I found this video fascinating:

I imagine the Yeti should be capable of doing as much as the Passat. Though I suspect it being a 2007 Passat it will only have the Haldex 2 system where the Yeti has Haldex 4.

Interesting how the Honda CR-V was completely incapable of transfering ANY power to its rear wheels!!! What is the point of having a 4x4 if it can't even transfer power to where it is needed? Though in saying that the same happened to the Toyota.

Thats a good find

I found this video fascinating:

I imagine the Yeti should be capable of doing as much as the Passat. Though I suspect it being a 2007 Passat it will only have the Haldex 2 system where the Yeti has Haldex 4.

Interesting how the Honda CR-V was completely incapable of transfering ANY power to its rear wheels!!! What is the point of having a 4x4 if it can't even transfer power to where it is needed? Though in saying that the same happened to the Toyota.

I do not know anything about the specific Honda, but the behavior is typical of a purely mechanical 4WD lay-out with a non-locking transfer case (diffentíal) and two non-locking axle differentials. If just one wheel spins, the torque on the other three is exactly the same as the spinning wheel can transmit. As long as NO wheels are spinning, performance is better than 2WD only because the torque on each wheel is half of the 2WD. Once a wheel spins all the advantages are gone.

I assume that the Passat, like the Yeti, does NOT have a transfer case or center differential. The output to the front and rear axles are always tied together. In normal dry conditions, the front wheels drive and the Haldex coupling is open, transferring only the power to the rear, which is caused by internal friction in the open Haldex. For the Yeti, most situations are rather clear to me - except one. Loose traction on one rear, and the rear axled Haldex differential lock ties the rear axle halves together and rotates both rear wheels at the same torque. If there is no traction on the front axle, the torque is transferred to the rear - and the front wheels should rotate at the same speed as the rear with traction. The question comes if only one front wheel has traction and the other three not. If the electronics are smart enough to brake the spinning front wheel, then all is well and the car would transfer the torque to the other front wheel. If not, then the same would happen as happened to the Passat in the video.

My guess is that the Yeti is smart enough and does the right thing.

Incidentally, this has nothing to do with the Haldex, which only works on the rear axle.

Edited 20 April, 201016 yr by Agerbundsen

Yes, you are correct, and the electronics should lock the brakes on the spinning wheel within about 1/8th of a revolution.

I remember when the Freelander first came out seeing one having three of it's wheels on skates with free running rollers, leaving one wheel on the tarmac ......and it still would drive along.

New here is an interesting twist on the video above. It is clear in the first video that the VAG Haldex system was vastly superior to the other systems. Now BMW did this at a press event:

From this website: http://carscoop.blogspot.com/2010/10/video-bmw-x3-vs-audi-a5-in-all-wheel.html?

Can anyone explain why that happened?

New here is an interesting twist on the video above. It is clear in the first video that the VAG Haldex system was vastly superior to the other systems. Now BMW did this at a press event:

From this website: http://carscoop.blog...-all-wheel.html?

Can anyone explain why that happened?

My BMW 525iX had permanent 4wd; 40% front 60% rear, so I suspect similar here. Regard the Quattro if it is running a Haldex system then I :wonder: if it's transferred most of the drive to the rear due to the angle creating a weight off nose signal, therefore the fronts arn't helping much. Other option is BMW have 'spiked' it for the demo

Regards,

TP

I sense a stitch up. It just doesn't look right. Call me a cynic.............

Something just doesn't look right with the Audi response, and from experience of the BMW's and grass fields, they aren't normally that effective. I towed a few with my old Freelander, much to their embarassment!

New here is an interesting twist on the video above. It is clear in the first video that the VAG Haldex system was vastly superior to the other systems. Now BMW did this at a press event:

From this website: http://carscoop.blogspot.com/2010/10/video-bmw-x3-vs-audi-a5-in-all-wheel.html?

Can anyone explain why that happened?

The Audi does not have a Haldex system, but Torsen differentials on each axle. Not sure about the rest, but there is probably a center differential, so if one axlespins, the torque on the other is limited to the torque of the spinning axle.

The Yeti does not have a center differential, but a fixed power take-off from the gearbox to the rear axle with the Haldex clutch in between and a similar Haldex clutch betwen the two parts of the rear axle. Spin the front axle and the Haldex closes and both axles are driven equally - The ESP brakes the front axle and the torque is diverted to the rear - so all wheels rotatated at more or less the same speed.

Edited 28 October, 201015 yr by Agerbundsen

Fascinating thread, thanks - and what knowledge there is here...