[V8] 4.2 V8Q at Winter Driving School

[Buchholz, Steven]

... to be clear, while the automatic V8 center diff is computer
controlled, it is still a switch ... i.e. the diff is either open or
locked ... there is no sort of variable torque split or lock up mode a
la Porsche 959 ... at one point I had misunderstood this to be the case
...

It is also my understanding that the tranny ECU simply gets the speed
signals from the ABS sensors to determine whether the center diff should
be locked or not.  I thought it was apparent from the wiring diagram,
but I just checked and found that there were four separate wires going
from the ABS ECU to the Tranny ECU ... it must have been something I
read somewhere else ... 

Steve B
San Jose, CA (USA)
> 
> Does that signal cause variable locking up?   Full lock in 
> ABS failure is
> not variable, right?  The former would be a more "sensitive" 
> application
> while the latter would be directly mechanical?
> 
> At 05:50 PM 2/7/2005 -0600, Tony and Lillie wrote:
> >
> >>
> >> Generation III (1990-94 Audi V8):
> >> Open front differential; Planetary gear center with
> >> electronically-controlled multi-plate locking clutch
> >> (Torsen center differential with manual-transmission);
> >> Torsen rear differential.
> >>
> >
> >Yes, and what that means is, it relies on a difference in 
> speed from the ABS 
> >sensors in order to lock up. From my experience, if the ABS 
> >doesn't work, it will remain locked.