[CanAutM3]

Originally Posted by Robin_NL

IRL my M2C on PSS has a lot of tractionproblems. Which I generally like(sideways fun) , no worries, but on track for faster laptimes it's not the ideal setup, stock.
Suspension is too hard, just make it a tad softer on both ends and you're getting even less understeer and more traction. Take a look at the M2Comp Sportauto video on Nordschleife. Driver Gebhardt is experiencing more and more understeer. Thanks overheated PSS!
Unfortunately Sportauto didn't mention any in depth suspension setup differences between Comp and CS.
Does M2CS sit lower than M2 Comp?
Cheers
Robin

You are right, a softer suspension usually results in more mechanical grip at the expense of less sharp response.

IMO, the most significant difference between the M2C and M2cs is the addition of adaptive suspension on the CS which dynamically adapts in milliseconds to the driving conditions: softer when more grip is needed and stiffer when more response is needed.

Given what they did on the M4cs, where they optimized the chassis tuning for R-comp tires, I am pretty sure they did the same for the M2cs. I guess we will learn more about the details at the official unveiling.

As for ride height, I have not read anything on the specification thus far.

[akkando]

I wonder if the last model year of the m2 we will see the adaptive suspension and CF roof become options on the m2 or make it's way to other special additions?

[ChrisK]

Originally Posted by devo

I get where you are coming from, however, the weight loss going 763>788 is about 16-17lbs total. I have the 763s and absolutely love them AND can feel the difference.

Exactly my point. 763's and Inloose some weight :Lol:

[Karmic Man]

Originally Posted by Robin_NL

IRL my M2C on PSS has a lot of tractionproblems. Which I generally like(sideways fun) , no worries, but on track for faster laptimes it's not the ideal setup, stock.
Suspension is too hard, just make it a tad softer on both ends and you're getting even less understeer and more traction. Take a look at the M2Comp Sportauto video on Nordschleife. Driver Gebhardt is experiencing more and more understeer. Thanks overheated PSS!
Unfortunately Sportauto didn't mention any in depth suspension setup differences between Comp and CS.
Does M2CS sit lower than M2 Comp?
Cheers
Robin

The M2C is definitely under tyred...I have found by swapping the stock rims to lighter rims (2 kg per side) that helped to reduce the understeer and promote better handling.

I think changing to the CF bonnet (dropping around 10 Kg at the front) will help even further which I might end up doing should I decide to keep the Comp.

The next thing I will do when the PSS wears out is to change the tyres to Yoko A052

[Robin_NL]

Originally Posted by Karmic Man

The M2C is definitely under tyred...I have found by swapping the stock rims to lighter rims (2 kg per side) that helped to reduce the understeer and promote better handling.
I think changing to the CF bonnet (dropping around 10 Kg at the front) will help even further which I might end up doing should I decide to keep the Comp.
The next thing I will do when the PSS wears out is to change the tyres to Yoko A052

Which rims do you have now?
Any photos?

Choosing between 763s (with or without Cup tyres) or a Remus exhaust.....

Cheers
Robin

[hellrotm]

Originally Posted by Robin_NL

It was almost freezing(Zero(0) Celsius is freezing point overhere in Europe LOL)
The last sentence, I was already thinking about that yesterday, but someone said a couple of times PSS should be ok in 1 degrees Celsius

Track temps near freezing with a harder compound made even harder by the weather. I'd rather be in the car with the warmer weather and softer compound, guaranteed to have a lot more grip.

[CanAutM3]

Originally Posted by Karmic Man

The M2C is definitely under tyred...I have found by swapping the stock rims to lighter rims (2 kg per side) that helped to reduce the understeer and promote better handling.
I think changing to the CF bonnet (dropping around 10 Kg at the front) will help even further which I might end up doing should I decide to keep the Comp.
The next thing I will do when the PSS wears out is to change the tyres to Yoko A052

Are you seriously saying that just installing lighter wheels reduced understeer ??

