I'm afraid mate that if you don't know what a VCU is, then its doubtful whether you should be trying to maintain your Freelander.
It is the starting point of knowing how your car works. You need to read up on it - it won't take you long to find out how it, and the transmission in general on Freelander works. Just Google it. There is no center diff on Freelander - so it is not permanent 4WD - but its not switchable 2 to 4WD either. It is essentially a front wheel drive design with a direct geared PTO (power take off) from the front diff (IRD) that drives a prop shaft to the back axle - essentially locked in 4WD. As that would destroy the transmission before the car got to the dealer's forecourt, the prop shaft is split in 2 and there is a Viscous Coupling Unit (VCU) separating them. It enables slippage between the front and rear axles but will still transfer a level of torque to the back axle that will 'lock up' should the amount of slippage be greater than expected in normal driving conditions - ie the (front) wheels have lost grip and are spinning.
This may or may not be anything to do with your car's problems - but it is important for you to know if you are maintaining a Freelander. Problems with mismatched tyres mean that axles turn at differing rates than is 'expected' - so the axles lock up - the VCU will become 'to tight' over time also meaning the axles lock up. In any 4WD that spells disaster for the vehicle.
