The M Differential is an engineering marvel

[JoeKixxon]

Very early this morning I was driving in the rain, and I accelerated somewhat briskly to catch a light before it changed. Nothing crazy, but maybe not the safest or best idea in the rain, but the car just inspires so much confidence. I noticed the traction control light flickering on the dash (TC full on), but the rear felt like it was hooking up nicely, and the acceleration was smooth.

I was contemplating my decision to make the light, thinking next time I'll just wait, but I was also just blown away once again by the performance and technology on tap in the M3. What a privilege to own and drive one of these cars. I still don't take it for granted.

I've done the M driving school, and experienced the wet skidpad and snap oversteer in a figure 8 with TC full off, and if the car loses complete traction on all four wheels, it's on it's own and the driver is essentially ballast. Its the the opposite of confidence inspiring. If it were not in a controlled environment it would be terrifying. So to feel the effectiveness of the M dif & TC is just awesome, but of course I do my best to be safe on the street, so I'll continue to use my power wisely.

"Maximum driving pleasure is guaranteed." says this page... I agree.

https://www.bmw-m.com/en/topics/maga...ferential.html

[FirstF80InSpace]

I hear ya. I've triggered the TC many times in my F80. Lol.

[dallastide]

Originally Posted by FirstF80InSpace

I hear ya. I've triggered the TC many times in my F80. Lol.

I'd say I see that light flashing at least 3-4 times a week if not every day

[SMGCFP]

I have not tried driving the car with DSC off. MDM for sure, but too much power to not have the DSC. I am not a great driver. I see the light flicker often. Maybe one day I'll try a burnout or a fishtail.

[georgere]

I agree. My M3 drives like AWD especially in the winter.
Safety - check, lower weight vs AWD- check, lower cost vs AWD- check, fun driving RWD - check....

[NickyC]

Originally Posted by SMGCFP

I have not tried driving the car with DSC off. MDM for sure, but too much power to not have the DSC. I am not a great driver. I see the light flicker often. Maybe one day I'll try a burnout or a fishtail.

By turning off DSC and launching the car correctly, you'll be amazed at just how quick off the line these cars are.

[JamesGames]

Originally Posted by JoeKixxon

Very early this morning I was driving in the rain, and I accelerated somewhat briskly to catch a light before it changed. Nothing crazy, but maybe not the safest or best idea in the rain, but the car just inspires so much confidence. I noticed the traction control light flickering on the dash (TC full on), but the rear felt like it was hooking up nicely, and the acceleration was smooth.

I was contemplating my decision to make the light, thinking next time I'll just wait, but I was also just blown away once again by the performance and technology on tap in the M3. What a privilege to own and drive one of these cars. I still don't take it for granted.

I've done the M driving school, and experienced the wet skidpad and snap oversteer in a figure 8 with TC full off, and if the car loses complete traction on all four wheels, it's on it's own and the driver is essentially ballast. Its the the opposite of confidence inspiring. If it were not in a controlled environment it would be terrifying. So to feel the effectiveness of the M dif & TC is just awesome, but of course I do my best to be safe on the street, so I'll continue to use my power wisely.

"Maximum driving pleasure is guaranteed." says this page... I agree.

https://www.bmw-m.com/en/topics/maga...ferential.html

What you're explaining is more TCS controlled than M-diff controlled, without the M-Diff the experience is exactly the same. You can thank the rear brakes for "cutting" power and giving you the "confidence inspiring" feeling. Turn that TCS off and let me know if your m-diff in the rain does the same thing, I am willing to bet the full send will change your mind faster than a TCS light can blink, similar to your M driving school experience.

[SenorFunkyPants]

Myself I'm not a massive fan of the F8x M diff.
The E9x M3 version was more consistent as it had mechanical lock up driven by a shear pump.
The F8x M version while similar to the E9x M version, has an electric motor directed by the DSC to lock the diff, and it doesn't have the same consistency.
The DSC runs a routine every ~1000 kms or so to reset the motor position and therefore the clutch pack pressure. The difference in how aggressive the diff locks just after the reset compared to just before its due to reset can be significant.

[CanAutM3]

Originally Posted by JoeKixxon

Very early this morning I was driving in the rain, and I accelerated somewhat briskly to catch a light before it changed. Nothing crazy, but maybe not the safest or best idea in the rain, but the car just inspires so much confidence. I noticed the traction control light flickering on the dash (TC full on), but the rear felt like it was hooking up nicely, and the acceleration was smooth.

I was contemplating my decision to make the light, thinking next time I'll just wait, but I was also just blown away once again by the performance and technology on tap in the M3. What a privilege to own and drive one of these cars. I still don't take it for granted.

I've done the M driving school, and experienced the wet skidpad and snap oversteer in a figure 8 with TC full off, and if the car loses complete traction on all four wheels, it's on it's own and the driver is essentially ballast. Its the the opposite of confidence inspiring. If it were not in a controlled environment it would be terrifying. So to feel the effectiveness of the M dif & TC is just awesome, but of course I do my best to be safe on the street, so I'll continue to use my power wisely.

"Maximum driving pleasure is guaranteed." says this page... I agree.

https://www.bmw-m.com/en/topics/maga...ferential.html

I'm confused. What does this episode have to do with the M e-diff ?

