Difference between Torsen and Haldex Diff?

[karlblues2]

Hi guys
I've had a search and can't find it. On one of the forums down here I've been asked the difference between the torsen diff used in the S2 and the Haldex type used in later S3 and the like.
Therefore can anyone point me in the right direction as I recall reading something about that comparison on here last year I think
Also does anyone know when Audi stopped using the Torsen diff and went onto the Haldex system and why?
Cheers
Karl
Oz

[GandalfS6]

Audi has not stopped using Torsen! The Torsen system is far superior to Haldex (having driven both) but is heavier and more bulky. For that reason, Audi uses Haldex in the A3 and the TT. The A4, A6 and A8 all uses Torsen.

You can find out more on Haldex at http://www.haldex-traction.com/default.htm.

[karlblues2]

Audi has not stopped using Torsen! The Torsen system is far superior to Haldex (having driven both) but is heavier and more bulky. For that reason, Audi uses Haldex in the A3 and the TT. The A4, A6 and A8 all uses Torsen.

You can find out more on Haldex at http://www.haldex-traction.com/default.htm.

Cheers for that.
I just found an interesting thread on the VWvortex forum where they suggest that Audi / VW may be moving away from Torsen to Haldex (b6 Passat). Not sure if it's true or that I read it right
http://forums.vwvortex.com/zerothread?id=1732646
Thoughts appreciated
Cheers
Karl

[Lee]

Haldex is a 4wd system and Torsen is a type of torque biasing differential.

Haldex's solution is suited to transverse layouts and it means a relatively easy conversion for the manufacturers to get 4wd from a normally fwd config. That is why Volvo use it too. Haldex is reportedly designed to handle 1000Nm but I would never want all those ****** electronics fecking about with the power delivery making the car behave totally differently all the time. Gimme a good old all-mechanical 4wd system any day.

Sorry can't be any more helpful on links as I don't have any.

[Lee]

Packaging will force Audi to move to fully haldex. Gives more space in the cabin area.

[s2driveruk]

IIRC haldex is also a part time 4wd system, i.e. in normal conditions its running front wheels only and engages the rears only when certain parameters are met..

[karlblues2]

IIRC haldex is also a part time 4wd system, i.e. in normal conditions its running front wheels only and engages the rears only when certain parameters are met..

I thinks its actually 95%/5% split front to rear that allegedly engages and increases within 20degree rotation of detection of slippage.
Personally, I much prefer the stable , know what its doing, mechanical full time 4wd torsen....But I'm old fashioned
Cheers
Karl

[S2central.net]

And Porsche use/used Haldex with heavy bias to rear on 911 4WD variants. It was setup that when drivers got into trouble, that it invoked more torque at the front !


Paul

[The Spanish]

And Porsche use/used Haldex with heavy bias to rear on 911 4WD variants. It was setup that when drivers got into trouble, that it invoked more torque at the front !


Paul

Rally Cars use a Torsen type Center Diff (usually). Wich I like because they are permanent 4WD.

Personally a dislike FWD cars and Haldex how is use in VAG is like having a FWD car with electronics to transfer power to the rear.

I wouldn't mind if Audi used Haldex on all cars but with this Layout:
- Engine longitidinal mounted behind front axel.
- RWD chasis
- 100% power to the rear with a Haldex in the middle/back that could shift power to the front.

Similar to a Nissan Skyline.

Audi did make an agreement with Masserati for the Chasis of the Quattroporte that is a mid front engine layout and the GearBox at the rear so maybe they are thinking about it.

[ottawa coupe]

While i certainly don't know all the ins and outs of the 2 systems, this is what the local dealer told me. there's an outdoor spot that is elevated to showoff a car if you so desire. the approach is a fairly steep one. basically he told me he could get the A4 up there but not the TT.

the way i rationalize things is that the torsen sytem is always "on" providing significant (alot more than 5%) to all wheels and will instantly and seamlessly transfer power to those that can take it whereas the haldex will only take action AFTER a problem is dectected. i suppose they'd have to increas the resiloution on the control loop to improve the ability to something close to that of the torsen system.

regardless, at the moment, the torsen systems are used on longitudinal mounted drivetrains and haldex on transverse. unfortunatly, if the dealer is to be believed, that will change all too soon. my guess is the next generation A6 or 8 (which is the next one out?!)

[S2central.net]

Rally Cars use a Torsen type Center Diff (usually). Wich I like because they are permanent 4WD.

Most modern WRC cars have very sophisticated electro-hydraulic differentials - front, centre and rear....

But the UR quattro was ALWAYS rallied with a locked centre diff - NOT a Torsen.

Pretty sure I have an old book that talks about use of Torsen diffs front and rear on the rallied UR, but the centre was ALWAYS locked for 50:50 front:rear torque split. Simple reason being it was the easiest to drive on the limit with predictable handling etc etc


Paul

[NoNonsense]

Most modern WRC cars have very sophisticated electro-hydraulic differentials - front, centre and rear....

But the UR quattro was ALWAYS rallied with a locked centre diff - NOT a Torsen.

Pretty sure I have an old book that talks about use of Torsen diffs front and rear on the rallied UR, but the centre was ALWAYS locked for 50:50 front:rear torque split. Simple reason being it was the easiest to drive on the limit with predictable handling etc etc


Paul

A shop I am close with here has a retired S1 rally car, and it's center diff is welded closed...there's no give at all...we've rolled it around the shop before and once you start to turn the steering wheel, it's impossible to push!

[The Spanish]

Most modern WRC cars have very sophisticated electro-hydraulic differentials - front, centre and rear....

But the UR quattro was ALWAYS rallied with a locked centre diff - NOT a Torsen.

Pretty sure I have an old book that talks about use of Torsen diffs front and rear on the rallied UR, but the centre was ALWAYS locked for 50:50 front:rear torque split. Simple reason being it was the easiest to drive on the limit with predictable handling etc etc


Paul

I did not explain me right. By Torsen Type Diff I did not mean just "Torsen" but any differential that is always providing power to both axel and depending of circustances it shifts more to the front or rear depending of the situation. (I just don't know how to call them)

My point was that I prefer permanent 4wd (variable) than any haldex with 100% front usually and then when problem occurs shifting away torque to the back.

BUT FOR TARMAC USE (road and track) a Haldex system with 100% rear and shifting forward when neccesary will have many advantages. The main being weight reducing and the possibility to mount the engine behind the front axel, helping weight distribution.

We have all heard that probably Haldex will be the way forward. But with the Masserati platform rights Audi has acquire maybe in the future that system will be base on a RWD chasis with 4WD and not the FWD chasis Audi is using now.

[Graham]

Here is the site which explains the difference between them and why our is no longer used (Too expensive)

[porkkis]

How come not used?

Torsen is used on the following current models: A4 A6 A8 Allroad Passat Phaeton