MDM mode at the track?

[Assimilator1]

Wheel bolts failed? Never heard of that before, sure you don't mean they came lose! (wasn't there vibrations before the wheel came off btw??).

amg6975
Did you mean roasting the pads?

Interesting about the pad life issue, perhaps that's a large reason why the stock brakes roast on the track after a little while too!?

I'm still not turning DSC fully off though, I'm not worried so much about losing it on slow to medium speed corners, but on faster corners (say 70+ mph I suppose), going sidewards if something went wrong could be really bad news!

I'm still not clear though as to what the differences are between MDM and DSC fully on (no one answered that).

Originally Posted by tsk94

Correct. You'd need to pull the fuse to disable ABS. Or some kind of fault in the module, failed wheel speed sensor, etc.

MDM is very intrusive, even in the Euro mode. The amount of brake application it does is crazy. Small amounts, but all the time during corning. Dogbone did a good write-up in his thread a while back. Showed the amount of brake pressure it was putting on each wheel throughout a corner and it was surprising, to say the least.

With that said, MDM is still much better than DSC fully on.

I looked through the threads that dogbone had started and didn't see one titled MDM/DSC testing, was it in his (huge!) track build thread?

[M3SQRD]

Originally Posted by Assimilator1

I looked through the threads that dogbone had started and didn't see one titled MDM/DSC testing, was it in his (huge!) track build thread?

I think this is what you’re looking for. There’s more discussion of the charts and MDM in later posts.

https://www.m3post.com/forums/showpo...&postcount=746

[Ximian]

Originally Posted by Assimilator1

Wheel bolts failed? Never heard of that before, sure you don't mean they came lose! (wasn't there vibrations before the wheel came off btw??).

Yes, 1 year old bolts (OEM-Rein) failed. Torque was checked before the session started while the bolts and wheel hub were cold. They didn't back out because on-track support spent a bit of time removing the remaining pieces of the bolts out of the wheel hub.

I had slicks and always pick up some tire chunks so always had some vibration but nothing out of the ordinary. It happened on a cool down lap so I wasn't entirely focused on making sure everything felt fine as I was nowhere near pushing it as far as pace.

[dogbone]

Originally Posted by Assimilator1

I'm still not clear though as to what the differences are between MDM and DSC fully on (no one answered that).

I looked through the threads that dogbone had started and didn't see one titled MDM/DSC testing, was it in his (huge!) track build thread?

The big post I did illustrating MDM's behavior can be found here on page 34 of my thread:
https://www.m3post.com/forums/showpo...&postcount=747

As far as the differences between MDM and DSC fully on-----there's not much difference in what it does or how it works; DSC fully on is simply more restrictive/more intrusive/kicks in sooner/doesn't let the car sideways hardly at all before kicking/doesn't allow for much slip angle before taming the situation. MDM gives you more leeway before it kicks in. And there's a USA version of MDM and and Euro version. The USA version is more restrictive than the Euro version, meaning you can get a bit more slip angle with the Euro version before kicking in.

The traction control system has two tools at its disposal to control the car based on what its sensors are detecting: 1. It can grab any individual brake caliper to keep the tail of the car where it's supposed to be---something obviously the driver cannot do. 2. It can restrict throttle response----basically, no matter how much you mash the gas pedal, the computer will decide when and how much throttle is actually applied.

The mistake people make is that they think if the DSC light isn't flashing, then traction control isn't doing anything. That is incorrect. It is working even when the light is not flashing.

When the car grabs an individual brake caliper to control the situation, you can feel it, if you're paying attention to it. It's even more noticeable if you have aggressive race pads in the calipers because you can feel the car slightly hesitating more as it's grabbing.

The 2nd method of throttle control is usually verrrrrry sneaky and subtle. The driver can mash on the throttle as much as they want on a corner exit, but the computer will very smoothly bring on the power as it sees fit. You don't even realize that it's doing it. It only becomes apparent when you turn DSC completely off, then mash the gas the way you normally do and-----surprise!----holy shit, the car has all kinds of power on exit and the tail steps out or you spin. Only then, do you realize that the computer was very subtly controlling the power output, and there was no indication of flashing lights or anything else. Now, there are dynamic moments when you may have initially mashed the throttle and got going and then the car got uncomfortable with the situation (ie. tail is quickly stepping out and the car is about to spin) and it harshly/immediately cuts power. But this is not the only time it's kicking in---it's just the most obvious.

[jmeenach]

Originally Posted by dogbone

The big post I did illustrating MDM's behavior can be found here on page 34 of my thread:
https://www.m3post.com/forums/showpo...&postcount=747

As far as the differences between MDM and DSC fully on-----there's not much difference in what it does or how it works; DSC fully on is simply more restrictive/more intrusive/kicks in sooner/doesn't let the car sideways hardly at all before kicking/doesn't allow for much slip angle before taming the situation. MDM gives you more leeway before it kicks in. And there's a USA version of MDM and and Euro version. The USA version is more restrictive than the Euro version, meaning you can get a bit more slip angle with the Euro version before kicking in.

