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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > All-Wheel-Drive (Xi / xDrive) Talk > does the 335Xi have the option to be RWD like an STI?



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      11-12-2010, 06:34 PM   #67
ajsalida
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Quote:
Originally Posted by issabmw View Post
I think that once the system is disengaged from the source, the stress is going to be far less than constant power through the front driveshaft.

If they say at high speeds the front disengages (im not sure) then there should be no problem permanently disabling it.
I think you are right about it going to 100% RWD at high speed.
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      11-12-2010, 07:02 PM   #68
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Wow....I am retarded.
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      11-12-2010, 08:02 PM   #69
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This kinda contradicts everything your buddy is claiming.

http://www.awdwiki.com/xdrive.html

The front wheels spin freely when they are off the ground, meaning they are not engaged. The rear wheels do not. If you pull the fuse when the car is off then I don't see how the front would be engaged damaging anything. The article also mentions that at high way speeds the rear is getting all the power. I'm assuming this won't hurt the car but I'm no mechanic. I could be wrong....
the xdrive have a engagement system that adds pressure to a multi disk wet clutch to move power to the front wheels. looks like the clutch on a motorbike.
when pulling the fuse what you do is to prevent the electric motor from adding any pressure to the wet clutch.

when just crousing down the highway whit all four wheels spinning in the same speed this i exaktly the state that the xdrive is in. no torque to the front and no pressure to the wet clutch. same whit or whitout the fuse in.


when spinning the back wheels and have the front standing still whit the fuse pulled what happens in the xdrive transfear case is that the wet clutch slips since the disks are fixed to the rear wheels and the hub is fixed to the front. (or other way around)
so does this hurt your xdrive? i think not! sure the clutch slips. but remember you do not have any pressure on the clutch disks. whit no pressure ther is no wear. right?

look at how the clutch on your car works. your clutch does not wear when you are standing still whit engine running, in gear and clutch disengage right?! not as long as you donīt add any pressure to the clutch disk making it transfear torque.
the clutch only wears when it slips and trys to equal the speed of the engine and the gearbox/wheels. when 100% engage or 100% dissengage the clutch just spins along.

im not going to put my as on the line telling everybody that this is safe to do.
but if i think about how the system works i would not be worried to do this myself.

and remember. bmw hate on everybody that trys to modify ther cars...

peace.
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      11-13-2010, 12:19 PM   #70
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Quote:
Originally Posted by mr p-j View Post
the xdrive have a engagement system that adds pressure to a multi disk wet clutch to move power to the front wheels. looks like the clutch on a motorbike.
when pulling the fuse what you do is to prevent the electric motor from adding any pressure to the wet clutch.

when just crousing down the highway whit all four wheels spinning in the same speed this i exaktly the state that the xdrive is in. no torque to the front and no pressure to the wet clutch. same whit or whitout the fuse in.


when spinning the back wheels and have the front standing still whit the fuse pulled what happens in the xdrive transfear case is that the wet clutch slips since the disks are fixed to the rear wheels and the hub is fixed to the front. (or other way around)
so does this hurt your xdrive? i think not! sure the clutch slips. but remember you do not have any pressure on the clutch disks. whit no pressure ther is no wear. right?

look at how the clutch on your car works. your clutch does not wear when you are standing still whit engine running, in gear and clutch disengage right?! not as long as you donīt add any pressure to the clutch disk making it transfear torque.
the clutch only wears when it slips and trys to equal the speed of the engine and the gearbox/wheels. when 100% engage or 100% dissengage the clutch just spins along.

im not going to put my as on the line telling everybody that this is safe to do.
but if i think about how the system works i would not be worried to do this myself.

and remember. bmw hate on everybody that trys to modify ther cars...

peace.
lol thanks? For rephrasing the link I provided....
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      11-13-2010, 12:25 PM   #71
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lol thanks? For rephrasing the link I provided....
i think that i quoted you by mistake. nevermind...
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      11-13-2010, 04:18 PM   #72
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So what can we do about the wipers?

Is there some easy way to unscrew the wipers and let the motors sway them form side to side...can we remove the arms? Place the parts in the trunk, in case it rains...with tools...pop them on if needed on the side of the road?

I miss RWD, it is the right way to drive...I have AWD for winter...where it is invaluable.
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      11-13-2010, 05:37 PM   #73
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There must be simply a fuse we can pull for the wipers...

Quote:
Originally Posted by TheRox View Post
So what can we do about the wipers?

Is there some easy way to unscrew the wipers and let the motors sway them form side to side...can we remove the arms? Place the parts in the trunk, in case it rains...with tools...pop them on if needed on the side of the road?

I miss RWD, it is the right way to drive...I have AWD for winter...where it is invaluable.
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      11-13-2010, 06:23 PM   #74
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Quote:
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Since when is the STI capable of this?
STI has an adjustable center differential. You can use it to set up the torque split. Of course, it does not ever go full RWD or full FWD, its closer to 35% front and 65% rear.

