say MDM on, and a few say DSC off. Don't even get me started on driving with DSC off on the street (why tho). I usually use the first session to see how they drive. Nine times out of ten, I tell the MDM crowd to leave DSC on for the next session because we're tank slapping all over the place.

I have never been in the right seat with someone in the Novice or Intermediate groups that has successfully proven they are faster with it off. They may feel it's faster, but seat of the pants and right seat stopwatch says differently. Advanced drivers are a different story.

I am completely baffled that most people can't tell the nannies are intervening. It's obvious (at least to me)

dparm · 06-27-2019, 09:16 AM

Quote:

Originally Posted by Montaver

Were talking 10+ year old DSC technology here, it really isn't that good.

I have to disagree here. It is not some rudimentary first-generation traction control system from the 1990s, but there are definitely newer/more sophisticated setups.

MDM is quite effective at keeping the car under control and can of course do things a person cannot, like braking an individual wheel and detecting/responding to wheel slip in a fraction of a second. There's a reason a lot of racing series have banned or heavily restricted these systems: they give an advantage. Hell, even the auto magazines talk about how some of their fastest lap times are actually set with these things turned on.

If you guys are faster with it off, more power to you. There is no shame in letting the computer help you out. I'm not out to impress anyone or set track records, I just want to have fun in a safe way. But let's not overgeneralize about "LOL nannies".

Quick read for anyone who thinks these "old" systems just slow you down (note the year and who is driving)...
https://www.roadandtrack.com/new-car...-how-it-works/

CorruptCommie · 06-27-2019, 10:18 AM

American apples to German oranges. 2012 Corvette vs 2008 BMW systems. And the sample size is one corner. Will modern traction control help even pro drivers go faster? Yes. Will they hamper your driver development? Also yes.

Montaver · 06-27-2019, 11:19 AM

Quote:

Originally Posted by dparm

I have to disagree here. It is not some rudimentary first-generation traction control system from the 1990s, but there are definitely newer/more sophisticated setups.

MDM is quite effective at keeping the car under control and can of course do things a person cannot, like braking an individual wheel and detecting/responding to wheel slip in a fraction of a second. There's a reason a lot of racing series have banned or heavily restricted these systems: they give an advantage. Hell, even the auto magazines talk about how some of their fastest lap times are actually set with these things turned on.

If you guys are faster with it off, more power to you. There is no shame in letting the computer help you out. I'm not out to impress anyone or set track records, I just want to have fun in a safe way. But let's not overgeneralize about "LOL nannies".

Quick read for anyone who thinks these "old" systems just slow you down (note the year and who is driving)...
https://www.roadandtrack.com/new-car...-how-it-works/

Interesting, however... He's fastest in mode 4, which fully disables yaw control. This is purely traction control modulating power through the rear wheels. He was slower in every mode where the car is controlling slip angle. The fact he's faster with TC and torque reduction when were talking about 600lb/ft of torque and 600hp going through the rear wheels isn't exactly surprising. This is effectively the same as pressing the ESC off button in a Pcar.

M3MPH1S · 06-27-2019, 11:59 AM

Interesting timing on this discussion. I'm finally at the point where I'm comfortable with my input smoothness and ability to safely react to loss of traction that I'm going to start driving with DSC off. With the normal MDM, it was fairly evident fairly early that it was getting in the way - I think the sensors especially didn't like how the car reacted with KW clubsports. I have been enjoying Euro MDM for a while now. The biggest difference is how it does not intervene over uneven terrain. And you can get the rear end out quite a bit with it still on. But it wasn't until recently that I was finally able to notice the small interventions in corners where I'm really starting to try and push the limit. Obviously like others have said, I'm not going to jump right into the same level of pushing the first time I turn it off, but I'm curious to see how it will (hopefully) let me push past my current limits. I feel like my driving ability has really started to improve but my lap times are only improving at a sluggish rate. Not that lap times are king, but it's my main metric since I don't have data logging.

Ximian · 06-27-2019, 12:53 PM

Quote:

Originally Posted by M3MPH1S

Not that lap times are king, but it's my main metric since I don't have data logging.

Sounds like we need to organize a group buy for https://store.m-world.us/products/ai...=3738872676392

dparm · 06-27-2019, 02:56 PM

Quote:

Originally Posted by CorruptCommie

American apples to German oranges. 2012 Corvette vs 2008 BMW systems. And the sample size is one corner. Will modern traction control help even pro drivers go faster? Yes. Will they hamper your driver development? Also yes.

