The S197s e-brake is not like the old drum e-brakes.
Its a caliper piston that screws out like a coke bottle lid
that presses on the brake disc. Thats why the e-brake
does not work like you expect it to work.
You will never impose the same pressures on the rear
disc brake pads with a screw lever/cable arrangement
as you can with the hydraulic master/slave cylinder set-up
the brake system uses. The parking brake for parking and
holding static loads, not stopping dynamic loads.
Its not intended for power slides and such.
In fact, Ford renamed it from the e-brake to the parking brake.
Check the owners manual and see.....
No more using it in an emergency to stop but to hold
the vehicle still once stopped and parked.
It was a legallity thing.....
It will soon gall up and get stuck and then where will you be?
A needin some new rear calipers and rotors....

Get some HP to do that and let the rear brakes alone.
If you are made $$, go buy something that has drums on
the rear for that power sliding fun.