I have owned my Yeti  59 plate 170 diesel from new and done 60k.  Recently its developed a judder coming on at approx 60mph.  The vibration transmits through the body and steering and gets worse if speed is increased.  Had wheels balanced and re-checked, tyres checked with no result.  New discs and pads.   Power is unaffected.  My mechanic is at a loss to diagnose it and so am I !!!  Any suggestions will be gratefully received.  Thanks