RE: Controlling torque v Marketing

[QSHIPQ@aol.com]

Dave E writes:

>there are at least 3 complete contradictions in this paragraph.

>please explain how a differential that can physically transfer 100% of
>torque to either axle (which you now seem to accept the haldex can do), is
>also not capable of controlling torque "beyond 50% rear"??????

Let's take a virtual drive.  Car 1:  959 with PSK, Car 2:  audi quattro with 
Haldex.

Car 1 (awd) diff computer takes input, decides that 60/40 r/f split is 
optimal for the current turning of the vehicle.  Computer can adjust this 
split thru all aspects of the turn (traction, slip angles, g sensors, yaw and 
rate)

Car 2 (4wd) diff takes computer input, decides that 60/40 r/f split is 
optimal for the current turning of the vehicle.  Computer CAN'T adjust or 
maintain this split at all, because anything over 50% of rear split can't be 
controlled by the computer.  

Remember, a fixed 50f/50r split is possible in both vehicles.

>please explain how, if "100% of available trg can be at either axle....it
>has nothing to do with the differential"????

Dave, it's not accepted practice to put one set of wheels on ice the other on 
pavement to make the above claim.  That isn't differential control, that is 
the nature of all LSD devices in "extreme" conditions.  The (marketing) 
definition of "extreme," is exactly the length of the wheelbase.

>with regards to the toyota *wrc* rally car (not the group 'a' car), you
>clearly have difficulty with the published spec of the car which, as
>"racecar engineering" states (see V7 #6, 1997, and v8 #10 1998), was sans
>centre differential and used a haldex-like clutch on the rear axle instead
>of a true centre diff.  par for the course.  i guess that the fact that the
>car won a number of rallies in this configuration is a little inconvenient
>for the haldex nay-sayers.

Hardly, you just got a point in time report.  I think if you look at what 
Toyota did to get to that point in time, you would realize that the early 
development is a little different than what RCE "states".  Toyota deserves a 
bunch of credit for what they did, in development and applicatoin.  Saying 
the part time Haldex is the "same" as Toyota, IMO, is no further from me 
calling the Haldex "Syncro Deux."  In fact, since the Toyota doesn't have ABS 
or EDL to worry about...

Following your S3 report, I'm very interested to see how your reported LTO 
fairs in very low cf high performance turning situations (enter left foot 
braking, abs, and edl into the Haldex traction equation)  My bet is that SII 
(tm) might be a closer comparo than WRC.  Steamboat should prove interesting 
next year.

HTH

Scott Justusson