Maybe, but the C6 was in production since 2004. PTM did get some revisions over time but it's not like that system is drastically newer than an E92. This is at least something objective. So far all we have in this discussion is a bunch of people providing subjective opinions on said technology.

Does anyone here have lap times of the same M3, on the same day, with the same driver using [Euro] MDM vs DSC off? What is the time differential? Also, I think a mostly stock car on a street tire is probably the most reasonable approach since that's what the DSC system was designed around. There is a valid argument that the system's utility decreases on a heavily modified car.

Again...show me the data. The more of it we have, the better. I'm more than willing to admit when I'm wrong.

Bartledoo · 06-27-2019, 03:26 PM

Quote:

Originally Posted by dparm

Maybe, but the C6 was in production since 2004. PTM did get some revisions over time but it's not like that system is drastically newer than an E92. This is at least something objective. So far all we have in this discussion is a bunch of people providing subjective opinions on said technology.

Does anyone here have lap times of the same M3, on the same day, with the same driver using [Euro] MDM vs DSC off? What is the time differential? Also, I think a mostly stock car on a street tire is probably the most reasonable approach since that's what the DSC system was designed around. There is a valid argument that the system's utility decreases on a heavily modified car.

Again...show me the data. The more of it we have, the better. I'm more than willing to admit when I'm wrong.

Does anybody know the exact inputs (e.g. Yaw rate/accel/jerk, roll rate/accel/jerk, pitch rate/accel/jerk, etc.) and their associated response functions? Intuitively, it would seem that mods which could control body rotation around the x, y, and z axes (accel/jerk particularly since they may provide some foresight to the future state of the vehicle's orientation) better than stock may actually reduce intervention.

roastbeef · 06-27-2019, 03:30 PM

fun site to poke around on if anyone is bored and wants to daydream.
https://racecarsdirect.com/Category

dparm · 06-27-2019, 05:13 PM

Quote:

Originally Posted by Bartledoo

Does anybody know the exact inputs (e.g. Yaw rate/accel/jerk, roll rate/accel/jerk, pitch rate/accel/jerk, etc.) and their associated response functions? Intuitively, it would seem that mods which could control body rotation around the x, y, and z axes (accel/jerk particularly since they may provide some foresight to the future state of the vehicle's orientation) better than stock may actually reduce intervention.

I would think that's secret sauce and you won't get it.

The Corvette chief engineer did provide some pretty detailed insight, however:
https://www.corvetteforum.com/forums...post1590304017

I assume all of the OEMs use similar thinking. This isn't some big secret that only GM knows, and a lot of the parts for the systems are from suppliers anyway.

Quote:

Although we have talked publicly many times and published quite a bit of documentation about PTM (and other chassis controls), there continues to be additional questions. Assuming this section of the forum attracts a very tech-savvy audience, we are going to give a more technical description than our usual public statements. At the risk of helping our competitors, I have asked Alex Macdonald, our lead Corvette development engineer and expert in chassis controls to provide the definitive treatise on PTM. So, thanks for asking….

Performance Traction Management was first brought to the market on C6 with the 2010 ZR1 and was available on C6 Z06’s with MR from 2011-2013. It has evolved with each new model of Corvette since then but still retains the same functions and philosophy as when it was introduced. All of this discussion applies to any Corvette with PTM, not just the C7. For C7 any Z51 with MR dampers and all Z06’s are equipped with PTM.

The first important part of PTM is the traction control function. This is the core of PTM. Later I will describe the other adjustments it makes to the chassis but the fundamental change in each mode is the logic and calibration of the traction control.

It will help to understand how the standard TCS system works when not in PTM. See Fig 1 for an example of a C7 Z06 turning left at 25mph and approximately 0.8G lateral acceleration (a spirited left turn). The driver steps to 100% throttle (point #1) which causes the rear wheels to start spinning. Prior to spinning up the tires, the TCS system doesn’t know much about the road surface conditions. It could be wet, dry, gravel, coarse concrete, smooth asphalt, etc. To determine the surface condition the engine torque is allowed to increase until the wheels start slipping a certain amount (point #2). They would continue to slip at this torque level so torque is quickly reduced to stop the slipping (point #3). The initial engine torque that caused the wheels to slip along with how much torque needed to be removed to reduce the wheel spin are used by the TCS to calculate the type of surface the car is on. Once the surface grip is known the torque is added back in to maintain an amount of slip that’s appropriate for that surface (point #5).