[Robin_NL]

Originally Posted by CanAutM3

Are you seriously saying that just installing lighter wheels reduced understeer ??

My winterwheels (18") also weigh less and you feel it in the steering, the whole car feels a tad lighter on its feet. But to really eliminate understeer you must have:

-a wider front tyre(on dry)
-a softer ARB front (or a bit softer frontend vs rear end)
-more neg camber front end
-a bit more neg toe(helps turning in to some dregree)
- more front aero(if possible)

Or a lighter front end (carbon parts) in general which makes the 52/48 FR balance go to 51.5/48.5 FR (example)
But not too much, you want to have weight(balance) on the front and not like an old Beetle with 'no mass' upfront plowing into a haybale

Cheers
Robin

[Boss330]

Originally Posted by Robin_NL

My winterwheels (18") also weigh less and you feel it in the steering, the whole car feels a tad lighter on its feet. But to really eliminate understeer you must have:

-a wider front tyre(on dry)
-a softer ARB front (or a bit softer frontend vs rear end)
-more neg camber front end
-a bit more neg toe(helps turning in to some dregree)
- more front aero(if possible)

Or a lighter front end (carbon parts) in general which makes the 52/48 FR balance go to 51.5/48.5 FR (example)
But not too much, you want to have weight(balance) on the front and not like an old Beetle with 'no mass' upfront plowing into a haybale

Cheers
Robin

Even the "ideal" 50/50 isn't the optimal weight distribution for a track car.

Don't forget that one of probably the best track day cars, the 991 GT3 RS, has a 39/61 weight distribution! (Kind of like that old beetle... )

Getting close to 50/50 is however as good as it gets for a front engine rwd sedan type of car. Which is one of the reasons BMW's generally tend to be better suited for track day use and fun to drive than the direct competitors with front engine and rwd (even though many have caught up in later years).

But ideally you want less than 50 % on the front axle, more like the GT3 for instance.

BTW: My big 6-series Gran Coupe has a real world 49/51 weight distribution (but at 2070kg it's not quite 911 nimble on the track. And yes, I have tracked it more than once )

Regarding the winter tires making your steering feel lighter, that is more than any other factor caused by the winter tires deeper thread depth and open thread design. This contributes to much more thread squirm, ie the tires «move around» on themselves. This creates the lighter feel that you get when changing to winter tires. Most pronounced effect when the tires are new and have deep threads.

[Boss330]

Originally Posted by CanAutM3

You are right, a softer suspension usually results in more mechanical grip at the expense of less sharp response.

IMO, the most significant difference between the M2C and M2cs is the addition of adaptive suspension on the CS which dynamically adapts in milliseconds to the driving conditions: softer when more grip is needed and stiffer when more response is needed.

Given what they did on the M4cs, where they optimized the chassis tuning for R-comp tires, I am pretty sure they did the same for the M2cs. I guess we will learn more about the details at the official unveiling.

As for ride height, I have not read anything on the specification thus far.

FWIW both cars are listed at 1410mm height in the Sport Auto spec sheet.

[Artemis]

Originally Posted by Boss330

FWIW both cars are listed at 1410mm height in the Sport Auto spec sheet.

M2 CS and M2C dimensions (length/width/height) and wheelbase are identical.

[CanAutM3]

Originally Posted by Robin_NL

My winterwheels (18") also weigh less and you feel it in the steering, the whole car feels a tad lighter on its feet. But to really eliminate understeer you must have:
-a wider front tyre(on dry)
-a softer ARB front (or a bit softer frontend vs rear end)
-more neg camber front end
-a bit more neg toe(helps turning in to some dregree)
- more front aero(if possible)
Or a lighter front end (carbon parts) in general which makes the 52/48 FR balance go to 51.5/48.5 FR (example)
But not too much, you want to have weight(balance) on the front and not like an old Beetle with 'no mass' upfront plowing into a haybale
Cheers
Robin

My comment was rhetorical as I do not believe that reducing wheel weight has any effect on understeer.

