Tyre slip

moff · 11-28-2019, 07:07 AM

Quote:

Originally Posted by Transfer

Quote:

Originally Posted by CaptSlow27

What temperature and what tires do you have on the car. If the stock summer tires, then they will naturally not work well in the cold and can actually be quite dangerous under 40 degrees Fahrenheit/4.5 Celsius.

How did it take 5 posts before this? This is the only question that matters and without the answer OP is on his own.

To be fair this is not the only question and it's not really true.

In the UK I'd guess that 98% of drivers do it use anything but summer tyres. I've done the same on every car I've own. Dangerous? No. Risky in bad ice and snow? Definitely. But we rarely get snow and ice on the roads is minimal too.

gatorfast · 11-28-2019, 07:20 AM

Quote:

Originally Posted by CaptSlow27

Quote:

Originally Posted by gatorfast

Where have you read anything to the contrary? It's a rear biased AWD system.

Several sources in fact, the most important being BMW itself. See F97/F98 Technical Manual Sec. 4.3.

Yea it's a little confusing the way it is worded. Essentially it's just an intelligent rear-biased AWD system capable of sending 100% of the power to the rear of front wheels depending on many different factors.

CaptSlow27 · 11-28-2019, 07:38 AM

Quote:

Originally Posted by gatorfast

Yea it's a little confusing the way it is worded. Essentially it's just an intelligent rear-biased AWD system capable of sending 100% of the power to the rear of front wheels depending on many different factors.

The BMWUSA press release is much clearer that the power is sent to the rear wheels until traction loss is detected:

The electronically controlled M xDrive, which works in tandem with the DSC (Dynamic Stability Control) system, only sends power to the front wheels when the rear wheels reach the limits of their traction.

gatorfast · 11-28-2019, 07:43 AM

Ok so aren't we saying the same thing lol? It's a rear-biased (meaning it sends most if not all of the power to the rear wheels) AWD system that distributes power as needed with a preference to the rear wheels.

CaptSlow27 · 11-28-2019, 07:48 AM

Quote:

Originally Posted by gatorfast

Ok so aren't we saying the same thing lol? It's a rear-biased (meaning it sends most if not all of the power to the rear wheels) AWD system that distributes power as needed with a preference to the rear wheels.

I’m with you - Just wanted to post for the benefit of all, as I agree the technical manual has quite the strange translation.

moff · 11-28-2019, 10:04 AM

Just google M xDrive to read how it works in conjunction with the M Diff - I've just posted an old article about it.

Overall it is rear biased when needed and 4WD Sport is even more RWD biased allowing for lots of slip.

The way I read it is that there are 4 driving modes - DSC on, DSC on MDM, DSC off, 4WD and DSC off 4WD Sport. The latter 2 are split into DSC off 4WD for wet circuits / tight and twisty, DSC off 4WD Sport dry circuits.

There's no real mention of bias, it's just assumed by how they relax the system and allow for more slip and drift.

Transfer · 11-28-2019, 10:10 AM

Quote:

Originally Posted by moff

Quote:

Originally Posted by Transfer

Quote:

Originally Posted by CaptSlow27

What temperature and what tires do you have on the car. If the stock summer tires, then they will naturally not work well in the cold and can actually be quite dangerous under 40 degrees Fahrenheit/4.5 Celsius.

How did it take 5 posts before this? This is the only question that matters and without the answer OP is on his own.

To be fair this is not the only question and it's not really true.

In the UK I'd guess that 98% of drivers do it use anything but summer tyres. I've done the same on every car I've own. Dangerous? No. Risky in bad ice and snow? Definitely. But we rarely get snow and ice on the roads is minimal too.

Talk to the guy that flew off the road in the dry because of summer tires in cold. Good luck out there.

moff · 11-28-2019, 10:11 AM

Little bit more from the X3M review in Car Magazine:

There’s no two-wheel drive drift-mode like you get with the M5 but the X3M is principally a rear-driver. Despite this being the latest generation of xDrive you can still sense power moving around under you – it’s not abrupt but it’s far from natural, although the mid-corner traction it summons up is remarkable.

When you’d rather explore the limits of grip yourself there is the clever M Dynamic Mode –which winds off the DSC interference and activates the M xDrive 4WD Sport setting, shifting more power aft. Do so and the rear of the X3M feels very involved, allowing you to steer on the throttle or tuck the nose into the apex when you’ve been a bit ambitious with your entry speed.

moff · 11-28-2019, 10:12 AM

Quote:

Originally Posted by Transfer

Talk to the guy that flew off the road in the dry because of summer tires in cold. Good luck out there.

Which one?

