facelift/pre-facelift & 1/2 model years??

[TiAgX5]

Originally Posted by PropellerHead

I drove a 10/2004 model for nearly 7 years. I loved that thing. Early 2004 X5's (including yours) have XDrive. A change to the standard all wheel drive of the pre-facelift. X Drive can put 100% of the engine power to the one wheel it senses with traction. The older ones were static 48/52.........

Not the case. Pre-facelift Xs were able to direct 100% of torque to front/rear axles and side to side using automatic brake activation. The XDrive just does this using the transfer case actuator to adjust fore/aft and still uses the brake actuation for side to side (just like pre-facelift).

Here's a good example of a pre-facelift transferring torque. You can see the X spinning front/rear/front/rear tires in search of grip......

BMW x5 summer tyres on snow - YouTube

[PropellerHead]

Originally Posted by TiAgX5

Not the case. Pre-facelift Xs were able to direct 100% of torque to front/rear axles and side to side using automatic brake activation.

I'd like your source on that one. Everything I have seen including my experience with a 2001 X5 since new and the two Xdrive 2004's is different. If you're saying it's 100% of *available* torque, that would be correct, but the available TQ to front and rear is not 100% of the engine power in the earlier cars. The later cars transfer allows this.

Also, I am reading I had the earlier ratio incorrect. Still fixed, but fixed at 38/62.

The video shows an X5 with ZERO grip on all wheels. The later portion of the video shows that the other wheels are spinning at the same rate or close to it until the braking kicks in. This happened quite a bit on my '04 3.0 in the snow and would be expected in that case.

[bcredliner]

Originally Posted by PropellerHead

I'd like your source on that one. Everything I have seen including my experience with a 2001 X5 since new and the two Xdrive 2004's is different. If you're saying it's 100% of *available* torque, that would be correct, but the available TQ to front and rear is not 100% of the engine power in the earlier cars. The later cars transfer allows this.

Also, I am reading I had the earlier ratio incorrect. Still fixed, but fixed at 38/62.

The video shows an X5 with ZERO grip on all wheels. The later portion of the video shows that the other wheels are spinning at the same rate or close to it until the braking kicks in. This happened quite a bit on my '04 3.0 in the snow and would be expected in that case.

Are you talking about the loss of torque from the engine flywheel to the tires?

[TiAgX5]

Originally Posted by PropellerHead

I'd like your source on that one. Everything I have seen including my experience with a 2001 X5 since new and the two Xdrive 2004's is different. If you're saying it's 100% of *available* torque, that would be correct, but the available TQ to front and rear is not 100% of the engine power in the earlier cars. The later cars transfer allows this.

Also, I am reading I had the earlier ratio incorrect. Still fixed, but fixed at 38/62.

The video shows an X5 with ZERO grip on all wheels. The later portion of the video shows that the other wheels are spinning at the same rate or close to it until the braking kicks in. This happened quite a bit on my '04 3.0 in the snow and would be expected in that case.

The TC torque split on pre-facelift was 38%f/62%r while driving without tire slippage. When slippage was detected the brakes on the slipping wheels were activated automatically which transferred torque to the wheels with grip. Not sure of the absolute limit BMW programmed into the system.

[bcredliner]

Originally Posted by TiAgX5

The TC torque split on pre-facelift was 38%f/62%r while driving without tire slippage. When slippage was detected the brakes on the slipping wheels were activated automatically which transferred torque to the wheels with grip. Not sure of the absolute limit BMW programmed into the system.

I don't know the absolute % either and don't why it would be less than 100% at the wheels that aren't spinning.

[TiAgX5]

Originally Posted by bcredliner

I don't know the absolute % either and don't why it would be less than 100% at the wheels that aren't spinning.

I don't see why seeing how all modern cars/trucks are required to have braking systems that can overcome the max torque produced by their powerplants.

[PropellerHead]

Originally Posted by TiAgX5

I don't see why seeing how all modern cars/trucks are required to have braking systems that can overcome the max torque produced by their powerplants.

Because it was based on the the legacy AWD system that had been in use since the early iX cars from the 80's. On the early X5's, this is a planetary gearing that fixes the amount of TQ/power to the front or rear axle. In the early X's- 38 Front:62 Rear. Front rear power/TQ transfer is not programmed at all in the early X5's. It's fixed by the gears.

Xdrive uses a multiplate clutch system on the output side of the transmission that allows the system to modulate/vary the amount of TQ between the front and rear axles. XDrive computer control is able to activate this clutch within something like 1/10 of a second for up to 100% to the front or rear axle. The drive is normally split at 40F:60R for XDrive cars.

It is a significant difference from the early/non facelift cars. XDrive is one of the main reasons I bought one in 2004.

[TiAgX5]

Originally Posted by PropellerHead

Because it was based on the the legacy AWD system that had been in use since the early iX cars from the 80's. On the early X5's, this is a planetary gearing that fixes the amount of TQ/power to the front or rear axle. In the early X's- 38 Front:62 Rear. Front rear power/TQ transfer is not programmed at all in the early X5's. It's fixed by the gears.

Xdrive uses a multiplate clutch system on the output side of the transmission that allows the system to modulate/vary the amount of TQ between the front and rear axles. XDrive computer control is able to activate this clutch within something like 1/10 of a second for up to 100% to the front or rear axle. The drive is normally split at 40F:60R for XDrive cars.

It is a significant difference from the early/non facelift cars. XDrive is one of the main reasons I bought one in 2004.

The torque split is fixed by the gearing UNTIL brake actuation causes the torque to the slipping axle to TRANSFER to the non-slipping axle.

Well aware of how Xdrive works.

You mentioned prior that Xdrive transfers 100% torque to any ONE wheel, how do you think it does that when there are NO actuators or clutch packs in the front or rear diffs.........may be brake actuation? Carried over from the pre-facelift E53?

[PropellerHead]

Originally Posted by TiAgX5

The torque split is fixed by the gearing UNTIL brake actuation causes the torque to the slipping axle to TRANSFER to the non-slipping axle.

Well aware of how Xdrive works.

You may be, but appear not to be aware of how a non XDrive/prefacelift AWD system works:

Originally Posted by TiAgX5

Not the case. Pre-facelift Xs were able to direct 100% of torque to front/rear axles and side to side using automatic brake activation.

This just isn't true. It should read "Pre-facelift Xs were able to direct fixed power of 38% to the front and 62% of engine power to the respective axle." You might have then offered that DSC/braking allows this transfer from side to side, but the ratio is the main thing that you have wrong.

I don't have any issue with how this happens- DSC enabled. Never said any different. What I said was that the face lift models with XDrive offer this up to 100% of available TQ to either axle. Pre-face lift X's do not. Plain and simple.

Here is a source from BMW that explains the difference. Pay attention to the 2nd and last paragraphs. The differences in the systems are clearly not what you think they are:

[TiAgX5]

Originally Posted by PropellerHead

You may be, but appear not to be aware of how a non XDrive/prefacelift AWD system works:This just isn't true. It should read "Pre-facelift Xs were able to direct power to 38% to the front or 62% to the axles."

I don't have any issue with how this happens- DSC enabled. Never said any different. What I said was that the face lift models with XDrive offer this up to 100%. Pre-face lift X's do not. Plain and simple.

Here is a source from BMW that explains the difference. Pay attention to the 2nd and last paragraphs. The differences in the systems are clearly not what you think they are:

When the DSC/traction control activates the brakes on a slipping axle where do you think that axles disrupted torque go? The other axle by chance? If you don't think that's the case you don't understand the basics of driveline dynamics.