As for weight distribution, don't believe the BMW marketeers, 50-50 is far from "ideal". A rear weight bias makes for a much nimbler car that is easier to get to change direction.

The reason that is, is that when a car turns, it pivots around the center point on the rear axle. The total rotational inertia of an object is the addition if the object's own moment of inertia plus the square of the distance between the center of gravity and the pivot point multiplied by the object's mass. So the farther the Cg is relative to the rear axle, the greater the force required to get the car to change direction. This is why the great majority of purpose built sport and race cars have a rear weight bias.

[CanAutM3]

Originally Posted by Boss330

FWIW both cars are listed at 1410mm height in the Sport Auto spec sheet.

That anwers this then

[CanAutM3]

Originally Posted by hellrotm

Track temps near freezing with a harder compound made even harder by the weather. I'd rather be in the car with the warmer weather and softer compound, guaranteed to have a lot more grip.

Folks that keep insisting on this point show little to no track experience. I will just paste what I posted earlier:

Let's not confuse things. I think we can agree that in the same conditions the PSC2 should generally offer more grip than the PSS on track. No? However, when you compare the minimum cornering speeds in the OP, the M2C on its PSS is able to equal or even beat the M2cs on its PSC2 on some corners. Doesn't this tell us that the M2C was not suffering that much at 1degC compared to the M2cs at 32degC?

How would you explain this otherwise?

[Boss330]

Originally Posted by CanAutM3

Folks that keep insisting on this point show little to no track experience. I will just paste what I posted earlier:

Let's not confuse things. I think we can agree that in the same conditions the PSC2 should generally offer more grip than the PSS on track. No? However, when you compare the minimum cornering speeds in the OP, the M2C on its PSS is able to equal or even beat the M2cs on its PSC2 on some corners. Doesn't this tell us that the M2C was not suffering that much at 1degC compared to the M2cs at 32degC?

How would you explain this otherwise?

I think people just compare to their own experience with normal street driving, where you dont build heat in the tires like you do on the track.

One big advantage of cold vs hot track temperature is that you can push harder and longer on a cooler track surface before the tire overheat and looses grip.

[Karmic Man]

Originally Posted by CanAutM3

My comment was rhetorical as I do not believe that reducing wheel weight has any effect on understeer.
As for weight distribution, don't believe the BMW marketeers, 50-50 is far from "ideal". A rear weight bias makes for a much nimbler car that is easier to get to change direction.
The reason that is, is that when a car turns, it pivots around the center point on the rear axle. The total rotational inertia of an object is the addition if the object's own moment of inertia plus the square of the distance between the center of gravity and the pivot point times the vehicle weight. So the farther the Cg is relative to the rear axle, the greater the force required to get the car to change direction. This is why the great majority of purpose built sport and race cars have a rear weight bias.

That's what I felt but I don't have empirical evidence to prove it.

But again what you 'believe in' also don't have any data to support you...

The other thing is the offset of my lighter rims is about 6mm more aggressive so that might play apart too.

May be someone can do a track test with the stock wheels and lighter wheels and see how they affect handling

[Karmic Man]

Originally Posted by CanAutM3

Folks that keep insisting on this point show little to no track experience. I will just paste what I posted earlier:
Let's not confuse things. I think we can agree that in the same conditions the PSC2 should generally offer more grip than the PSS on track. No? However, when you compare the minimum cornering speeds in the OP, the M2C on its PSS is able to equal or even beat the M2cs on its PSC2 on some corners. Doesn't this tell us that the M2C was not suffering that much at 1degC compared to the M2cs at 32degC?
How would you explain this otherwise?