Big fat case of running out of talent

Transfer · 11-28-2019, 10:41 AM

Quote:

Originally Posted by moff

Quote:

Originally Posted by Transfer

Talk to the guy that flew off the road in the dry because of summer tires in cold. Good luck out there.

Which one?

Big fat case of running out of talent

Doesn't sound like talent had anything to do with it.

Freezing/snow driving on the summer tires! https://www.bimmerpost.com/forums/sh....php?t=1667742

moff · 11-28-2019, 12:01 PM

Quote:

Originally Posted by Transfer

Doesn't sound like talent had anything to do with it.

Freezing/snow driving on the summer tires! https://www.bimmerpost.com/forums/sh....php?t=1667742

Well, talent comes in a variety of ways. Choosing when to drive being one of them. Driving too fast for the conditions being another.

M5 TT · 11-28-2019, 12:17 PM

So, rwd until the ecu decides otherwise. That's how I understood it. Same as the GTR-R35. Can be scary as I said

X3MSteve · 11-28-2019, 02:14 PM

Same as the F Type R I had stupidly sideways in the wet with 'trac dsc' on (a less intrusive traction control)

Seems a lot of cars do this rwd bias awd now

Also I've now had my X3M test drive, definately getting one. It has the space we need, the calmness in efficient for the wife and the speed required for me at the other end of the rev range!

moff · 11-28-2019, 02:37 PM

Quote:

Originally Posted by X3MSteve

Same as the F Type R I had stupidly sideways in the wet with 'trac dsc' on (a less intrusive traction control)

Seems a lot of cars do this rwd bias awd now

Also I've now had my X3M test drive, definately getting one. It has the space we need, the calmness in efficient for the wife and the speed required for me at the other end of the rev range!

11-28-2019, 07:43 AM	#26
gatorfast Major General 5061 Rep 6,880 Posts Drives: 718 Cayman Join Date: Jan 2008 Location: SoFla iTrader: (4)	Ok so aren't we saying the same thing lol? It's a rear-biased (meaning it sends most if not all of the power to the rear wheels) AWD system that distributes power as needed with a preference to the rear wheels.
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11-28-2019, 10:04 AM	#28
moff Colonel 1360 Rep 2,495 Posts Drives: X4M Competition Join Date: Jan 2008 Location: Nottingham GB iTrader: (0)	Just google M xDrive to read how it works in conjunction with the M Diff - I've just posted an old article about it. Overall it is rear biased when needed and 4WD Sport is even more RWD biased allowing for lots of slip. The way I read it is that there are 4 driving modes - DSC on, DSC on MDM, DSC off, 4WD and DSC off 4WD Sport. The latter 2 are split into DSC off 4WD for wet circuits / tight and twisty, DSC off 4WD Sport dry circuits. There's no real mention of bias, it's just assumed by how they relax the system and allow for more slip and drift. __________________ Arrived! 2022 X4M Competition, SPY + Black Merino Gone: 2019 X3M Competition, Toronto Red, Adelaide Grey.
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11-28-2019, 10:11 AM	#30
moff Colonel 1360 Rep 2,495 Posts Drives: X4M Competition Join Date: Jan 2008 Location: Nottingham GB iTrader: (0)	Little bit more from the X3M review in Car Magazine: There’s no two-wheel drive drift-mode like you get with the M5 but the X3M is principally a rear-driver. Despite this being the latest generation of xDrive you can still sense power moving around under you – it’s not abrupt but it’s far from natural, although the mid-corner traction it summons up is remarkable. When you’d rather explore the limits of grip yourself there is the clever M Dynamic Mode –which winds off the DSC interference and activates the M xDrive 4WD Sport setting, shifting more power aft. Do so and the rear of the X3M feels very involved, allowing you to steer on the throttle or tuck the nose into the apex when you’ve been a bit ambitious with your entry speed. __________________ Arrived! 2022 X4M Competition, SPY + Black Merino Gone: 2019 X3M Competition, Toronto Red, Adelaide Grey.
	Appreciate 0 Quote

11-28-2019, 12:17 PM	#34
M5 TT Captain 177 Rep 657 Posts Drives: F90 M5 Join Date: Sep 2008 Location: UK iTrader: (0)	So, rwd until the ecu decides otherwise. That's how I understood it. Same as the GTR-R35. Can be scary as I said
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11-28-2019, 02:14 PM	#35
X3MSteve Private 15 Rep 83 Posts Drives: X3M Join Date: Nov 2019 Location: NorthWest iTrader: (0)	Same as the F Type R I had stupidly sideways in the wet with 'trac dsc' on (a less intrusive traction control) Seems a lot of cars do this rwd bias awd now Also I've now had my X3M test drive, definately getting one. It has the space we need, the calmness in efficient for the wife and the speed required for me at the other end of the rev range!
	Appreciate 0 Quote