The drawback to this method is that the wheels have to over-slip past the ideal target at the start. This disturbs the cornering of the vehicle and requires the driver to adjust the steering angle. Further, bringing the wheels back down from the initial over-slip with a torque reduction dramatically reduces acceleration in order to regain stability.

The use of the PTM switch tells the car that it is definitely on dry asphalt (or wet asphalt in in mode 1) and that the driver is prepared for some amount of wheel slip. Since the surface is known the PTM system can make a good approximation of the maximum possible engine torque that will not over-slip the tires based on how hard the car is cornering and how fast it’s going. This torque estimate is used as a starting point (since no new information about the surface is needed in PTM) and then depending on the amount of slip that results more fine adjustments can be made. As the driver unwinds the steering wheel the tires gain grip and torque will be fed back in due to the lower slip. See Fig2 for the same maneuver described above but using PTM mode 2 this time.

As you look at these two examples one thing to note is how much more gradually steering and lateral acceleration can be reduced on corner exit in PTM vs normal TCS (Red and Tan lines). The initial over-slip in normal TCS is what prompts the driver to make this abrupt steering adjustment.

Each of the Traction Control modes in PTM are differentiated in two ways. First, the target slip levels are lower in the lower modes as you would expect. Second, the estimate we make for the starting torque is lower. In DRY we err on the low side with our estimation and may have to increase torque to reach the target slip. In RACE we err on the high side and the driver may have to use more steering correction to manage the extra slip in the rear until the target slip can be recovered.

Along with the traction control, the other chassis subsystems are modified for the conditions expected in each mode. The following is a chart of the status of each subsystem for each PTM mode:

Mode uses:
WET: This mode is intended for any driver who is on a wet track. The track should be wet enough to be glossy, not just damp. A damp or drying track will require the driver to decide between WET and DRY modes to get the best performance. Standing water is not recommended as hydroplaning is possible and no TCS system can accurately control a tire that is hydroplaning.

The slip targets are very low, lower than in standard TCS. The MR is in tour mode to maximize mechanical grip since the lower cornering forces don’t require the extra control offered in Sport or Track. ESC is on and uses the normal calibration, not the competitive calibration.

DRY: This mode is for a novice driver on any track or an experienced driver learning a brand new track. I also use it to warm up the tires or run the mold release off of new tires, especially if it’s cold out.

Slip targets here are very similar to normal TCS but will feel very different due to the entry prediction. MR is in Sport to compliment the usage we expect in this mode. ESC is on but uses the competitive calibration.

SPORT 1: This mode is for any driver who is ready to run very competitive lap times while still having stability control on in the background. I use this mode whenever I have a passenger, possible distractions such as data collection, or as I am continuing to become more familiar with a new track.

Slip targets are higher here than in normal TCS. MR is in track mode and ESC is on using the competitive calibration.

SPORT 2: This mode uses the exact same traction control settings as SPORT 1 but turns off ESC completely. This mode is designed as a way to turn off ESC while maintaining a fairly stable TCS calibration. I use it very often. Basically any time where tenths of a second are not critical to my testing or when the tires are getting too hot or wearing out. After 10 to 15 consecutive laps it is likely that your fastest times will be achieved in SPORT 2 rather than RACE.

Slip targets here are the same as SPORT 1. MR is still in track mode and ESC is turned OFF.

RACE: This one is pretty self-explanatory, it’s as fast as we know how to make the car go. This mode is for a well prepared car on relatively new tires with an advanced driver that is completely familiar with the track. The track should be somewhat warm and the tires should be up to temperature.

Slip targets are 100% optimized for forward acceleration, any small variances in the track or tires can result in momentary overslip that will have to be managed by the driver.

A few notes about RACE mode: I approach this mode as a tool to go faster meaning that I think specifically about it when I go to WOT and I try to change or optimize my throttle application point and steering to help the computer do its job. It can do the job better than me but only if I give it good information. A specific example is how I unwind the steering wheel mid corner and as the corner opens up. When learning to drive on track it is good practice to automatically unwind the steering wheel as you apply throttle regardless of the vehicle response (a string tied from throttle toe to steering wheel is the analogy used by some instructors). The problem in RACE PTM is that by doing that you are telling the car you are ready to go straight. It will add power and drive you to a wider line. The best results are found by holding the wheel as steady as you can and pointing the car to corner exit only when it’s time. Obviously you have to be ready to correct for overslip but as you gain trust you will find this is required less often than it feels at first. It is very useful to practice using PTM in the lower modes where you can focus on letting the car go where you point it and not correcting your steering too early.

