If the front shaft turns slower then the rear, how does it transfer power to the rear wheels ? it is a viscous coupling unit. To transfer power it needs to slip. The faster rotating side will send power to the slower side. Do you mean that with all tires the same size,there is a power transfer...

let me think a little bit... Freelander transmission uses a viscus coupling unit to put power in the rear wheels. to have power is needed an certain amount of difference in the rotation speed between the" front" and the "rear" shaft. with 4 equal tires LR as set this speed difference. Front...

good point. I'm stuck on that one for some time...