I've been wandering the web and think i may have found a source of small rear brakes for our cars.

Ford Ka's use 180mm drums (or 7". I've not yet got my hands on a pair to see if they'd fit a live axle but the four mounting bolts look identical to my 9" rear drums. Could be an easy way of saving some weight & making sure you can easily get parts for a while.

Does anyone know if this is a barking idea?

8" drums as per 1100 escort are as small you want to go.

Ka has a much higher percentage of its weight over the front wheels and the rear brakess do practically nothing when braking.