We find that the calibration settings that achieve the fastest lap times often result in expert drivers feeling like they are being held back slightly on corner exit. Most of the time that extra little bit of slip that an expert driver wants is over the traction peak of the tire and may feel good but is wasting forward acceleration. The restrictive feeling is not there as a safety net, rather, it’s as close as we can operate to the peak capability of the tire in a robust way.

Other notes: The eLSD “PTM mode” is only a slight alteration of its normal track mode. This alteration is required since it is likely to see engine torque values that would not occur without PTM. However, the philosophy of what it’s trying to do and how it’s controlling vehicle dynamics does not change between PTM and TCS/ESC OFF mode.

As for the nannies, that term is a big gray area. I would personally call TCS, PTM, ESC and active rev match nannies but would not call the eLSD or MR dampers nannies. ABS is very gray. ABS, TCS, PTM, ESC and active rev match are trying to do a better job of something you normally do as a driver, steering, throttle, brake or shifting. However, no driver ever controls a differential directly or a shock absorber directly. They are part of the base chassis tuning and can be thought of as a calibration component like a spring or anti roll bar.
ABS is more of a gray area but it is not allowed to be shut off because the capability of the vehicle is so limited without it. You may need 200 bar of brake pressure to get max decel from a wheel that’s on the outside of a corner but the inside wheel would be totally locked at 50 bar. Unless you want a lot of flat spotted tires you need ABS in that situation. Also, somewhat like eLSD and MR, individual wheel brake pressure is something even the best driver can’t physically control without the electronics.

That’s a long way of saying you can shut off TCS, PTM, ESC and active rev match but you can’t shut off MR, eLSD or ABS.

dogbone · 06-27-2019, 05:43 PM

Quote:

Originally Posted by dparm

Does anyone here have lap times of the same M3, on the same day, with the same driver using [Euro] MDM vs DSC off? What is the time differential?

Again...show me the data. The more of it we have, the better. I'm more than willing to admit when I'm wrong.

I'm not here to prove you wrong or right, but you asked a question, and I do have what I think is a legitimate and solid answer----probably the most solid answer you could get on this topic.

As I said before, I ran for 4 years with Euro MDM on. I even went one step beyond Euro MDM and altered the WERT setting to allow even MORE slip angle. I pushed the boundaries of MDM as faaaaaar as I could.

In November 2015, I went to Buttonwillow 13CW (technical 2.7 miles long course---not a high speed course) on a semi-exclusive day. I was there all by myself. The weather was ideal conditions---started at 52ºF and the high was 58ºF. This visit was to test out the ultimate setup on the car up to that point---fully gutted and caged, full aero, brand new BFG R1S. I was there to go for it.

I started the day with MDM on as I always did when I wanted to go for it. The fastest lap I ran with MDM on that day was 1:51.5. That was a new personal best for me. But MDM was intruding EVERYWHERE. You could feel it grabbing brakes in rounders to prevent any chance of a spin. You could tell the power of the engine was being held back when you pressed the gas. I pushing like hell, and the car was pushing back. After a few sessions of MDM on, I decided I could not go any faster. I had been driving Buttonwillow for years. I knew the track very well, and I was pushing the car everywhere. I am comfortable telling you that 1:51.5 was the fastest I could ever go with MDM on fresh R1S----ideal weather, open track, etc.

So, I took a break and decided that I had reached the limit of MDM. I let the car rest a bit. I decided that this was the day I would turn MDM off and "go for it" with DSC off. (Remember, this was not my first time with DSC off. As I mentioned before, I had practiced on the skid pad and I had spent about 25% of my time driving on track with it off for about a year. But I just had never gone at maximum pace with DSC off.)

I got back out there and started turning laps with DSC off. I immediately matched the 1:51.5. By the end of the day (9th session on the tires), I had run a 1:49.0 with DSC off. Same tires, same day, same open track. So, the tires were a bit older and I still ran 2.5 seconds faster with DSC off versus Euro MDM.

It was just a simple function of being able to get on the gas earlier, and the brakes not impeding my progress on rounders.

Since 2015, I have run even faster tires like new Pirelli DH. I have continued to reduce my lap time at Buttonwillow 13CW to 1:47.2. I would bet the car would not get much faster than a 1:51 with MDM on, even with slicks. It would reduce your pace on rounders and you'd still be waiting around for the power to be available on corner exit. The slicks would be wasted in terms of going maximum pace.

