Shimming an R200 or J30 vlsd

[feito]

15 years later and im still trying to understand this mod.
what is it about this mod that makes the viscous pack engage sooner and more agressive? is it the extra heat produced by the inappropriate backlash at the spider gears that confuses the viscous pack into thinking the wheels are spining?
Are the gears just binding together from the lack of clearance locking both wheels?
Ive opened vlsd's before and I just dont get how/why this works. The sealed viscous pack shouldnt react unless both of its ends spin in different directions creating friction.