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      07-08-2008, 01:22 PM   #1
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MDM at the track

Another laid back day at the track with the BMW CCA. I posted the following on another thread on the main page, but I think it will get lost.

This time, I pushed the car harder, and MDM was problematic--especially in 2nd gear coming out of a hairpin going uphill. You set the car up the right way, start gradually throttle steering, nothing's out of line or problematic, you apply just a bit more as you are tracking out, and then MDM doesn't like the slight drift and cuts power. The issue is the rear end is unloaded and the car gets unsettled. It's not as if that induces a spin or anything since who knows what else MDM is doing at that point to keep the car straight, but you just kind of get stuck there. I still don't feel comfortable with turning it completely off, but I was pretty close to doing so as this kept on happening.

Have you guys run into the same situation? Opinions on this?
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      07-08-2008, 02:25 PM   #2
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Similar thoughts to yours. MDM is nice and much better than DSC on(horrible); however it is still way to intrusive for me. Unfortunately, I’m not confident enough just yet to turn DSC completely off; so until then, I’m just going to have to keep my mouth shut, and feel the annoying sensation of gassing the car out of a turn, and waiting for DSC to release my throttle.

I think as good as MDM is, the car is programmed based on yaw/speed/braking. etc etc, which at the track is very hard for the car to tell if you're about to crash; as opposed to kicking the back end out a bit to make a fast turn. I guess, the way I look at it is, MDM's a happy medium and only makes me aspire to be confident enough one day to shut DSC entirely off.
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      07-08-2008, 11:12 PM   #3
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if you leave MDM on then think of it as an excersice in being so smooth with the car and rolling on the throttle so gentle as to not having it kick in. I think mashing the throttle and then waiting for MDM to release it is a bad habit to practice.
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      07-09-2008, 01:12 AM   #4
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if you leave MDM on then think of it as an excersice in being so smooth with the car and rolling on the throttle so gentle as to not having it kick in. I think mashing the throttle and then waiting for MDM to release it is a bad habit to practice.
thanks for the advice, but if your implying that's what i was describing...not the case. What i'm saying is no matter what the application rate is of the throttle, if DSC comes on due to the rear tires slipping through a turn(which at times you want to happen), throttle repsonse is cut (MDM is not as extreme obviously). Being smooth does not mean that traction doesn't break...if it did, DSC fully ON would not be a negative factor, make sense. However, i do agree with you that MDM is a great tool to safely improve your skill, which is why i stated I keep it on
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      07-09-2008, 10:17 AM   #5
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if you leave MDM on then think of it as an excersice in being so smooth with the car and rolling on the throttle so gentle as to not having it kick in. I think mashing the throttle and then waiting for MDM to release it is a bad habit to practice.
But that is the slow way to do it!You should learn proper car control before you are ever on a race track!
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      07-09-2008, 11:01 AM   #6
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if you leave MDM on then think of it as an excersice in being so smooth with the car and rolling on the throttle so gentle as to not having it kick in. I think mashing the throttle and then waiting for MDM to release it is a bad habit to practice.
Hmmm...who said I saw mashing the throttle (not sure if you directed your post at me or DJ9 by the way although we seemed to have a similar experience)? If you read my post, you'll see that I was mentioning a scenario where I slowly begin throttle steering the car and naturally it would start sliding a little but nothing out of control or undesired. My instructor's first comment of the day was that I did throttle steering well. I don't think there is anything wrong with that as long as the car doesn't start sliding around because you just floored it and you are about to lose it. As DJ9 is saying, MDM kicks in regardless. It just doesn't seem to like the wheels sliding for an extended period of time. That said, being smooth surely is a good thing and helps, but being smooth to the entent that MDM is kept at bay might mean slower exit speeds. Did you use MDM at the track? What was your experience like?
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      07-09-2008, 11:02 AM   #7
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I haven't tracked my M3 yet...but figure I'll start with DSC on....probably not like it and move to MDM..... I don't see myself using DSC off for more than maybe 1 lap at a mild pace.....
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      07-09-2008, 11:40 AM   #8
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just general comments. I prefer DSC off totally. but I advise beginners to drive with it on. we saw a large number of beginners crash e46 M3's as they couldnt control thier right foot with DSC off. for beginners DSC often kicks in because they are not smooth or not patient with the throttle. If you are advanced then any drifting or slipping confuses the computer into thinking you are crashing. also banking alone can kick DSC in.

