Well I'm calling this case closed!!.. after pulling the master cylinder off and screwing the adjusting blot in to give abit of clearance between the piston and master cylinder valve. literally a 5 minute job.. it makes sense as it seems to me that the brakes were dragging from the begining, and going for a trip to sydney the other day I had a interesting thing happen, I had the brake pedal go to the floor when trying to brake after cruising for awhile, after pulling over thinking that maybe there was air in the system or sumthing, (thought I may of been leaking fluid) I checked the fluid, all good, and then I noticed that the right rear wheel was smoking, hence confirming that the brakes were indeed dragging.. so when I got home I did the above^ and it's been a few good drives now and no random shuddering, so fingerz crossed!