My car violently shakes at anything over 70, about 40 it makes a quiet whirring sound like a wheel bearing and at 70 you get a slight steering wheel wobble, but anything over 70 the whole car shakes really badly........but strangely when you dip the clutch it stops it only happens when there's power going through it, so far I've had the wheels balanced and changed the propshaft as I thought it could have been the bearing in the prop.

Any idea's before I dig further?

 

I would check the whole front subframe for signs of damage or rot, wishbone mounting points aswell. Check front drive shafts for excessive movement

 

spigot rings or inner cv collapsed-both can cause serious vibration.

 

+ 1 on the inner cv joint....had this on a forester

 

Defo feels like it's rear end related