I'll be tracking mine the first time in a few weeks. and will try MDM first and then likely turn it all off.
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      07-09-2008, 12:06 PM   #9
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just general comments. I prefer DSC off totally. but I advise beginners to drive with it on. we saw a large number of beginners crash e46 M3's as they couldnt control thier right foot with DSC off. for beginners DSC often kicks in because they are not smooth or not patient with the throttle. If you are advanced then any drifting or slipping confuses the computer into thinking you are crashing. also banking alone can kick DSC in.

I'll be tracking mine the first time in a few weeks. and will try MDM first and then likely turn it all off.
What group do you run in, as you mention you exclusively attend BMW CCA events? A,B,C or D?

It think the point is, it’s not black and white. You can be at a skill level where your track speed produces intended drifting, slipping, and the type of braking that confuses the comp; while still not being entirely confident on turning off your DSC on your vehicle. This is where MDM is nice to have; however it does not remove the intrusiveness of DSC, it simply reduces it; which is what we are saying.

It's always good to keep in mind that some of us are not track stars or view our M's as a dedicated track vehicles; rather individuals who are skilled drivers and enjoy weekend track events...and do not want to thread the needle too thin; so we hedge risky pleasure with being intelligently conservative.

Remember, the definition of an "accident" is that it was not intended or foreseen to happen, regardless how good of a driver you are.

All the best.
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      07-09-2008, 01:50 PM   #10
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On another note, what oil temps are you guys seeing? Mine reaches the 255 mark at NHMS, which doesn't have a long straight.
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      07-09-2008, 02:41 PM   #11
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Quote:
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What group do you run in, as you mention you exclusively attend BMW CCA events? A,B,C or D?

It think the point is, it’s not black and white. You can be at a skill level where your track speed produces intended drifting, slipping, and the type of braking that confuses the comp; while still not being entirely confident on turning off your DSC on your vehicle. This is where MDM is nice to have; however it does not remove the intrusiveness of DSC, it simply reduces it; which is what we are saying.

It's always good to keep in mind that some of us are not track stars or view our M's as a dedicated track vehicles; rather individuals who are skilled drivers and enjoy weekend track events...and do not want to thread the needle too thin; so we hedge risky pleasure with being intelligently conservative.

Remember, the definition of an "accident" is that it was not intended or foreseen to happen, regardless how good of a driver you are.

All the best.
haha - accidents is a poor term for a vehicle collision. most collisions are purely human error. yeah there is the rare tire blow out or oil on the track that could never have been seen. but mostly human errror. I run in the I group.

If you run in C or D I say leave it on. If you run in B then its optional between you and your instructor. I see no reason for A students to have DSC on in most cases.
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      07-09-2008, 02:42 PM   #12
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On another note, what oil temps are you guys seeing? Mine reaches the 255 mark at NHMS, which doesn't have a long straight.



why not start a new thread - get more responses.
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      07-09-2008, 03:29 PM   #13
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haha - accidents is a poor term for a vehicle collision. most collisions are purely human error. yeah there is the rare tire blow out or oil on the track that could never have been seen. but mostly human errror. I run in the I group.

If you run in C or D I say leave it on. If you run in B then its optional between you and your instructor. I see no reason for A students to have DSC on in most cases.
What's your story bud. Not sure if you're trying to be insulting or rude; but this is 2nd instance in this thread that you've made a post with a derogatory tone/remark about the comments we've expressed and are speaking extremely authoritively about your opinion, as if it is a proven fact or guidline to follow.


Still not sure what run group you are in...what is 'I"? Attempt at humor?