This article discusses it further:
http://www.driveperformance.subaru.c.../blueprint.asp
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      11-13-2010, 06:34 PM   #75
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Quote:
Originally Posted by Tortfeasor 335xi View Post
STI has an adjustable center differential. You can use it to set up the torque split. Of course, it does not ever go full RWD or full FWD, its closer to 35% front and 65% rear.

This article discusses it further:
http://www.driveperformance.subaru.c.../blueprint.asp
He's right. The DCCD module (driver controlled center differential) allowed max 65% to the rear and you.can permanently lock in that ratio which allows those endless donuts.
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      11-13-2010, 06:40 PM   #76
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I don't mind driving with the speedo disabled in place of RWD fun. That's what the speedo app for iphone is for

I think im going to bring out the soldering iron and make a switch for this until shiv and terry come up with something. Rwd on this car is too much fun.

Ill mount it to the fuse box cover.
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      11-14-2010, 06:19 AM   #77
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so by having the option to pull the fuse....our X is now officially not AWD but 4wd on Demand!!!
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      11-14-2010, 02:18 PM   #78
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that and it appears the rear diff is some how locked. Notice how the burnouts have both tires laying down rubber.
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      11-14-2010, 11:25 PM   #79
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Quote:
Originally Posted by Avery View Post
that and it appears the rear diff is some how locked. Notice how the burnouts have both tires laying down rubber.
Very true. But...

When i floored it upon making a u turn, i could have sworn the inside wheel was spinnning thru second gear. Then again, when making an L turn, the rear whipped evenly instead of exhibiting biased slippage.

Can anyone shed some light on this?
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      11-14-2010, 11:29 PM   #80
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Quote:
Originally Posted by E36graduate View Post
so by having the option to pull the fuse....our X is now officially not AWD but 4wd on Demand!!!
Take that "i" owners

I will be testing the diff lock theory in a series of tests tomorrow. Will post up results tomorrow.
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      11-15-2010, 12:53 AM   #81
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subscribed. This is very interesting news for us xi owners.
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      11-15-2010, 07:26 AM   #82
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Probably what remains is the 2WD version of the 4WD pseudo e-diff feature of xDrive (I know it does not have a true e-diff). There is some evidence that even with DSC/DTC completely off, you still have the brakes allocating torque by stopping wheel spin on all four wheels. So maybe with the TC disabled/running open, you have RWD-only version of this.

It would make sense, suppose somehow front diff blows up, front driveshaft breaks whatever, you'd want some kind of e-LSD left in RWD as a default.
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      11-15-2010, 08:57 AM   #83
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Quote:
Originally Posted by issabmw View Post
Take that "i" owners

I will be testing the diff lock theory in a series of tests tomorrow. Will post up results tomorrow.
We still have that very heavy added weight of the driveshaft and xdrive...price we pay!

Lets get a solution for these wipers though!
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      11-15-2010, 06:49 PM   #84
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Referencing the Bentley ECL-19 to 23, to disable the wipers on a 2006 build date, pull fuse 39, it should be a 30amp.

2007: Fuse 39, 30amp
2008: Fuse 50, 30amp

Do this at your own risk...

Last edited by cyphr; 11-15-2010 at 06:53 PM. Reason: added add'l years
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      11-16-2010, 01:06 AM   #85
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Quote:
Originally Posted by cyphr View Post
Referencing the Bentley ECL-19 to 23, to disable the wipers on a 2006 build date, pull fuse 39, it should be a 30amp.

2007: Fuse 39, 30amp
2008: Fuse 50, 30amp

Do this at your own risk...
Does this fuse cut anything else off?

Btw, for a 2009 335xi...its also fuse 50?
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      11-16-2010, 10:04 AM   #86
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Quote:
Originally Posted by e93ro View Post
for GT-R is possible through software, I think if somebody put his brains for this it might be possible
my buddy has an R32 and its as easy as pulling the big green fuse under the dash. here is a quick video in RWD mode...



I dont think that STI's can be converted to 100% rear wheel drive. They like the evo depending on which mode it is in, will transfer more power to the rear 30/70 split rear or 40/60 and 50/50 from tarmac,gravel, and of course snow.
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      11-16-2010, 10:53 AM   #87
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Does the odometer work? i did this to my cayenne and the odometer stopped lol
also made a switch for the cayenne

Last edited by MusclezMarinara; 11-16-2010 at 10:59 AM.
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      11-16-2010, 05:28 PM   #88
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Quote:
Originally Posted by TheRox View Post
Does this fuse cut anything else off?

Btw, for a 2009 335xi...its also fuse 50?
The Bentley lists the fuses as controlling only the wipers.

Unfortunately, I only have diagrams from MY2006-2008. Have you referenced the diagram that's on the back of the fuse panel?
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