Torsen AWD Vs Haldex AWD/XWD

[ds.raikkonen]

After having a look at the cars with a haldex clutch operated AWD system or a Torsen differential AWD:
a) Haldex clutch seems to be used in cars with utility in mind i.e. with front transverse mounted engines and transfer little torque to the rear wheels.
b) SAAB's Haldex Cross Wheel Drive does the above and can transfer 100% torque to the rear wheels, even shift between them when the situation demands.
c) Torque sensing center differential transfers torque between the front and rear differentials, which in turn split the torque between the two wheels. Locking can be done to fix the power going to all 4 wheels. And it is used in cars with longitudinally placed engines i.e. mostly performance saloons and SUVs etc.
Kindly point out any errors in the above three statements and add more info, if necessary. Which one of these is the most efficient system for an AWD car, considering the performance, packaging, engine layout, weight and the required torque split? Actually my sister is deciding between a Toyota Fortuner, which has a Torsen LSD and the VW Tiguan, which has the Haldex clutch system.

[strad]

I don't know about the Haldex but the Torsen is great and seamless.

[mike]

https://sites.google.com/site/awdand4wd/

hope that helps

[strad]

Like I said,

[ds.raikkonen]

Like I said,

You were right mate, but I needed some data, which was not readily available on the net
However, we have decided to go for the Skoda Yeti, which has the Haldex clutch operated on-demand AWD system

[strad]

I'm sure it will probably do everything you need. Just don't expect miracles

[ds.raikkonen]

Yeah, we re not getting it for serious off-road stuff or anything. Perhaps a hill there or a puddle there. The system is really good, it drives really well, you can't feel the torque shifting underneath. Although very little torque goes to the rear wheels. The grip is good from the front wheels, thanks to the weight of both the engine and the gearbox! Feels a bit heavy around corners, but the turbo-lag is acceptable.

[strad]

Well then...Enjoy and happy motoring

[mx_tifoso]

Yeah, we re not getting it for serious off-road stuff or anything. Perhaps a hill there or a puddle there. ...

In that case, why not just get a 2WD vehicle and put on some proper tyres? I've done miracles with just rear wheel drive and good all terrain tyres through snow, ice, mud, etc. Especially if said vehicle spends the majority of it's life on-road, 2WD will be more efficient and troublesome over in the long run. Imo.

[PhillipM]

I regularly take a 2wd car places many can't get in 4wd, just takes the right tyres!

[strad]

and driver

[Pierce89]

My 4wd Toyota Tacoma will go places no 2wd could dream of. Of course, it does have off-road tires and an electrically locking rear differential. But, it, has a traditional lever operated, gear driven transfer case(for those that don't know a transfer case is a combination of center diff and extra gear reduction together in the same box)

[autogyro]

Transfer box should also contain central diff lock if it is a proper off road vehicle for heavy use.
In 1976 I drove my converted Range Rover across the Sahara in four and a half days.
That had a manual cable operated front diff locker and a Salisbury plate rear diff as well as the conventional central diff lock transfer box with a strait cut very low bottom ratio.
It had a hand throttle and in deep sand up to the axles and half way up the wheels (forward control land rover with XXY Michelin tyres with multi steel chord side walls) the vehicle could be driven at two miles an hour walking alongside it using the hand throttle. The tyres were narrow and the side walls heat capable, they were not wide mud pluggers for little lanes and farm yards in Europe. Those tyres would burst in the Sahara every five miles or so as the side walls overheated.
Far to much has been evangelised over four wheeled drive being better off road than two wheeled drive.
In soft sand a two wheeled drive beach buggy with baloon tyres and no transmission locks is far better if the weight can be kept low.
It is horses for courses and most said about it is BS from those who have never been off road in anger.
I have never found any reason to use 4x4 in the UK for ordinary driving and it makes me mad seeing little women driving huge blobby 4x4s to school every day wasting energy and resources for absolutely no reason other than for the ego of their macho chav other halves and the pockets of the car salesmen that conned them. I also find blobby 'blocks of flats hugely ugly.

[aussiegman]

I don't know about the Haldex but the Torsen is great and seamless.

Torsen does have issues with slip where very low to zero load occurs on one drive wheel. During this they act basically as an open diff, sending sending all torque to the one lifted wheel. As such they require a degree of resistance (traction) to work effectively to enable them to see a torque bias across the driven wheels and distribute torque accordingly.

That is where a locked diff, Haldex or plate diff works much better as it does not require both wheel have load (traction) to provide drive. One wheel can have large slip values such as where one is lifted off the road surface into the air or there is on a very low friction surface (ice, mud, water, oil, dirt etc).

There is a hybrid diff from Wavetrac diffs that are a modified Torsen unit which uses a ramped friction surface to overcome the traditional Torsen short comings by engaging when there is a drive substantial differential between the driven wheels.

[strad]

grazie