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      03-15-2012, 05:28 AM   #58
OC3
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Drives: 2013 M3 E92 Jerez Blk DCT ZCP
Join Date: Nov 2010
Location: SoCal

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Quote:
Originally Posted by Groundpilot View Post
It would be interesting to see lap times with MDM on vs MDM off. Anyone has done it?
I have.

I'm probably in a unique situation in that, I ran 27 track days over an 11 month period (started tracking in April of last year) at 95% in MDM mode.

During that time, I've progressed from a complete track n00b to running in (according to local track event organizers' run group systems) high intermediate or advanced groups (whatever that means).

Using Buttonwillow track as an example (and, it's a good example as it's a technical track and it's a track where time attacks are held & measured at), I did 2:06 both in MDM and with DSC off. Not the fastest, but not slow either. The point is, at this point (8 times on this track), my lap times are the same in both traction control modes. It should be noted that I only ran 1 track day here in DSC off mode all day.

While I'm sure I can reduce that lap time further by going DSC off exclusively, the prospect of going slower for a while (probably several track days) to eventually go faster is something I don't relish. I guess I'm impatient.

Bottom line is, as several people mentioned, each to his own. I'm having a ton of fun out there at HPDE/track events and there ain't nobody who is going to convince me to run in one traction control mode over another. I've been ridiculed and needled, but (as the song goes) I'll do it my way.

I know the arguments, pros & cons, of MDM vs DSC off. And, with my car's particular setup right now (Ground Control suspension & aggressive camber, Brembo BBK w/ Endless pads & squared R-S3 tires, and otherwise, completely stock), I don't expect to shave substantial amount of time any time soon by going DSC off. If anything, I'll be slower for a while. What will get me faster lap time quickly is mods such as better suspension (Moton, JRZ, etc), aero (wing, front splitter), more power (exhaust & tune), etc.

So, what about driver skill? I think I'm decent. Will going DSC off make me a better driver? Possibly. But, to what extent? Will it eventually get me a seat on the Formula 1 circuit? Hah.

Perhaps in hindsight, I should've transitioned to DSC off before I got too comfortable with MDM mode. The thought of doing 5 Southern California tracks that I regularly go to in slower learn-how-to-drive-these-tracks-all-over-again fashion on at least 3 or more visits for each tracks is not exciting.

As for driving in MDM mode, sure, it interferes at slow tight corners when you get on the throttle. At Buttonwillow 13CW, the section that connects the Sweeper to beginning of Esses, at Sunset, at Sunrise and, most of all, at Off-ramp, the faster you get at this track, more the prominent the effect of MDM interference at these corners. It had gotten to the point where, when you get on the throttle, the long silence where everything seem to go in slow motion, seems just forever lasting.

But, I've developed a way to minimize the MDM's negative effect at these corners. MDM, of course, kicks in when it senses that (what it thinks is) too much throttle is being applied "while" the steering wheel is turned. So, you briefly unwind the steering wheel (i.e. straighten it out) to fool the MDM, whence, you see the RPM needle start to climb again and hear the engine sound. But wait, you need to complete the turn, so you turn in again. And, MDM kicks in again. So, you unwind again. So on & so forth. So, videos show the steering wheel being played back & forth, back & forth thru the tight turns. But, that's done with DSC off also, but obviously for a different reason -> to counter against oversteers (and, when you're oversteering, and hence, not going straight, you're losing a bit of time too, aren't you?). So, what's the end result? I feel decently quick thru tight turns (but, obviously not as quick as when DSC off).

As for the upside, well, obviously it's safer than DSC off. I can be very aggressive in attacking the tracks with MDM, and just can't be similarly aggressive with DSC off. To do so would require substantial track equipment upgrades (as mentioned above) or some private lessons from Christian Vettel. Or, several more years of track experience with the same current car setup. At certain sections, I'm slower with DSC off, as the speed is too high and the car (as good a car as M3 is) tends to have more lateral movement than it does in MDM at the same sections. So, I find myself throttling back a bit. And, yes, you definitely take different lines around the tracks when going DSC off.

But, MDM of course won't save you at all situations. Fling the car at 120 mph into a 50 mph turn, lulz, good luck. Physics takes over.

Someone mentioned "thinking about some stupid sh*t" while on the track - i.e. momentarily lose focus. That happened to me this past Saturday at Buttonwillow. As I was going through Bus Stop and approaching left-hand turn 9, I caught a glimpse in the mirror of a track buddy's Stohr F1000 coming up fast behind me. And, for a brief moment, I was admiring its open-wheeled outline. It's a beautiful machinery. Well, when I re-focused on the turn in front of me, I wound up taking the turn a fraction of a second later than I usually do. So, upon exiting, I wound up further out to the right side of the track than usual, and so the rear passenger side wheel went into the dirt, and even in MDM mode, let me tell you, that corner of the car (because the steering wheel was still turned to the left a bit) came swinging out to the right much more so than what MDM usually allows on asphalt. I quickly counter-steered into the slide, but that's when a very interesting thing happened. The backend snapped back (to the left, and so I straightened out the steering wheel), but snapped back neatly inline to the direction of the track. The sensation felt like something spring-loaded rattling back in place rapidly. Here's the video: first is my side window mounted cam, and the second is from Stohr F1000 close up behind me:





While I feel somewhat comfortable with car control, counter-steering, etc, if I was DSC off at that time, I don't think I could've managed the backend of the car to fall so neatly back inline (probably would've fishtailed a bit before getting it straightend). I mean, MDM, with what, its computer taking hundreds of samples a second, was simply marvelous on that close call.

Now, here's another video of an incident at the same corner on several track day events prior. This was from a session that day wherein I wanted to try running DSC off. Well, keenly aware that I was DSC off, I took it easy a bit up to this corner. But, after I made this left turn, I momentarily forgot that I was DSC off and started pumping/modulating the throttle, which is (along with playing w/ the steering wheel back & forth) what I usually had to do in MDM mode (i.e. you're essentially fighting the computer). It, after so many track days, had become a sort of muscle memory.



At least I kept the car from fishtailing around, lulz.

Here's a video of the same spinout taken from thorny's car:



Anyhow, we're obviously not out there racing for money or trophy, and not trying to move up a race class. I'm addicted and having a lot of fun. Not sure what the future will hold for me in terms of traction control setting...

Here's a 2:06.x run in MDM this past Saturday:



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Last edited by OC3; 03-15-2012 at 06:01 AM.
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