Can someone confirm that my basic idea of Haldex clutch operation is correct ?

 

The clutch pack "slips" in normal ( e.g. cruising ) driving.

 

If this is correct, is this the reason that the Haldex clutch needs oil and filter changing or screen cleaning periodically, because the slipping plates in the clutch are continuously generating fine debris off the sliding surfaces ?

 

Have I got this right ? 

 

Thanks. 

 

 

Yes they are not engaged but there is no significant slippage when driving straight and if the front and rear tyres are of equal diameters.

 

And yes, if driven really hard so the 4wd is solicited then there is far less oil contamination which is the opposite of recieved wisdom.

Thanks JR,

 

So is it correct to say that when the Haldex clutch is fully "locked up" ( i.e. transmitting max. torque to the rear wheels ), there is little oil contamination because the clutch plates are not moving relative to each other ? 

 

In my reading, someone likened part of the Haldex clutch to a motorcycle wet clutch and the latter definitely contaminates the oil when the fibre plates and steel plates move relative to each another i.e. slip

 

Also do you know any web-site that explains how the Haldex works ? Surprisingly difficult to find any details on this  !

 

 

  

 

Edited 20 January, 20242 yr by gumdrop

Thanks gumdrop. The whole concept ( Haldex solution to AWD ) is brilliantly simple but the deeper you try to understand how specific components work, the more you realise how much engineering expertise you need. That first video you linked gave me a major breakthrough in understanding how the clutch plates engage and disengage. 👍

 

The next best thing to having one in front of you on your bench ! Now I see where the metal powder comes from and why you have to regularly service these units. It looks like mine has never been done going by service records. ( 130 000 km ). Hope that's not going to be an issue for me...Also I wonder if this "non-rebuildable/ lifetime part" claim is a German car thing. Certainly helps the throwaway car mentality and VW's bottom line.

Interesting video, the owner of the vehicle that the Haldex came from got shafted for a complete new unit, $3500 plus fitting when there was absolutely nothing wrong with the old one, possibly the motor or pump but that is all, the clutch pack was fine, small embedded particles like that are completely normal.