Have you adjusted the girling's rod lengths correctly
Do a search on here for brake bias set-up when I first set mine then had issues on track at the Clubstylus Llandow trackday . Then having done that , turn the bias bar screw all the way towards the front braking cylinder --- then back 2 or 3 complete turns of the threaded bias bar (I put a tipex blob on the thread to be sure of complete turns) -- drive to check then adjust to suit the balance you want , maybe more to the rear on wet roads , less in the dry etc.
I can't remember exactly how much in mm's slack I actually set the rods , hence telling you to search
Another point is to have the '' bar '' a little slack each side of the centre tube or you'll have problems too.