X-Delete App, and disabling front drive on x-drive

mpathic · 12-26-2021, 04:35 AM

Been trying out the x-delete app on my new-to-me E61 535iT x-drive.
What a solid, stable, great handling tank on the road.
After flashing the Rear Drive Only mode from X-Delete, the butt dyno says the acceleration is a bit more lively.
Steering feels a bit more responsive too.
Watching mpg, with the stock AWD settings, I was getting ~18mpg on a daily 30 mile round trip commute. after x-deleting the front drive, I'm seeing 19-20-ish.
Some posts on the E90 list are reporting better mpg too.

Anyone else been trying out x-delete?

Also interested in firsthand experiences with removing the front driveshaft and/or halfshafts, and if removing the front diff is feasible too.

maxcbrdriver · 12-27-2021, 12:41 PM

There shouldn't be any benefits from a mpg standpoint bc the entirety of the front drive system still gets accelerated by the road via power put down at the rear. So net zero.

mpathic · 12-28-2021, 02:16 AM

Don't understand enough about how the transfer case operates to know where and how the parasitic loss is reduced. I would like to learn.
Your answer is one of the "shoulds". I've seen "shoulds" on the E9x threads too. Firsthand, myself and a bunch of others are seeing better MPG. The transfer case isn't engaging to put torque to the front drive section, the front drive section is turning passively, while full power is being sent to the rear.
Enough users reporting the same result gives enough data to conclude x-delete is doing something interesting in its programming, that its not just the front drive section being mechanically disabled.

maxcbrdriver · 12-28-2021, 10:20 AM

My mistake in using the word ’should’. XDelete will not reduce drivetrain losses associated with the front wheel drive system. XDrive is just a computer controlled multi plate wet clutch designed to transfer torque with a finite capability to absorb speed differences via wear. It is not a differential of any kind.

To illustrate operation, let's take the example of standing start going straight with no traction issues (assuming
tires are all exactly the same). Regardless of the tx case clutch engagement level, there will be no slippage in those clutch plates. Torque split may change, but there will not be a speed difference. How? In the 0% engagement case, the rear pushes the car, front wheels gets pushed by road, front drivetrain turns. Since there are no traction issues, all those things happen in unison and in sync. In the 100% engagement case, front and rear are turned by engine in unison. From an energy perspective, there is no difference. Vehicle speeds and drivetrain rotational speeds are the same, at all points in time. Therefore, there is no energy savings.

Operation gets more complicated on traction limiting surfaces and turns, but it's important to note that anytime you have speed differences between tx case clutch plates and there is any engagement, you are wearing the plates and throwing away energy. That being said, the computer monitors such things and tries to avoid wear.

Hope this helps.

mpathic · 12-31-2021, 01:57 AM

Nice explanation, thx.
The 'should' part makes sense. I and others have observed and posted about an MPG increase. So something else is going, beside the basic physics that we all agree on. The transfer case still has some parasitic loss and drag. What if x-delete is shutting down the transfer case action, so its 100% locked to the rear, with the front driveshaft left to spin freely? Same as the locking top gear on the auto-trans.
I'm considering removing the front driveshaft, and taking a close look at if/how the front halfshafts and differential can be removed.

maxcbrdriver · 12-31-2021, 10:06 PM

https://www.manualslib.com/manual/1007995/Bmw-E61-Sports-Wagon-530xit.html?page=14

The tx case takes the transmission output as its input. The rear output is solidly linked to the input, while the front output is clutched. There are no components in the entirety of the drivetrain that don't get spun up during driving one way or another. See my earlier description.

Mpg comparisons aren't worth much without a sufficiently large number of samples as there are so many variables at play. I've never seen anyone compile such data when making mod mpg claims, so "evidence" is just anecdotal at this point.

Xdelete Manual
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.xdelete.app/xdelete_manual.pdf&ved=2ahUKEwi-y7es1I_1AhVNJBoKHftoCAYQFnoECBsQAQ&sqi=2&usg=AOvVa w1-IsEHg6UC3CUUDJ3xlA_4

https://rbttuning.atlassian.net/wiki/spaces/RBTTUNING/pages/16252941/xDelete+-+xDrive+Configurations

