why is it called a 4wd

[bimfest]

just curious as to why the x5 (non xDrive) is referred to as 4x4 or 4wd. When at anytime its only 2 wheels turning because of the non locking diffs

[lo_jack]

Originally Posted by bimfest

just curious as to why the x5 (non xDrive) is referred to as 4x4 or 4wd. When at anytime its only 2 wheels turning because of the non locking diffs

Marketing.

You wouldn't know about this because for the most part, Australians seem to be immune to marketing as far as functional items go. Something about living on a remote island has apparently had a cultural impact.

It's technically AWD as long as all of the tires have traction. More important is the non-locked transfer case...at least the NV125. The chain drive feeds all the torque to exactly the half shaft that has no traction/resistance in concert with aforementioned open diffs.

[PropellerHead]

Originally Posted by lo_jack

It's technically AWD as long as all of the tires have traction. More important is the non-locked transfer case...at least the NV125. The chain drive feeds all (available) the torque to exactly the half shaft that has no traction/resistance in concert with aforementioned open diffs.

Added a bit there.

Since the NV125 is fixed at 68R/32F, the power cannot drive all/100% of the provided TQ to any half shaft. It will only drive up to what is available to either axle as distributed by the NV125.

This is different with XDrive in later models with the clutched ATC500. It can move something close to (or maybe all the way up to) 100% of the engines TQ to either the front or real axle.

[lo_jack]

Originally Posted by PropellerHead

Added a bit there.

Since the NV125 is fixed at 68R/32F, the power cannot drive all/100% of the provided TQ to any half shaft. It will only drive up to what is available to either axle as distributed by the NV125.

This is different with XDrive in later models with the clutched ATC500. It can move something close to (or maybe all the way up to) 100% of the engines TQ to either the front or real axle.

All well and good. But if you have one half shaft pop out of the diff, you will have zero forward power, unless you get out and push. Lockers/ locking xfer case could possibly mitigate that, which was more OP's point.

[Joshdub]

Originally Posted by bimfest

just curious as to why the x5 (non xDrive) is referred to as 4x4 or 4wd. When at anytime its only 2 wheels turning because of the non locking diffs

Pretty much. The AWD sucks on these things. They have "EDL"s which is just a gimmick. I have been passively looking into LSDs.

[bimfest]

Are lsd a option? Didnt know e53 had an lsd that can be swapped in. This would make me more confident in taking my x onto the beach....

[Emory39]

here are some threads that talk about LSD.

http://www.xoutpost.com/bmw-sav-foru...ted-slips.html

http://www.xoutpost.com/bmw-sav-foru...ferential.html

[bimfest]

So basically no, its a custom application.

[PropellerHead]

Originally Posted by bimfest

So basically no, its a custom application.

It's not too bad. I had a Quaiffe installed into the factory housing on my E39. Anyone who knows the way around a diff can do it. I don't know my way around it. It's been durable, too. I'm guessing it's been 12 years by now in the E39.

[PropellerHead]

Originally Posted by lo_jack

All well and good. But if you have one half shaft pop out of the diff, you will have zero forward power, unless you get out and push. Lockers/ locking xfer case could possibly mitigate that, which was more OP's point.

I could see that if you had TWO half shafts pop out- one in front and one in rear. But why wouldn't up to 100% power transfer to the f/r axle (ATC500) and deliver what it can to the axle with traction (NV125)? Wouldn't the driven/powered wheels provide forward motion?