[torsen] Re: Haldex differential

QSHIPQ at aol.com QSHIPQ at aol.com
Tue Nov 19 08:12:23 EST 2002

Keith and Dave:
You are both correct that a "locked up" haldex is *capable* of supporting 
100% of driveline torque.  As is a locked center.  Another terminology issue 
I suspect. 100% torque shift is theoretically possible for exactly the length 
of the wheelbase.  Not a commonly thought of in the context of any 
differentials (redefining a torsen to include 0torque?).  Torque allocation 
is commonly thought of more in the context of the ability to SHIFT, not the 
ability to support.  In the case of the haldex vc it can shift up to 45% of 
the available engine torque to the rear axle.  Another one for the SAE boys 
to figure out I suppose.

Keith.  IMU exactly that the current *device* is capable of being a full time 
awd system.  Not enough knowlege I'm afraid, to ask specifically *how* that 
is done, or whether that included full lockup all the time, tho I suspect, 
the pump and/or the throttle/relief valve (more likely) is capable of it.  I 
do know the conversation was in regards to what was *currently* in the TT 
haldex design.  I suspect the Gen II will likely reveal more of the details 
here.  A view of the Haldex technical page "control samples" would certainly 
indicate to me that 100% electronic control of lockup is possible (see 
offroad switch comment).  That would aslo indicate to me GenI is quite 
capable of this mode, however it's accomplished.

Dave, wrt your torsen differential applications, the family album doesn't 
support your contention, nor does Zexel, but then again, it doesn't support 
audis own that the S4tt or the RS4 have  different bias raitos than the 
standard ur-s cars either.  Remember too, that the T1 in the "old" 
configuration is NLA.


Scott Justusson

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