12-26-2021, 04:35 AM	#1
mpathic First Lieutenant 35 Rep 310 Posts Drives: Z4 MCoupe,3.0Si R,E61 535xiT Join Date: Oct 2014 Location: California iTrader: (0)	X-Delete App, and disabling front drive on x-drive Been trying out the x-delete app on my new-to-me E61 535iT x-drive. What a solid, stable, great handling tank on the road. After flashing the Rear Drive Only mode from X-Delete, the butt dyno says the acceleration is a bit more lively. Steering feels a bit more responsive too. Watching mpg, with the stock AWD settings, I was getting ~18mpg on a daily 30 mile round trip commute. after x-deleting the front drive, I'm seeing 19-20-ish. Some posts on the E90 list are reporting better mpg too. Anyone else been trying out x-delete? Also interested in firsthand experiences with removing the front driveshaft and/or halfshafts, and if removing the front diff is feasible too. __________________ And you may ask yourself, "Where is that large automobile?" Last edited by mpathic; 12-26-2021 at 04:48 AM..
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12-27-2021, 12:41 PM	#2
maxcbrdriver Second Lieutenant 168 Rep 287 Posts Drives: 2010 BMW 535xiT; 2021 BMW M2C Join Date: Jul 2015 Location: NJ iTrader: (1)	There shouldn't be any benefits from a mpg standpoint bc the entirety of the front drive system still gets accelerated by the road via power put down at the rear. So net zero.
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12-28-2021, 02:16 AM	#3
mpathic First Lieutenant 35 Rep 310 Posts Drives: Z4 MCoupe,3.0Si R,E61 535xiT Join Date: Oct 2014 Location: California iTrader: (0)	Don't understand enough about how the transfer case operates to know where and how the parasitic loss is reduced. I would like to learn. Your answer is one of the "shoulds". I've seen "shoulds" on the E9x threads too. Firsthand, myself and a bunch of others are seeing better MPG. The transfer case isn't engaging to put torque to the front drive section, the front drive section is turning passively, while full power is being sent to the rear. Enough users reporting the same result gives enough data to conclude x-delete is doing something interesting in its programming, that its not just the front drive section being mechanically disabled. __________________ And you may ask yourself, "Where is that large automobile?"
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12-28-2021, 10:20 AM	#4
maxcbrdriver Second Lieutenant 168 Rep 287 Posts Drives: 2010 BMW 535xiT; 2021 BMW M2C Join Date: Jul 2015 Location: NJ iTrader: (1)	My mistake in using the word ’should’. XDelete will not reduce drivetrain losses associated with the front wheel drive system. XDrive is just a computer controlled multi plate wet clutch designed to transfer torque with a finite capability to absorb speed differences via wear. It is not a differential of any kind. To illustrate operation, let's take the example of standing start going straight with no traction issues (assuming tires are all exactly the same). Regardless of the tx case clutch engagement level, there will be no slippage in those clutch plates. Torque split may change, but there will not be a speed difference. How? In the 0% engagement case, the rear pushes the car, front wheels gets pushed by road, front drivetrain turns. Since there are no traction issues, all those things happen in unison and in sync. In the 100% engagement case, front and rear are turned by engine in unison. From an energy perspective, there is no difference. Vehicle speeds and drivetrain rotational speeds are the same, at all points in time. Therefore, there is no energy savings. Operation gets more complicated on traction limiting surfaces and turns, but it's important to note that anytime you have speed differences between tx case clutch plates and there is any engagement, you are wearing the plates and throwing away energy. That being said, the computer monitors such things and tries to avoid wear. Hope this helps.
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12-31-2021, 01:57 AM	#5
mpathic First Lieutenant 35 Rep 310 Posts Drives: Z4 MCoupe,3.0Si R,E61 535xiT Join Date: Oct 2014 Location: California iTrader: (0)	Nice explanation, thx. The 'should' part makes sense. I and others have observed and posted about an MPG increase. So something else is going, beside the basic physics that we all agree on. The transfer case still has some parasitic loss and drag. What if x-delete is shutting down the transfer case action, so its 100% locked to the rear, with the front driveshaft left to spin freely? Same as the locking top gear on the auto-trans. I'm considering removing the front driveshaft, and taking a close look at if/how the front halfshafts and differential can be removed. __________________ And you may ask yourself, "Where is that large automobile?"
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12-31-2021, 10:06 PM	#6
maxcbrdriver Second Lieutenant 168 Rep 287 Posts Drives: 2010 BMW 535xiT; 2021 BMW M2C Join Date: Jul 2015 Location: NJ iTrader: (1)	https://www.manualslib.com/manual/1007995/Bmw-E61-Sports-Wagon-530xit.html?page=14 The tx case takes the transmission output as its input. The rear output is solidly linked to the input, while the front output is clutched. There are no components in the entirety of the drivetrain that don't get spun up during driving one way or another. See my earlier description. Mpg comparisons aren't worth much without a sufficiently large number of samples as there are so many variables at play. I've never seen anyone compile such data when making mod mpg claims, so "evidence" is just anecdotal at this point. Xdelete Manual https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.xdelete.app/xdelete_manual.pdf&ved=2ahUKEwi-y7es1I_1AhVNJBoKHftoCAYQFnoECBsQAQ&sqi=2&usg=AOvVa w1-IsEHg6UC3CUUDJ3xlA_4 https://rbttuning.atlassian.net/wiki/spaces/RBTTUNING/pages/16252941/xDelete+-+xDrive+Configurations
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