This AWD dyno thing, goes right back to, why the US version is different to the European version.
When the SVX was designed, it was the European version that was the preferred one. Constant AWD through geared shafts.
Unfortunately the US technology wasn't up to the standard that the car was designed to use. AWD dynos didn't exist. This caused a major rethink and the US AWD version was built to allow the car to run on a two wheel drive dyno by inserting the FWD fuse to disconnect the rear drive.
This will allow the car to run only on a two wheel dyno. If the car is run on a 4WD dyno or uncoupled rollers, with the fuse in, and the front, rear rollers, are not coupled the near wheels will not be driven, this will cause the center transfer clutch to have maximum speed difference, the driven plates will run at front wheel speed, the driven plates are stationary along with the rear wheels.
If it is run on the same 4WD dyno without fitting the FWD fuse. The TCU will detect the speed difference and will constantly attempt to bring them to the same speed. The delayed action of transfer clutch accelerating the rear wheels up to speed, checking rotation and accelerating again produces a surging effect that wants to spit the car off the rollers.
If the 4WD dyno rollers are coupled but there is some play between the rollers, the same effect will happen due to the difference in the wheel speed.
The European version, would do the same thing on a loosely coupled dyno or drum rollers, but it has the DIFF LOCK fuse that locks front and rear wheels together to prevent surging.
The end result is the US version should only be run on a two wheel dyno or drum rollers with the FWD fuse in place. The rear wheels should not be driven or allowed to be driven on the test they should be stationary, and the test should only be for a minimum time.
The European version should only be run on a 4WD dyno with the DIFF LOCK fuse in place.
Harvey.