The traction control system has two tools at its disposal to control the car based on what its sensors are detecting: 1. It can grab any individual brake caliper to keep the tail of the car where it's supposed to be---something obviously the driver cannot do. 2. It can restrict throttle response----basically, no matter how much you mash the gas pedal, the computer will decide when and how much throttle is actually applied.

The mistake people make is that they think if the DSC light isn't flashing, then traction control isn't doing anything. That is incorrect. It is working even when the light is not flashing.

When the car grabs an individual brake caliper to control the situation, you can feel it, if you're paying attention to it. It's even more noticeable if you have aggressive race pads in the calipers because you can feel the car slightly hesitating more as it's grabbing.

The 2nd method of throttle control is usually verrrrrry sneaky and subtle. The driver can mash on the throttle as much as they want on a corner exit, but the computer will very smoothly bring on the power as it sees fit. You don't even realize that it's doing it. It only becomes apparent when you turn DSC completely off, then mash the gas the way you normally do and-----surprise!----holy shit, the car has all kinds of power on exit and the tail steps out or you spin. Only then, do you realize that the computer was very subtly controlling the power output, and there was no indication of flashing lights or anything else. Now, there are dynamic moments when you may have initially mashed the throttle and got going and then the car got uncomfortable with the situation (ie. tail is quickly stepping out and the car is about to spin) and it harshly/immediately cuts power. But this is not the only time it's kicking in---it's just the most obvious.

I tested MDM vs DSC OFF Saturday at Willow Springs and can confirm. I could feel the brakes being applied rather aggressively, especially in turn 8-9 to the point where it felt like the car was trying to pull me into the apex cone on 9. The best lap I could muster with MDM was 1:35.7, whereas my best lap with DSC completely off was 1:34.4.

[Assimilator1]

Originally Posted by M3SQRD

I think this is what you’re looking for. There’s more discussion of the charts and MDM in later posts.

https://www.m3post.com/forums/showpo...&postcount=746

No mention of MDM testing in that post...

Originally Posted by Ximian

Yes, 1 year old bolts (OEM-Rein) failed. Torque was checked before the session started while the bolts and wheel hub were cold. They didn't back out because on-track support spent a bit of time removing the remaining pieces of the bolts out of the wheel hub.

I had slicks and always pick up some tire chunks so always had some vibration but nothing out of the ordinary. It happened on a cool down lap so I wasn't entirely focused on making sure everything felt fine as I was nowhere near pushing it as far as pace.

Oh ok, fair enough, and very weird! (And scary!)
That said, my experience is nearly all with road cars (on road) and not with tracks cars.

[M3SQRD]

Originally Posted by Assimilator1

No mention of MDM testing in that post...

Oops, sorry…dogbone provided the correct link above.

[Assimilator1]

Originally Posted by M3SQRD

Oops, sorry…dogbone provided the correct link above.

Hehe, no worries
Just going through his posts now...

Originally Posted by dogbone

..........

The 2nd method of throttle control is usually verrrrrry sneaky and subtle. The driver can mash on the throttle as much as they want on a corner exit, but the computer will very smoothly bring on the power as it sees fit. You don't even realize that it's doing it. It only becomes apparent when you turn DSC completely off, then mash the gas the way you normally do and-----surprise!----holy shit, the car has all kinds of power on exit and the tail steps out or you spin. Only then, do you realize that the computer was very subtly controlling the power output, and there was no indication of flashing lights or anything else. Now, there are dynamic moments when you may have initially mashed the throttle and got going and then the car got uncomfortable with the situation (ie. tail is quickly stepping out and the car is about to spin) and it harshly/immediately cuts power. But this is not the only time it's kicking in---it's just the most obvious.

Thanks for your detailed reply, and the link
Weird that there's even a different version for the US and Europe!

I find if I over do the power on exit (rather than just mash it, I don't normally mash it ), then the DSC light flashes, even if it otherwise feels ok. If you're saying it can still do it to a more subtle degree when being gentler on the throttle, then I guess (like you said) I'd never know.

But I do know that on Snetterton, after lunch, when I'd discovered I'd cooked the rear pads and worn them down to just a few mm! When I went back on track I was quite a bit later on the power out of the exits (no DSC light came on, and I was easier on the brakes in general too) and I managed to do another 2 sessions without any more significant wear. So at the least, on that occasion, I'm reasonable sure the DSC wasn't doing anything significant.

Anyway, your post is interesting and useful, food for thought.
Although I'm never going to turn DSC fully off! I may well try MDM at some point.
Nice data on your MDM test from 2018, fascinating!