and more 4wd question
 

finally got to take my SVX out on the highway for a drive and just have a querry. I was travelling at 115kph, @2500rpm with cruise control engaged and no problems at all except that after reaching (going up) a slight and main incline the moment the car was over the crest, leveling out or just beginning to go down you could feel 'a shunt' is the best was to describe it. At first I thought it was the cruise control but to increase and deacrease the speed was all good. The rpm stayed steady at all times, no hunting or changing of gears - but just seams like when the car goes to reduce power 'cause it is no longer climbing the hills something is thumping back or is there a power/load shift from the rear to the front?
Of note is that when the car goes from the bottom of a decline (cruise/low power) and starts to climb it is flawless.
Any ideas or similar experiences?

Relax - my SVX does exactly the same thing!

It is the only disadvantage of having the VTD AWD system, rather than the Transfer Clutch system that the US models use.

The VTD system uses a mechanical centre differential, in the form of a planetary gearset. As a result, the slight amount of gear backlash in the differential causes that slight shunt.

I find that it is most apparent when travelling up or down a steep hill, with the transmission in "3" or "2", while releasing and re-applying the throttle.

This alternates between the engine driving the transmission, and vice versa, thereby causing the gear backlash to alternate from one side of the gear teeth to the other.

It is much less apparent in 4th, since no engine braking is available in this gear, and when the throttle is released, the transmission "disconnects" from the engine. The exception to this is if 4th is engaged, and the torque converter lock-up clutch is active.

Jason.