Here is an AIM chart comparing the two laps. Red lap MDM on. Blue lap DSC off. I don't have time to analyze the whole chart right now, but I wanted to put it out there so you could check it out. (I'm on vacation. Need to run out right now.) Anyway, there is a LOT of information to see in this chart. A couple quick things. Look how much the calipers activate with MDM on when I'm not pressing the brake pedal. Look how much higher the speeds get in the second half of the track with DSC off. Take a look at the chart and let's see what kind of conclusions people can draw from it. I'll try to check back in later tonight and go through some conclusions. Hey---I just gave everyone homework!

kyippee · 06-27-2019, 06:08 PM

dogbone when you turned off MDM at that point, did the car catch you off guard any time during that day? Or was it just smooth sailing because you had already been tracking the car and had lots of seat team?

dparm · 06-27-2019, 06:18 PM

Quote:

Originally Posted by dogbone

I'm not here to prove you wrong or right, but you asked a question, and I do have what I think is a legitimate and solid answer----probably the most solid answer you could get on this topic.

This is good stuff, man. Thanks for sharing!

What jumps out the most in those graphs is how your gas pedal application was much more "binary" when MDM was on. Not sure if that was intentional or not, but the blue lines have a less-steep slope. You're actually at full throttle much sooner with MDM on, though. Could be down to driver confidence? Would be curious to hear your subjective thoughts.

Does AIM let you graph the DSC or TCS activation? In Pi Toolbox, there is a way to do it because the ECU sends a signal when it is actively intervening. Unsure if BMW ECU does it.

ThunderMoose · 06-27-2019, 08:22 PM

Quote:

Originally Posted by dparm

Quote:

Originally Posted by dogbone

I'm not here to prove you wrong or right, but you asked a question, and I do have what I think is a legitimate and solid answer----probably the most solid answer you could get on this topic.

This is good stuff, man. Thanks for sharing!

What jumps out the most in those graphs is how your gas pedal application was much more "binary" when MDM was on. Not sure if that was intentional or not, but the blue lines have a less-steep slope. You're actually at full throttle much sooner with MDM on, though. Could be down to driver confidence? Would be curious to hear your subjective thoughts.

Does AIM let you graph the DSC or TCS activation? In Pi Toolbox, there is a way to do it because the ECU sends a signal when it is actively intervening. Unsure if BMW ECU does it.

What are the TC modes on your vette? What modes do you run?

In my 911, I ran with TC on and didn't really notice it much but I was pretty slow.

In my E46M3, it's not driveable with it on once you get past intermediate level.

dparm · 06-27-2019, 09:15 PM

Quote:

Originally Posted by ThunderMoose

What are the TC modes on your vette? What modes do you run?

In my 911, I ran with TC on and didn't really notice it much but I was pretty slow.

In my E46M3, it's not driveable with it on once you get past intermediate level.

See the red/black chart from my above post. I almost always run in sport 1 as I feel it still gives me the safety net I want without being intrusive. It cuts the timing slightly (you can hear it) to dial the power back, which gives me instant feedback that I probably overcooked it coming out of the corner. It's fairly rare that I see stability light flashing when I'm mid-corner and the telemetry doesn't show any silent intervention.

Now that I'm more familiar with COTA I might try race mode on my next outing.

ThunderMoose · 06-27-2019, 09:24 PM

Quote:

Originally Posted by dparm

See the red/black chart from my above post. I almost always run in sport 1 as I feel it still gives me the safety net I want without being intrusive. It cuts the timing slightly (you can hear it) to dial the power back, which gives me instant feedback that I probably overcooked it coming out of the corner. It's fairly rare that I see stability light flashing when I'm mid-corner and the telemetry doesn't show any silent intervention.

Now that I'm more familiar with COTA I might try race mode on my next outing.

Have you ever spun in the Vette? Seems like a very sophisticated system that will let you drive fast but not lose control, even in Race mode.

COTA is actually fairly safe as long as you don't try be a hero and save a tank slapper. Plenty of room just to drive straight off if you lose traction. Of course my car is less powerful than yours so I probably have a bit more safety margin.

rhyary · 06-27-2019, 09:34 PM

Quote:

Originally Posted by dparm

Quote:

Originally Posted by CorruptCommie

American apples to German oranges. 2012 Corvette vs 2008 BMW systems. And the sample size is one corner. Will modern traction control help even pro drivers go faster? Yes. Will they hamper your driver development? Also yes.

