OK so fitted some new wheels which required spacers, but only had 2. So I fitted the new alloys to the front with 20mm spacers and left the back as standard.
Now the DCCD bangs and crunches if its set to anything but to the rear, and once set completely to the front it sounds like calipers rubbing.

 

Different rolling radius, Same size front and rear?

 

To be honest I'm not 100% but as the standard wheels fitted over 4 pots, and the new don't then I'd say no. But the spacers are 20mm, meaning the front is now 40mm wider.
Would it really have an affect on the DCCD?

 

Possibly but what i was getting at is are they the same size wheel EG 17" with a 40 or whatever profile front and rear(same rolling radius) as if they are not and one of them is turning more than the other could explain it?

 

Ah I think you've hit the nail on the head. Both are only 16" but the rears are 45 profile whilst i think the fronts are now 50

 

Change them back or dont drive it like that mate you`ll trash your box or diff.

 

Thought you would of known that kWIK.

 

You learn something new every day!