Here's an intriguing problem.
In normal use, the brakes on my TD Cortina operate perfectly satisfactorily.
However,
When the car is used in reverse and the brakes applied, more often then not the pedal sinks nearly to the floor and there is very little to no braking effect.
After rapidly pressing the pedal approximately five times there is pressure again.
This can be very disconcerting when reverse parking, etc....
It's a 1974 Cortina with a mileage of 55 000 km's.
The car is fitted with the original booster, but the previous owner has fitted an oversize disc & caliper upgrade. The original rear drums are there with good shoes fitted.

Has anyone else experienced this problem? And can anyone shed some light on an answer?

Are the brake shoes adjusted properly????? are the shoes fitted correctly ( leading and trailling )?????