Maybe, but the C6 was in production since 2004. PTM did get some revisions over time but it's not like that system is drastically newer than an E92. This is at least something objective. So far all we have in this discussion is a bunch of people providing subjective opinions on said technology.

Does anyone here have lap times of the same M3, on the same day, with the same driver using [Euro] MDM vs DSC off? What is the time differential? Also, I think a mostly stock car on a street tire is probably the most reasonable approach since that's what the DSC system was designed around. There is a valid argument that the system's utility decreases on a heavily modified car.

Again...show me the data. The more of it we have, the better. I'm more than willing to admit when I'm wrong.

Off Course.
The difference for me was about a .5 second slower with the DSC off. Both DSC off and on I can do 1:38 at NYST. but so far I was able to do 1:37 range only with the DSC on (Euro MDM)

roastbeef · 06-27-2019, 09:48 PM

The trailer parking construction is progressing nicely. Now I just need a trailer... and a truck.

06-26-2019, 10:18 PM	#9639
kyippee Lieutenant Colonel 1066 Rep 1,617 Posts Drives: E92 M3, Supra MK5, F44 235GC Join Date: Feb 2017 Location: SF Bay Area iTrader: (0)	This MDM discussion is good. I'll admit I've been driving with euro MDM on, winning some HPDE trophies (really low-level TT stuff) and running in advance groups keeping my shit together. I've had friends ride along and get the "why don't you turn it fully off? you're reacting correctly when things go sideways and it's slowing you down" and may make the leap soon. Will step down run groups to something like a high-intermediate (fast advance > slow advance > high int > low int > novice) so I can dial things down to a few notches in pace and get comfortable. I think I've hit a wall in driver development with euro MDM.
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06-27-2019, 10:18 AM	#9643
CorruptCommie First Lieutenant 346 Rep 396 Posts Drives: 2011 X5d Join Date: May 2014 Location: Cincinnati, OH iTrader: (0)	American apples to German oranges. 2012 Corvette vs 2008 BMW systems. And the sample size is one corner. Will modern traction control help even pro drivers go faster? Yes. Will they hamper your driver development? Also yes. __________________
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06-27-2019, 11:59 AM	#9645
M3MPH1S Captain 586 Rep 769 Posts Drives: 2010 E92 M3 Join Date: Mar 2015 Location: Atlanta iTrader: (8)	Interesting timing on this discussion. I'm finally at the point where I'm comfortable with my input smoothness and ability to safely react to loss of traction that I'm going to start driving with DSC off. With the normal MDM, it was fairly evident fairly early that it was getting in the way - I think the sensors especially didn't like how the car reacted with KW clubsports. I have been enjoying Euro MDM for a while now. The biggest difference is how it does not intervene over uneven terrain. And you can get the rear end out quite a bit with it still on. But it wasn't until recently that I was finally able to notice the small interventions in corners where I'm really starting to try and push the limit. Obviously like others have said, I'm not going to jump right into the same level of pushing the first time I turn it off, but I'm curious to see how it will (hopefully) let me push past my current limits. I feel like my driving ability has really started to improve but my lap times are only improving at a sluggish rate. Not that lap times are king, but it's my main metric since I don't have data logging.
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06-27-2019, 03:30 PM	#9649
roastbeef Lieutenant General 11405 Rep 12,626 Posts Drives: E92 M3 Join Date: Nov 2010 Location: Orange County, CA iTrader: (4)	fun site to poke around on if anyone is bored and wants to daydream. https://racecarsdirect.com/Category __________________ Instagram; @roastbeefmike
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06-27-2019, 06:08 PM	#9652
kyippee Lieutenant Colonel 1066 Rep 1,617 Posts Drives: E92 M3, Supra MK5, F44 235GC Join Date: Feb 2017 Location: SF Bay Area iTrader: (0)	dogbone when you turned off MDM at that point, did the car catch you off guard any time during that day? Or was it just smooth sailing because you had already been tracking the car and had lots of seat team?
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06-27-2019, 09:48 PM	#9658
roastbeef Lieutenant General 11405 Rep 12,626 Posts Drives: E92 M3 Join Date: Nov 2010 Location: Orange County, CA iTrader: (4)	The trailer parking construction is progressing nicely. Now I just need a trailer... and a truck. Attached Images __________________ Instagram; @roastbeefmike
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