It's simply DSC in action.

[Rxpert]

Originally Posted by georgere

I agree. My M3 drives like AWD especially in the winter.
Safety - check, lower weight vs AWD- check, lower cost vs AWD- check, fun driving RWD - check....

I'm not sure what winters are like where you're from, but where I live the M3 most definitely does NOT drive like an AWD car.

Before the M3, I had a 435i xDrive and that thing could run circles around the M3 in snow. xDrive is in another league.

Don't get me wrong, I'm not trying to hate, just provide reasonable expectations. I was extremely pleasantly surprised how well the M3 does drive & handle the winter, but it's a far cry from AWD territory (if you're driving in several inches of snow everyday at least).

[behindthen0thing]

My traction control light is triggered almost every time i drive. Is this a special occurrence?

[Tepr05]

Originally Posted by behindthen0thing

My traction control light is triggered almost every time i drive. Is this a special occurrence?

It's a bit more rare on the ZCP with the flatter more gradual torque curve and wider rears.

[georgere]

Originally Posted by Rxpert

I'm not sure what winters are like where you're from, but where I live the M3 most definitely does NOT drive like an AWD car.

Before the M3, I had a 435i xDrive and that thing could run circles around the M3 in snow. xDrive is in another league.

Don't get me wrong, I'm not trying to hate, just provide reasonable expectations. I was extremely pleasantly surprised how well the M3 does drive & handle the winter, but it's a far cry from AWD territory (if you're driving in several inches of snow everyday at least).

Agreed. M3 is not AWD but the diff and other tech make it very capable in the winter. I have been driving RWD exclusively as my only car for almost 15 years and have had no issues.
Deep snow (higher than car belly) and in situations when you'd need the front wheels to grab - M3 looses but on those days in my area nobody drives anyway. Schools closed and pple work from home. For people who need to drive in all conditions 100% of the time, they well know they need F150 or the like.

[clutchdj]

Enjoy your ///M Joe.

[2011zx10R]

Agreed; we are very fortunate to drive such an iconic vehicle.

[behindthen0thing]

Originally Posted by Tepr05

It's a bit more rare on the ZCP with the flatter more gradual torque curve and wider rears.

thats fine but I'm running 285's on the back with an R compound.

[Zoli007]

As you gain experience, you'll see what an amazingly good drift machine this car is in stock form with everything off. So controllable its awesome, and it has the power to maintain a great slide

[dezzracer]

Originally Posted by CanAutM3

I'm confused. What does this episode have to do with the M e-diff ?

It's simply DSC in action.

Wouldn't M E-diff contribute to episode he describes because it smartly and quickly locks to increase traction and forward motion.:

[jpy1980]

Not sure if sarcasm or not.....

Haha

[SenorFunkyPants]

Originally Posted by dezzracer

Wouldn't M E-diff contribute to episode he describes because it smartly and quickly locks to increase traction and forward motion.

Indeed...The diff lock up is controlled by the DSC and works in partnership with the TC to optimise traction. The part of DSC system that operates the diff electric motor takes a large amount of data from sensors across the car such as yaw, steering angle, wheel speeds etc to decide on how much lock to set.
The more aggressive the diff lock up, the less TC interference and the better acceleration.

[CanAutM3]

Originally Posted by dezzracer

Wouldn't M E-diff contribute to episode he describes because it smartly and quickly locks to increase traction and forward motion.:

It's actually the opposite. While a locking diff does improve traction, it can also be very traitorous in wet weather. Traction is not always your ally.

I had an episode on track where one rear wheel hit a puddle of water at 110mph at WOT in a slight kink with DSC off. That wheel aquaplanned and lost traction, so the diff sent the power to the opposite wheel as it should. This created a torque vectoring effect that instantly sent the car 90 degrees sideways. Believe me, it is not very pleasant to be looking through the side window at 110mph on a wet track (even if I am usually quite comfortable drifting a car around a track). From this day I learnt the downside of a locking diff and now use MDM when the track has water accumulation.

Another track buddy of mine totalled his M3 in very similar conditions. In his case, the diff caused a 180 degree rotation and he backed up into a post.

This is why I am saying that what the OP experienced is mostly the result of DSC action. If anything, the DSC counteracted the negative effect of the locking diff in those conditions.

[CanAutM3]

Originally Posted by SenorFunkyPants

Indeed...The diff lock up is controlled by the DSC and works in partnership with the TC to optimise traction. The part of DSC system that operates the diff electric motor takes a large amount of data from sensors across the car such as yaw, steering angle, wheel speeds etc to decide on how much lock to set.
The more aggressive the diff lock up, the less TC interference and the better acceleration.

Not necessarily, see post above.

Further, the M-Diff is not controlled by the DSC system, as it is still functional even with DSC off. While the two systems are tuned to work together and use input from the same sensors, the locking diff still does its own thing. From the e-diff Deep Dive and Interview:

"Tuning of the Active M differential is performed hand in hand with that of the chassis and the control systems, such as the DSC. All in all, it is a repetitive process. The responsible engineers conduct their testing activities jointly. The interplay of the individual systems is optimised as they are developed."