It's either A through D...so you are an Instructor I take it?
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      07-09-2008, 03:53 PM   #14
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On another note, what oil temps are you guys seeing? Mine reaches the 255 mark at NHMS, which doesn't have a long straight.
I saw 125c on a 29c day.I normally see 90-100 c on the street and 150c is the upper end of the scale.
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      07-09-2008, 04:54 PM   #15
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I saw 125c on a 29c day.
OK, so that's about 257F. Matches what I saw on a 30c day. Thanks.
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      07-09-2008, 04:55 PM   #16
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why not start a new thread - get more responses.
Nah, it's OK, I'm jacking my own thread.
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      07-09-2008, 05:01 PM   #17
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I haven't tracked my M3 yet...but figure I'll start with DSC on....probably not like it and move to MDM..... I don't see myself using DSC off for more than maybe 1 lap at a mild pace.....
I don't use full DSC in any dry driving situation anywhere. It is way too intrusive IMO. It won't even let you accelerate properly on a daily driving sitaution such as making a left turn onto a busy main steet from a side street. I'm sure I'll need it in the winter though. It would be way OT on the track.
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      07-10-2008, 12:08 AM   #18
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[quote=lucid;2952763]This time, I pushed the car harder, and MDM was problematic--especially in 2nd gear coming out of a hairpin going uphill. You set the car up the right way, start gradually throttle steering, nothing's out of line or problematic, you apply just a bit more as you are tracking out, and then MDM doesn't like the slight drift and cuts power. The issue is the rear end is unloaded and the car gets unsettled. It's not as if that induces a spin or anything since who knows what else MDM is doing at that point to keep the car straight, but you just kind of get stuck there. I still don't feel comfortable with turning it completely off, but I was pretty close to doing so as this kept on happening./QUOTE]

Did you try third gear in the same corner and what was the outcome? What was your RPM at entry, apex and exit? I assume you entered in second gear.

How did you set the car up for the turn? You only say you set the car up the right way. Did you late apex the hairpin which will give you a faster exit in a straighter line? How did you throttle steer at around the apex and approching the exit of the turn? At this point in the turn, you should be gradually applying throttle to make a smooth exit under maximum power without wheel spin. How are you drifting on exit of a hairpin turn? You may have been power sliding the rear through the turn but not four wheel drifting out of the exit at those speeds. Maybe just a confusion of the word.

Please don't take any offense to these observations/comments. They are intended to figure out why your are experiencing your observation at this particular section of the track. I think you are using too much throttle and speed through the corner. You should be at maximum braking into a hairpin and may do all your braking in a straight line before turn in, or may utilize trail braking up to or before the apex, after which time you will be on the throttle at a position capable of transitioning the car back to an appropriate exit speed. If you wheels are spinning or the rear end is getting out of line, you are slower through this corner than if you are not spinning, and remember this car has an LSD. With an open diff, it would be much worse. To really determine how much power you are really using, when safe to do so and no other cars are in back of you, turn off stability completely and drive this corner the same way and at the same speed as with it on. You will see just how smooth you are and when and how much power you need to keep everything in check. Just be careful and spend an entire session just working on this corner trying different lines and speeds until you get it right. Most drivers use too much throttle and driving with stability off teaches you good throttle management. The gas pedal is not a light switch with an on and off only position. It is a dimmer switch with 100 points of adjustment between on and off.

Good luck with your testing
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      07-10-2008, 12:21 AM   #19
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Quote:
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What's your story bud. Not sure if you're trying to be insulting or rude; but this is 2nd instance in this thread that you've made a post with a derogatory tone/remark about the comments we've expressed and are speaking extremely authoritively about your opinion, as if it is a proven fact or guidline to follow.


Still not sure what run group you are in...what is 'I"? Attempt at humor?

It's either A through D...so you are an Instructor I take it?
don't take it personal. my job involves some traffic engineering and I see many stupid accident reports people are invlovled. believe me its a large part human error and stupidity. not trying to be insulting to you or anyone. I have been tracking cars for 14 years so I do have some experience.
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      07-10-2008, 12:25 AM   #20
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I don't use full DSC in any dry driving situation anywhere. It is way too intrusive IMO. It won't even let you accelerate properly on a daily driving sitaution such as making a left turn onto a busy main steet from a side street. I'm sure I'll need it in the winter though. It would be way OT on the track.

