Is the max power split between front/rear 50/50?

JohnyS · 02-22-2011, 07:51 PM

I tried looking this up, but couldn't find an answer. I have heard that the max power split between the front and rear wheels is 50% front, and 50% rear, with the ability to go 100% rear. If this is true, is there a way to allow the power split to go 100% front?

sorryiwasnapping · 02-22-2011, 07:52 PM

i can't answer this, but any particular reason you would want 100% in the front?

also, pretty sure the answer is no.

JohnyS · 02-22-2011, 08:07 PM

Its mainly for when Im driving in very slippery conditions. It seems to me that this car drives almost like a rear wheel drive car when Im in the snow. My last car was a Subaru WRX and it felt much more stable taking corners at speeds in the snow than this one, and it was much easier to control once I started sliding. The only real difference that I can see between these two cars is the way the awd system works and the weight. I had the WRX tuned so it was faster, and the turbo spool time was about the same, so its not the power thats making it harder to drive in the snow. And I am using the same tires too.

sorryiwasnapping · 02-22-2011, 08:41 PM

what type of tires are you using? What size wheels are you using? Do you have the DSC on? How fast are you going?

Even with worn out all season RFTs and flooring it in a few inches of snow I havn't experienced any "unwanted" sliding, granted I have a 328xi and not a 335xi, but still. When I do get the "wanted" sliding it's very easy to take control of.

ajsalida · 02-23-2011, 11:00 AM

The design of the transfer case is such that the rear diff is ALWAYS engaged via the rear driveshaft to the tranny output (inside the TC there is a chain that hangs off of the rear DS that connects to clutches & the front DS). Therefore when the transfer case is 100% locked up, the front driveshaft and the rear are each getting exactly half the TQ, and that is the most the front can ever get.

In order to go 100% front (or just more than 50%) you'd need a way to disconnect the rear DS with another set of clutches, and that is not possible with this configuration. Another way to say this is the TC is not a differential. It is just a variable clutch pack added to a conventional RWD system that engages or disengages a front drive shaft.

Windjammer · 02-23-2011, 12:21 PM

X-Drive is different from xi. I know that with "xi" the drivetrain for the Front-Left wheel is matched to the Rear-Right. (and the Front-Right to the Rear-Left)

With X-Drive, you start with 35% of power to the Front two wheels and 65% power to the rear two wheels. Depending on driving conditions/style/etc., X-Drive is intelligent enough to redirect 100% of the power to ANY two wheels.

I confirmed this at the BMW Performance Center in SC last summer.

wrickem · 02-23-2011, 12:24 PM

Quote:

Originally Posted by Windjammer

X-Drive is different from xi. I know that with "xi" the drivetrain for the Front-Left wheel is matched to the Rear-Right. (and the Front-Right to the Rear-Left)

With X-Drive, you start with 35% of power to the Front two wheels and 65% power to the rear two wheels. Depending on driving conditions/style/etc., X-Drive is intelligent enough to redirect 100% of the power to ANY two wheels.

That's not true at all. Xi and X-drive on E9X are the same thing, BMW Marketing changed its name. Whoever you talked to at the perfomance center was blowing smoke up yours.

Windjammer · 02-23-2011, 12:28 PM

No, the 'xi' wasn't an 'intelligent' system. BMW re-engineered the system into X-Drive to compete with Audi's Quattro.

wrickem · 02-23-2011, 12:35 PM

Quote:

Originally Posted by Windjammer

No, the 'xi' wasn't an 'intelligent' system. BMW re-engineered the system into X-Drive to compete with Audi's Quattro.

It doesn't matter to me if you believe me or not, but you are wrong if you're talking about the xi vs X-drive in E92's. They're the exact same thing, x-drive is a marketing name.

Windjammer · 02-23-2011, 12:36 PM

The info on the BMW site says the power distro is 40:60 typically. Here's the link: http://www.bmw.com/com/en/insights/t...icle=mm_xdrive

wrickem · 02-23-2011, 12:37 PM

http://www.e90post.com/forums/showth...light=drive+xi

Windjammer · 02-23-2011, 12:46 PM

I see your meaning. I was told the cross-wheel power was the predecessor to the X-Drive and the original designs for "xi." That may have been true in the past, and BMW has been using the X-Drive technology in 'xi' models for some time now. Thanks for catching my error!