Well back in 2018, a M2C did have higher cornering speed in summer climate condition compared to the cold 'icy' one over 4 of the 5 corners so the verdict is still out there

Same day with the same driver on the same track and we can have a more meaning scientific discussion, any further vindication attempt is pointless at this stage

[Karmic Man]

Originally Posted by Robin_NL

Which rims do you have now?
Any photos?
Choosing between 763s (with or without Cup tyres) or a Remus exhaust.....
Cheers
Robin

I have the Volk Racing G16...lighter rims make a difference in handling even on the street Getting off the line is easier than before, more like my 1M now where as with the stock wheels before I can feel the extra weight dragging the car down at low speed

I think you can't go wrong with either mods

[Boss330]

Originally Posted by Karmic Man

Well back in 2018, a M2C did have higher cornering speed in summer climate condition compared to the cold 'icy' one over 4 of the 5 corners so the verdict is still out there
Same day with the same driver on the same track and we can have a more meaning scientific discussion, any further vindication attempt is pointless at this stage

Just to point it out once again;
The article written by the people who did the tests and knows the track clearly states that the M2 C was tested in favourable temoeratures with regard to lap times.

The hot track temp for the M2 CS overheats the tires much quicker and the hot air temperature is detrimental to engine performance.

[CanAutM3]

Originally Posted by Karmic Man

That's what I felt but I don't have empirical evidence to prove it.
But again what you 'believe in' also don't have any data to support you...
The other thing is the offset of my lighter rims is about 6mm more aggressive so that might play apart too.
May be someone can do a track test with the stock wheels and lighter wheels and see how they affect handling

I was being polite. I won't be able to show data that demonstrates that lighter wheels don't reduce understeer simply because there is no data that proves the opposite either: it is basic vehicle dynamics.
The offset will definitely make a difference. Further, you seem to have high quality wheels. Wheel rigidity also play an important role in handling performance.

[CanAutM3]

Originally Posted by Karmic Man

Well back in 2018, a M2C did have higher cornering speed in summer climate condition compared to the cold 'icy' one over 4 of the 5 corners so the verdict is still out there

So, you imply that PSS offer better grip than PSC2?

Originally Posted by Karmic Man

Same day with the same driver on the same track and we can have a more meaning scientific discussion, any further vindication attempt is pointless at this stage

This we agree on .

[Moflow]

Originally Posted by CanAutM3

My comment was rhetorical as I do not believe that reducing wheel weight has any effect on understeer.

As for weight distribution, don't believe the BMW marketeers, 50-50 is far from "ideal". A rear weight bias makes for a much nimbler car that is easier to get to change direction.

The reason that is, is that when a car turns, it pivots around the center point on the rear axle. The total rotational inertia of an object is the addition if the object's own moment of inertia plus the square of the distance between the center of gravity and the pivot point multiplied by the object's mass. So the farther the Cg is relative to the rear axle, the greater the force required to get the car to change direction. This is why the great majority of purpose built sport and race cars have a rear weight bias.

I think you're confusing polar moment of inertia with weight distribution (or maybe you're not confusing them, but we should note that you're talking about two distinct things here.)

You've described polar moment of inertia (how quickly/willing an object is to rotate) however, polar moment of inertia doesn't care if the engine is in the front or back, just how close it is to the center of mass. That's the real reason mid engined cars make good race cars. Yes having more weight over the rear axle helps traction when accelerating, but the biggest benefit is having the engine closer to the middle of the car for quicker rotation. Like a figure skater pulling their arms in to do a triple axle. In practice, this does mean cars with engines behind the driver tend to rotate quicker, as you correctly pointed out.

I personally believe that there isn't an "ideal" weight distribution, anything between about 35 percent to 55 percent front weight can work fine as long as your polar moment of inertia and center of mass height off the ground are set up to make sense and the whole thing matches the drivers preferred style.

As for the 2kg lighter wheels....I dunno. Could maybe be reducing understeer, unsprung weight can make a big difference (evidence here) but the wheels in my example are also carbon fiber wheels which are reducing flex in addition to being really light. Still, 2 seconds a lap over a 2 minute lap is pretty great for a reduction in weight of just 0.5 to 1.5 kg per wheel.