I have to agree on the street I really like the MDM. I use it all the time. the e46 m3 DSC was waaaaaay too intrusive. but I didnt like it fully off for the street. I like the 3 stage approach in the e92. thumbs up BMW.
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      07-10-2008, 12:32 AM   #21
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don't take it personal. my job involves some traffic engineering and I see many stupid accident reports people are invlovled. believe me its a large part human error and stupidity. not trying to be insulting to you or anyone. I have been tracking cars for 14 years so I do have some experience.
No worries then, all good. And for the record, I do appreciate many of your posts and comments
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      07-10-2008, 03:21 PM   #22
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Did you try third gear in the same corner and what was the outcome? What was your RPM at entry, apex and exit? I assume you entered in second gear.

How did you set the car up for the turn? You only say you set the car up the right way. Did you late apex the hairpin which will give you a faster exit in a straighter line? How did you throttle steer at around the apex and approching the exit of the turn? At this point in the turn, you should be gradually applying throttle to make a smooth exit under maximum power without wheel spin. How are you drifting on exit of a hairpin turn? You may have been power sliding the rear through the turn but not four wheel drifting out of the exit at those speeds. Maybe just a confusion of the word.

Please don't take any offense to these observations/comments. They are intended to figure out why your are experiencing your observation at this particular section of the track. I think you are using too much throttle and speed through the corner. You should be at maximum braking into a hairpin and may do all your braking in a straight line before turn in, or may utilize trail braking up to or before the apex, after which time you will be on the throttle at a position capable of transitioning the car back to an appropriate exit speed. If you wheels are spinning or the rear end is getting out of line, you are slower through this corner than if you are not spinning, and remember this car has an LSD. With an open diff, it would be much worse. To really determine how much power you are really using, when safe to do so and no other cars are in back of you, turn off stability completely and drive this corner the same way and at the same speed as with it on. You will see just how smooth you are and when and how much power you need to keep everything in check. Just be careful and spend an entire session just working on this corner trying different lines and speeds until you get it right. Most drivers use too much throttle and driving with stability off teaches you good throttle management. The gas pedal is not a light switch with an on and off only position. It is a dimmer switch with 100 points of adjustment between on and off.

Good luck with your testing
Good questions. I appreciate most of your comments, but you are making some assumptions. As I've said earlier, I was not flooring the throttle; I know that the gas pedal is not a light switch, and that one should break in a straight line and the other basics.

Anyway, here is some clarification:

1. About this particular turn: This is where you get off the NHMS oval at the middle of its back straight. The hairpin leads to a steep uphill which should be driven across with a wide radius. So you go from the straight of the oval to a steep banked hill. The transition is not smooth, and there is no clear best line through the hairpin itself. People take different approaches. But whatever you do, you need to make sure the car lands on the bank pointing in the right direction after the apex up the hill. This usually means kicking the tail out just a little bit right after the hairpin as you begin to transition onto the banked surface. I've watched several races there, and that's just about what every single car did.

2. Kicking the tail out a bit is not an issue, and is not necessarily a must. When I do it carefully, I don't get MDM intervention as that the car regains traction quickly on its own when it hits the bank. So, it's like you get on the throttle just a bit when you are past the apex, the tail kicks out slightly, you land on the bank, car regains traction, and hopefully you are pointing in the right direction up the hill.

3. Prior to the hairpin, just before hitting the brakes, the car is close to redline in 3rd gear, which is probably around 100mph. I complete braking and downshifting before I reach the apex, so those are not issues. However, I don't know what the rpms are exactly before the entering the turn.

4. I tried taking this corner in 3rd many times. If the turn led to a level surface, that would fine/desirable. But 3rd gear does not pull hard enough for climbing the steep hill, and you end up being real slow.

5. The issue has to do with what happens after you land on the bank and start climbing the hill. The track is wide there, so you naturally want to unwind, gradually get on the throttle, and track all the way out in the process. The track out cone was placed right before the top of the hill, which, according to my instructor, is the ideal line. So, as you get on the throttle gradually and track out, the car naturally starts slowly drifting to the side, but in a controllable fashion, meaning you can control the rate of the slide with the throttle. This is where I experience the problem as after a second or so of this MDM decides the car should not be drifting gradually to the side, and cuts power. Then the car is unsettled, and you are kind of stuck there.

That said, I agree that getting on the throttle at an even slower rate might keep MDM at bay. But what I am trying to learn by posting here is if that would be the faster or slower way. My feeling is that would be slower not faster.
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