Both of our links do answer this thread's question of whether the power can go 100% to the front. Both those links say 'Yes. ...but only when the car feels it's necessary."

wrickem · 02-23-2011, 01:19 PM

Quote:

Originally Posted by Windjammer

I see your meaning. I was told the cross-wheel power was the predecessor to the X-Drive and the original designs for "xi." That may have been true in the past, and BMW has been using the X-Drive technology in 'xi' models for some time now. Thanks for catching my error!

Both of our links do answer this thread's question of whether the power can go 100% to the front. Both those links say 'Yes. ...but only when the car feels it's necessary."

In earlier "x" (they used to be "ix"), the all wheel drive systems were completely different, but e9x are all the same with xi or x-drive badges, but I definitely understand any confusion. And let's face it, a lot of people who should know how things work (performance center employees included), don't. I am lucky that at my dealership, most of the CA's are enthusiasts and not just salesmen.

There always seems to be some vagueness to an actual answer on the split, so I am keeping my mouth shut on that one though.

ajsalida · 02-23-2011, 04:03 PM

Quote:

Originally Posted by Windjammer

Both of our links do answer this thread's question of whether the power can go 100% to the front. Both those links say 'Yes. ...but only when the car feels it's necessary."

This is completely wrong. There have been many threads on this, I suggest you read them. xDrive on current e90 cannot divert more than 50% power to front, look inside the transfer case. Sleazy BMW marketing types have discovered that there is one rare instantaneous situation when both the rears have exactly zero traction and the front do have traction that can be considered in court to mean that the fronts get 100%. That is total BS in the real world, there is NO WAY to transfer over 50% useable power to the front if the rear driveshaft is a hard link between tranny and diff, which it is.

JohnyS · 02-23-2011, 05:11 PM

Thanks for the info, the links answered my question extremely well. This brings me to my next question, would adding a lsd in the rear help reduce the oversteer or would it make it worse? Sorry if this is a bad question, but I am not sure.

MMOTION · 03-09-2011, 03:51 PM

Quote:

Originally Posted by Windjammer

The info on the BMW site says the power distro is 40:60 typically. Here's the link: http://www.bmw.com/com/en/insights/t...icle=mm_xdrive

