Thanks all for the advice and i have solved it!
Scotty was right about the seal groves, they were filthy, so i cleaned it all and changed the seals, put it all back together. While i was bleeding the brakes the bleed valve broke away from the caliper!! so i had to repair my original caliper enough to be able to put the pistons back in so i had to go through the whole process again! what a nightmare but i sorted it and now works great... took it for a test ride and reached 60mph!! scared me ****less lol. thanks again to you all.
Dave.