40 front : 60 rear

02-22-2011, 07:51 PM	#1
JohnyS New Member 3 Rep 10 Posts Drives: 335i x-drive Join Date: Jun 2010 Location: N. Van iTrader: (0)	Is the max power split between front/rear 50/50? I tried looking this up, but couldn't find an answer. I have heard that the max power split between the front and rear wheels is 50% front, and 50% rear, with the ability to go 100% rear. If this is true, is there a way to allow the power split to go 100% front?
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02-22-2011, 07:52 PM	#2
sorryiwasnapping Private First Class 1 Rep 137 Posts Drives: '12 VW GTI Join Date: Feb 2011 Location: New Jersey iTrader: (0)	i can't answer this, but any particular reason you would want 100% in the front? also, pretty sure the answer is no.
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02-22-2011, 08:07 PM	#3
JohnyS New Member 3 Rep 10 Posts Drives: 335i x-drive Join Date: Jun 2010 Location: N. Van iTrader: (0)	Its mainly for when Im driving in very slippery conditions. It seems to me that this car drives almost like a rear wheel drive car when Im in the snow. My last car was a Subaru WRX and it felt much more stable taking corners at speeds in the snow than this one, and it was much easier to control once I started sliding. The only real difference that I can see between these two cars is the way the awd system works and the weight. I had the WRX tuned so it was faster, and the turbo spool time was about the same, so its not the power thats making it harder to drive in the snow. And I am using the same tires too.
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02-22-2011, 08:41 PM	#4
sorryiwasnapping Private First Class 1 Rep 137 Posts Drives: '12 VW GTI Join Date: Feb 2011 Location: New Jersey iTrader: (0)	what type of tires are you using? What size wheels are you using? Do you have the DSC on? How fast are you going? Even with worn out all season RFTs and flooring it in a few inches of snow I havn't experienced any "unwanted" sliding, granted I have a 328xi and not a 335xi, but still. When I do get the "wanted" sliding it's very easy to take control of.
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02-23-2011, 11:00 AM	#5
ajsalida Colonel 226 Rep 2,387 Posts Drives: 95 M3, 02 R1150GSA, 09 335xi Join Date: Aug 2010 Location: SW USA iTrader: (2)	The design of the transfer case is such that the rear diff is ALWAYS engaged via the rear driveshaft to the tranny output (inside the TC there is a chain that hangs off of the rear DS that connects to clutches & the front DS). Therefore when the transfer case is 100% locked up, the front driveshaft and the rear are each getting exactly half the TQ, and that is the most the front can ever get. In order to go 100% front (or just more than 50%) you'd need a way to disconnect the rear DS with another set of clutches, and that is not possible with this configuration. Another way to say this is the TC is not a differential. It is just a variable clutch pack added to a conventional RWD system that engages or disengages a front drive shaft.
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02-23-2011, 12:21 PM	#6
Windjammer it's all about the sound 2 Rep 29 Posts Drives: '11 E90 335xi M-Sport 6MT Stg1 Join Date: Apr 2010 Location: USA iTrader: (0)	X-Drive is different from xi. I know that with "xi" the drivetrain for the Front-Left wheel is matched to the Rear-Right. (and the Front-Right to the Rear-Left) With X-Drive, you start with 35% of power to the Front two wheels and 65% power to the rear two wheels. Depending on driving conditions/style/etc., X-Drive is intelligent enough to redirect 100% of the power to ANY two wheels. I confirmed this at the BMW Performance Center in SC last summer.
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02-23-2011, 12:28 PM	#8
Windjammer it's all about the sound 2 Rep 29 Posts Drives: '11 E90 335xi M-Sport 6MT Stg1 Join Date: Apr 2010 Location: USA iTrader: (0)	No, the 'xi' wasn't an 'intelligent' system. BMW re-engineered the system into X-Drive to compete with Audi's Quattro.
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02-23-2011, 12:36 PM	#10
Windjammer it's all about the sound 2 Rep 29 Posts Drives: '11 E90 335xi M-Sport 6MT Stg1 Join Date: Apr 2010 Location: USA iTrader: (0)	The info on the BMW site says the power distro is 40:60 typically. Here's the link: http://www.bmw.com/com/en/insights/t...icle=mm_xdrive
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02-23-2011, 12:37 PM	#11
wrickem Big Beaver Smile 2101 Rep 3,791 Posts Drives: What he wants to Join Date: Mar 2006 Location: lambertville nj iTrader: (0)	http://www.e90post.com/forums/showth...light=drive+xi __________________ ______________________________________________ Current- '21 430 , '19 911, 07 M6 ,'17 Jeep Wrangler, "23 Bronco OBXluxsquatch
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02-23-2011, 12:46 PM	#12
Windjammer it's all about the sound 2 Rep 29 Posts Drives: '11 E90 335xi M-Sport 6MT Stg1 Join Date: Apr 2010 Location: USA iTrader: (0)	I see your meaning. I was told the cross-wheel power was the predecessor to the X-Drive and the original designs for "xi." That may have been true in the past, and BMW has been using the X-Drive technology in 'xi' models for some time now. Thanks for catching my error! Both of our links do answer this thread's question of whether the power can go 100% to the front. Both those links say 'Yes. ...but only when the car feels it's necessary."
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02-23-2011, 05:11 PM	#15
JohnyS New Member 3 Rep 10 Posts Drives: 335i x-drive Join Date: Jun 2010 Location: N. Van iTrader: (0)	Thanks for the info, the links answered my question extremely well. This brings me to my next question, would adding a lsd in the rear help reduce the oversteer or would it make it worse? Sorry if this is a bad question, but I am not sure. Last edited by JohnyS; 02-23-2011 at 05:16 PM..
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